JP2000258295A - Screening method for fusion spliced part of optical fiber - Google Patents

Abstract

(57) [Summary] [PROBLEMS] A screening apparatus for changing the value of the strength guarantee of a fusion spliced portion of an optical fiber to be inspected and changing the number of fusion spliced portions of an optical fiber to be inspected. A method for screening a fusion spliced portion of an optical fiber which can be easily dealt with without complicating the structure of the optical fiber, and a method for screening a fusion spliced portion of an optical fiber which can express a value of its strength as a tensile strength. provide. SOLUTION: The holding parts of the optical fibers 2 and 3 after the fusion splicing by the clamping devices 14 and 14 are brought close to each other by a predetermined distance, and the fusion spliced portions 2 of these optical fibers 2 and 3 are brought close to each other.
Curve 0. As a result, a predetermined amount of tensile force is generated on the outer peripheral side in the bending direction of the fusion splicing portion 20, and it is known that the fusion splicing portion 20 can withstand the predetermined magnitude of pulling force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for screening a fusion spliced portion of an optical fiber, in particular, a method for inspecting the tensile strength of a fusion spliced portion of a plurality of optical fibers. is there.

[0002]

2. Description of the Related Art Optical fibers are connected by fusion splicing their ends. Since the fusion spliced part of the optical fiber is greatly reduced in strength compared to the original optical fiber by being heated during fusion splicing, the fusion spliced part can withstand the subsequent use environment Inspection of the strength of the fusion spliced portion of the optical fiber, that is, screening of the fusion spliced portion of the optical fiber is performed to ensure the above. As a conventional method for screening a fusion spliced portion of an optical fiber, a screening device is used in which both ends of the fusion spliced portion of an optical fiber are gripped, and a fixed force is applied to the gripped portion to move in a direction to separate them from each other. A method of applying a certain amount of tensile force to a fusion spliced portion of an optical fiber is known.

[0003]

The above-mentioned conventional method for screening a fusion spliced portion of an optical fiber has the following problems. Since the tensile force applied to the fusion spliced portion of the optical fiber is generated by moving the grip portions at both ends of the optical fiber spliced portion so as to be separated from each other by applying a constant force, for example, in a severe environment. If you want to apply an unusually high tensile force to the fusion spliced part of the optical fiber, such as when inspecting an optical fiber that requires a higher strength assurance value than that normally used for the fusion spliced part. In addition, in order to cope with the case where the number of optical fibers to be inspected is increased or decreased, it is necessary to provide a mechanism for adjusting the pulling force of the screening device, which complicates the screening operation and increases the size of the screening device. There was a problem. Also, conventionally, the value of the strength guarantee of the fusion spliced part of the optical fiber is represented by the tensile strength, so when screening by another method,
There is a problem that the strength guarantee values of the optical fibers cannot be directly compared.

The present invention has been made in view of the above circumstances, and is intended for changing the value of the strength assurance of a fusion spliced portion of an optical fiber to be inspected, and for inspecting an arbitrary number of optical fibers. Another object of the present invention is to provide a method for screening a fusion spliced portion of an optical fiber, which can be easily performed without complicating the structure of the screening apparatus, and the value of the strength guarantee can be expressed by a tensile strength. It is another object of the present invention to provide a method for screening a fusion spliced portion of an optical fiber.

[0005]

According to a first aspect of the present invention, there is provided a method for screening a fusion spliced portion of an optical fiber. The two ends are gripped and the gripping portions are brought closer to each other to bend the fusion splice (20) between the gripping portions, whereby the fusion splice (2)
0) a predetermined amount of tensile force σp on the outer circumferential side in the bending direction
And that the fusion spliced portion (20) can withstand the predetermined magnitude of the pulling force σp. In the thus configured screening method of the fusion spliced portion of the optical fiber, the bending direction of the fusion spliced portion (20) is obtained by bending the fusion spliced portion (20) of the optical fiber (2, 3). A predetermined amount of tensile force σp is applied to the outer peripheral side, and it is known that the fusion spliced portion (20) can withstand the predetermined amount of tensile force σp.

