JPH10300982A - Optical connector fitting method and optical cord with optical connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical cord with an optical connector which is neither buckled nor increases in transmission loss even when a coated optical fiber has a thin clad. SOLUTION: By the method for fitting an optical connector which has its ferrule 4a, fixing the coated optical fiber 1, pressed from behind by an elastic member 8 such as a spring and also moved back at the time of engagement to the optical cord 7 having a clad 3 outside a coated optical fiber 1, an end part of the clad 3 of the optical cord 7 is cut and fixed to a component of the optical connector and the coated optical fiber 1 is covered with a tube 6 which is longer than (length L-5 mm from the rear end part of the ferrule to the clad cut part) from the ferrule 4a to the optical cord 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connector mounting method in which a ferrule for fixing an optical fiber core wire is pressed from behind by an elastic member, and the ferrule retreats backward when fitted, and the optical connector. Related to an optical cord attached with.

[0002]

2. Description of the Related Art A ferrule for fixing an optical fiber core wire is pressed from behind by an elastic member onto an optical cord in which a tensile strength member and a sheath are applied to the optical fiber core wire, and the ferrule retreats rearward when fitted. A conventional optical connector has been mounted.

FIG. 5 shows a typical example. In FIG. 5, an optical cord 7 is composed of an optical fiber core 1 in which glass fiber is coated with an ultraviolet curing resin or the like, a tensile strength member 2 made of aramid fiber or the like, and a jacket 3 made of plastic such as vinyl chloride resin. . Reference numeral 4 denotes an optical connector, and reference numeral 5 denotes a protective boot made of rubber or the like. The optical connector 4 includes components such as a ferrule 4a attached to the tip of the optical fiber core, a ring 4b for stopping the strength member 2, a ring 4c for stopping the jacket 4, a housing 4d, and an elastic member 8 such as a spring.

In the case where the optical connector is not fitted, FIG.
As shown in (A), the ferrule 4a is pressed forward by the elastic member 8 such as a spring, but when the optical connector is fitted, the ferrule 4a is pressed from the front. Pressing elastic member 8
Is compressed, and the ferrule 4a moves backward slightly by X. At that time, the optical fiber core 1a behind the ferrule is also pushed backward together, so that the optical fiber core 1a
Is not pushed into the optical cord 7, the optical fiber core 1a bends behind the ferrule as shown in FIG. 5B.

[0005]

In the case where the optical fiber is a relatively thick optical fiber obtained by coating a glass fiber with an ultraviolet curable resin and nylon, etc., the optical fiber is hardened by the rigidity of the optical fiber. By pushing the optical fiber into the cord, it is absorbed by the elongation of the jacket of the optical cord, etc., and the optical fiber is not damaged or the transmission loss is not deteriorated. When the diameter of the optical fiber is reduced and the thickness of the coating on the glass fiber is reduced, the optical fiber is likely to be buckled and damaged or transmission loss is increased. . An object of the present invention is to provide an optical cord with an optical connector that does not buckle or reduce transmission loss even when the coating of the optical fiber core is thin.

[0006]

According to the present invention, there is provided an optical connector in which a ferrule for fixing an optical fiber is pressed from behind by an elastic member, and the ferrule retreats backward when fitted. In the method of attaching to an optical cord having a jacket outside, the end of the jacket of the optical cord is cut open and fixed to a part of the optical connector, and from the rear end of the ferrule toward the optical cord (after the ferrule) The optical fiber is covered with a tube having a length of at least L-5 mm from the end to the cutout portion of the jacket.

If the tube is made of a synthetic resin and the length M is equal to or more than (the length L from the rear end of the ferrule to the cut-out portion of the jacket), the tube is formed in a portion where the jacket is not cut open. Even when the ferrule is retracted, the optical fiber core coming out from the rear end of the ferrule is pushed into the optical cord, and the optical fiber core does not bend.

Further, the tube is made of metal or ceramic, and its length Y is equal to or more than (the length from the rear end of the ferrule to the cut-out portion of the jacket) is not less than (L-5 mm). (Length to the part L-1mm)
In the following, the distance (LY) between the rear end of the tube and the cut portion of the jacket can be 1 to 5 mm. If the portion of the optical fiber cable coming out of the tube has a length of about 1 to 5 mm, the optical fiber cable does not bend or buckle even if it is retracted by about 1 mm. Pushed into the code.

In addition, the length Y behind the ferrule is (the length L-5 from the rear end of the ferrule to the cut-out portion of the jacket).
mm) or more, and a metal or ceramic tube (length from the rear end of the ferrule to the cut-out portion of the jacket) of less than or equal to (L-1 mm) is arranged to cover the optical fiber core wire. The length of the ferrule (the length from the rear end of the rear part of the ferrule to the cut-out part of the jacket) is 1 to 5 m.
A similar effect can be expected by specially making and using a ferrule having m.

