WO2013089737A2

WO2013089737A2 - Optical connector

Info

Publication number: WO2013089737A2
Application number: PCT/US2011/065135
Authority: WO
Inventors: Nozomi Tsuzaki; Norman R. Lampert
Original assignee: Yazaki Corporation
Priority date: 2011-12-15
Filing date: 2011-12-15
Publication date: 2013-06-20
Also published as: WO2013089737A3; JP2015500516A

Abstract

An optical connector includes: an optical cable in which an end part including a tip of a plastic optical fiber is exposed; a tubular strength member that receives the end part of the plastic optical fiber and a covering layer therein, and retains a lateral surface of the covering layer; and a housing including a coupling part that includes a through-hole which communicates bottoms of first and second tubular parts. The first tubular part receives a part of the end part of the plastic optical fiber therein so that the tip of the plastic optical fiber projects from an edge of the first tubular part, and the second tubular part comes in close contact with a lateral surface of the received part of the strength member. Further a space allowing a curvature of the end part of the plastic optical fiber is formed within the strength member.

Description

DESCRIPTION

Title of the Invention:

OPTICAL CONNECTOR

Technical Field

The present invention relates to an optical connector that enables optical communication through an optical fiber that is connected to an optical module such as an optical receptacle or an optical adaptor.

Background Art

An optical connector is used for enabling an optical communication by connecting an optical fiber to an optical module such as an optical receptacle or an optical adaptor (for example, refer to Patent Literature l).

In recent years, plastic optical fibers inexpensive and excellent in noise resistance performance are used as optical fibers for optical communication. However, in connection of the plastic optical fiber to the optical module, in order to suppress a transmission loss, a tip of the plastic optical fiber is required to be abutted against a different connection member such as a light receiving element of the optical module.

As described above, as the optical connector in which the tip of the plastic optical fiber is abutted against the connection member, there has been known a structure in which, for example, as illustrated in FIGS. 5 and 6, an optical cable 1 is urged by a spring 2, and a tip of a plastic optical fiber 3 is projected from a front end surface of a housing 4. As a result, the tip of the plastic optical fiber 3 is connected to the optical module, the tip of the plastic optical fiber 3 is abutted against a plastic optical fiber 5 of the connection member, and this state is maintained (for example, refer to Patent literature 2).

Citation List

Patent Literature

Patent Literature l: JP-A-2011-75829

Patent Literature U.S. Patent No. 5923805

Summary of Invention

Technical Problem

However, the above optical connector is structured such that the spring 2 is incorporated into the optical connector, and the optical cable 1 is urged by the spring 2 so that the tip of the plastic optical fiber 3 is abutted against the connection member with an appropriate pressing force. This leads to a complicated structure and an increase in the number of components, resulting in an increase in cost.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical connector that is reduced in the costs with a simplified structure and a reduced number of components.

Solution to Problem

In order to achieve the above object, the optical connector according to aspects of the present invention has the following features (l) to (3). (l) An optical connector, including:

an optical cable including a plastic optical fiber and a covering layer that covers a lateral surface of the plastic optical fiber, wherein an end part of the plastic optical fiber including a tip of the plastic optical fiber is exposed from the covering layer!

a tubular strength member that receives a part of the end part of the plastic optical fiber and a part of the covering layer therein, and retains a lateral surface of at least a part of the covered part of the covering layer;

a housing including a first bottomed tubular part located at a side close to the tip of the plastic optical fiber in the optical cable, a second bottomed tubular part located at a side far from the tip of the plastic optical fiber in the optical cable, and a coupling part that couples a bottom of the first tubular part with a bottom of the second tubular part, and includes a through-hole, having an inner diameter smaller than that of the second tubular part, which communicates the bottom of the first tubular part with the bottom of the second tubular part, wherein the first tubular part receives a part of the end part of the plastic optical fiber therein so that the tip of the plastic optical fiber projects from an edge of the first tubular part, and the second tubular part receives a part of the strength member therein so that the second tubular part comes in close contact with a lateral surface of the received part of the strength member, wherein

a space which is formed within the strength member and the housing, and allows a curvature of the end part of the plastic optical fiber.

(2) The optical connector including the configuration (l), wherein an inner diameter of the through-hole is slightly larger than an outer diameter of the plastic optical fiber.

(3) The optical connector including the configuration (l) or (2), wherein the bottom of the second tubular part includes a tapered guide part so that an inner diameter of the second tubular part is decreased toward the through-hole.

