JP2001228360A - Optical connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical connector which has a high optical coupling efficiency, which is hardly scratched in the end face of an optical fiber, and which facilitates the handling as well as the manufacturing or assembling. SOLUTION: The ferule 31 of the plug 30 attached to the end of an optical fiber 40 is formed, in the center of the end face, with a concave opening 31b-2 whose diameter increases from the inside to the outside. In the end of a coated optical fiber 41, a convex lens 41a is formed having a spherical face at a position flush with or inside of the end face 31b-1. When the plug 30 with the optical fiber 40 connected is inserted into a receptacle 50, an outgoing light from the receptacle 50 is converged by the concave opening 31b-2 and also by the convex lens 41a. As a result, it further enhances an optical coupling effect between the plug 30 and the receptacle 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connector such as a plug for connecting an optical fiber in a digital home electric appliance or the like.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
For example, there was one as shown in FIG. FIG. 2 is a longitudinal sectional view showing an example of a configuration of a plug which is one of conventional optical connectors. The plug 10 which is one of the optical connectors
Is attached to an end of the optical fiber 20, and is detachably fitted to, for example, a receptacle (not shown) to optically couple the optical fiber 20 to the receptacle. The optical fiber 20 has a fiber core 21 for transmitting light,
In order to protect the circumference of the fiber core 21, a jacket 22 is provided.
Etc. The plug 10 has a ferrule 11 for holding an end of the optical fiber 20, and a grip 12 is attached to the rear end of the ferrule 11.

The ferrule 11 has a fiber insertion hole 11a for receiving and holding the optical fiber 20 from the rear end side, and further has a cylindrical core wire holding portion 11b protruding from the front end side of the ferrule 11. . Cord holding part 11b
The end face 11b-1 is in contact with the optical reference plane PS of the receptacle, and a core insertion hole 11c is formed at the center of the core holding part 11b. Wire insertion hole 1
Reference numeral 1c communicates with the fiber insertion hole 11a and receives and holds the fiber core 21 exposed from the end face of the optical fiber 20 inserted into the fiber insertion hole 11a. An annular fitting concave portion 11d for fitting with the receptacle is formed on the outer periphery of the core wire holding portion 11b, and a fitting abutting surface 11d-1 at the bottom of the fitting concave portion 11d is fitted to the fitting convex portion of the receptacle. Abuts on the fitting abutment surface at the tip of the. The grip 12 attached to the rear end of the ferrule 11 covers the optical fiber 20 protruding from the rear end of the ferrule 11 and is gripped when the optical fiber 20 is attached to and detached from the receptacle.

When the plug 10 of such an optical connector is inserted into a receptacle (not shown) at the time of use, the fitting projection of the receptacle fits into the fitting recess 11d of the plug 10, and the fitting projection is formed. Abuts against the fitting abutment surface 11d-1 at the bottom of the fitting recess 11d, and the end surface 11b-1 of the core wire holding portion 11b contacts the optical reference plane PS of the receptacle. Thereby, the end face 21a of the fiber core wire 21 located on the same plane as the end face 11b-1 of the core wire holding part 11b is optically coupled to, for example, a light emitting element or a light receiving element provided in the receptacle. For this reason, the light transmitted through the fiber core 21 of the optical fiber 20 is emitted from the end face 21a of the fiber core 21 and received by the light receiving element in the receptacle. Alternatively, light emitted from the light emitting element in the receptacle enters the end face 21 a of the fiber core 21 and is transmitted by the fiber core 21. In addition, such an optical connector plug 10
In use, is connected to another optical connector via a receptacle (not shown), and is optically coupled to another optical fiber with low loss.

In the plug 10 of this type of optical connector, the end face 21a of the fiber core 21 is optically polished in order to satisfy the requirements of low loss connection and reproducibility. Further, in order to improve the optical coupling efficiency, for example, Japanese Unexamined Patent Application Publication No.
In the invention described in Japanese Patent Publication No. 2111, a device as shown in FIG. 3 is employed.

FIG. 3 is an enlarged longitudinal sectional view showing the vicinity of the plug end portion of FIG. In the plug 10 of FIG. 3, a convex lens portion 21b having a spherical surface located on the optical reference plane PS of the receptacle is formed at the end of the fiber core 21. When such a convex lens portion 21b is formed, light is converged as indicated by a one-dot chain line, and the light converging function improves the efficiency of light coupling with the receptacle.

