JP2011033731A - Optical connector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical connector in which a built-in optical fiber and an inserted optical fiber are optically connected at a low loss even when the end face of the inserted optical fiber is not flat but irregular on the inserted optical fiber butted and connected to the built-in optical fiber which is inserted and fixed in a ferrule. <P>SOLUTION: The optical connector uses the built-in optical fiber 320 which has a structure in which a chamfered portion 32b is formed on the outer periphery of the back end of the body 32 of the built-in optical fiber which is inserted and fixed in the ferrule, and a refractive index matching material layer 321 made of an optically transparent high polymer material is provided on the back end face 32a of the body 32 of the built-in optical fiber. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an optical connector, and in particular, has an optical fiber (built-in optical fiber) inserted and fixed in a ferrule, and is inserted into a housing that houses the ferrule from the rear end side (inserted optical fiber). And an optical connector that is assembled (attached) to the distal end of an insertion optical fiber.

As an example of a so-called field assembly type optical connector that can be assembled to the tip of an optical fiber on site, a short optical fiber (bare optical fiber; hereinafter also referred to as a built-in optical fiber) that is inserted and fixed to a ferrule. Another optical fiber (for example, an optical fiber core wire; hereinafter also referred to as an insertion optical fiber) and the built-in optical fiber that are inserted into the housing that houses the ferrule from the rear end side thereof, 2. Description of the Related Art Conventionally, a structure that can be assembled at the tip of a fiber is known.
As this type of field-assembled optical connector (hereinafter also simply referred to as an optical connector), for example, a mechanical splice-type clamp portion is provided on the rear end side of the ferrule (the side opposite to the joining end surface for butting), A connection part in which the end part of the built-in optical fiber extending to the rear side of the ferrule and the insertion optical fiber is butted and connected is held and fixed by the clamp part to maintain the connection state between the optical fibers. (For example, Patent Document 1), the built-in optical fiber whose length is shorter than the fiber hole is inserted into the fiber hole, which is a fine hole formed in the ferrule, with its one end (tip) exposed at the joint end surface of the ferrule. The inserted optical fiber, which is fixed and inserted from the rear end side of the ferrule into the fiber hole, abuts the rear end of the built-in optical fiber in the fiber hole. Which is configured to be allowed access (for example, Patent Document 2) are known.
In addition, a liquid refractive index matching agent such as silicone-based grease is provided at a butt connection portion between the built-in optical fiber and the insertion optical fiber to reduce connection loss (for example, Patent Document 2).

  When assembling the optical connector at the tip of the insertion optical fiber, the bare optical fiber is removed by removing the coating from the tip of the insertion optical fiber, and the tip of the bare optical fiber is cut. The optical fiber is inserted into the housing from the rear end of the optical connector, and the bare optical fiber at the front end is abutted with the built-in optical fiber of the optical connector. The bare optical fiber cut is to adjust the lead length of the bare optical fiber to a desired length, and to form a flat mirror-like tip surface perpendicular to the optical axis of the bare optical fiber on the bare optical fiber, This is performed using a dedicated cleaver (cutting machine) capable of realizing this (for example, Patent Document 3).

As shown in FIG. 16 (a), the rear end surface 111 of the built-in optical fiber 110 of the field assembly optical connector (the end surface on the rear end opposite to the front end exposed at the joining end surface of the ferrule. The end surface is generally a flat surface perpendicular to the optical axis of the built-in optical fiber 110. In assembling the optical connector to the distal end of the insertion optical fiber, the flat rear end surface 111 of the built-in optical fiber 110 and the bare optical fiber 120 (hereinafter also referred to as an insertion-side bare optical fiber) led out to the distal end of the insertion optical fiber. The optical connection between the optical fibers is realized by abutment with the flat distal end surface 121). If the rear end surface 111 of the built-in optical fiber 110 and the front end surface 121 of the insertion-side bare optical fiber 120 are flat, the core portions 110a and 120a of the optical fibers 110 and 120 can be abutted with each other. The optical connection between each other can be reliably realized. In FIG. 16A, reference numeral 110b denotes a clad portion of the built-in optical fiber 110, and 120b denotes a clad portion of the insertion-side bare optical fiber 120.
FIG. 16A illustrates a configuration in which a refractive index matching agent 130 is provided at a connection portion between the built-in optical fiber 110 and the insertion-side bare optical fiber 120.

JP-A-10-206688 JP 2006-178105 A JP 2003-202425 A

By the way, in the assembly work of the above-mentioned field assembly type optical connector, the insertion-side bare optical fiber 120 cannot be accurately cut in the field, and a flat end face may not be obtained. In this case, as shown in FIG. 16 (b), due to the irregularities at the tip of the insertion-side bare optical fiber 120, there is a gap between the rear end surface 111 of the built-in optical fiber 110 and the tip of the insertion-side bare optical fiber 120 abutted against this. The gap 140 may be formed and connection loss may increase. In particular, if the gap 140 is formed between the core portions 110a and 120a (or the mode field diameter portion) of the optical fibers 110 and 120, the influence on the connection loss is increased.
Further, when the convex portion 122 formed on the outer periphery of the distal end surface of the insertion-side bare optical fiber 120 hits the edge portion of the outer periphery of the rear end surface of the built-in optical fiber 110, the convex portion 122 and / or the distal end of the insertion-side bare optical fiber 120 and / or Chipping may occur in the edge portion of the outer periphery of the rear end surface of the built-in optical fiber 110, which may cause deterioration of mechanical characteristics. In addition, there is a possibility that a fragment generated by the chipping is sandwiched between the built-in optical fiber 110 and the insertion-side bare optical fiber 120 and hinders the butt connection.

  FIG. 16B shows a case where the refractive index matching agent is not provided at the connection portion where the built-in optical fiber 110 and the insertion-side bare optical fiber 120 are abutted with each other. When an air gap is formed between the built-in optical fiber rear end surface 111 and the insertion-side bare optical fiber 120 tip due to the unevenness, the insertion-side bare optical fiber 120 is abutted against the built-in optical fiber 110 as shown in FIG. Even if a liquid refractive index matching agent 130 such as silicone grease is provided at the connection portion, the bubbles 150 are likely to remain between the rear end surface 111 of the built-in optical fiber 110 and the front end of the insertion-side bare optical fiber 120, and the connection loss increases. May end up.

  In view of the above-mentioned problems, the present invention inserts the built-in optical fiber into the built-in optical fiber even if the end surface of the inserted optical fiber that is butt-connected to the built-in optical fiber that is inserted and fixed to the ferrule is not flat and has unevenness. An optical connector capable of optically connecting an optical fiber with low loss is provided.

In order to solve the above problems, the present invention provides the following configuration.
1st invention is light-transmitting to the rear end surface opposite to the front-end | tip aligned with the joint end surface of the said ferrule front-end | tip of the optical fiber inserted and fixed to the said ferrule, the housing which accommodates this ferrule A built-in optical fiber having a refractive index matching material layer made of a polymer material and a tip of an inserted optical fiber that is an optical fiber inserted into the housing separately can be connected to this built-in optical fiber. A built-in optical fiber body, which is an optical fiber inserted and fixed to the ferrule, has a chamfered portion formed on the outer periphery of the rear end thereof, and abuts against the refractive index matching material layer. The optical connector is characterized in that the insertion optical fiber is optically connected to the built-in optical fiber body through the refractive index matching material layer functioning as a cushion layer. To provide the data.
The second invention provides the optical connector according to the first invention, wherein the refractive index matching material layer is formed of a synthetic resin film adhered to a rear end surface of the built-in optical fiber body. .
According to a third aspect of the invention, the refractive index matching material layer is a resin film formed by coating or vapor deposition of a liquid polymer material on the rear end face of the built-in optical fiber body. An optical connector is provided.
According to a fourth aspect of the present invention, in any one of the first to third aspects, the chamfered portion is a curved surface that curves from an outer edge of a rear end surface of the built-in optical fiber body to an outer peripheral surface of the built-in optical fiber body. An optical connector according to the present invention is provided.
In a fifth aspect of the present invention, the built-in optical fiber and the insertion optical fiber abutted against the refractive index matching material layer at the rear end of the built-in optical fiber are sandwiched between half-divided elements by the elasticity of a spring, and the built-in optical fiber is inserted. A clamp portion that maintains a butt connection state between the optical fiber and the insertion optical fiber is provided, and one or both of the opposing surfaces of the pair of elements of the clamp portion facing each other include the built-in optical fiber and the insertion optical fiber. The optical connector according to any one of the first to fourth aspects is provided, wherein an alignment groove is formed so that the alignment groove is butt-connectable, and the alignment groove functions as the alignment portion. .
According to a sixth aspect of the invention, a ferrule with a clamp portion is provided on the rear side of the ferrule, in which the clamp portion having the structure in which the half element is housed inside a sleeve-like spring is assembled. An optical connector of a fifth invention is provided.
According to a seventh aspect of the present invention, an insertion member that maintains an open state between the elements is interposed between the pair of elements of the clamp portion so as to be removable from between the elements. Alternatively, an optical connector according to the invention of 6 is provided.
In an eighth aspect of the invention, the built-in optical fiber body having a length shorter than the fiber hole is inserted and fixed in a fiber hole penetrating the ferrule, and the fiber hole is inserted from the rear end side of the ferrule. An insertion optical fiber is configured to be butt-connected to the rear end of the built-in optical fiber in a fiber hole, and a portion of the fiber hole on the rear end side from the built-in optical fiber functions as the aligning portion. An optical connector according to any one of the first to fourth inventions is provided.
According to a ninth aspect of the present invention, in the resin coating material, the optical fiber is vertically attached to the optical fiber at the rear end opposite to the front end where the joint end face of the ferrule of the housing is disposed. An optical fiber cable terminal of an optical fiber cable having an embedded and integrated structure is provided, and a cable holding portion for holding the optical fiber cable terminal in the housing is provided, and the insertion optical fiber is an optical fiber of the optical fiber cable. The optical connector according to any one of the first to eighth inventions is characterized in that the leading end of the portion led out is connected to the rear end of the built-in optical fiber.

