JPH0561608B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to an optical cable retention structure in an optical connector, and more particularly to an optical cable retention structure in an optical connector in which the end portion of the optical cable can be securely and firmly secured.

"Prior Art" FIG. 4 shows an example of an optical cable having a tensile strength member, and reference numeral 1 in the figure indicates the optical cable. This optical cable 1 consists of a tensile strength body 2 made of steel wire or stranded steel wire, etc.
Smaller-diameter secondary tensile strength members 3, 3 and optical fibers 4 are twisted, and on the outside of these are JUUT, foamed silicone rubber, Kevlar (trade name of polyamide fiber, etc.).
An intervening layer 5 made of a material such as Dupont Co., Ltd.) is coated.
Furthermore, the outermost layer of the intervening layer 5 is a sheath 6 made of an aluminum laminate polyethylene sheath (LAP sheath), a polyethylene sheath, or the like. The optical fiber 4 may be of a bare wire type, a core wire type, or the like.

Conventionally, an optical connector as shown in FIG. 5, for example, has been used to fasten the end of the optical cable 1 having such a configuration.

FIG. 5 shows an optical cable retaining structure in a conventional optical connector, and reference numeral 7 in the figure indicates the optical connector. In the drawings, the left side is the front and the right side is the rear.

The optical connector 7 is a substantially cylindrical member that fixes the end of the optical cable 1 to the inside of its rear part, and is composed of a plug 8 and an adapter (not shown). The plug 8 is a cylindrical metal member that holds the end of the optical cable 1, and consists of a cylindrical housing 9 and a rubber boot 10 attached to the rear outside of the housing 9. It is something.

The end portion of the optical cable 1 from which the sheath 6 and the intervening member 5 have been removed to expose the tensile strength member 2, sub-tensile strength members 3, 3, and optical fibers 4 is inserted into the rear inside of the housing 9.
The tensile strength member 2, sub-tensile strength members 3, 3, and optical fibers 4, etc. are adhesively fixed in the housing 9 by an adhesive 11 filled in the space between the inner rear part of the housing 9 and the end of the optical cable 1. has been done.

"Problems to be Solved by the Invention" However, the optical cable retaining structure of the optical connector 7 has the following problems.

The optical connector 7 is assembled by fixing the tensile strength member 2 and the sub-tensile strength members 3, 3 inside the optical connector 7 with adhesive.
If the adhesive 11 takes time to harden, it is necessary to hold the optical cable 1 immobile inside the optical connector 7 during the curing, which is time-consuming and troublesome. It was hot.

When trying to securely hold the optical cable 1 inside the optical connector 7, it is necessary to apply tension to the tensile strength member 2 and the sub-tensile strength members 3, 3.
Moreover, the adhesion length of the auxiliary tensile strength members 3, 3 must be increased, and the overall length of the optical connector 7 also becomes longer, resulting in a drawback that the optical connector 7 becomes larger.

Since the optical fibers 4 are also adhesively fixed together with the tensile strength member 2 and the sub-tensile strength members 3, 3, if the adhesive length is long and there is a partial deviation in the curing time of the adhesive 11, the adhesion will be delayed due to the deviation. Agent 11
Internal stress is generated in the adhesive layer made of the optical fibers 4, and this internal stress causes problems such as an increase in connection loss of the optical fibers 4.

``Means for Solving the Problems'' Therefore, the present invention includes a cylindrical first fixing portion in which a first tensile strength member accommodation hole is formed along the longitudinal direction of the optical connector, and and a second fixing part in which two or more tensile strength body accommodation holes are formed, and two or more of the second tensile strength body accommodation holes are symmetrically located at positions with the first tensile strength body accommodation hole as a center of symmetry. An optical cable retaining structure was obtained in which a tension member of the optical cable was inserted into the first tension member accommodation hole and fixed by caulking, and a sub-tensile strength member was similarly inserted and fixed into the second tension member accommodation hole. By doing so, the above problems were solved.