[0007]

However, the plug 10 of the optical connector shown in FIG. 3 has the following problems (1) and (2). (1) As shown by the solid line and the one-dot chain line in FIG. 3, a convex lens formed at the end of the fiber core 21 in order to substantially increase the exit area and the entrance area of the end face of the fiber core 21. The spherical surface of the portion 21b protrudes from the end surface 11b-1 of the core wire holding portion 11b. For this reason, the plug 10
During storage, etc., the spherical surface of the convex lens portion 21b is easily damaged. Therefore, the spherical surface of the convex lens 21b must be protected by covering the end surface 11b-1 of the core wire holding portion 11b with a protective cap or the like. Cost. Further, since the spherical surface of the convex lens portion 21b protrudes from the end surface 11b-1, when the plug 10 is inserted into the receptacle, the vertex of the spherical surface of the convex lens portion 21b is set to the optical reference plane P of the receptacle.
A total load is applied to the apex in contact with S, and the spherical surface is easily damaged. (2) In order to solve the problem (1), as shown by a two-dot chain line in FIG.
(That is, inside the opening end face of the core wire insertion hole 11c)
It is conceivable to retreat. However, with such a structure, the exit area and the entrance area of the end face of the fiber core 21 are substantially reduced, so that the optical axis shift and the angle shift at the fiber core end face are liable to occur. It takes time to assemble.

An object of the present invention is to provide an optical connector which solves the problems of the prior art, has high optical coupling efficiency, does not easily damage the end face of the fiber core, is easy to manufacture and assemble, and is easy to handle. With the goal.

[0009]

According to a first aspect of the present invention, an end portion of an optical fiber having a sheath coated around an optical fiber core for transmitting light. An optical connector having a ferrule attached to the optical fiber, wherein the ferrule has a fiber insertion hole for receiving and holding the optical fiber, a cylindrical core holding portion having an end surface in contact with an optical reference surface of a receptacle, and the fiber A core insertion hole formed in the core holding portion in communication with the insertion hole, for receiving and holding the fiber core exposed from the end face of the optical fiber in the fiber insertion hole; and the core insertion hole Formed at the end of the fiber core wire having a concave opening having a larger diameter toward the end face of the core wire holding portion from the inside to the outside, at the end of the fiber core wire exposed from the opening, The cord It forms a convex lens portion having a spherical surface located inside the end surface flush with or end surface of the lifting portion.

[0010] By adopting such a configuration, for example, when the core holding portion of the ferrule attached to the end of the optical fiber is inserted into the receptacle, the end face of the core holding portion becomes the optical reference of the receptacle. The optical axis of the convex lens portion at the end of the fiber core held in the core wire insertion hole and the optical axis of the receptacle coincides with the surface. The light transmitted by the fiber core is focused by the convex lens at the end of the fiber core, and is sent to the receptacle side. Further, the light emitted from the receptacle side is focused toward the center of the core wire insertion hole at the opening of the core wire holding portion, and is focused toward the center of the fiber core wire by the convex lens portion of the fiber core. . As described above, light focused toward the center of the fiber core by the opening of the core holding part and the convex lens part of the fiber core is transmitted by the fiber core.

According to a second aspect of the present invention, in the optical connector of the first aspect, the convex lens portion formed at the end of the fiber core has a diameter substantially equal to the outer diameter of the fiber core. . In a third aspect, in the optical connector according to the second aspect, the jacket at the end of the optical fiber is peeled off by a predetermined length to expose the fiber core, and a convex lens portion is provided at the end of the fiber core. The ferrule is formed such that the convex lens portion of the fiber core is inserted from the fiber insertion hole of the ferrule into the core wire insertion hole, and the convex lens portion is fixed at a predetermined position in the opening of the ferrule. By adopting such a configuration, when attaching a ferrule to the end of the optical fiber, for example, peeling the jacket of the end of the optical fiber to expose the fiber core, and attaching the ferrule to the end of this fiber core A convex lens portion is formed. Then, by inserting the convex lens portion of the fiber core wire from the fiber insertion hole of the ferrule into the core wire insertion hole and fixing the convex lens portion at a predetermined position in the opening of the ferrule, the ferrule is attached to the end of the optical fiber. .

According to a fourth aspect, in the optical connector according to the first aspect, the convex lens portion formed at the end of the fiber core has a shape having a diameter larger than the outer diameter of the fiber core. As a result, the area of the exit port and the area of the entrance port at the end of the fiber core are widened. For example, even if the light emitted from the receptacle side spreads, these are efficiently focused at the center of the fiber core.