According to the optical connector of the present invention, the refractive index matching material is obtained by abutting the tip of the inserted optical fiber inserted into the housing against the refractive index matching material layer at the rear end of the built-in optical fiber that is inserted and fixed to the ferrule. The optical connection between the built-in optical fiber body and the insertion optical fiber can be realized through the layers. For this reason, even if the front end surface of the insertion optical fiber is not flat and uneven, the gap between the rear end surface of the built-in optical fiber body and the front end surface of the insertion optical fiber is embedded with a refractive index matching material layer that also functions as a cushion layer. As a result, low loss optical connection can be realized.
In addition, it is difficult for the edge portion of the outer periphery of the insertion optical fiber tip and the convex portion formed on the tip surface of the insertion optical fiber to directly abut against the outer peripheral portion of the rear end of the built-in optical fiber body. Contributes effectively to prevention of chipping of the rear end of the built-in optical fiber body. By avoiding abutment of the convex portion present on the outer peripheral portion of the front end surface of the insertion optical fiber against the outer peripheral portion of the rear end of the built-in optical fiber body, the refractive index matching material layer provided on the rear end surface of the built-in optical fiber main body is avoided. There is also an advantage that the distal end surface of the insertion optical fiber can be pressed and bonded reliably.
Further, the insertion optical fiber tip abutted against the refractive index matching material layer at the rear end of the built-in optical fiber is slightly inclined with respect to the rear end of the built-in optical fiber body (the optical axis of the tip of the insertion optical fiber relative to the optical axis of the rear end of the built-in optical fiber body). Even if there is an inclination, the cushioning property of the refractive index matching material layer can prevent the formation of a gap between the refractive index matching material layer and the end face of the inserted optical fiber, and the optical refractive index can be reduced as a whole. It is possible to obtain an excellent effect that the optical coupling between the built-in optical fiber and the insertion optical fiber can be reliably realized through the refractive index matching material layer functioning as a uniform light transmission layer.

1 is an overall view showing the structure of an optical connector according to an embodiment of the present invention. It is a perspective view which shows the ferrule with a clamp part of the optical connector of FIG. It is sectional drawing which shows the internal structure of the optical connector of FIG. It is a disassembled perspective view explaining the structure of the ferrule with a clamp part of FIG. FIG. 3 is an explanatory diagram showing a schematic structure in which opposing surfaces of elements of the ferrule with a clamp portion in FIG. 2 are arranged side by side. It is a figure which shows the cross section (cross section orthogonal to the extending direction of the alignment groove | channel) structure of the clamp part of the ferrule with a clamp part of FIG. 2, Comprising: (a) is the state which inserted the insertion member between elements, ( b) shows a state where the insertion member is pulled out from between the elements and the insertion optical fiber (specifically, the bare optical fiber of the insertion optical fiber) is held and fixed between the elements. It is a figure explaining the butt connection operation | work of the bare optical fiber of an insertion optical fiber with respect to the built-in optical fiber rear end provided in the ferrule with a clamp part of FIG. 2, Comprising: (a) before butting | matching, (b) is a butting state Indicates. It is a figure explaining an example of the formation method of the refractive index matching material layer of a built-in optical fiber. (A), (b) is an optical connector of one embodiment concerning the present invention, and is a figure showing an example of an optical connector which can be assembled to an optical fiber cable terminal. It is a perspective view explaining an example of the optical fiber cable used as the object which assembles the optical connector of FIG. It is a figure which shows an example of the jacket holding member fixed to the optical fiber cable terminal of FIG. 10, and sees through the cover body of this jacket holding member in the state which fixed this jacket holding member to the optical fiber cable terminal. FIG. FIG. 12 is a perspective view showing the structure of the jacket gripping member of FIG. 11. It is sectional drawing explaining other embodiment of the optical connector which concerns on this invention. It is a figure explaining an example (nail clipper) of the simple cutting instrument for cutting the front-end | tip of the bare optical fiber pierced to the front-end | tip of an insertion optical fiber. It is a graph which shows the test result which attached the optical connector which concerns on this invention to the front-end | tip of an insertion optical fiber, and investigated the connection loss fluctuation characteristic with respect to a heat cycle. (A)-(c) is a figure explaining the relationship between the built-in optical fiber of the conventional field assembly type optical connector, and the front end surface shape of the bare optical fiber of the insertion optical fiber butt-connected to this built-in optical fiber. is there.

Hereinafter, an optical connector according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 3, the optical connector 10 is connected to a sleeve-like housing 20 between optical fibers on the rear side of the ferrule 31 (on the side opposite to the joining end surface 31a at the front end, right side in FIG. 1). The ferrule 30 with a clamp part having a structure in which the clamp part 33 for gripping and fixing the butt connection part is assembled is housed.

  The ferrule 30 with a clamp portion includes the ferrule 31, a built-in optical fiber 320 that is an optical fiber inserted and fixed in a fiber hole 31b formed in the ferrule 31, and the housing at the rear end of the built-in optical fiber 320. And a clamp portion 33 for holding and fixing the connection portion 11 in which the tip portion of another optical fiber 1 (hereinafter also referred to as an insertion optical fiber) inserted separately into the butt 20 is butt-connected (optical connection by butt). Has been.

  As shown in FIGS. 5, 7A, and 7B, the built-in optical fiber 320 includes an optical fiber 32 (here, a bare optical fiber; hereinafter referred to as built-in light) inserted and fixed in the fiber hole 31b of the ferrule 31. The optical fiber main body) has a refractive index matching material layer 321 made of a light-transmitting polymer material on the end surface (rear end surface 32a) of the portion extending to the rear side of the ferrule 31. The built-in optical fiber main body 32 is provided by fixing a portion inserted into the fiber hole 31b to the ferrule 31 by bonding with an adhesive or the like.

The ferrule 31 (ferrule body) of the ferrule 30 with a clamp portion of the optical connector 10 in the illustrated example is a capillary single-core ferrule made of, for example, zirconia ceramics or glass. The fiber hole 31 b of the ferrule 31 is a through hole that penetrates the inside of the ferrule 31.
As the ferrule 31, for example, an SC type optical connector (SC type optical connector (F04 type optical connector established in JIS C 5973; SC: Single fiber Coupling optical fiber connector), MU type optical connector (established in JIS C 5973). A ferrule used for a single-fiber optical connector such as a MU (Miniature-Unit coupling optical fiber connector) can be used.

  The insertion optical fiber 1 shown in FIGS. 1 to 3 and the like is a single-core optical fiber here, and a bare optical fiber 1a (hereinafter also referred to as an insertion-side naked optical fiber) is removed by removing the coating at the tip. In the exposed state, the housing 20 is inserted into the housing 20 from the rear end (the end opposite to the front side where the joining end surface 31a of the ferrule 31 is disposed). As shown in FIGS. 3, 7A and 7B, the insertion optical fiber 1 is formed of the bare optical fiber 1a inserted from the rear end of the housing 20 into the clamp portion 33 of the ferrule 30 with a clamp portion. The optical fiber 32 of the built-in optical fiber 320 (built-in optical fiber) with its tip abutted against the refractive index matching material layer 321 (see FIGS. 7A and 7B) at the rear end of the built-in optical fiber 320 in the clamp portion 33. Main unit) and optically connected.

As shown in FIG. 5 and the like, the optical fiber 32 (built-in optical fiber body) of the built-in optical fiber 320 includes a portion inserted and fixed in the fiber hole 31b of the ferrule 31, and a portion protruding from the rear end of the ferrule 31. Have A portion of the built-in optical fiber main body 32 that protrudes from the rear end of the ferrule 31 is disposed in the clamp portion 33. The built-in optical fiber main body 32 is a short optical fiber that extends from the rear end disposed in the clamp portion 33 to the tip (tip surface) provided at the same position as the joining end surface 31 a of the ferrule 31.
The built-in optical fiber 320 has a configuration in which the refractive index matching material layer 321 is provided on the end surface (rear end surface 32a) of the portion disposed in the clamp portion 33 of the built-in optical fiber body 32.