"Function" With this configuration, each tensile strength member of the optical cable is firmly fixed to each accommodation hole of the retaining fitting,
The optical cable and optical connector are firmly coupled.
Further, even if an external force in a torsional direction is applied to the optical cable, since the auxiliary tensile strength member is symmetrically fixed to the tensile strength member, the optical cable can sufficiently withstand this external torsional force.

"Example" Hereinafter, the optical cable retaining structure in the optical connector of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of an optical cable retaining structure in an optical connector of the present invention, and FIGS. 2 and 3 show examples of a retaining fitting for the optical connector.

First, to explain the configuration of the optical connector 12 shown in FIG. 1, the optical connector 12 accommodates the optical cable 1 shown in FIG.
It is constructed so that it can be reliably fastened, and consists of a plug 13 and an adapter (not shown).

The plug 13 is a substantially cylindrical metal member that holds the end of the optical cable 1, and is generally comprised of a front housing 14 and a rear housing 15.
, a cable retainer 16 , and a boot 17 .

The front housing 14 is a substantially cylindrical metal member in which the optical fiber (not shown) of the optical cable 1 is accommodated, and the rear part of this member has a reduced diameter and a screw thread on the outer periphery. A peripheral surface 14 having
a is formed, and a flat end surface 1 is formed at the rear end.
4b is formed.

The rear housing 15 is a substantially cylindrical metal member that accommodates the tensile strength member 2 and sub-tensile strength members 3, 3 of the optical cable 1, optical fiber core wire, etc.
In this case, the diameter of the rear part is gradually reduced from that of the front part. The front part of this rear housing 15 is formed with a circumferential surface 15a having threads on its inner circumferential part to be screwed into the circumferential surface 14a of the front housing 14, and the rear inner surface of this inner circumferential surface 15a is , a contact surface 15b is formed that is perpendicular to the longitudinal direction of the rear housing 15 and extends along the circumferential direction of the rear housing 15. Further, a groove 15c is formed in the outer peripheral portion of the rear housing 15 along the circumferential direction. Furthermore, a cylindrical cable holding part 15d is formed at the rear of the rear housing 15 to guide the optical cable 1 into the rear housing 15 when the optical cable 1 is inserted into the rear housing 15, and to hold the optical cable 1. There is.

A cable retainer 16 is sandwiched between the rear end surface 14b of the front housing 14 and the contact surface 15b of the rear housing 15. The cable retainer 16 is made of stainless steel, copper alloy, or aluminum alloy, and as shown in FIGS. (first fixing part) 16b.

The housing clamping portion 16a is a rectangular plate whose long side length is approximately equal to the outer diameter of the rear end of the front housing 14 and the inner diameter of the front end of the rear housing 15. The short side thereof is approximately equal to the inner circumferential surface of the front end of the rear housing 15, and an arc is formed therein. On the rear surface of this housing clamping portion 16a, a cylindrical cable fixing portion 1 is provided at the center thereof and protrudes perpendicularly to the rear surface.
6b, and a first tensile strength body housing hole 16c is formed in the end surface of the cable fixing part 16b along the longitudinal direction of the cable fixing part 16b.
This first tensile strength body accommodation hole 16c is a hole that penetrates from the end face of the cable fixing part 16b to the front surface of the housing clamping part 16a, and its inner diameter is slightly larger than the outer diameter of the strength body 2 of the optical cable 1 to be accommodated. It is set. In addition, the housing clamping portion 16
A pair of second tensile strength member accommodation holes 16d, 16d are formed at both longitudinal ends of a in the same direction as the first tensile strength member accommodation hole 16c. These second tensile strength member accommodation holes 16d, 16d are holes that penetrate through the housing clamping portion 16a, and the inner diameter thereof is set to be slightly larger than the outer diameter of the auxiliary tensile strength members 3, 3 of the optical cable 1. .

The boot 17 has the function of protecting the optical cable 1 held in the optical connector 12 from external forces, and is a substantially cylindrical rubber member whose diameter is gradually reduced at the rear than at the front. be. The inner periphery of the front end of the boot 17 has a protrusion 1 that fits into the groove 15c of the rear housing 15.
7a is formed.