In the optical connector having the above configuration (l), the space formed within the strength member and the housing allows the plastic optical fiber located within the space to be bent. An elastic force caused by the rigidity of the plastic optical fiber by which the bend of the plastic optical fiber is to be returned is exerted on the bent plastic optical fiber. When the tip of the plastic optical fiber is connected to an optical module, and abutted against a different connection member such as a light receiving element, a state in which the plastic optical fiber is bent is maintained due to the elastic force. The housing over-travels to allow the latch to function, and then, the elastic force from the optical fiber returns the housing to a proper position. The optical fiber is abutted against or in close proximity to the light receiving element, for example. The excellent connection state can be realized by the optical connector which is simple in structure and small in the number of components as compared with the optical connector complicated with the use of the spring, and large in the number of components.

A length of the end part of the plastic optical fiber which projects from a front edge of the first tubular part is slight, and the total reflection of the plastic optical fiber which is bent just for the length is not prevented. For that reason, the occurrence of the transmission loss can be suppressed.

In the optical connector having the above configuration (2), when the plastic optical fiber is inserted into the through-hole, the through-hole corrects the curl of the plastic optical fiber, and aligns the optical axis with that of the connection member. As a result, the occurrence of the transmission loss can be suppressed.

In the optical connector having the above configuration (3), when the tip of the plastic optical fiber is received in the housing, the tip of the plastic optical fiber is guided along a slope surface of the second tubular part whose inner diameter is decreased toward the through-hole. This configuration makes it possible to facilitate the assembling of the plastic optical fiber into the housing.

Advantageous Effects of Invention

According to aspects of the present invention, there can be provided an optical connector that is reduced in cost with the simplified structure and the reduced number of components.

The present invention is described in brief above. The details of the present invention will be further clarified by reading the description of embodiments in conjunction with the drawings.

Brief Description of Drawings

FIG. 1A is a perspective view illustrating an optical connector viewed from a front end side thereof according to an embodiment;

FIG. IB is an exploded perspective view illustrating the optical connector viewed from the front end side thereof according to the embodiment!

FIG. 2A is a perspective view illustrating the optical connector viewed from a rear end side thereof according to the embodiment;

FIG. 2B is an exploded perspective view illustrating the optical connector viewed from the rear end side thereof according to the

embodiment;

FIG. 3 is a cross-sectional view illustrating the optical connector according to the embodiment;

FIG. 4 is a cross-sectional view illustrating the optical connector that is connected to an optical module;

FIG. 5 is an exploded perspective view illustrating an optical connector in a background art; and

FIG. 6 is a cross-sectional view illustrating the optical connector in the background art.

Description of Embodiments

Hereinafter, an embodiment according to the present invention will be described with reference to the accompanying drawings.

FIG. 1A is a perspective view illustrating an optical connector viewed from a front end side thereof according to an embodiment. FIG. IB is an exploded perspective view illustrating the optical connector viewed from the front end side thereof according to the embodiment. FIG. 2A is a perspective view illustrating the optical connector viewed from a rear end side thereof according to the embodiment. FIG. 2B is an exploded perspective view illustrating the optical connector viewed from the rear end side thereof according to the embodiment. FIG. 3 is a cross-sectional view illustrating the optical connector according to the embodiment.

As illustrated in FIGS. 1A, IB, 2A, and 2B, an optical connector 21 according to the embodiment includes a housing 23 molded with resin such as plastic, and a tubular strength member 24 made of metal.

Aplastic optical fiber 31 connected with the optical connector 21 has a lateral surface covered with a covering layer 32 to form an optical cable with the optical connector 21 and the covering layer 32. An end part 31b of the plastic optical fiber 31 including a tip 31a of the plastic optical fiber 31 is exposed from the covering layer 32. The plastic optical fiber 31 is formed of a plastic optical fiber (POF) having a core and a clad made of plastic, and excellent in noise-resistant performance.

As illustrated in FIG. 3, the housing 23 configuring a part of the optical connector 21 includes a front tubular part (a first tubular part) 41 having a bottomed tubular shape, and a rear tubular part (a second tubular part) 42 having a bottomed tubular shape. The front tubular part 41 is located at a side close to the tip 31a of the plastic optical fiber 31, and the rear tubular part 42 is located at an opposite side of the front tubular part 41, i.e., located at a side far from the tip 31a of the plastic optical fiber 31. In the description and figures, it is assumed that, for the sake of

convenience, the side of the front tubular part 41 (left side in Fig. 3) refers to a front side, and the side of the rear tubular part 42 (right side in Fig. 3) refers to a rear side.

The front tubular part 41 of the housing 23 forms an insertion part that is inserted into and connected to the optical module such as an optical receptacle or an optical adaptor, which is a different connection member of the optical connector 21.