  The refractive index matching material layer 321 used in the present invention needs to have refractive index matching. The refractive index matching in this case refers to the degree of proximity between the refractive index of the connecting member and the refractive index of the optical fiber (the bare optical fiber of the insertion optical fiber 1 and the built-in optical fiber). Therefore, the refractive index of the refractive index matching material layer 321 used in the present invention is not particularly limited as long as it is close to the refractive index of the optical fiber, but from the viewpoint of transmission loss due to avoidance of Fresnel reflection, the refractive index with the optical fiber. Is preferably within ± 0.1, more preferably within ± 0.05. When the refractive indexes of the bare optical fiber 1a and the built-in optical fiber body 32 of the insertion optical fiber 1 are different, the difference between the average refractive index of these optical fibers and the refractive index of the refractive index matching material layer 321 is different. It is desirable to be within the above range.

  As the refractive index matching material layer 321, for example, a polymer film (synthetic resin film) having refractive index matching and adhesiveness is bonded to the rear end surface 32a of the built-in optical fiber body 32, but is not limited thereto. First, a resin film obtained by solidifying a coating film (including printing, spraying, etc.) coated with a liquid polymer material, CVD (Chemical Vapor Deposition) or PVD (Physical Vapor Deposition. PVD : A vapor deposition film (resin film) formed by Physical Vapor Deposition.

  The refractive index matching material layer 321 made of a polymer film is formed on the rear end surface 32a of the built-in optical fiber body 32 by cutting a small piece cut out from the film base material (polymer film) into a size suitable for the rear end surface 32a of the built-in optical fiber body 32. For example, as shown in FIG. 8, an optical fiber used as the built-in optical fiber body 32 (bare optical fiber; indicated by reference numeral 32 in FIG. 8) is an outer peripheral surface of an adjacent optical fiber 32. A plurality of optical fibers 32 are assembled so as to be in contact with each other, and the end faces of the optical fibers 32 arranged on the same plane are arranged on one side in the longitudinal direction (end face used as the rear end face 32a of the built-in optical fiber body 32). A single polymer film arranged so as to be covered at once is bonded, and the polymer film is attached to the end face of each optical fiber 32 by photolithography technology. Is patterned to remove other parts leaving only portions response, it is also possible to obtain an optical fiber whose refractive index matching material layer 321 is provided.

  In addition, as shown in FIG. 8, the formation of a coating film by vapor deposition of a liquid polymer material and the formation of a vapor-deposited film are performed as follows. As shown in FIG. Can be performed in a state where a plurality of optical fibers 32 are assembled so as to be in contact with each other and the end faces of the optical fibers 32 are arranged on the same plane. In this case, coating film formation and vapor deposition film formation can be performed on many optical fibers 32 at a time. In this case, it is preferable to form the coating film and the vapor deposition film by using a mask that exposes the end face of the optical fiber 32 and covers other portions.

Examples of the material of the refractive index matching material layer 321 include acrylic, epoxy, vinyl, silicone, rubber, urethane, methacryl, nylon, bisphenol, diol, polyimide, fluorinated epoxy, Examples thereof include polymer materials such as fluorinated acrylic.
As the polymer film, an adhesive material made of such a polymer material in the form of a film can be used, and in particular, from the viewpoint of environmental resistance and adhesiveness, silicone-based and acrylic-based materials are generally used. A thing can be used suitably. Moreover, a crosslinking agent, an additive, a softening agent, or the like may be added to the above material to arbitrarily adjust flexibility, and water resistance or heat resistance may be added.
In the case of a polymer film in which the adhesive material is in the form of a film, this film can be attached to the end face of the optical fiber without using an adhesive or the like due to the self-adhesiveness of the film. It is preferable in terms of ensuring the stability of desired optical characteristics (such as optical transmission loss).

The insertion-side bare optical fiber 1a and the built-in optical fiber main body 32 are silica-based optical fibers, and the refractive index matching material layer 321 is a soft layer whose hardness is significantly lower than that of the silica-based optical fibers. Cushion layer that reduces the impact force caused by the abutment when the end of the bare optical fiber 1a is abutted, and prevents damage such as chipping of the rear end of the built-in optical fiber body 32 and the end of the bare optical fiber 1a of the inserted optical fiber 1 Function as.
The thickness of the refractive index matching material layer 321 is, for example, 5 to 40 μm, but is not limited thereto.

  As the insertion optical fiber 1, a coated optical fiber having a configuration in which a bare optical fiber is coated (attached) with a resin coating material, such as an optical fiber core or an optical fiber strand, is employed. The coated optical fiber is inserted into the housing 20 from the rear end in a state in which the coating at the tip is removed to expose the bare optical fiber.

  As shown in FIGS. 1 and 4, the clamp portion 33 of the ferrule 30 with a clamp portion is rearward from the ring-shaped flange portion 34 that is externally fixed to the rear end portion of the ferrule 31 (in FIGS. 1 and 3). An element portion 331 having a halved structure composed of an elongated base side element 35 that extends to the right side) and a lid side element 36 provided along the base side element 35 is formed on a metal plate. The sleeve is housed and held inside a sleeve-shaped spring 37 having a C-shaped or U-shaped section (C-shaped section in the illustrated example).

  In the clamp portion 33 of the illustrated example, the base side element 35 is a plastic or metal member formed integrally with the flange portion 34. However, in the present invention, the base side element 35 and the flange portion 34 are not limited to a configuration in which the plastic side or the metal integrally formed product is formed. The element 35 may be integrated by insert molding, adhesive fixing, fitting fixing, or the like.

  The lid side element 36 includes a first lid side element 361 and a second lid side element disposed on the opposite side (rear side) of the ferrule 31 and the flange portion 34 via the first lid side element 361. 362. Hereinafter, the first lid side element 361 is also referred to as a front side element, and the second lid side element 362 is also referred to as a rear side element.

The clamp portion 33 closes the opposing surfaces facing each other of the pair of elements 35 and 36 (base side element and lid side element) of the element portion 331 having a halved structure by the elasticity of the spring 37. It is configured to be elastically biased and collectively held inside the spring 37.
4, 5, 6 </ b> A and 6 </ b> B, reference numeral 35 f is provided on the opposing surface of the base side element 35, reference numeral 361 f is provided on the opposing surface of the front element 361, and reference numeral 362 f is provided on the opposing surface of the rear element 362. Is attached.

  As shown in FIGS. 2 and 4, the spring 37 has a front spring portion 37 b (see FIG. 4) on the front side (ferrule 31 side) from the slit 37 a by a slit 37 a formed in the center in the longitudinal direction. The rear spring portion 37c (see FIG. 4) on the rear side from the slit 37a. As shown in FIGS. 2 and 4, the spring 37 is formed with a side opening 37 d extending over the entire length in the longitudinal direction (the direction of the central axis). The slit 37a is a portion of the spring 37 that is located opposite to the side opening 37d via the element part 331 inside the spring 37 from both ends of the spring 37 facing the side opening 37d (back side continuous portion). Two are formed so as to extend along the circumferential direction of the spring 37 toward 37e). The front spring portion 37b and the rear spring portion 37c of the spring 37 are connected via only the back side continuous portion 37e secured between the two slits 37a and function as independent sleeve-like springs.

  As shown in FIGS. 2 and 3, of the two elements (the front element 361 and the rear element 362) constituting the lid side element 36, the rear element 362 is entirely composed of the rear spring portion 37 c of the spring 37. And is held together with the rear end portion of the base side element 35 by the elasticity of the rear spring portion 37c. On the other hand, the front element 361 is housed inside the front spring part 37 b and the rear spring part 37 c of the spring 37, and is held together with the base side element 35 by the elasticity of the spring 37.

  As shown in FIGS. 4 and 5, on the opposing surface 35 f of the base side element 35, a rear extension portion 322 that is a portion extending rearward from the ferrule 31 of the built-in optical fiber 320 and an insertion optical fiber are provided. 1 and a covering groove accommodating groove 38b for accommodating and positioning the covering portion 1b which is a portion covered with the covering material of the insertion optical fiber 1; A fiber positioning groove 38 is formed.

The alignment groove 38a extends from the front end of the base side element 35 (the left end of the base side element 35 in FIG. 5) along the extending direction (longitudinal direction) so as to be continuous with the fiber hole 31b that penetrates the ferrule 31. Is formed. The rear extension 322 of the built-in optical fiber 320 is accommodated in the alignment groove 38a. The rear end (refractive index matching material layer 321) of the built-in optical fiber 320 is disposed at the center in the longitudinal direction of the alignment groove 38a (in the illustrated example, a position slightly shifted from the center in the longitudinal direction to the front side (ferrule 31 side)). ing.
The covering portion receiving groove 38b is formed from the rear end of the alignment groove 38a (the end opposite to the front end on the ferrule 31 side) from the rear side of the base side element 35 along the extending direction of the base side element 35. It extends to the end.

  As shown in FIGS. 6A and 6B, the alignment groove 38a in the illustrated example is a V-groove, but is not limited thereto, and for example, a round groove (groove having a semicircular cross section), a U groove, or the like is also employed. Is possible.