Next, the optical connector 12 configured as described above is
A method of securing the end of the optical cable 1 using the following will be explained. First, the rear part of the rear housing 15 is inserted into the front opening of the boot 17, and the protruding strip 17a of the boot 17 is inserted into the groove 15c of the rear housing 15.
The front end of the optical cable 1 is inserted into the rear opening of the rear housing 15 and the boot 17, and with the front end protruding from the front opening of the rear housing 15, the interposer 5 and the sheath at the end of the optical cable 1 are inserted. 6 is removed to expose the tensile strength member 2, sub-tensile strength members 3, 3, and optical fiber core wire. Next, the tensile strength body 2 of the optical cable 1 is inserted into the first tensile strength body housing hole 16c of the cable retaining fitting 16 so that its tip slightly protrudes from the front side of the housing clamping part 16a, and this protruding portion is applied with an expansion force. The body 2 is bent in a direction perpendicular to the longitudinal direction. Next, use a caulking tool or the like to tighten the cylindrical cable fixing part 16b from the outside.
caulk in the radial direction of the first tensile member housing hole 16c.
The tensile strength member 2 of the optical cable 1 is fixed inside. Further, insert the sub tensile members 3, 3 of the optical cable 1 into the second tensile member housing holes 16d, 16d of the cable retainer 16, respectively, and while maintaining this inserted state, move the front surface of the cable retainer 16 to the front. The end surface 14b of the housing 14 is brought into contact with the contact surface 15b of the rear housing 15 attached to the optical cable 1, and the contact surface 15b of the rear housing 15 attached to the optical cable 1 is brought into contact with the rear surface of the cable retaining fitting 16. Next, the front part of the rear housing 15 is screwed into the rear part of the front housing 14 so that the cable retaining fitting 16 is sandwiched between the front housings 14 and 15. At this time, cable retaining fitting 1
The auxiliary tensile strength members 3, 3 inserted into the second tensile strength member housing holes 16d, 16d of the rear housing 1
It is pressed from the outside by the corner of the stepped portion 15b of No. 5 and is fixed in that position. The optical fiber core wire within the optical cable 1 is fixed within a ferrule (not shown) disposed within the front housing 14.

The optical cable 1 held in the plug 13 in this manner has its tensile strength member 2 caulked into the first strength member accommodation hole 16c of the cable retaining fitting 16 and is firmly fixed, and the auxiliary tensile strength members 3, 3 Since it is fixed within the second tensile strength body housing holes 16d, 16d, it will not come off from the plug 13.

In the above embodiment, the tensile strength member 2 of the optical cable 1
the first tensile strength member accommodation hole 1 of the cable retaining fitting 16
6c, the sub-tensile members 3, 3 are accommodated in the second tensile member housing holes 16d, 16d, and the cable is secured by pressing at the corner of the stepped portion 15b of the rear housing 15. , the secondary tensile strength members 3, 3 may be fixed by caulking in the same manner as the tensile strength member 2;
It is also possible to have a structure in which adhesive is filled in advance in the areas c and 16d, and fixing with this adhesive and fixing by caulking are used together. In this case, it is preferable that the adhesive has a relatively short curing time at a low temperature.

Further, in the above embodiment, the optical cable 1 to be held down has a configuration as shown in FIG. body 3,
3 is twisted, the optical cable may have a structure in which not only optical fibers but also conductive wires such as insulated copper wires are twisted around the tensile strength member 2.

Hereinafter, the effects of this invention will be clarified by showing experimental examples.

(Experiment example) After securing the end of the optical cable using the stainless steel cable retaining fitting 16 of the plug 13 shown in Figures 2 and 3, the current required weight is approximately 60 kg.
However, the optical fiber core did not break. Furthermore, the amount of increase in connection loss of the optical cable before and after the application of this tensile force was measured. As a result, the increase in optical fiber splice loss is approximately
It was below 0.02dB.