According to a fifth aspect of the present invention, in the optical connector according to the fourth aspect of the present invention, the sheath at the end of the optical fiber is peeled off by a predetermined length to expose the fiber core, and the end of the fiber core is removed. A convex lens portion is formed at the end of the fiber core wire by penetrating from the fiber insertion hole of the ferrule to the core wire insertion hole, and the convex lens portion of the fiber core wire is pulled back to the end side of the core wire insertion hole. The convex lens portion is fixed to a predetermined position in the opening of the ferrule. This allows
When a ferrule is attached to the end of the optical fiber, for example, the sheath of the end of the optical fiber is peeled to expose the fiber core, and the end of the fiber core is inserted from the fiber insertion hole of the ferrule to the core insertion hole. Through. Then, a convex lens portion is formed at the end of the fiber core wire protruding from the core wire insertion hole, and the convex lens portion of the fiber core wire is pulled back to the end portion side of the core wire insertion hole, and the convex lens portion is inserted into the ferrule opening. Is fixed at the predetermined position, the ferrule is attached to the end of the optical fiber.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS.
FIG. 3 (3) is a configuration diagram of a rectangular optical connector showing a first embodiment of the present invention. FIG. 1 (1) is a longitudinal sectional view of a plug, and FIG. 2 (2) is a diagram showing the plug of FIG. (3) is an enlarged vertical cross-sectional view near the plug end of FIG. (1). This rectangular optical connector
It has a rectangular plug 30, and an optical fiber 40 is connected to the rectangular plug 30. When the rectangular plug 30 is detachably fitted to the rectangular receptacle 50, the optical fiber 40 and the receptacle 50 are optically coupled.

The plug 30 is composed of a ferrule 31 attached to the end of the optical fiber 40 and a grip 32 for covering the vicinity of the connection between the ferrule 31 and the optical fiber 40. The ferrule 31 is formed of a synthetic resin or the like, and has a fiber insertion hole 31a that receives and holds the optical fiber 40 from the rear end side. Ferrule 31
A cylindrical core wire holding portion 31b is protrudingly provided at the tip end of the wire. The end surface 31b-1 of the core wire holding portion 31b abuts on the optical reference plane PS of the receptacle 50 when inserted into the receptacle 50, and a core wire insertion hole 31c is formed at the center thereof. One end of the cord insertion hole 31c communicates with the fiber insertion hole 31a, and the other end of the cord insertion hole 31c.
The opening b is open at the end face 31 b-1 of the optical fiber 40, and receives and holds the fiber core 41 of the optical fiber 40.

On the opening side of the core wire insertion hole 31c, there is formed a concave opening 31b-2 whose diameter increases from the inside toward the end face 31b-1. An annular fitting concave portion 31d for fitting with the receptacle 50 is formed on the outer periphery of the core wire holding portion 31b, and the fitting abutment surface 31d-1 at the bottom of the fitting concave portion 31d has a tip end portion of the receptacle 50. Abuts. At the position of the mechanical reference plane MS on the outer periphery of the ferrule 31, the locking projections 31 are vertically arranged.
e and 31f are formed respectively. A fiber stopper 31 g for fixing the optical fiber 40 is provided on the outer periphery of the rear end side of the ferrule 31. The grip 32 covering the rear end side of the ferrule 31 is made of synthetic resin or the like, and fixes and protects the vicinity of the connection point between the ferrule 31 and the optical fiber 40.

As the optical fiber 40, various fibers such as a plastic fiber and a glass fiber are used. The optical fiber 40 includes a core, which is an optical transmission region, and a fiber core 4 formed of a clad surrounding the core.
1 and a jacket 42 made of plastic resin or the like for protecting the periphery of the fiber core 41. The end of the optical fiber 40 is inserted into the fiber insertion hole 31a, and the fiber core 41, which is exposed by peeling the jacket 42 of the optical fiber 40 by a predetermined length, is inserted into the core insertion hole 31c. I have. At the end of the fiber core 41, the core holding part 3 is provided.
1b, the same plane as the end face 31b-1 or the end face 31b-1
A convex lens portion 41a having a spherical surface located on the inner side is formed. The convex lens portion 41a is
1 has substantially the same diameter as the outer diameter.

Receptacle 50 into which plug 30 is inserted
Is made of a synthetic resin or the like and has a bottomed cylindrical shape. Above and below this tubular tip-side annular protrusion 51,
Locking notches 52 and 53 for engaging with the locking projections 31e and 31f are formed. Receptacle 50
A cylindrical fitting projection 55 is protruded from the bottom 54 of the plug 3, and a fitting abutment surface 55 a on the distal end side of the fitting projection 55 is connected to the plug 3.
It comes into contact with the fitting abutment surface 31d-1 on the 0 side. A through hole 56 is formed in the cylindrical fitting projection 55,
The core wire holding portion 31b on the plug 30 side is inserted into the through hole 56. A light emitting element and a light receiving element are provided on the optical reference plane PS of the receptacle 50, or an optical system or the like for optically coupling with another optical fiber is provided.