The covering portion receiving groove 38b has a larger groove width and depth than the aligning groove 38a in order to receive and position the covering portion 1b thicker than the bare optical fiber 1a of the insertion optical fiber 1.
As shown in FIGS. 3 and 5, the clamp portion 33 of the illustrated optical connector 10 has a configuration in which a covering portion receiving groove 38 c is also formed on the facing surface 362 f of the rear element 362. The covering portion storing groove 38 c formed on the facing surface 362 f of the rear side element 362 is formed at a position corresponding to the covering portion storing groove 38 b of the base side element 35.
Further, the front end portions of the covering portion receiving grooves 38b and 38c of the base side element 35 and the lid side element 36 (specifically, the rear side element 362) are formed in a tapered shape, and the fiber is formed from the rear end of the clamp portion 33. When the insertion optical fiber 1 is inserted into the positioning groove 38 (described later), the bare optical fiber 1a at the tip of the insertion optical fiber 1 can be smoothly introduced into the alignment groove 38a.

  In addition, as a clamp part of the optical connector which concerns on this invention, the structure by which the coating | coated part accommodation groove | channel is formed in one or both of the opposing surface of the base side element 35 and the opposing surface of the rear side element 362 is employable. The covering portion receiving grooves 38 b and 33 c of the elements 35 and 352 of the clamp portion are formed so as to open at the rear end of the clamp portion 33. In addition, the covering portion storage grooves 38b and 33c are V-grooves here, but are not limited thereto, and for example, round grooves (grooves with a semicircular cross section), U-grooves, square grooves, and the like can be employed.

  As shown in FIG. 6A, a plate interposed between the pair of elements 35 and 36 (the base side element 35 and the lid side element 36) of the clamp portion 33 of the optical connector 10 is interposed between the elements 35 and 36. The bare optical fiber 1a and the covering portion 1b of the insertion optical fiber 1 exposed at the tip of the insertion optical fiber 1 are pushed into the fiber positioning groove 38 from the rear end of the clamp portion 33. Insertion (push-in) is possible. The state of the clamp part 33 at this time is hereinafter referred to as an open state. In addition, as shown in FIG. 1, the optical connector 10 in which the insertion member 40 is inserted into the pair of elements 35 and 36 of the clamp portion 33 is hereinafter also referred to as an optical connector with an insertion member.

The insertion member 40 functions to maintain the open state between the pair of elements 35 and 36 against the elasticity of the spring 35 of the clamp portion 33.
As shown in FIGS. 4 and 5, the insertion member 40 is formed between the side opening 37 d of the spring 37 and the pair of elements 35, 36 of the clamp 33, that is, the opposing surfaces 35 f of the pair of elements 35, 36, It is inserted so as to interrupt between 361f and 362f. Further, as shown in FIG. 1, the insertion member 40 is inserted into an insertion member insertion hole (not shown) penetrating the outer peripheral wall of the sleeve-like housing 20 of the optical connector 10, so that the housing 20 The tip 40a is provided between the pair of elements 35 and 36 of the clamp 33 so as to penetrate the outer peripheral wall.
As shown in FIGS. 6A and 6B, the distal end portion 40 a of the insertion member 40 is inserted between the pair of elements 35, 36 of the clamp portion 33 so as not to reach the fiber positioning groove 38 of the element 35. So that the insertion operation of the optical fiber 1 into the fiber positioning groove 38 is not hindered.

As shown in FIGS. 1 and 4, the insertion member 40 corresponds to the two elements of the lid side element 36 (the front side element 361 and the rear side element 362), and the front side element 361 and the base side element 35. And between the rear element 362 and the base element 35, respectively. That is, the insertion member 40 corresponds to the two elements 361 and 362 of the lid-side element 36, and a pair of clamp parts 33 at different positions in the front-rear direction (left-right direction in FIG. 1) of the ferrule 30 with a clamp part. A total of two elements are inserted between the elements 35 and 36.
In FIG. 1, reference numeral 41 denotes an insertion member 40 interposed between the front side element 361 and the base side element 35, and an insertion member inserted between the rear side element 362 and the base side element 35. Reference numeral 42 is attached to 4.

Further, as shown in FIG. 1, the insertion member 40 has a proximal end opposite to the distal end portion 40a protruding outside the housing 20, and a portion protruding outward from the housing 20 is optically It can be used as an extraction operation part for extraction operation for extracting the insertion member 40 from the connector 10.
As the insertion member 40, the open state between the pair of elements 35, 36 can be maintained against the elasticity of the spring 35 of the clamp portion 33, and the removal operation from between the pair of elements 35, 36 is performed. However, the present invention is not limited to a plate shape, and may be a flexible sheet shape or a rod shape, for example.

Next, the built-in optical fiber 320 will be described more specifically.
As shown in FIGS. 7A and 7B, a chamfered portion 32 b is formed on the entire outer periphery of the rear end of the optical fiber 32 (built-in optical fiber main body) of the built-in optical fiber 320. The rear end portion of the built-in optical fiber main body 32 is tapered by the chamfered portion 32 b on the outer periphery of the rear end of the built-in optical fiber main body 32.

The refractive index matching material layer 321 is formed so as to cover the entire end surface (rear end surface 32a) of the rear end portion of the tapered built-in optical fiber body 32.
Further, as illustrated in FIGS. 7A and 7B, the refractive index matching material layer 321 may be formed so as to overlap not only the rear end surface 32a of the built-in optical fiber body 32 but also the chamfered portion 32b. . However, the formation range of the refractive index matching material layer 321 is limited to a range that does not protrude outward from the virtual extension (virtual cylindrical surface) of the outer peripheral surface of the rear end portion of the built-in optical fiber body 32, and the refractive index matching material layer 321 is The alignment accuracy of the rear extension 322 of the built-in optical fiber 320 by the alignment groove 38a is not affected.

The chamfered portion 32 b at the rear end of the built-in optical fiber body 32 of the built-in optical fiber 320 in the illustrated example is a curved surface that curves from the outer edge of the rear end surface 32 a of the built-in optical fiber body 32 to the outer peripheral surface of the built-in optical fiber body 32. Yes. For example, the chamfered portion 32b is disposed between the discharge electrodes at the end of an optical fiber (a bare optical fiber not forming the chamfered portion 32b) for producing the built-in optical fiber body 32. The edge portion around the end face is heated and melted by the energy of the arc discharge (hereinafter also referred to as electric discharge machining).
The chamfered portion 32b is formed in the range of 40 to 55 μm along the optical axis direction of the built-in optical fiber main body 32 from the rear end surface 32a when the outer diameter of the built-in optical fiber main body 32 is 125 μm. Hereinafter, the formation range of the chamfered portion 32b in the direction along the optical axis of the built-in optical fiber main body 32 is also referred to as a chamfer length (reference numeral Lc in FIG. 7A).
Further, the chamfered portion 32b is formed only in the cladding portion 32d of the built-in optical fiber body 32 so as not to reach the core portion 32c (or the mode field diameter portion) of the built-in optical fiber body 32.

  The rear end surface 32a of the built-in optical fiber body 32 of the built-in optical fiber 320 illustrated in FIGS. 7A and 7B is a flat surface perpendicular to the optical axis at the rear end of the built-in optical fiber body 32. The configuration of the built-in optical fiber according to the present invention is not limited to this, and includes a configuration in which the rear end surface of the built-in optical fiber body is a curved convex surface. However, the rear end surface of the built-in optical fiber main body having the curved convex surface is a curved surface that curves more slowly than the chamfered portion 32b. The rear end surface of the curved convex convex built-in optical fiber body can be formed simultaneously with the formation of the chamfered portion 32b by arc discharge. The curved convex surface can also be formed by polishing the end face of an optical fiber (bare optical fiber) used for manufacturing the built-in optical fiber body 32, for example.

  As shown in FIG. 3, the rear end of the built-in optical fiber 320 is disposed between the front element 361 of the lid side element 36 and the base side element 35 so as to be positioned inside the front side spring portion 37 b of the spring 37. ing. When the insertion-side bare optical fiber 1a is butted and connected to the rear end of the built-in optical fiber 320, the connecting portion 11 is positioned inside the front-side spring portion 37b.

The optical connector 10 is a field assembly type optical connector.
In order to attach (assemble) the optical connector 10 to the distal end portion of the insertion optical fiber 1, as shown in FIG. 1 and FIG. 36 in the state where the insertion optical fiber 1 is opened by the insertion member 40 interrupted by 36 (that is, the state of the optical connector with the insertion member), the element 35 of the clamp portion 33 from the rear end opening of the housing 20, 36. Inserted into the fiber positioning groove 38 secured between 36, and the leading end of the bare optical fiber 1a previously struck to the tip of the inserted optical fiber 1 is used as the rear end (refractive index matching material layer 321) of the built-in optical fiber 320. Match. And the butt | matching state with respect to the back end of the built-in optical fiber 320 of the bare optical fiber 1a of the insertion optical fiber 1 is maintained with the pushing force of the insertion optical fiber 1 to the fiber positioning groove | channel 38 back side (front end side, ferrule 31 side). Then, all of the insertion member 40 that is interrupted between the pair of elements 35 and 36 of the clamp portion 33 is removed (see FIG. 6B).