An optical cord comprising a silica glass fiber having an outer diameter of 125 μm coated with an ultraviolet curing resin to form an optical fiber core having an outer diameter of 250 μm, a tensile strength member disposed thereon, and a jacket further provided. Using an optical cord having a Young's modulus and a cross-sectional area of 7 kg or less using a thermoplastic resin as a jacket, a ferrule for fixing an optical fiber is pressed by an elastic member from the rear, and at the time of fitting, By attaching an optical connector in which the ferrule retreats backward, buckling does not occur in the optical fiber core even in the case of a small-diameter optical cord whose outer diameter is 250 μm. Can be.

Further, the ratio of the total cross-sectional area of the tensile strength member to a value obtained by subtracting the cross-sectional area of the optical fiber core from the inner cross-sectional area of the outer sheath of the optical cord is set to 60% or less, so that the optical fiber core is reduced. The deflection is smoothly absorbed into the optical cord, and the effect of not damaging the optical fiber or deteriorating the transmission loss can be further improved.

[0012]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention. An optical cord 7 is made of an optical fiber core 1, a tensile strength member 2 made of aramid fiber or the like, or a plastic such as a vinyl chloride resin. And an outer jacket 3. 4 is an optical connector, 5 is a protective boot made of rubber or the like, and 6 is a tube made of a synthetic resin such as nylon. The optical connector 4
Ferrule 4 attached to the tip of optical fiber
a, a ring 4b for stopping the tensile strength member 3, a ring 4c for stopping the jacket 4, a housing 4d, elastic members 8 such as springs, etc., and a ferrule 4a is attached to the tip of the optical fiber core 1. Since the strength member 2 is made of a fiber such as aramid fiber, the space between the jacket 3 and the optical fiber 1 is almost uniformly filled with the strength member 2.

In this case, the tube 6 is put on the optical fiber 1 from the rear of the ferrule 4a over the cutout portion 3a of the jacket of the optical cord 7. Tube 6
Is passed through the optical fiber before the ferrule is attached. The length M of the tube 6 is longer than the length L from the rear end of the ferrule to the cutout portion of the jacket, and a part of the tube is pushed into the optical cord from the cutout portion of the jacket. It should be noted that the length M of the tube 6 is set to be 5 times smaller than the length L from the rear end of the ferrule to the cutout portion of the jacket.
It is desirable that the length be at least 5 mm or more, and be pushed into the inside of the optical cord by 5 mm or more from the cutout portion of the jacket.
The ferrule 4a side of the tube 6 is a ferrule 4
It is also possible to slightly enter the hole a. In this case, the length M of the tube 6 is the length of the portion protruding outside the hole of the ferrule 4a.

The tube 6 is preferably made of a material having a higher rigidity than the optical fiber core 1.
Synthetic resins such as tetrafluoride resins are suitable. Further, since the tube 6 is pushed into the inside of the optical cord 7, when the outer diameter of the optical fiber core wire 1 is 250 μm, the tube 6 preferably has an inner diameter of about 350 μm and an outer diameter of about 650 μm.

As described above, by covering the optical fiber core behind the ferrule with the tube 6, even if the ferrule retreats backward against an elastic member such as a spring when the optical connector is fitted, the optical fiber core is prevented. Is pushed into the optical cord without bending, and the extra length due to the retraction of the ferrule is absorbed by elongation of the coating on the optical cord side or the like.
In addition, the tensile strength member 2 opens the fiber in a tapered shape to form a ring 4b.
The jacket 3 is cut open in one or more places in the length direction, opened in a tapered shape, and held by the ring 4c.

FIG. 1 shows an example in which a relatively long tube made of a synthetic resin is disposed behind the ferrule to cover the optical fiber core wire. However, the tube disposed behind the ferrule is made relatively short. However, the same effect can be obtained. FIG. 2 is a longitudinal sectional view showing the embodiment,
FIG. 2A shows a state before the ferrule retreats.
(B) shows the state after the ferrule has retreated. The same reference numerals as those in FIG. 1 indicate the same components.

In the example shown in FIG. 2, a tube 9 made of metal or ceramics is arranged behind the ferrule 4a to cover the optical fiber core 1. The length Y of the tube 9 is (from the rear end of the ferrule to the jacket). Length L-5 up to the slit
mm) or more and (L-1 mm from the rear end of the ferrule to the cut-out portion of the jacket). By making such a tube length,
Since the length (LY) from the rear end of the tube to the cut-out portion of the jacket can be 1 to 5 mm, even if the tube 9 is retracted together with the ferrule 4a, the rigidity of the optical fiber core wire 1 causes The optical fiber core 1 is pushed into the optical cord 7 without bending or buckling.