Next, an example of manufacturing and assembling the plug 30 shown in FIG. 1 will be described. First, the sheath 42 at the end of the optical fiber 40 is peeled off by a predetermined length to expose the fiber core 41, and the end of the fiber 41 is substantially the same as the outer diameter of the fiber 41. Lens portion 41a having a diameter of
To form As a method of forming the convex lens portion 41a, for example, when the optical fiber 40 is a plastic-based fiber, the end of the fiber core 41 is pressed against a heated concave lens-shaped mold, and the end is thermally deformed. Part 4
1a is formed. The convex lens portion 41a of the plastic fiber may be formed by polishing the end of the fiber core 41 with a polishing machine or the like. Similarly, in the case of a glass-based fiber or the like, using a polishing machine or the like, the fiber core 41 is used.
Is optically polished to form a convex lens portion 41a.

After the convex lens portion 41a of the fiber core 41 is formed, the convex lens portion 41a side is inserted from the fiber insertion hole 31a of the ferrule 31 into the core wire insertion hole 31c, and the apex of the convex lens portion 41a is held in a core wire. End face 3 of part 31b
It is located on the same plane as 1b-1 or inside the end face 31b-1. Then, the outer periphery of the optical fiber 40 is fixed by a fiber stopper 31g provided on the rear end side of the ferrule 31. Thereafter, if the grip portion 32 is put on the rear end side of the ferrule 31 by insert molding or the like, the vicinity of the connection portion between the ferrule 31 and the optical fiber 40 is covered and protected by the grip portion 32, and the optical fiber 40 is attached. The plug 30 is completed.

An example of the use of the plug 30 manufactured and assembled in this manner will be described below. Holding the grip portion 32 of the plug 30 by hand, the outer peripheral surface of the ferrule 31 is applied to the inner peripheral surface of the annular projecting portion 51 of the receptacle 50,
The ferrule 31 is inserted into the receptacle 50. Then, the core holding portion 31b of the plug 30 is connected to the receptacle 50.
Of the plug 50, the cylindrical fitting projection 55 of the receptacle 50 is inserted into the annular fitting recess 31d of the plug 30, and the fitting abutment surface 31d of the plug 30 is formed. -1 and the fitting abutment surface 55 of the receptacle 50
a contacts. When the fitting abutment surfaces 31d-1 and 55a abut, the locking projections 31e and 31f of the plug 30 fit into the locking notches 52 and 53 of the receptacle 50. As a result, the plug 30 is fitted into the receptacle 50, and the end surface 31b-1 of the core holding portion 31b of the plug 30 is formed.
Are located on the optical reference plane PS of the receptacle 50.

With the plug 30 inserted into the receptacle 50, for example, light transmitted from the left side to the right side of the optical fiber 40 in FIG. 1 is transmitted at the interface between the core at the center of the fiber core 41 and the surrounding clad. , While repeating total reflection,
End face 31b-1 of plug 30 confined inside the core
It is transmitted in the direction. The light transmitted to the end of the plug 30 is transmitted to the convex lens 41 at the end of the fiber ribbon 41.
The light is focused at a and sent to the optical reference plane PS of the receptacle 50. The light transmitted to the optical reference plane PS is received by, for example, a light receiving element, or enters an optical system or the like and is transmitted to another optical fiber.

The light emitted from the light emitting element in the receptacle 50 or the light emitted from the optical system or the like is
As shown by the one-dot chain line in FIG. 1 (3), the light is focused toward the center of the core wire insertion hole 31c by the concave opening 31b-2 on the plug 30 side, and furthermore, the fiber core 41 is formed by the convex lens part 41a. The light is focused in the center direction and is incident on the core at the center of the fiber core 41. Light incident on the core at the center of the fiber core 41 is at the interface with the surrounding cladding,
While repeating total reflection, it is confined inside the core and transmitted.

In the first embodiment, the following (a) to
There is an effect as shown in FIG. (A) Since the convex lens portion 41a is formed at the end of the fiber core 41, the light coupling function of the convex lens portion 41a improves the optical coupling efficiency. Moreover, the core wire holding portion 31b
The concave opening 31b-2 is formed at the end of the receptacle 5 so that the receptacle 5
Light emitted from 0 is focused toward the center of the core wire insertion hole 31c. Thereby, the light coupling efficiency is further improved in combination with the light focusing function of the convex lens portion 41a. Further, since the concave opening 31b-2 is formed, the exit area and the entrance area of the end face of the fiber ribbon 41 are substantially increased. As a result, the optical axis shift and the angle shift at the fiber core end face are less likely to occur, and the manufacture and assembly are facilitated.