According to a second aspect of the present invention, there is provided a method for screening a fusion spliced portion of an optical fiber.
Based on the radius r, cross-sectional area Af, and Young's modulus Ef of the optical fibers (2, 3), the predetermined outside of the fusion spliced portion (20) of the optical fibers (2, 3) in the bending direction is obtained. A bending radius R of the optical fiber (2, 3) to which a large tensile force σp is applied is calculated, and the optical fiber (2, 3) is divided based on the bending radius R and the distance L between the gripped portions. Calculate the amount of movement ΔL of the gripping portions in the direction of relatively approaching each other required to bend at the bending radius R,
The gripping portions are moved relatively to each other by ΔL, whereby a predetermined amount of pulling force σp is applied to the outer peripheral side in the bending direction of the fusion splicing portion (20), whereby the fusion splicing is performed. It is characterized in that it is known that the part (20) can withstand the predetermined magnitude of the pulling force σp.

In the screening method for the fusion spliced portion of the optical fiber configured as described above, the optical fiber (2, 3)
An optical fiber (A) in which a predetermined amount of tensile force σp is applied to the outer peripheral side in the bending direction of the fusion spliced portion (20) of the optical fibers (2, 3) based on the radius r, the cross-sectional area Af, and the Young's modulus Ef of The bending radius R of the optical fiber (2, 3) is calculated based on the bending radius R and the distance L between the holding portions.
Is calculated in the direction in which the gripping parts approach each other relatively to bend with the bending radius R, and the gripping parts are moved so as to approach each other by ΔL. A predetermined amount of tensile force σp is applied to the outer peripheral side in the bending direction of the connection section (20).

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for screening a fusion spliced portion of an optical fiber according to the present invention will be described below. FIG. 1 shows an embodiment of a screening apparatus 1 used for carrying out a method for screening a fusion spliced portion of an optical fiber according to the present invention. The screening apparatus 1 grips the ends of the optical fiber tapes 4 and 5 in which the plurality of optical fibers 2 and 3 are put together in a tape shape, and aligns the axes of the plurality of optical fibers 2 and 3 with each other. While maintaining the state, these optical fibers 2,
3 for screening, and comprises optical fiber gripping devices 6 and 7 which are arranged to face each other while gripping the ends of the optical fiber tapes 4 and 5 and the optical fibers 2 and 3, respectively. .

The optical fiber gripping device 6 is provided with a movable base 12 so as to be movable back and forth in a direction from the base 11 to the optical fiber gripper 7, and a tape holder for holding the optical fiber tape 4 above the movable base 12. 13 is provided, and a clamping device 14 for fixing the optical fiber 2 is provided on the optical fiber holding device 7 side of the moving table 12. The moving table 12 and the clamping device 14 are provided with a driving device 15 provided on the base 11.
As a result, they are integrally moved in the direction toward the optical fiber holding device 7.

[0010] The clamp device 14 is provided with the optical fiber tape 4.
A plurality of optical fibers 2 exposed from the tip of the optical fiber are held in a state where their axes are aligned with the plurality of optical fibers 3 exposed from the tip of the optical fiber tape 5 held by the optical fiber holding device 7. It is composed of a V-groove 16 and a clamp 17 which presses and fixes the plurality of optical fibers 2 to the V-groove 16. The driving device 15 is provided on the base 11, and presses or moves so that the rod 18 b expands and contracts by rotating and driving the base 18 a, and moves the moving base 12 back and forth in the direction toward the optical fiber holding device 7. The micrometer 18 is configured to include a micrometer 18 to be pulled and a drive motor 19 that rotates a base 18a of the micrometer 18 by a drive gear 19b provided on a drive shaft 19a.

The optical fiber holding device 7 has the same configuration as that of the optical fiber holding device 6 and is disposed so as to face the optical fiber holding device 6. In this specification, each component of the optical fiber gripping device 7 is represented by the same name and reference numeral as each corresponding component of the optical fiber gripping device 6, and detailed description is omitted.

The screening of the optical fibers 2 and 3 by the method for screening a fusion spliced portion of an optical fiber according to the present invention is performed by using the optical fiber holding devices 6 and 7 of the screening device 1.
In this state, the ends of the optical fibers 2 and 3 of the optical fiber tapes 4 and 5 are brought closer to each other by a predetermined distance, and the optical fibers 2 and 3 are fusion-spliced in this state. The screening of the optical fibers 2 and 3 by the method for screening the fusion spliced portion of the optical fiber of the present invention is performed as follows. The clamping devices 14, 14 of the optical fiber holding devices 6, 7 are moved in a direction approaching each other, and the clamping device 1 of the optical fibers 2, 3 after fusion splicing.
The gripping portions of the optical fibers 2 and 3 are brought closer to each other by a predetermined distance, and the fusion spliced portion 20 of the optical fibers 2 and 3 (hereinafter, referred to as the fusion spliced portion 20) is curved. As a result, a predetermined amount of tensile force is generated on the outer peripheral side in the bending direction of the fusion splicing portion 20, and it is known that the fusion splicing portion 20 can withstand the predetermined magnitude of pulling force. The fusion spliced portion 20 here refers to a portion of the optical fibers 2 and 3 that is located between the gripping portions of the optical fiber gripping devices 6 and 7 by the clamp devices 14 and 14. FIG. 2 schematically shows how the fusion spliced portion 20 bends. Here, the fusion splicing portion 20 is very small as shown in a specific example described later, but the curvature of the fusion splicing portion 20 is emphasized in FIG.