Further, since the retreat dimension of the ferrule 4a and the tube 9 is about 1 mm, the tube 9 does not enter the optical cord 7 even if it retreats. Therefore, the tube 9
The tube 9 can be made of metal or ceramic, and the outer diameter of the tube 9 can be made larger than that of a synthetic resin tube.

The length Y behind the ferrule is (the length L-5 from the rear end of the ferrule to the cutout portion of the jacket).
mm) or more, and a metal or ceramic tube (length from the rear end of the ferrule to the cut-out portion of the jacket) of less than or equal to (L-1 mm) is arranged to cover the optical fiber core wire. The length of the ferrule (the length from the rear end of the rear part of the ferrule to the cut-out part of the jacket) is 1 to 5 m.
The ferrule shown in FIG. 3B, which is m, can be specially made and used.

The ferrule 4a shown in FIG. 3A has a rear portion 4a-1 of a normal length, and the ferrule 10 shown in FIG. 3B has a longer rear portion 10-1 and has a rear portion. The portion 10-1 is the length + Y of the normal rear portion 4a-1. Even when such a ferrule 10 is used, the length from the rear end portion of the rear portion 10-1 of the ferrule to the cutout portion of the jacket can be set to 1 to 5 mm. The same effect can be expected. Also, by integrating the rear part of the ferrule and the tube, it is possible to manufacture the ferrule in the same manner as in manufacturing the ferrule alone, so that it is possible to manufacture the ferrule and the tube at a lower cost than when manufacturing the ferrule and the tube separately.

Further, the structure of an optical cord suitable for absorbing the movement of the optical fiber core due to the retraction of the ferrule in the connection of the optical connector was examined. When the material and dimensions of the jacket of the optical cord were examined, the following findings were obtained. An optical cord in which an ultraviolet curable resin is coated on a glass fiber having an outer diameter of 125 μm to form an optical fiber core wire having an outer diameter of 250 μm, and an aramid fiber is used as a tensile member and a vinyl chloride jacket is provided on the outside thereof. Was manufactured by changing the material and dimensions of the jacket,
The increase in transmission loss when the ferrule was retracted by 1 mm during coupling was investigated. In the prototype, the optical fiber core wire behind the ferrule was covered with a nylon tube.

The test results of the prototype are shown in FIG. 4, and those having a high vinyl chloride cross-sectional area × vinyl chloride Young's modulus have a large increase in transmission loss. It was found that vinyl having a low Young's modulus did not increase transmission loss. Also, its limitations are:
It was also found that the cross-sectional area of vinyl chloride × Young's modulus of vinyl chloride = 7 kg.

This is because, when the optical fiber core is going to retreat backward, if the cross-sectional area of the jacket × the Young's modulus is small, the retreat stress of the optical fiber core is likely to be absorbed as the elongation or bulging of the jacket. If the cross-sectional area of the jacket x Young's modulus is large, the elongation or swelling of the jacket is unlikely to occur,
It is presumed that this is because the retreat stress of the optical fiber is hardly absorbed. Therefore, the same effect can be expected if the jacket is not a vinyl chloride but a thermoplastic resin.

Further, the effect of the filling rate of the aramid fiber vertically attached between the optical fiber core and the jacket was examined.
As a result, when the ratio of the total cross-sectional area of the aramid fiber to the value obtained by subtracting the cross-sectional area of the optical fiber core from the inner cross-sectional area of the vinyl chloride jacket is set to 60% or less, when the optical connector is attached and coupled. It was confirmed that transmission loss did not increase. It is presumed that the reason for this is that when the filling rate of the strength member is low, the backward stress of the optical fiber is easily absorbed in the strength member. In addition, the total cross-sectional area of the aramid fiber as the tensile strength member was calculated from the weight of the aramid fiber per unit length of the optical cord and the specific gravity of the material of the aramid fiber.

[0025]

According to the present invention, the end of the jacket of the optical cord is cut open and fixed to a part of the optical connector. From the ferrule toward the optical cord (from the rear end of the ferrule to the cut-out part of the jacket). The length of the optical fiber is covered with a tube having a length of L-5 mm or more, so that the ferrule retreats backward when the optical connector is fitted, and the optical fiber core fixed to the ferrule causes a retreat stress. Even if received, the stress is smoothly absorbed into the optical cord without the optical fiber core buckling. Therefore, the transmission characteristics of the optical fiber are not deteriorated.