(B) The apex of the spherical surface of the convex lens portion 41a is located on the same plane as or inside the end surface 31b-1 of the core wire holding portion 31b.
Since it is not exposed from b-1, that is, it does not protrude, the convex lens portion 41a is not easily damaged when the plug 30 is stored, inserted into the receptacle 50, or fitted. This eliminates the need for measures to prevent damage and facilitates handling. (C) When the plug 30 is inserted into and fitted into the receptacle 50, the end surface 31 b-1 of the core wire holding portion 31 b is on the convex lens portion 4 on the optical reference plane PS of the receptacle 50.
Since it covers the periphery of 1a, it is possible to prevent intrusion of light from the outside which causes noise, and a light-shielding effect is obtained.

(Second Embodiment) FIG. 4 is a view showing the configuration of a round optical connector according to a second embodiment of the present invention. Are denoted by common symbols. FIG. 4 shows a vertical cross-sectional view of a state where the plug and the receptacle are fitted. The round optical connector of the present embodiment has a round plug 30A indicated by a solid line.
And a round receptacle 50A indicated by a two-dot chain line.

The plug 30A comprises a ferrule 31A made of metal or the like attached to the end of the optical fiber 40, and a grip 32A made of synthetic resin or the like attached around the rear end of the ferrule 31A. ing. The ferrule 31A has a substantially cylindrical shape, at the center of which a fiber insertion hole 31a and a core wire insertion hole 31c are formed as in FIG. On the end surface 31b-1 of the core wire holding portion 31b,
A concave opening 31b-2 is formed as in FIG. 1, and a convex lens portion 41a formed at the end of the fiber ribbon 41 is inserted into the opening 31b-2. The locking projections 31e and 31 of FIG.
An annular concave portion 31h for locking corresponding to f is formed. Further, a flange 31i serving as a mechanical reference plane MS is provided on the outer periphery on the rear end side of the ferrule 31A. A cylindrical protruding portion 32a that receives the distal end of the receptacle 50A is provided on the distal end of the grip portion 32A that covers the rear end of the ferrule 31A.

The receptacle 50A is, for example, attached to the panel outer surface 70 and has a through hole 56 for receiving the ferrule 31A. A cylindrical protrusion 57 is provided on the distal end side of the receptacle 50A, and the protrusion 57 is inserted into the protrusion 32a of the grip 52A. Locking engagement portions 58 corresponding to the lock notches 52 and 53 in FIG. 1 are provided in the through holes 56. The engaging portion 58 is formed by a contact piece or the like, and is adapted to engage with the annular concave portion 31h of the ferrule 31A.

The optical connector having such a structure is manufactured and assembled in substantially the same manner as in the first embodiment. When the manufactured and assembled optical connector is used, for example, when the core holding portion 31b of the plug 30A with the optical fiber 40 is inserted into the through hole 56 of the receptacle 50A, the receptacle 50A is inserted into the projection 32a of the plug 30A. Is inserted and hits. And ferrule 31
A of the engagement portion 5 of the receptacle 50A in the annular concave portion 31h of FIG.
8, the core holding portion 31b of the ferrule 31A is held in the through hole 56 of the receptacle 50A, and the end surface 31b-1 of the core holding portion 31b is located on the optical reference plane PS of the receptacle 50A. . Thus, similarly to the first embodiment, the plug 30A and the receptacle 50A are optically coupled, and light is transmitted from the optical fiber 40 to the optical reference plane PS of the receptacle 50A, or light is transmitted from the optical reference plane PS. Light is transmitted to the fiber 40. This second
In the optical connector of the embodiment, the same effects as those of the first embodiment can be obtained.

(Third Embodiment) FIG. 5 shows a third embodiment of the present invention.
FIG. 1 is a configuration diagram of a round optical connector according to an embodiment of the present invention.
Elements common to those in FIG. 1 showing the second embodiment or FIG. 4 showing the second embodiment are denoted by the same reference numerals. FIG. 5 shows a vertical cross-sectional view of a state where the plug and the receptacle are fitted. The round optical connector of the present embodiment includes a round plug 30B shown by a solid line and a round receptacle 50B shown by a two-dot chain line.