The bending radius of the fusion splicing portion 20 in which a predetermined amount of tensile force is applied to the outer peripheral side in the bending direction of the fusion splicing portion 20 can be obtained as follows. Assuming that the radius of the fusion splicing portion 20, that is, the radius of the optical fibers 2 and 3, is r,
When the fusion splicing portion 20 is bent at the bending radius R, the strain εp generated on the outer peripheral side in the bending direction of the fusion splicing portion 20 is expressed by the following equation. εp = r / (R + r) (1) From the definition of the Young's modulus, the Young's modulus of the optical fibers 2 and 3 is Ef, the tensile force generated on the outer peripheral side of the fusion splicing portion 20 in the bending direction is σp, and the fusion splicing portion is Assuming that the cross-sectional area of 20 is Af, the strain εp is expressed by the following equation. εp = σp / (Ef × Af) = r / (R + r) (2) From this equation, the tensile force σp can be expressed by the following equation using the radius r of the fusion spliced portion 20 and the bending radius R thereof. . .sigma.p = (r / (R + r)). times. (Ef.times.Af) (3) By rearranging equation (3) for R, the following equation is obtained. R = (r × Ef × Af) / σp-r (4)

Next, in order to bend the fusion spliced portion 20 with the bending radius R, the amount by which the gripping portions at both ends of the fusion spliced portion 20 are brought close to each other, that is, the clamping devices 14 of the optical fiber gripping devices 6 and 7, The amount of movement for moving the fourteen in the direction approaching each other is obtained as follows. Fusion splicing part 2
Assuming that the length is 0, that is, the distance between the clamping devices 14 and 14 of the optical fiber holding devices 6 and 7 is L, a movement amount さ せ る for moving the clamping devices 14 and 14 in a direction approaching each other.
L is represented by the following equation. ΔL = L−4R sin (45 L / πR) (5)

By substituting equation (4) into equation (5), the pulling force σp
Is required, the amount of movement ΔL of the clamping devices 14 and 14 in the approaching direction necessary to provide the following.

A specific example of calculation of the amount of movement ΔL of the clamp devices 14 in the approaching direction will be described below. The radius r is 0.
0625 (m), Young's modulus Ef is 7300 (N /
m ² ) of the fusion spliced portion 20 of the optical fibers 2 and 3
The amount of movement ΔL of the clamping devices 14 in the approaching direction when it is desired to guarantee that the pulling force can withstand the pulling force of g is obtained. Here, the distance L between the clamping devices 14, 14
Is 0.005 (m), the bending radius R of the fusion spliced portion 20 when 180 g of tensile force is applied to the outer peripheral side in the bending direction of the fusion spliced portion 20 is given by R = (0 .00625 × 7300 × 0.01227) /
0.18-0.00625 When this is solved, R = 0.03104 (m) = 31.04
(Mm). Subsequently, R is set to 31 (mm) and substituted into equation (5). ΔL = 5− (4 × 31) sin (45 × 5 / 31π) = 1.4 × 10 ⁻³ mm = 1.4 μm Therefore, the radius r is 0.00625 (m) and the Young's modulus Ef
If it is desired to assure that the fusion spliced portion 20 of the optical fibers 2 and 3 having a diameter of 7300 (N / m) can withstand a pulling force of 180 g, the clamping devices 14 and 14 are brought closer to each other by 1.4 μm. Just move it.