Thereby, the part inserted in the fiber positioning groove 38 of the insertion optical fiber 1 and the rear side extension part 322 of the built-in optical fiber 320 are paired with the pair of elements 35 of the clamp part 33 by the elasticity of the spring 35 of the clamp part 33. The optical connector 10 is attached (assembled) to the distal end portion of the insertion optical fiber 1 by being gripped and fixed between 36 and being restricted from being pulled out from the clamp portion 33 of the insertion optical fiber 1.
Regarding the clamp portion 33, a state in which the portion inserted into the fiber positioning groove 38 of the insertion optical fiber 1 and the rear side extension portion 322 of the built-in optical fiber 320 are held and fixed between a pair of elements 35 and 36 is hereinafter referred to as a fiber. Also called gripped state.

  The rear extension 322 of the built-in optical fiber 320 is maintained in the alignment groove 38a due to the rigidity of the built-in optical fiber body 32 when the clamp 33 is in the open state. Therefore, the insertion-side bare optical fiber 1 a can be easily abutted only by pushing the insertion optical fiber 1 into the fiber positioning groove 38 from the opening at the rear end of the clamp portion 33 of the fiber positioning groove 38.

  The insertion optical fiber 1 to be inserted into the fiber positioning groove 38 of the clamp portion 33 is inserted into the fiber positioning groove 38 after removing the coating at the tip (leading out of the bare optical fiber 1a) and cutting at the site. As shown in FIG. 3, the insertion optical fiber 1 has a leading end of the bare optical fiber 1a inserted into the fiber positioning groove 38 after the built-in optical fiber 320 by setting the lead length L (see FIG. 1) of the bare optical fiber 1a. When abutted against the end, the bare optical fiber 1 a is accommodated in the alignment groove 38 a of the fiber positioning groove 38, and the covering portion 1 b is accommodated in the covering portion receiving grooves 38 b and 38 c of the fiber positioning groove 38. Accordingly, the leading end of the insertion-side bare optical fiber 1a is abutted against the rear end of the built-in optical fiber 320, the insertion member 40 that is interrupted between the pair of elements 35 and 36 of the clamp portion 33 is removed, and the clamp portion 33 is gripped by the fiber. In this state, the bare optical fiber 1a at the tip of the insertion optical fiber 1 is held and fixed between the front side element 361 and the base side element 35 together with the rear extension 322 of the built-in optical fiber 320, and the covering of the insertion optical fiber 1 is performed. The portion 1 b is gripped and fixed between the rear element 362 and the base element 35.

As the insertion optical fiber 1, an optical fiber whose outer diameter is the same as that of the optical fiber 32 of the built-in optical fiber 320 (built-in optical fiber main body, here, a bare optical fiber) is adopted.
Further, the portion facing the alignment groove 38a of the facing surface facing the facing surface 351 of the base side element 35 of the lid side element 36 (here, the facing surface 361f of the front side element 361; see FIG. 5) has high flatness. It is a secured flat surface. When the insertion member 40 inserted between the pair of elements 35 and 36 of the clamp portion 33 is removed, the bare optical fiber 1a at the tip of the insertion optical fiber 1 and the rear extension portion 322 of the built-in optical fiber 320 are formed. The front element 361 and the base are pressed against the alignment groove 38a by the elasticity of the spring 35 of the clamp portion 33, precisely positioned (alignment) by the alignment accuracy of the alignment groove 38a, and optically connected (butt connection) to each other. It is held and fixed between the side elements 35.

According to this optical connector 10, as shown in FIGS. 7A and 7B, the front end surface 1c of the bare optical fiber 1a of the inserted optical fiber 1 inserted into the housing 20 is connected to the refractive index of the rear end of the built-in optical fiber 320. By abutting against the matching material layer 321, optical connection between the built-in optical fiber main body 32 and the insertion optical fiber 1 can be realized via the refractive index matching material layer 321. For this reason, even if the front end surface 1c of the bare optical fiber 1a of the insertion optical fiber 1 is not flat and uneven, the space between the built-in optical fiber rear end surface 32a and the insertion optical fiber front end surface 1c also functions as a cushion layer. By being embedded with the refractive index matching material layer 321, an optical connection with low loss can be realized.
Even when the central portion of the distal end surface 1c of the insertion-side bare optical fiber 1a is a recess, or when the convex portion 1d is present on the outer peripheral portion of the distal end surface 1c, the built-in optical fiber body 32 and the insertion-side bare light The core portions 32c and 1e (or mode field diameter portions) of the fiber 1a are filled with a soft refractive index matching material layer 321. Thereby, an optical connection with low loss can be realized.
In addition, the code | symbol 1f is a clad part of the insertion side bare optical fiber 1a.

  Further, according to this optical connector 10, as described above, the refractive index matching provided on the end surface (rear end surface 32a) of the rear end portion of the built-in optical fiber body 32 tapered by the formation of the chamfered portion 32b. Since the distal end surface 1c of the insertion optical fiber 1 is abutted against the material layer 321, the edge portion of the outer periphery of the distal end of the insertion optical fiber 1 and the convex portion formed on the distal end surface 1c of the insertion optical fiber directly to the outer peripheral portion of the built-in optical fiber. It is hard to produce a butt. For this reason, chipping of the front end of the insertion optical fiber 1 and the rear end of the built-in optical fiber body 32 is unlikely to occur.

  Even if the convex portion at the tip of the insertion optical fiber 1 comes into contact with the chamfered portion 32b at the rear end of the built-in optical fiber body 32 and the insert optical fiber 1 and / or the built-in optical fiber body 32 is chipped, the tip of the insertion optical fiber 1 is inserted. Since the protruding position of the convex portion is in contact with the rear end of the built-in optical fiber body 32 at a position deviated from the bonding interface between the refractive index matching material layer 321 and the front end of the inserted optical fiber 1, the fragments generated by chipping are refractive index matched. Inconveniences such as being sandwiched between the material layer 321 and the distal end of the insertion optical fiber 1 hardly occur. Therefore, it is advantageous in preventing the formation of a gap between the refractive index matching material layer 321 and the tip of the insertion optical fiber 1 due to the sandwiched pieces.

  Further, as described above, the refractive index matching material layer 321 is provided on the end surface (rear end surface 32a) of the rear end portion of the built-in optical fiber body 32 that is tapered by the formation of the chamfered portion 32b. For example, as shown in FIGS. 7A and 7B, even if the convex portion 1d exists on the outer peripheral portion of the insertion optical fiber tip surface 1c, the center of the insertion optical fiber tip surface 1c of the convex portion 1d is provided. If the protruding dimension from the portion is smaller than the thickness of the refractive index matching material layer 321, the convex portion 1 d does not directly contact the chamfered portion 32 b on the outer periphery of the rear end of the built-in optical fiber body 32, and the refractive index matching material layer 321. The insertion optical fiber front end surface 1c can be pressed against and securely joined to. As long as the convex portion 1d does not directly contact the chamfered portion 32b on the outer periphery of the rear end of the built-in optical fiber main body 32, the insertion optical fiber front end surface 1c can be reliably pressed against the refractive index matching material layer 321 and bonded.

  The configuration in which the refractive index matching material layer 321 is provided on the end face (rear end face 32a) of the rear end portion of the built-in optical fiber body 32 tapered by the formation of the chamfered portion 32b is the thickness of the refractive index matching material layer 321. And the chamfered portion 32b on the outer periphery of the rear end of the built-in optical fiber body 32 effectively contributes to avoiding direct contact of the convex portion 1d existing on the outer periphery of the inserted optical fiber front end surface 1c with the built-in optical fiber body 32. For example, the distal end surface of the insertion-side bare optical fiber 1a is directly abutted and connected to the end surface (rear end surface 32a) of the built-in optical fiber body 32 that has no index matching material layer 321 and is tapered by the chamfered portion 32b. Compared to the configuration, the direct contact with the built-in optical fiber main body 32 of the convex portion 1d on the outer peripheral portion of the insertion optical fiber distal end surface 1c is less likely to occur, which is advantageous in avoiding this direct contact. .

  In addition, according to the present invention, even if a slight inclination with respect to the rear end of the built-in optical fiber body 32 occurs at the tip of the inserted optical fiber 1 abutted against the refractive index matching material layer 321 at the rear end of the built-in optical fiber body 32, the refraction is refracted. Due to the cushioning property of the index matching material layer 321, it is possible to ensure the bonding state of the insertion optical fiber distal end surface 1 c to the index matching material layer 321. The refractive index matching material layer 321 functions as a light transmission layer in which the light refractive index is uniformly uniform over the whole, so that the built-in optical fiber main body 32 and the inserted optical fiber are interposed via the refractive index matching material layer 321. 1 (specifically, the bare optical fiber 1a) can be surely realized.