The plug 30B is made of a ferrule 3 made of metal or the like.
1B and a grip portion 32B made of synthetic resin or the like that covers the rear end side of the ferrule 31B. Ferrule 3
1B has substantially the same shape as the ferrule 31A of FIG. That is, the ferrule 31B has a substantially cylindrical shape, and a locking engagement portion 31j having a shape different from that of the locking annular concave portion 31h of FIG. 4 is formed on the outer periphery of the core wire holding portion 31b on the distal end side. . The diameter of the engaging portion 31j is narrowed like a step, and the end surface 31b-
The diameter gradually increases toward 1. The gripping portion 32B that covers the rear end side of the ferrule 31B has a distal end surface located on the mechanical reference plane MS, and is configured to contact the distal end portion of the receptacle 50B. The receptacle 50B has a cylindrical plug holding portion 59 for receiving the ferrule 31B, and the distal end surface of the plug holding portion 59 comes into contact with the mechanical reference surface MS of the distal end surface of the grip portion 32B. I have. The ferrule 31B is provided in the plug holding portion 59.
Is provided with a locking engaging portion 60 for engaging with the engaging portion 31j.

The optical connector having such a structure is manufactured and assembled in substantially the same manner as the optical connector shown in FIG. 1 or FIG. When using manufactured and assembled optical connectors,
For example, the ferrule 31B of the plug 30B is inserted into the plug holding portion 59 of the receptacle 50B. Then, the mechanical reference surface MS of the grip portion 32B abuts on the plug holding portion 59, the engaging portion 31j of the ferrule 31B engages with the engaging portion 60 of the receptacle 50B, and the end surface 31b-1 of the core wire holding portion 31b is moved. Optical reference plane P of receptacle 50B
S, and the core wire holding portion 31b is held at this position. As a result, the plug 30B and the receptacle 50B are optically coupled, and the same effect as in the first embodiment can be obtained.

(Fourth Embodiment) FIG. 6 shows a fourth embodiment of the present invention.
FIG. 6 is an enlarged vertical cross-sectional view of the vicinity of a plug end showing an embodiment of the present invention. Elements common to the elements in FIGS. 1, 4 and 5 showing the first, second and third embodiments are denoted by the same reference numerals. Is attached. In the present embodiment, the ferrules 31, 31A, 31B
And the shape of the convex lens 41b formed at the end of the fiber core 40 is the first.
This is different from the second and third embodiments.

That is, the end surface 31b-1 of the core wire holding portion 31b
, The concave opening 31b of FIGS. 1, 4 and 5
-2 having a diameter larger than -2 or the opening 31b-
2, a concave opening 31b-3 having the same diameter as the opening 2 is formed. The concave opening 31b-3 is provided with a core wire insertion hole 31c.
And the diameter increases from the inside toward the end face 31b-1 of the core wire holding section from the inside to the outside. A convex lens portion 41b having a larger diameter than the outer diameter of the fiber core 41 is formed at an end of the fiber core 41 inserted into the core insertion hole 31c.
Is located on the same plane as the end face 31b-1 of the core wire holding portion 31b or inside the end face 31b-1. The outer peripheral portion 41b-1 of the convex lens portion 41b is
1 has an aperture larger than the outer diameter of the opening 31b.
-3 so as to be engaged with the opening 31b-3.

The plug 30, 30A, 3 having such a structure
To manufacture and assemble the optical fiber 40B, for example, the sheath 42 at the end of the optical fiber 40 is peeled off by a predetermined length to expose the fiber core 41, and the end of the fiber core 41 is connected to the ferrules 31 and 31A. , 31B from the fiber insertion hole 31a to the core wire insertion hole 31c. Then, after forming the convex lens portion 41b at the end of the fiber core wire 41 in the same manner as in the first embodiment, the convex lens portion 41b is pulled back to the end portion side of the core wire insertion hole 31c, and the convex lens portion 41b is drawn. If the outer peripheral part 41b-1 of 41b is engaged with the concave opening part 31b-3, the convex lens part 41b is fixed at a predetermined position.

In the fourth embodiment, substantially the same effects as those of the first embodiment can be obtained, and the following (i) and (ii)
There is also an effect as follows. (I) The convex lens portion 41b at the end of the fiber core 41
Has a diameter larger than the outer diameter of the fiber core 41, so that the light focusing function is increased and the optical coupling efficiency is further improved. In addition, since the area of the exit port and the area of the entrance port of the fiber core 41 are substantially larger, the optical axis shift and the angle shift at the end face of the fiber core are less likely to occur, and the manufacture and assembly are easier. (Ii) Since the outer peripheral portion 41 b-1 of the convex lens portion 41 b is engaged with the concave opening portion 31 b-3, the tensile strength with respect to the fiber core 41 increases, and the convex lens portion 4
1b can be more firmly fixed in the opening 31b-3.