According to the screening method for the optical fibers 2 and 3 configured as described above, the pulling force σp applied to the fusion spliced portion 20 of the optical fibers 2 and 3 causes the gripped portions of the fusion spliced portion 20 to move. Since it is caused by bending the fusion splicing portion 20 by approaching, even when it is desired to change the value of the strength guarantee of the fusion splicing portion 20, the movement amount ΔL for bringing the gripped portions closer together is changed by the fusion splicing. By simply changing the degree of curvature of the portion 20, the magnitude of the pulling force σp can be adjusted without using any special adjustment or adjustment mechanism. Even if the number of the optical fibers 2 and 3 is arbitrary, the respective optical fibers are curved in the same manner, so that the fusion splicing of the respective optical fibers can be performed without using any special adjustment or adjustment mechanism. A uniform tensile force σp can be applied to the portion. Also, the value of the strength guarantee of the fusion spliced portion of the optical fiber can be represented by the conventionally used tensile strength.

In the above-described embodiment, an example is used in which the gripping portions of the fusion splicing portion 20 are brought closer to each other by moving both of the clamping devices 14 and 14 of the optical fiber gripping devices 6 and 7. However, the present invention is not limited to this, and one of the clamping devices 14 and 14 of the optical fiber holding devices 6 and 7 is fixed, and the other is moved, so that the fusion splicing portion 2 is formed.
Zero grip portions may be brought close to each other.

[0019]

According to the method for screening a fusion spliced portion of an optical fiber according to the first aspect, the optical fiber (2, 3).
The tensile force σp applied to the fusion spliced part (20) of
This is caused by bending the fusion splicing part (20) by bringing the gripping parts of the fusion splicing part (20) relatively close to each other, so that it is necessary to change the strength guarantee value of the fusion splicing part (20). This can also be dealt with simply by changing the amount of movement of the gripped portions closer to each other and changing the degree of curvature of the fusion splicing portion (20). Optical fiber to be inspected (2, 3)
When the number of the optical fibers (2, 3) is increased or decreased, the respective optical fibers (2, 3) are curved in the same manner, so that the respective optical fibers (2, 3) can be used without using any special adjustment or adjusting device. A uniform tensile force σp can be applied to the fusion spliced portion (20).

According to the method for screening a fusion spliced portion of an optical fiber according to claim 2, the optical fiber (2,
Since the amount of movement ΔL of the grip portions in the direction of relatively approaching each other to apply the pulling force σp to the fusion spliced portion (20) of 3) is calculated, the grip portions are relatively moved. By moving the fusion spliced portions (2, 3) closer by the amount ΔL, a tensile force σp can be applied to the fusion spliced portions (2, 3). Further, the fusion spliced portion (2) of the optical fibers (2, 3)
The value of the strength guarantee of 0) can be represented by the tensile strength conventionally used.

[Brief description of the drawings]

FIG. 1 is a front view showing the configuration and structure of a screening method and a screening apparatus for a fusion spliced portion of an optical fiber according to an embodiment of the present invention.

FIG. 2 is a perspective view schematically showing a state of bending of a fusion spliced portion of the optical fiber according to the embodiment of the present invention.

[Explanation of symbols]

1 ... Screening device, 2, 3 ... Optical fiber, 4,
5 optical fiber tape, 6, 7 optical fiber holding device,
12: moving table, 14: clamping device, 20: fusion splicing part

Claims (2)

[Claims] 1. A fusion splicing part (2) for an optical fiber (2, 3).
0) are gripped at both ends, and the gripped portions are relatively approached to each other to bend the fusion spliced portion (20) between the gripped portions, whereby the bending direction of the fusion spliced portion (20) A fusion splicing of an optical fiber, characterized in that a predetermined amount of tensile force σp is applied to the outer peripheral side to know that the fusion spliced portion (20) can withstand the predetermined amount of tensile force σp. How to screen connections. 2. The method for screening a fusion spliced part of an optical fiber according to claim 1, wherein the optical fiber is based on a radius r, a cross-sectional area Af, and a Young's modulus Ef of the optical fiber. (2, 3) calculating a bending radius R of the optical fiber (2, 3) in which the predetermined magnitude of the tensile force σp is applied to the outer peripheral side in the bending direction of the fusion spliced portion (20); And the distance L between the gripping portions,
The amount of movement ΔL of the gripping portions in the direction of approaching each other relatively required to bend the optical fibers (2, 3) at the bending radius R is calculated. ΔL, so that a predetermined amount of tensile force σp is applied to the outer peripheral side in the bending direction of the fusion splicing portion (20), and the fusion splicing portion (20) is moved to the predetermined magnitude. 2. The method for screening a fusion spliced portion of an optical fiber according to claim 1, wherein it is known that the optical fiber can withstand a tensile force .sigma.p.