  Further, according to this optical connector 10, the insertion member 40 is inserted from the clamp portion 33 by abutting the leading end surface 1 c of the bare optical fiber 1 a of the insertion optical fiber 1 against the refractive index matching material layer 321 at the rear end of the built-in optical fiber 320. When the clamp 33 is pulled out and held in a fiber gripping state, for example, due to bending bending of the insertion-side bare optical fiber 1a itself or residual deflection due to the abutting force when abutting against the rear end of the built-in optical fiber 320, the insertion side When the bare optical fiber 1a has a slight lift from the alignment groove 38a (a fine lift within a sufficiently possible range in which the optical connection between the built-in optical fiber main body 32 and the insertion-side bare optical fiber 1a is possible). Even so, the cushioning property (flexibility) of the refractive index matching material layer 321 eliminates the lifting from the alignment groove 38a of the insertion-side bare optical fiber 1a over time, and is possible. The to high aligning accuracy can be ensured.

  If the insertion-side bare optical fiber 1 a is abutted against the refractive index matching material layer 321 at the rear end of the built-in optical fiber 320, the insertion-side optical fiber with respect to the rear end of the built-in optical fiber main body 32 due to deformation of the refractive index matching material layer 321. Displacement of the 1a tip easily occurs. For example, compared with the case where the refractive index matching material layer 321 is omitted and the distal end surface of the insertion-side bare optical fiber 1a is directly butted and connected to the end surface (rear end surface 32a) of the built-in optical fiber body 32, the clamp portion 33 is formed. It is possible to reliably realize as much as possible alignment of the insertion-side bare optical fiber 1a after the fiber is held.

  As described above, when the refractive index matching material layer 321 is omitted and the leading end surface of the insertion-side bare optical fiber 1a is directly butted and connected to the rear end surface 32a of the built-in optical fiber body 32, the insertion-side bare optical fiber 1a There is a case where the insertion-side bare optical fiber is incapable of displacement of the distal end of the insertion-side optical fiber 1a with respect to the rear end of the built-in optical fiber body 32 when the convex portion present on the distal-end surface 1c is in contact with the chamfered portion 32b. The convex portion present on the distal end surface 1c of 1a has a great influence on the displacement of the distal end of the insertion-side bare optical fiber 1a. On the other hand, if the configuration adopts the built-in optical fiber 320 in which the refractive index matching material layer 321 is provided at the rear end of the built-in optical fiber body 32 as in the present invention, the distal end of the insertion-side bare optical fiber 1a. Even if a convex portion exists on the surface 1c, the insertion-side optical fiber 1a tip can be easily displaced with respect to the rear end of the built-in optical fiber body 32 as long as the convex portion does not directly contact the built-in optical fiber body 32. There is an advantage in that the alignment of the insertion-side bare optical fiber 1a after the clamp portion 33 is in the fiber gripping state can be realized.

(Example of optical connector having cable retaining portion)
The optical connector according to the present invention is not limited to the one that is assembled to the distal end portion of the insertion optical fiber 1 that is a coated optical fiber such as an optical fiber core wire or an optical fiber strand, as in the above-described embodiment, For example, as shown in FIGS. 9A and 9B, the rear end side of the optical connector body 51 in which the ferrule 30 with a clamp portion is housed in a sleeve-shaped housing 511 (the right side of FIGS. 9A and 9B). ) Having a cable retaining portion 52 for retaining the optical fiber cable 2 terminal and being assembled to the optical fiber cable 2 terminal (optical connector 50) can also be employed.

As shown in FIG. 10, the optical fiber cable 2 is integrated by embedding an optical fiber 2a in a resin coating material 2c (hereinafter also referred to as a jacket) together with a linear strength member 2b vertically attached to the optical fiber 2a. The optical fiber cable having a substantially rectangular cross section having the above-described configuration is used as an optical drop cable, an optical indoor cable, or the like.
The optical fiber 2 a is disposed at the center of the cross section of the optical fiber cable 2, and the strength member 2 b is disposed at a position separated from the optical fiber 2 a on both sides in the longitudinal direction of the cross section of the optical fiber cable 2. The optical fiber 2a is a coated optical fiber such as an optical fiber core or an optical fiber.

In order to assemble (attach) the optical connector 50 to the end of the optical fiber cable 2, first, as shown in FIGS. 11 and 12, the optical fiber cable 2 a is already connected to the end of the optical fiber cable 2. An outer gripping member 60 having a cable fitting groove 61a for fitting and fixing 2 is fixed.
The envelope gripping member 60 illustrated in FIGS. 11 and 12 is an integrally molded product made of plastic. The gripping member main body 61 in which the cable fitting groove 61a is formed, and the gripping member main body 61 functions as a hinge portion. And a lid 62 that is rotatably connected through a thin-walled portion 63. In the lid 62, the gripping member main body 61 is protruded in parallel with each other on the bottom plate portion 61d in which the side wall portions 61b and 61c form the groove bottom of the cable fitting groove 61a through the cable fitting groove 61a. The member has a U-shaped cross section. Both ends in the longitudinal direction of the cable fitting groove 61 a are opened on the outer surface of the jacket gripping member 60.

  The lid body 62 of the jacket holding member 60 in the illustrated example has an L-shaped plate shape, and one of the pair of side wall portions 61b and 61c (in the illustrated example, the side wall portion denoted by reference numeral 61b. Hereinafter also referred to as the first side wall portion). Is connected to the gripping member main body 61 via the thin-walled portion 63 so as to be rotatable. When the lid 62 is closed with respect to the gripping member main body 61, the first lid plate portion 62a continuing from the thin portion 63 has a cable fitting groove between the protruding ends of the side wall portions 61b and 61c and the protruding ends. A second lid plate portion 62b that covers the opening portion of 61a and projects perpendicularly to the end of the first lid plate portion 62a opposite to the thin-walled portion 63 is the first side wall of the grip member main body 61. It overlaps with the side surface (hereinafter also referred to as the outer surface) opposite to the cable fitting groove 61a of the second side wall portion 61c facing the portion 61b via the cable fitting groove 61a.

  In order to fix the jacket gripping member 60 to the optical fiber cable 2 end, the optical fiber cable 2 end is fitted into the cable fitting groove 61a in a state where the lid 62 is opened with respect to the gripping member main body 61. Thereafter, the lid 62 is closed to the gripping member main body 61. Here, the lid body 62 causes the latching claw 61e protruding from the outer surface of the second side wall portion 61c of the gripping member main body 61 to enter the latching opening 62c formed in the second lid plate portion 62b. Thus, the locking claw 61e is locked to the second side wall portion 61c to restrict the opening to the gripping member main body 61. As a result, the jacket gripping member 60 is attached to the optical fiber cable 2 so as to surround the optical fiber cable 2 end, and the optical fiber 2 a led out to the optical fiber cable 2 end is outside the sheath gripping member 60. It will be in the state extended to.

When the end of the optical fiber cable 2 is fitted into the cable fitting groove 61a, a plurality of projecting claws 61f projecting from the surfaces (inner surfaces) of the pair of side wall portions 61b and 61c facing the cable fitting groove 61a. Bites into the jacket 2c of the optical fiber cable 2, and the end of the optical fiber cable 2 is gripped and fixed between the pair of side wall portions 61b and 61c.
In addition, as described above, the L-shaped plate-like lid 62 is locked by the locking claws 61e on the outer surface of the second side wall 61c of the gripping member main body 61 to maintain the closed state with respect to the gripping member main body 61. Thus, separation between the protruding ends of the pair of side wall portions 61b and 61c of the gripping member main body 61 and separation from the cable fitting groove 61a from between the protruding ends of the pair of side wall portions 61b and 61c can be reliably prevented. The fixed state of the member 60 with respect to the end of the optical fiber cable 2 can be kept stable.

When the fixing of the outer gripping member 60 to the end of the optical fiber cable 2 is completed, the optical fiber 2a extending from the end of the optical fiber cable 2 is then connected to the opening (rear end) of the housing 511 of the optical connector body 51. The fiber positioning groove 38 (see FIG. 5) of the element portion 31 of the clamp portion 33 of the ferrule 30 with a clamp portion is inserted into the housing 511 from the end opening portion 513) and the tip of the bare optical fiber 2a1 is previously led out. 5), and the leading end of the bare optical fiber 2a1 is fed along the alignment groove 38a to abut against the refractive index matching material layer 321 at the rear end of the built-in optical fiber 320. 9A, the retaining cover 522 pivotally attached to the rear end portion of the housing 511 of the optical connector main body 51 is moved from the housing 511 to the rear end portion of the housing 511. This is performed in an open state with respect to the base portion 521 protruding so as to extend rearward.
The optical fiber 2a of the optical fiber cable 2 functions as an insertion optical fiber according to the present invention.

The element portion 331 of the clamp portion 33 of the ferrule 30 with a clamp portion of the optical connector main body 51 is inserted into the optical fiber 2a of the optical fiber cable 2 by the distal end portion 40a of the insertion member 40 inserted between the elements 35 and 36. Is open. The insertion member 40 is inserted in two places (insertion members 41 and 42) of the element portion 331 corresponding to the two members (front element 361 and rear element 362) constituting the lid side element 36. .
The insertion member 40 protrudes to the outside of the housing 511 from an insertion member insertion hole (not shown) formed on the housing 511 on the base end side opposite to the distal end portion 40a. The protruding portion can be used as an extraction operation portion for an extraction operation for extracting the insertion member 40 from the optical connector 50.