As is clear from the results, it was found that the optical cable retaining structure of this optical connector has extremely low connection loss of the optical cable when a tensile force is applied to the optical connector.

By the way, the maximum tensile force exerted by human power is said to be about 60 kg, and it can be seen that the connection loss of optical cables does not increase within the scope of normal optical cable connection work.

"Effects of the Invention" As explained above, the optical cable retaining structure in the optical connector of the present invention has
A cylindrical first fixing part in which a first tensile strength member accommodation hole is formed along the longitudinal direction of the optical connector;
and a second fixing part in which two or more tensile strength body accommodation holes are formed, and two or more of the second tensile strength body accommodation holes are arranged symmetrically at positions with the first tensile strength body accommodation hole as a center of symmetry. A tension member of the optical cable is inserted into the first tension member accommodation hole and fixed by caulking, and an auxiliary tension member is similarly inserted and fixed into the second tension member accommodation hole. Optical connectors can be firmly and reliably fixed and connected. In addition, since it is mechanically fixed by both the first fixing part and the second fixing part, strong fixing is possible, and the space required for the restraining structure is smaller compared to conventional adhesive fixing. I can do it. Furthermore, since mechanical fixing means such as caulking is used, the work can be done quickly.
In addition, since the second tensile strength member accommodation hole is located symmetrically with respect to the first tensile strength member accommodation hole, the two or more sub-tensile strength members are symmetrically centered around the optical cable tensile strength member, and the fixing portions are separated. Therefore, even if the optical cable itself is twisted with a large force in any direction, the twist will not be transmitted into the optical connector, and the optical fiber core will not be twisted and broken. Even if the optical cable is pulled diagonally behind the connector, a high fixing force can be ensured, and the optical cable will not come off. Furthermore, the tensile force from the tensile strength member and the sub-tension member will be applied to the part of the optical cable near the connector mounting base, so a force will act to keep the optical cable in that part in a straight line, and the tension near the connector mounting base will work. It is also possible to prevent the optical cable from being sharply bent, and to suppress an increase in loss due to bending of the optical fiber.

[Brief explanation of the drawing]

FIG. 1 is a partially omitted schematic configuration diagram showing an example of an optical cable retention structure in an optical connector of the present invention, and FIG. 2 is a cable retention diagram of an optical connector that can implement the optical cable retention structure in an optical connector of the present invention. 3 is a front view of the metal fittings, FIG. 4 is a schematic cross-sectional view showing an example of an optical cable to be held by the optical cable holding structure in the optical connector of the present invention, and FIG. 5 is a conventional one. FIG. 2 is a partially omitted schematic configuration diagram showing an example of an optical cable retaining structure in an optical connector. DESCRIPTION OF SYMBOLS 1... Optical cable, 2... Tensile member, 3... Sub-tensile member, 4... Optical fiber, 12... Optical connector, 16... Cable retainer (retainer), 1
6a...Housing clamping part (second fixing part), 16
b...Cable fixing part (first fixing part), 16c...
...First tensile strength member accommodation hole, 16d...Second tension member accommodation hole.

Claims (1)

[Scope of Claims] 1. An optical cable retention structure in an optical connector for securing an end of an optical cable having a tensile strength member, two or more sub-tensile strength members, and a plurality of optical fibers, wherein a plate-shaped second fixing portion is provided in the optical connector. , a retaining fitting consisting of a column-shaped first fixing part is installed in the center of this fixing part, and the first fixing part of this retaining fitting has a stopper that extends along the longitudinal direction of the optical connector to the second fixing part. An extending first tensile strength body housing hole is formed, and two or more second tensile strength body housing holes are formed in the second fixing part at positions with the first tensile strength body housing hole as a center of symmetry, and the above-mentioned An optical cable retaining structure in an optical connector, characterized in that the tensile strength body is inserted and caulked into the first strength body accommodation hole, and the auxiliary strength body is inserted and fixed in the second strength body accommodation hole.