(Fifth Embodiment) FIG. 7 shows a fifth embodiment of the present invention.
FIG. 13 is an enlarged vertical cross-sectional view of the vicinity of a plug end according to the fourth embodiment, and components common to those in FIG. 6 illustrating the fourth embodiment are denoted by the same reference numerals. In the present embodiment, the opening 31b formed in the end face 31b-1 of the core wire holding part 31b
6 is different from that of FIG. 6 in the shape of the convex lens portion 41c accommodated in the opening 31b-4.

That is, the opening 31b-4 has a concave portion whose diameter increases from the inner side toward the end surface 31b-1 of the outer core holding portion 31b. A hole having substantially the same diameter is formed toward 1. The convex lens portion 41c accommodated in the opening portion 31b-4 has a larger diameter than the outer diameter of the fiber core 41, and the outer peripheral portion 41c-1 of the convex lens portion 41c engages with the opening portion 31b-4. are doing. In the fifth embodiment, substantially the same operation and effect as in the fourth embodiment shown in FIG. 6 are obtained, but since the diameter of the opening 31b-4 is slightly smaller than that in FIG. There is an effect that the convex lens portion 41c is not easily damaged during storage or the like.

(Modifications) The present invention is not limited to the above embodiment, and various modifications are possible. For example, there are the following modifications (1) to (5). (1) By the openings 31b-2, 31b-3, 31b-4 formed in the end face 31b-1 of the core wire holding part 31b,
When excessive light reflection that lowers the optical coupling efficiency occurs, the openings 31b-2, 31b-3, 31b-
The surface of No. 4 may be roughened, or a plating, a film, or the like may be formed on the surface, and a treatment for suppressing reflection may be performed. (2) In order to absorb the dimensional variation of the optical connector, the grip portions 32, 32A, 32B and the ferrules 31, 31A,
31B, an elastic member such as a spring is attached, and the ferrule end face 31b-1 is pressed by a predetermined pressing force into the receptacle 50,
The structure may be such that the optical reference surfaces PS of 50A and 50B are brought into contact with each other. Further, an elastic member such as a spring may be mounted on the receptacle 50, 50A, 50B side.

(3) The plugs 30, 30A, 30B and the receptacles 50, 50A, 50B are not limited to the shapes and structures shown in the figures, but may be changed to other shapes and structures than those shown. For example, the grippers 32, 32A, 32
B has two or more ferrules 31, 31A, 3
1B may be attached to form a multipolar structure. FIG. 8 is a plan view illustrating a configuration example of a two-pole rectangular optical connector according to another embodiment of the present invention. In the plug 30C of the rectangular optical connector, a grip portion 32C is attached to a ferrule 31C having two cylindrical core wire holding portions for transmitting light and receiving light. Correspondingly, two cylindrical fitting projections 55-1 and 55-2 are also provided on the receptacle 50C side, and plugs are provided in these fitting projections 55-1 and 55-2. Two core wire holding portions on the 30C side are inserted. The optical connector having such a structure can be downsized as a whole.

(4) Ferrules 31, 31A, 31B
Are made of a conductive material, and the ferrules 31, 31
A, Receptacles 50, 50A, 50B via 31B
The structure may be such that an electric signal can be transmitted between them. Thereby, light and electricity can be transmitted, and usability is further improved. (5) FIG. 9 is a side view of a plug in an optical connector according to another embodiment of the present invention. The plug 30D of the optical connector has a ferrule 31D substantially similar to that of FIG. 5, and a male terminal 33 for connecting an electric signal is fixed to the ferrule 31D. The male terminal portion 33 has, for example, a rectangular plate shape, and one or a plurality of contacts is mounted on a side surface thereof. Correspondingly, a female terminal for receiving the male terminal 33 is also provided on the receptacle side (not shown). In such an optical connector, light and electricity can be transmitted.

[0042]

As described above in detail, according to the first aspect, since the concave opening is formed at the end of the core wire insertion hole, the light emitted from the receptacle is centered by the opening. Focused in the direction. Moreover, since the convex lens portion is formed at the end of the fiber core, the light coupling efficiency is further improved by the synergistic effect of the light focusing function of the convex lens portion and the light focusing function of the opening. In addition, since the exit area and the entrance area at the end of the fiber core are substantially widened, optical axis shift and angle shift at the end face of the fiber hardly occur, thereby facilitating manufacture and assembly. Since the spherical surface of the convex lens portion is located on the same plane as the end surface of the core wire holding portion or inside the end surface, the convex lens portion is not easily damaged when the plug is stored, inserted into the receptacle, or fitted. This eliminates the need for a protective cap or the like to prevent damage, and facilitates handling. Furthermore, when the plug is inserted into the receptacle and fitted, the end face of the core wire holding portion covers around the convex lens portion, so that the intrusion of light from the outside which causes noise can be prevented.