When the butting of the tip of the optical fiber 2a inserted between the elements 35 and 36 along the fiber positioning groove 38 of the element part 311 of the ferrule 30 with a clamp part of the optical connector main body 51 with the rear end of the built-in optical fiber 320 is completed. As shown in FIG. 9B, the retaining cover 522 is closed with respect to the base portion 521. As a result, the holding member storage case 54 for storing the outer cover holding member 60 is assembled by the holding cover 522 and the base portion 521, and the optical fiber cable 2 terminal can be held to the optical connector body 51.
The retaining cover 522 and the base portion 521 constitute the cable retaining portion 52 of the optical connector 50.

The retaining cover 522 includes a top plate portion 522 a that covers the outer cover gripping member 60 installed on the base portion 521, and a rear plate portion 522 b that is disposed on the rear side of the cover gripping member 60. When the outer gripping member 60 is stored in the gripping member storage case 54, the outer gripping member 60 is located between the rear end of the housing 511 of the optical connector body 51 and the rear plate portion 522b in the connector longitudinal direction. The connector is arranged to allow movement in the front-rear direction or allow fine movement.
The optical fiber cable 2 extending rearward from the outer gripping member 60 is rearward from the gripping member storage case 54 while being passed through a notch-shaped cable insertion port 522c formed in the rear plate portion 522b. It will be in the state extended to the side.

  When the gripping member storage case 54 is assembled and the jacket gripping member 60 is stored, the insertion member 40 inserted between the elements 35 and 36 of the clamp part 33 of the ferrule 30 with a clamp part is pulled out from the element part 311. Thereby, the butted state of the rear end of the built-in optical fiber 320 of the ferrule 30 with a clamp part and the optical fiber 2a of the optical fiber cable 2 is maintained, and the assembly of the optical connector 50 to the end of the optical fiber cable 2 is completed.

The optical connector 50 is assembled when the outer gripping member 60 is housed in the gripping member housing case 54, so that the optical fiber 2a is placed between the rear end of the ferrule 30 with a clamp portion and the optical fiber cable 2 terminal. The lead length of the optical fiber 2a of the optical fiber cable 2 is set so that a slight deflection is formed, and the elasticity of the optical fiber 2a itself causes the elasticity of the optical fiber 2a to the built-in optical fiber 320 of the ferrule 30 with a clamp portion. Make sure that the butt force is applied.
The insertion member 40 inserted between the elements 35 and 36 of the clamp portion 33 of the ferrule 30 with a clamp portion is pulled out by the built-in optical fiber 320 and the bare optical fiber 2a1 at the distal end of the optical fiber 2a (hereinafter referred to as insertion-side bare light). The insertion-side bare optical fiber 2a1 is kept in a butt-matched state with respect to the refractive index matching material layer 321 at the rear end of the built-in optical fiber 320. Then, it is held and fixed between the elements 35 and 36 of the clamp part 33. The optical fiber 2a of the optical fiber cable 2 (specifically, the insertion-side bare optical fiber 2a1) is optically connected to the built-in optical fiber body 32 via the refractive index matching material layer 321 at the rear end of the built-in optical fiber 320. Even if the insertion-side bare optical fiber 2a1 has an uneven surface, the butt connection with the built-in optical fiber 320 and the optical connection with the built-in optical fiber main body 32 can be reliably realized.

(Another embodiment)
FIG. 13 shows an optical connector 70 according to another embodiment of the present invention.
This optical connector 70 has a ferrule 71 as a built-in optical fiber 320A having a shorter length than the fiber hole 71a in a fiber hole 71a passing through the ferrule 71, and one end (tip) in the longitudinal direction of the ferrule 71. A configuration in which the inner end is fixed so as to be aligned with the joining end surface 71 b is employed, and the ferrule 71 is accommodated in a sleeve-like housing 72.

As described above, the insertion optical fiber 1 is a coated optical fiber such as an optical fiber core or an optical fiber. Further, the insertion optical fiber 1 may be an optical fiber (coated optical fiber) led out to the end of the optical fiber cable 2.
In the optical connector 70, the insertion optical fiber 1 can be inserted into the housing 72 from the rear end side opposite to the front end side of the housing 72 where the joining end face 71b of the ferrule 71 is disposed. Then, the bare optical fiber 1a exposed by removing the coating at the tip of the insertion optical fiber 1 is inserted into the fiber hole 71a from the rear end side of the ferrule 71, and the refractive index matching material at the rear end of the built-in optical fiber 320A. By being in contact with the layer 321, it can be connected to the built-in optical fiber 320 </ b> A.

In the case of this optical connector 70, the fiber hole 71a itself of the ferrule 71 functions as a centering part that aligns the insertion-side bare optical fiber 1a so that the built-in optical fiber 320A can be abutted and connected. An empty portion (alignment portion 71c) for aligning the insertion-side bare optical fiber 1a is secured in the fiber hole 71a on the rear end side from the built-in optical fiber 320A.
The built-in optical fiber 320A is shorter than the fiber hole 71a and has the same configuration as the built-in optical fiber 320 except that its entire length is inserted and fixed in the fiber hole 71a. It is the composition of.

(Verification test 1)
The present inventor uses a single-core optical fiber as the insertion optical fiber, and uses a nail clipper 91 to cut the tip of the bare optical fiber 1a pierced to the tip of the insertion optical fiber as shown in FIG. A sample (hereinafter also referred to as a first test optical fiber) in which an end surface defect is intentionally formed, and a sample (hereinafter also referred to as a second test optical fiber) in which the tip of the bare optical fiber is cut using a cleaver. The optical connector 10 illustrated in FIGS. 1 and 2 was assembled at the tips of the test optical fibers, and optical characteristics (comparison of connection loss characteristics) were evaluated.

The bare optical fibers of the optical fibers used for the production of the first and second test optical fibers are silica-based single mode optical fibers having a diameter of 125 μm.
The built-in optical fiber 320 of the ferrule 30 with a clamp portion of the optical connector 10 uses a silica-based single mode optical fiber having a diameter of 125 μm as the built-in optical fiber main body 32, and matches the refractive index to the rear end face 32a of the built-in optical fiber main body 32. A film attached and provided with a refractive index matching material layer 321 was used. The built-in optical fiber main body 32 is formed by forming a chamfered portion 32b by electric discharge machining on the outer periphery of the end surface of a bare optical fiber for producing the built-in optical fiber main body 32.
The refractive index matching film is a polymer film having refractive index matching, and has a self-adhesive property made of Yodogawa Paper Mill FW2L-30-EF (trademark). The refractive index matching film has a film thickness of 5 to 40 μm and an insertion loss of 1 dB or less.

In the test, ten first and second test optical fibers were prepared, the optical connector 10 was assembled for each test optical fiber, and two types of test light with wavelengths of 1310 nm and 1550 nm were sent to the inserted optical fiber. The connection loss was measured for each wavelength.
The results are summarized in Table 1.
In Table 1, “nail clipper” is “loss” when the first test optical fiber is used as the insertion optical fiber, and “high-precision cleaver” is “loss” when the second test optical fiber is used as the insertion optical fiber. Indicates connection loss.

  As shown in Table 1, for both test light wavelengths 1310 nm and 1550 nm, when the optical connector was assembled using the first test optical fiber using a nail clipper for cutting the bare optical fiber, It was confirmed that the splice loss characteristics comparable to those of the test optical fiber were obtained.

(Verification test 2)
A heat cycle test was performed on a specimen (an optical fiber with a connector) in which an optical connector was assembled at the tip of the first and second optical fibers to be tested. In this heat cycle test, the specimen was housed in the test chamber, and the temperature (air temperature) in the test chamber was changed in the range of −35 ° C. to 75 ° C. to examine the connection loss variation of the specimen. The temperature inside the test chamber was raised from normal temperature (25 ° C. here) to 75 ° C., lowered from 75 ° C. to normal temperature, lowered from normal temperature to −35 ° C., raised from −35 ° C. to normal temperature, normal temperature The temperature was raised from 1 to 75 ° C. in this order with a required time of 1 hour. That is, the temperature was raised from room temperature to 75 ° C., the temperature was lowered to −35 ° C., and then the temperature was raised again to 75 ° C. In addition, a holding time at 75 ° C. and −35 ° C., a holding time at room temperature during a temperature lowering from 75 ° C. to −35 ° C. and a temperature rising from −35 ° C. to 75 ° C. are secured for 1 hour, respectively, for a total of 12 Time testing was performed.

The results of the heat cycle test are shown in FIG. In FIG. 15, “Sample 1” is a specimen (hereinafter also referred to as a first specimen) assembled using the first sample optical fiber, and “Sample 2” is assembled using the second specimen optical fiber. A specimen (hereinafter also referred to as a second specimen).
As can be seen with reference to FIG. 15, the second specimen showed almost no variation in connection loss with respect to temperature change in the test chamber. On the other hand, the first specimen has a temperature range (−35 ° C.) in which the variation of the connection loss is slightly larger than that of the second specimen, but the variation width of the connection loss in the temperature range is about 0.02 dB. It was confirmed that a characteristic comparable to that of the first specimen was obtained.