Alternatively, a ferrule having a long rear portion of the ferrule may be manufactured, and the length from the rear end of the rear portion of the ferrule to the cut-out portion may be set to 1 to 5 mm. In this case, it is possible to obtain an effect that stress is smoothly absorbed into the optical cord without buckling of the optical fiber.
Also, in this case, there is no need to manufacture the ferrule and the tube as separate bodies, and the mounting work is reduced, so that the manufacturing cost can be reduced as compared with the case where the ferrule and the tube are manufactured and mounted separately.

If an optical connector is attached by using an optical cord having a Young's modulus and a cross-sectional area of 7 kg or less using a thermoplastic resin as a jacket, the ferrule retreats backward at the time of fitting. However, even if the optical fiber core is subjected to the backward stress, the stress is absorbed by the sheath, and the optical fiber core is buckled even in the case of a small-diameter optical cord having an outer diameter of 250 μm. Can be prevented from occurring.

Further, the ratio of the total cross-sectional area of the tensile strength member to a value obtained by subtracting the cross-sectional area of the optical fiber core from the inner cross-sectional area of the outer sheath of the optical cord may be set to 60% or less. It is effective in absorbing the receding stress received inside the optical cord.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an optical cord with an optical connector according to an embodiment of the present invention, when a ferrule is not retracted.

2A and 2B are longitudinal sectional views showing an optical cord with an optical connector according to another embodiment of the present invention, wherein FIG. 2A shows when the ferrule is not retracted, and FIG. 2B shows when the ferrule is retracted.

FIG. 3A is a longitudinal sectional view of a normal ferrule, and FIG.
FIG. 4 is a longitudinal sectional view of a ferrule having a longer rear portion.

FIG. 4 is a diagram showing the results of a test on the presence or absence of a change in transmission loss when the outer diameter of the optical cord is varied by changing the cross-sectional area of the jacket × Young's modulus.

5A and 5B are longitudinal sectional views showing an optical cord with an optical connector according to the related art, wherein FIG. 5A shows a state where the ferrule is not retracted, and FIG. 5B shows a state where the ferrule is retracted.

[Explanation of symbols]

1: Optical fiber core wire 2: Tensile member 3: Jacket 4: Optical connector 4a, 10: Ferrule 4a-1, 10-1: Rear part 4b: Ring for stopping the tensile member 4c: Ring for stopping the jacket 4d: Housing 5: Protective boots 6, 9: Tube 7: Optical cord 8: Elastic member L: Length from the rear end of the ferrule to the cutout portion of the ferrule M, Y: Length of the tube

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinichi Furukawa 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (6)

[Claims] 1. An optical connector in which a ferrule for fixing an optical fiber core is pressed from behind by an elastic member, and the ferrule retreats rearward when fitted, and has a jacket outside the optical fiber core. In the method of attaching to the optical cord, the end of the jacket of the optical cord is cut out and fixed to the optical connector part, and at least from the rear end of the ferrule toward the cutout of the jacket of the optical cord (the rear end of the ferrule). An optical connector mounting method, characterized in that the optical fiber core is covered with a tube having a length of not less than -5 mm from the length of the outer sheath to the cutout portion of the sheath. 2. The optical connector mounting method according to claim 1, wherein the tube is made of a synthetic resin and has a length equal to or more than (a length from a rear end portion of the ferrule to a cut-out portion of the jacket). . 3. The tube is made of metal or ceramic, and the length of the tube is (length from the rear end of the ferrule to the cutout portion of the jacket −5 mm) or more, and the length of the tube is the cutout portion from the rear end of the ferrule. Length-1m
m) The method according to claim 1, wherein: 4. An optical connector in which a ferrule for fixing an optical fiber core is pressed from behind by an elastic member, and the ferrule retreats rearward when fitted, and has a jacket outside the optical fiber core. In the method of attaching to the optical cord, the end of the jacket of the optical cord is cut out and fixed to a part of the optical connector, and the length from the rear end of the rear part of the ferrule to the cut-out part of the jacket is 1 mm or more and 5 mm or less. A method for mounting an optical connector, comprising: using a ferrule having a long tubular rear portion to cover an optical fiber core wire with the rear portion. 5. An optical cord comprising a silica glass fiber having an outer diameter of 125 μm coated with an ultraviolet curable resin to form an optical fiber core having an outer diameter of 250 μm, a tensile strength member disposed thereon, and a jacket provided thereon. A ferrule for fixing an optical fiber is pressed from behind by an elastic member to an optical cord having a Young's modulus and a cross-sectional area of 7 kg or less using a thermoplastic resin as a jacket. An optical cord with an optical connector, wherein an optical connector of a type that retreats backward is attached. 6. The ratio of the total cross-sectional area of the tensile member to a value obtained by subtracting the cross-sectional area of the optical fiber from the inner cross-sectional area of the jacket of the optical cord is 60% or less. 6. The optical cord with an optical connector according to 5.