A coupling part 44 forming a bottom 41b of the front tubular part 41 and a bottom 42b of the rear tubular part 42 is formed with a through-hole 46. The through-hole 46 communicates the bottom 41b of the front tubular part 41 with the bottom 42b of the rear tubular part 42. The through-hole 46 couples the bottom 41b of the front tubular part 41 with the bottom 42b of the rear tubular part 42. An inner diameter of the through- hole 46 is formed to be slightly larger than an outer diameter of the plastic optical fiber 31 so that the plastic optical fiber 31 can be inserted into the through-hole 46.

In the through-hole 46, the plastic optical fiber 31 to be inserted comes in slide contact with a wall forming the through-hole 46 so that the optical axis of the plastic optical fiber 31 is aligned with the center axis of the housing 23. Also, the curl of the plastic optical fiber 31 such as bent is corrected, and the plastic optical fiber 31 becomes into a straight state, and is extended toward the front end. That is, the through-hole 46 serves as an alignment and correction part that aligns and corrects the plastic optical fiber 31.

In the housing 23, the plastic optical fiber 31 is inserted into the through-hole 46 from a rear side of the rear tubular part 42 which opens at a rear end.

Also, an inner diameter of the rear tubular part 42 is decreased toward the through-hole 46. That is, the bottom 42b of the rear tubular part 42 includes a tapered guide part 48 that is gradually narrowed toward the through-hole 46. With this configuration, the plastic optical fiber 31 inserted from the rear side of the rear tubular part 42 is guided and smoothly inserted into the through-hole 46 by the guide part 48.

One end side (a crimp part 24a) of the strength member 24 is retained to a lateral surface of an end part of the covering layer 32 of the plastic optical fiber 31, and crimped and fixed to the end part of the covering layer 32. A part 24b of the other end side of the strength member 24 is press-fitted and mated into the rear tubular part 42 of the housing 23, and received within the rear tubular part 42. With this configuration, the rear tubular part 42 comes in close contact with a lateral surface of the received part of the strength member 24. Each of a rear side of the housing 23 and the strength member 24 has an inner diameter sufficiently larger than the outer diameter of the plastic optical fiber 31 so that a space S permitting a curvature of the end part 31b is internally formed between the plastic optical fiber 31 and the strength member 24 even if the end part 31b of the plastic optical fiber 31 is curved.

In the housing 23, the tip 31a of the plastic optical fiber 31 projects from a front edge 41a of the front tubular part 41, and the tip 31a is arranged at a given position from the front edge 41a of the front tubular part 41.

The housing 23 of the optical connector 21 is formed with a latch 28, and the latch 28 is engaged with a housing of the optical module, and maintains a connection state thereof when the optical connector 21 is inserted into and connected to the optical module. Subsequently, a description will be given of a case in which the optical connector 21 is connected to the optical module having an FOT (Fiber Optic Transceiver).

As illustrated in FIG. 4, an optical module 50 of an optical receptacle includes a housing 52 having a connection recess 51, and a fiber optic transceiver (FOT) 55 having a light emitting element or a light receiving element is received in the housing 52. A cylindrical part 54 having an insertion hole 53 with a tapered entry 53a is formed in the housing 52. The insertion hole 53 of the cylindrical part 54 is arranged at a position facing a light receiving and emitting surface 55a provided on the FOT 55. When the FOT 55 includes a light emitting element, the light receiving and emitting surface 55a serves as a light emitting surface that emits an optical signal. When the FOT 55 includes a light receiving element, the light receiving and emitting surface 55a serves as a light receiving surface that receives the optical signal.

When the optical connector 21 is inserted into the connection recess 51 of the housing 52 in the optical module 50, the end part 31b of the plastic optical fiber 31 arranged within the front tubular part 41 is inserted into the insertion hole 53 of the cylindrical part 54 in the optical module 50.

Further, when the optical connector 21 is inserted into the connection recess 51 of the optical module 50, the cylindrical part 54 is fitted into the front tubular part 41 of the optical connector 21.

Thereafter, the tip 31a of the plastic optical fiber 31 is abutted against the light receiving and emitting surface 55a of the FOT 55 in the optical module 50, and the plastic optical fiber 31 is slightly pushed toward the rear end side of the housing 23. With this configuration, the plastic optical fiber 31 can be elastically deformed and slightly curved within the space S formed in a cavity between the strength member 24 and the tapered surface 42b. Then, an elastic force caused by the rigidity of the plastic optical fiber 31 per se, by which the curvature of the plastic optical fiber 31 is to be restored, occurs in the end part 31b of the plastic optical fiber 31. As a result, the tip 31a of the plastic optical fiber 31 is urged toward the FOT 55 side by the elastic force of the end part 31b. Accordingly, an excellent abutment or a close proximity state of the tip 31a against the light receiving and emitting surface 55a of the FOT 55 is maintained, and an excellent optical transmission can be conducted between the plastic optical fiber 31 and the light receiving and emitting surface 55a of the FOT 55.