  Regarding the first specimen, the connection loss fluctuated with a fluctuation range of about 0.02 dB appeared only when the temperature inside the test chamber was around -35 ° C. Although this point requires further verification, one guess is the low temperature brittleness of the resin forming the refractive index matching film. According to this inference, it is considered that the variation of the connection loss under a low temperature environment can be further reduced by adopting a refractive index matching film having a low embrittlement temperature.

From the results of the verification tests 1 and 2, it was confirmed that the first specimen had characteristics inferior to those of the first specimen.
In the optical connector according to the present invention, even when the bare optical fiber tip of the inserted optical fiber is cut using a simple cutting instrument such as a nail clipper, the connection loss is almost the same as when a dedicated cleaver is used. Since the characteristics (connection loss characteristics of the connection portion where the built-in optical fiber and the inserted optical fiber are connected to each other) can be secured, it is possible to omit the delivery of the dedicated cleaver to the site. In addition, it is easy to ensure good connection loss characteristics even if there is unevenness on the end face of the bare optical fiber tip cut out from the end of the inserted optical fiber, so that the connector assembly due to the bare optical fiber cut failure There is also an advantage that the number of rework can be reduced.

In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the main point, it can change suitably.
For example, as described above, the element part of the clamp part of the ferrule with a clamp part is configured by the base side element 35 fixed to the ferrule 31 and the lid side element 36 composed of two members, the front side element 361 and the rear side element 362. However, it is also possible to employ a single member as the lid-side element.
Further, the configuration is not limited to the configuration in which the alignment groove is formed in the base side element, and a configuration in which the alignment groove is formed in the lid side element can also be adopted.

  The housing of the optical connector that houses the ferrule with the clamp portion is not particularly limited. For example, an SC type optical connector, a so-called SC2 type optical connector (a knob is omitted from the SC type optical connector), an MU type optical connector. The same housing as that in which the insertion member insertion hole is formed can be adopted.

In the above-described embodiment, an optical connector (an optical connector with an insertion member) having a configuration in which an insertion member is inserted between the elements in advance and the elements are opened is exemplified. The insertion member is not inserted between the elements of the clamp part of the ferrule with a clamp part, and the insertion member is inserted between the elements when the insertion optical fiber is inserted between the elements. Therefore, it is possible to adopt a configuration in which the work for opening the elements can be performed.
For example, as shown in FIGS. 2 and 6B, the elements 35 and 36 of the clamp part 33 of the ferrule with a clamp part illustrated in the above-described embodiment are inserted so as to be interrupted between the elements 35 and 36. The insertion recesses 35 a and 36 a in which the distal end portion 40 a of the insertion member 40 is disposed are formed so as to open at positions facing the side opening 37 d of the spring 37. As shown in FIG. 4, the insertion recesses 35 a and 36 a are formed by recessing the end portions on the side opening 37 d side of the facing surfaces of the elements 35 and 36. After the insertion member 40 inserted between the elements 35 and 36 in a state where the distal end portion 40a is housed in the insertion recesses 35a and 36a, the insertion member 40 is pulled out from between the elements 35 and 36, and then the insertion The elements 35 and 36 can be opened by inserting the insertion member 40 into the recesses 35a and 36a so as to be interrupted between the elements 35 and 36. That is, the optical connectors 10 and 50 of the above-described embodiment are configured so that the insertion member 40 is interrupted between the elements 35 and 36 from the state where the insertion member 40 is not interposed between the elements 35 and 36 and the elements 35 and 36 are inserted. 36 can be opened.

The built-in optical fiber body of the built-in optical fiber is not limited to a bare optical fiber, and may be an optical fiber core wire, an optical fiber strand, or the like.
The present invention is not limited to the configuration in which the bare optical fiber exposed at the tip of the insertion optical fiber is abutted against the rear end of the built-in optical fiber, and the insertion light is a coated optical fiber such as an optical fiber core or an optical fiber. It is also possible to employ a configuration in which the coating portion coated with the fiber coating material is directly butted and connected to the rear end of the built-in optical fiber.
In the above-described embodiment, the insertion-side bare optical fibers 1a and 2a1 themselves also function as insertion optical fibers.

In the above-described embodiment, the optical connector having a configuration in which the ferrule with the clamp portion is housed in the housing is illustrated. However, the present invention is not limited to this, and the clamp portion includes a centering portion and is separate from the ferrule. The optical connector of the structure which accommodated this in the housing is also included.
In the present invention, a liquid refractive index matching material such as silicone grease may be provided at a connection portion where the built-in optical fiber and the insertion optical fiber are abutted.

DESCRIPTION OF SYMBOLS 1 ... Insertion optical fiber, 1a ... Insertion optical fiber (bare optical fiber), 2 ... Optical fiber cable, 2a ... Optical fiber, 2a1 ... Insertion optical fiber (bare optical fiber), 2b ... Strength member, 2c ... Resin coating material,
DESCRIPTION OF SYMBOLS 10 ... Optical connector, 20 ... Housing, 30 ... Ferrule with clamp part, 31 ... Ferrule, 31a ... Joining end surface, 31b ... Fiber hole, 32 ... Built-in optical fiber main body, 32a ... Rear end surface, 32b ... Chamfering part, 33 ... Clamp 35: Base element, 35f: Opposing surface, 36: Lid element, 361: Lid element (front element), 361f: Opposing surface, 362: Lid element (rear element), 362f: Opposing surface, 37 ... Spring, 38a ... Alignment part (alignment groove), 40, 41, 42 ... Insertion member,
50 ... Optical connector, 511 ... Housing, 52 ... Cable retainer,
70... Optical connector, 71... Ferrule, 72... Housing, 71 c.

Claims (9)

The ferrule (31, 71), the housing (20, 511, 72) for housing the ferrule, and the joint end surface (31a, 71b) of the ferrule tip of the optical fiber (32) inserted and fixed to the ferrule Built-in optical fibers (320, 320A) having a configuration in which a refractive index matching material layer (321) made of a light-transmitting polymer material is provided on the rear end surface (32a) opposite to the combined tip, and the built-in light A centering portion (38a, 71c) for positioning the insertion optical fiber (1, 2a), which is an optical fiber inserted into the housing separately with respect to the fiber, so as to be able to butt and connect,
The built-in optical fiber body (32), which is an optical fiber inserted and fixed to the ferrule, has a chamfered portion (32b) formed on the outer periphery of the rear end thereof, and the inserted optical fiber abutted against the refractive index matching material layer is An optical connector (10, 50, 70), wherein the optical connector (10, 50, 70) is optically connected to the built-in optical fiber body through the refractive index matching material layer functioning as a cushion layer.   The optical connector according to claim 1, wherein the refractive index matching material layer is formed of a synthetic resin film adhered to a rear end surface of the built-in optical fiber body.   2. The optical connector according to claim 1, wherein the refractive index matching material layer is a resin film formed by applying or vapor-depositing a liquid polymer material on a rear end surface of the built-in optical fiber body.   The optical connector according to claim 1, wherein the chamfered portion is a curved surface that curves from an outer edge of a rear end surface of the built-in optical fiber body to an outer peripheral surface of the built-in optical fiber body. .   The built-in optical fiber and the insertion optical fiber butted against the refractive index matching material layer at the rear end of the built-in optical fiber are sandwiched between the half elements (35, 36) by the elasticity of the spring (37). A clamp portion (33) for maintaining a butt connection state between the built-in optical fiber and the insertion optical fiber is provided, and one or both of the opposing surfaces (35f, 361f) of the pair of elements of the clamp portion facing each other are provided. An alignment groove (38a) for aligning the built-in optical fiber and the insertion optical fiber so as to be able to butt and connect is formed, and the alignment groove functions as the alignment portion. The optical connector in any one of 1-4.   The ferrule with a clamp part (30) formed by assembling the said clamp part of the structure which accommodated the said element of the half inside the sleeve-like spring inside the said ferrule is characterized by the above-mentioned. The optical connector described.   An insertion member (40, 41, 42) for maintaining an open state between the elements is interposed between the pair of elements of the clamp part so as to be removable from between the elements. Item 7. The optical connector according to item 5 or 6.   The internal optical fiber body having a shorter length than the fiber hole is inserted and fixed in a fiber hole (31b) that penetrates the ferrule, and the inserted optical fiber is inserted into the fiber hole from the rear end side of the ferrule. Is configured to be butt-connected to the rear end of the built-in optical fiber in a fiber hole, and a portion (71c) on the rear end side from the built-in optical fiber of the fiber hole functions as the aligning portion. An optical connector (70) according to any of the preceding claims.   At the rear end portion opposite to the front end side where the joint end face of the ferrule of the housing is arranged, the resin coating material (2c) is combined with a linear strength member (2b) in which the optical fiber (2a) is vertically attached to the optical fiber. ) Is provided with a cable retaining portion (52) for holding the terminal of the optical fiber cable (2) embedded and integrated in the housing and retaining it on the housing, and the inserted optical fiber is an optical fiber of the optical fiber cable. The light according to any one of claims 1 to 8, wherein a tip of a portion of the optical fiber led to an optical fiber cable terminal is connected to a rear end of the built-in optical fiber. Connector (50).

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