According to the second and third aspects of the present invention, the convex lens portion has substantially the same diameter as the outer diameter of the fiber core.
For example, when manufacturing or assembling, if a convex lens portion is formed in advance at the end of the fiber core wire, and this fiber core wire is inserted into a ferrule and fixed at a predetermined position, manufacture and assembly can be easily performed.

According to the fourth aspect, the convex lens portion has a shape having a diameter larger than the outer diameter of the fiber core wire.
The light focusing function is larger than in the first invention, and the light coupling efficiency is further improved. In addition, since the exit area and the entrance area at the end of the fiber core are substantially larger, manufacture and assembly are easier. According to the fifth invention, the fiber core is penetrated into the ferrule to form a convex lens portion having a diameter larger than the outer diameter of the fiber core, and the convex lens portion is provided on the end side of the core wire insertion hole. Since it is configured to be pulled back and fixed at a predetermined position in the opening of the ferrule, the convex lens portion is engaged in the opening of the ferrule, and the tensile strength to the fiber core is increased.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a rectangular optical connector according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a plug which is one of conventional optical connectors.

FIG. 3 is an enlarged longitudinal sectional view showing the vicinity of a plug end portion in FIG. 2;

FIG. 4 is a configuration diagram of a round optical connector according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a round optical connector according to a third embodiment of the present invention.

FIG. 6 is an enlarged vertical cross-sectional view near a plug end showing a fourth embodiment of the present invention.

FIG. 7 is an enlarged vertical cross-sectional view near a plug end showing a fifth embodiment of the present invention.

FIG. 8 is a plan view of a rectangular optical connector showing another embodiment of the present invention.

FIG. 9 is a side view of a plug showing another embodiment of the present invention.

[Explanation of symbols]

30, 30A, 30B, 30C, 30D Plug 31, 31A, 31B, 31C, 31D Ferrule 31a Fiber insertion hole 31b Core holding part 31b-1 End face of core holding part 31b-2, 31b-3, 31b-4 Concave surface Opening 31c core wire insertion hole 32, 32A, 32B, 32C gripping part 40 optical fiber 41 fiber core wire 41a, 41b, 41c convex lens part 42 jacket 50, 50A, 50B, 50C receptacle

Claims (5)

[Claims] 1. An optical connector having a ferrule attached to an end of an optical fiber coated with a jacket around a fiber core for transmitting light, wherein the ferrule receives and holds the optical fiber. A fiber insertion hole, a tubular core wire holding portion having an end surface in contact with an optical reference surface of the receptacle, and a light receiving portion formed in the core wire holding portion communicating with the fiber insertion hole, A core wire insertion hole that receives and holds the fiber core wire exposed from the end face of the fiber, and is formed at an end of the core wire insertion hole, and has a diameter from the inside toward the end face of the core wire holding part from outside. A convex opening having an enlarged concave opening, and an end of the fiber core exposed from the opening having a spherical surface located on the same plane as the end face of the core holding section or inside the end face. Les An optical connector characterized by forming a lens portion. 2. The optical connector according to claim 1, wherein the convex lens portion formed at the end of the fiber core has a diameter substantially equal to the outer diameter of the fiber core. 3. An optical fiber end is peeled off by a predetermined length to expose a fiber core, a convex lens portion is formed at the end of the fiber core, and a convex lens portion of the fiber core is formed. 3. A structure in which a convex lens portion is inserted into a core wire insertion hole from a fiber insertion hole of a ferrule, and the convex lens portion is fixed at a predetermined position in an opening of the ferrule.
Optical connector as described. 4. The optical connector according to claim 1, wherein the convex lens portion formed at the end of the fiber core has a diameter larger than the outer diameter of the fiber core. 5. A fiber core is exposed by peeling a jacket at an end of an optical fiber by a predetermined length, and an end of the fiber is penetrated from a fiber insertion hole of a ferrule to a core insertion hole. Forming a convex lens portion at the end of the fiber core wire, pulling the convex lens portion of the fiber core wire back toward the end of the core wire insertion hole, and fixing the convex lens portion at a predetermined position in the opening of the ferrule. 5. The optical connector according to claim 4, wherein the optical connector has a structure.