The housing 23 of the optical connector 21 moves forward beyond the latch-point of the housing 52 of the optical module 50 for the latch 28 to be engaged. After the latch engagement, the fiber elasticity of the plastic optical fiber 31 can move the housing 23 rearward.

In this state, the latch 28 of the optical connector 21 is engaged with the housing 52 of the optical module 50, and a connection state of the optical connector 21 to the optical module 50 is maintained.

As described above, according to the optical connector of the above embodiment, the space S formed within the cavity between the strength member 24 and the housing 23 allows the bent of the plastic optical fiber 31 located within the space S. The elastic force caused by the rigidity of the plastic optical fiber 31 by which the bent is to be returned is exerted on the bent plastic optical fiber 31. When the tip 3 la of the plastic optical fiber 31 connected to the optical module 50 is abutted against or in close proximity to the light receiving and emitting surface 55a of the FOT 55, the state in which the plastic optical fiber 31 is bent is maintained due to the elastic force. The excellent connection state can be realized by the optical connector which is simple in structure and small in the number of components as compared with the optical connector complicated with the use of the spring, and large in the number of components.

A length of the end part 31b of the plastic optical fiber 31 including the tip 31a which projects from the front edge 41a of the front tubular part 41 is slight, and the total reflection of the plastic optical fiber 31 which is bent just for the length is not prevented. For that reason, the transmission loss can be reduced.

Incidentally, an unused plastic optical fiber 31 is normally bundled in a circular shape. For that reason, the plastic optical fiber 31 in use is slightly curved. If the curvature remains as it is, when the plastic optical fiber 31 is connected to the optical module 50, the optical axis of the plastic optical fiber 31 received in the optical connector 21 does not match the optical axis of the light receiving and emitting surface 55a of the FOT 55, resulting in transmission loss.

To avoid such a situation, in the optical connector according to the embodiment, when the plastic optical fiber 31 is inserted into the through-hole 46, the through- hole 46 corrects the curl of the plastic optical fiber 31, and aligns the optical axis of the plastic optical fiber 31 with the optical axis of the light receiving and emitting surface 55a of the FOT 55. As a result, the transmission loss can be reduced. Also, when the tip 31a of the plastic optical fiber 31 is to be received in the housing 23, the tip 31a of the plastic optical fiber 31 is guided by the guide part 48 which is a slope surface of the rear tubular part 42. This configuration makes it possible to facilitate the assembling of the plastic optical fiber 31 into the housing 23.

The optical connector 21 may be connected to not the optical module of the optical receptacle, but may be connected to an optical connector of a different connection member through the optical adaptor. Similarly, in this case, the tips 31a of the respective plastic optical fibers 31 are excellently abutted against each other by the elastic force generated in the end parts 31b of the plastic optical fibers 31 whereby the excellent optical

transmission can be conducted between the respective plastic optical fibers 31. In a case of mating two connectors, the fiber extension must be more carefully set to prevent excessive force.

The above embodiment is exemplified by the one-core optical connection that connects the plastic optical fiber 31 to the optical module. However, the present invention can be also applied to a multicore optical connector.

The present invention is not limited to the above-described embodiment, but can be appropriately deformed or improved. In addition, materials, shapes, dimensions, numbers, and installation places of the respective components in the above-mentioned embodiment are arbitrary and not limited only if the present invention can be achieved.

Claims

1. An optical connector, comprising:

an optical cable including a plastic optical fiber and a covering layer that covers a lateral surface of the plastic optical fiber, wherein an end part of the plastic optical fiber including a tip of the plastic optical fiber is exposed from the covering layer;

a housing including a first bottomed tubular part located at a side close to the tip of the plastic optical fiber in the optical cable, a second bottomed tubular part located at a side far from the tip of the plastic optical fiber in the optical cable, and a coupling part that couples a bottom of the first tubular part with a bottom of the second tubular part, and includes a through-hole, having an inner diameter smaller than that of the second tubular part, which communicates the bottom of the first tubular part with the bottom of the second tubular part, wherein the first tubular part receives a part of the end part of the plastic optical fiber therein so that the tip of the plastic optical fiber projects from an edge of the first tubular part, and the second tubular part receives a part of the strength member therein so that the second tubular part comes in close contact with a lateral surface of the received part of the strength member, and

a space which is formed within the strength member and the housing and allows a curvature of the end part of the plastic optical fiber.

2. The optical connector according to claim 1, wherein

an inner diameter of the through-hole is slightly larger than an outer diameter of the plastic optical fiber.

3. The optical connector according to claim 1 or 2, wherein the bottom of the second tubular part includes a tapered guide part so that an inner diameter of the second tubular part is decreased toward the through- hole.