JPH06235826A - Fixing structure for fusion spliced part of optical fibers - Google Patents

Abstract

PURPOSE:To provide a fixing structure for the fusion spliced part of optical fibers which does not degrade the optical characteristics of the optical fibers even if the reliability of fixing is enhanced by increasing fixing power. CONSTITUTION:A reinforcing material (steel core 2) is placed longitudinally along the fusion spliced part of the optical fibers 1, 1 and is fixed by a hot meltable adhesive tube 3 and a heat shrinkable tube 4. The part of the steel core 2 not placed along the optical fibers is clamped by a base plate 5 and a retaining member 7 and, therefore, the optical fibers are not applied with a strong side pressure even if clamping power is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing structure for stably fixing and supporting a fusion splicing portion of an optical fiber.

[0002]

2. Description of the Related Art A fusion splicing portion of an optical fiber is reinforced by attaching a protective sleeve in order to peel off an outer cover. The protective sleeve used for the reinforcement covers the heat-meltable adhesive tube and the heat-shrinkable tube so as to overlap each other, and by heating the heat-meltable adhesive tube, the heat-meltable adhesive tube is melted and at the same time, the outer tube that has been heat-shrinked is used as an optical fiber. It is often used that is adhesively fixed on top. A reinforcing material such as a steel core may be put inside the heat shrinkable tube.

The portion reinforced in this way has a large outer diameter and is easy to grasp, and since the bending rigidity is also sufficiently large, this portion ( It is common to grip the protective sleeve with a fixture.

In the case of an optical fiber mounted on a vehicle or the like, the fixing tool at this time is required to have a high reliability because a disconnection or the like may be caused when the protective sleeve is disengaged or moves due to vibration.

Therefore, the present applicant has proposed a fixture shown in FIG. 6 in Japanese Patent Application No. 3-18829 in order to meet the demand. This fixture includes two elastic plates 21,
21 is arranged between the housing 22 and the pressing member 23, and the protective sleeve 24 is sandwiched between them to attach the pressing member 23 to the screw 2
It is tightened with 5.

[0006]

When an optical fiber receives a strong lateral pressure, the transmission loss of light increases. Further, if the optical fiber to be fixed is a constant polarization (polarization maintaining) optical fiber, the state of the polarized wave propagating in the lateral pressure applying unit may change.

Therefore, the fixture shown in FIG. 6 has the elastic plate 21.
As the foam rubber, a pressing member 23 is tightened to prevent the movement of the member by the housing so as not to become excessive. However, when the entire protective sleeve is tightened as shown in the figure, lateral pressure is inevitably applied to the optical fiber. This lateral pressure is not constant because there is a change in tightening pressure due to temperature changes, etc. Therefore, if lateral pressure is disliked, tightening by the pressing member 23 must be loosened to some extent. However, this reduces the fixed reliability.

Therefore, the present invention is intended to provide a fixing structure of an optical fiber fusion splicing portion which can perform strong fixing without applying lateral pressure to the optical fiber.

[0009]

In order to solve the above-mentioned problems, the present invention is to attach a reinforcing material vertically to a fusion splicing portion of an optical fiber, and fix the optical fiber non-attaching portion of the reinforcing material with a fixture. It has a structure to hold.

The reinforcing material may be attached to the fusion splicing portion by adhesion, but the outer periphery of the longitudinal portion of the reinforcing material is covered with a heat-melting adhesive tube and a heat-shrinkable tube to heat the inner tube. It is more desirable in terms of protection of the optical fiber if it is attached by melting due to the above and contraction due to heating of the outer tube.

[0011]

[Function] Since the reinforcing material is held so that the optical fiber is not caught between the holding points, the lateral pressure applied to the optical fiber at the fusion splicing part becomes extremely small, and it is also affected by changes in tightening pressure due to temperature changes and the like. hard.

Therefore, even if the fastener is tightly tightened to improve the reliability of the fixing, the optical characteristics of the optical fiber are stabilized and the transmission loss is not increased and the polarization state is not changed.

[0013]

FIG. 1 shows an example of the fixing structure of the present invention. The optical fibers 1 and 1 are made by abutting the element wires exposed at the terminals and fusing them. 2 is a steel core for reinforcement. This steel core 2
As shown in FIG. 2 (a), it is vertically attached to the fusion splicing portion. Reference numeral 3 is a heat-meltable adhesive tube, and 4 is a heat-shrinkable tube, which are covered on the outside as shown in FIG. 2B and heated with warm air or the like. This melts the tube 3,
The tube 5 contracts and the steel core 2 is fixed to the fusion spliced portion.

The protected connection portion 10 assembled in this manner
1 is sandwiched and fixed between the substrate 5 and a holding member 7 attached to the substrate with a screw 6, as shown in FIG. At this time, the optical fiber orients the protected connection portion 10 so as to be out of the line connecting the contact points P and Q in FIG. 1B.

The fusion splicing part may be fixed by press fitting the protected splicing part 10 of FIG. 1 between the holding plates 8 provided upright on the substrate 5 as shown in FIG.

Further, as shown in FIG. 4, a reinforcing plate 9 is vertically provided, and the jacket portions of the optical fibers 1 and 1 are fixed to the reinforcing plate with an adhesive 11, and the reinforcing plate 9 is fixed by an appropriate fixing tool. You may pick it up in the direction of the arrow. Reference numeral 12 is a protective cover, which is preferable in the structure of FIG.

FIG. 5 shows a case in which a plurality of protected connection portions 10 are fixed by one fixing tool. In this way, when the protected connection portion 10 is sandwiched via the sponges 13 and 14, the effect of protecting from impact is further enhanced.

The structure shown in FIG. 5 was adopted in a vehicle-mounted optical fiber gyro to confirm the effect. An optical fiber gyroscope is a sensor that finds the angular velocity of rotation by the phase difference of the light propagating in the optical fiber coil in the reverse direction, and is a fusion splicer that connects the optical fiber coil, optical fiber type polarizer, optical fiber coupler, etc. There are usually a plurality of cases.
Further, the optical fiber connected via the fusion splicing part includes a polarization-maintaining optical fiber which is very sensitive to external stress. Therefore, the presence or absence of a change in the optical characteristics due to the fixing of the fusion splicing greatly affects the performance reliability of the gyro, but even if the holding force is increased more than before, no particular problem occurs, and the change in the optical characteristics is greater than that of the conventional structure. It was confirmed that it would be smaller.

[0019]

As described above, according to the present invention, the reinforcing member vertically attached to the fusion splicing portion of the optical fiber is held by the fixing tool so that the optical fiber is not caught between the holding points. It is possible to increase the fixing force and stabilize the optical characteristics of the optical fiber at the same time, which leads to improvement in performance and reliability of the in-vehicle optical fiber sensor device.

[Brief description of drawings]

FIG. 1A is a perspective view showing an example of a fixing structure of the present invention. FIG. 1B is an enlarged end view of the same.

FIG. 2A is a side view showing a procedure for attaching a steel core, and FIG. 2B is a sectional view showing a procedure for attaching a steel core.

FIG. 3 is a perspective view of another embodiment.

FIG. 4 is a perspective view of still another embodiment.

FIG. 5 is a diagram showing an example of fixing a plurality of pieces.

FIG. 6 is a view showing a fixing structure using a conventional fixing tool.

[Explanation of symbols]

 1 Optical Fiber 2 Steel Core 3 Heat Melt Adhesive Tube 4 Heat Shrinkable Tube 5 Substrate 6 Screw 7 Holding Member 8 Holding Plate 9 Reinforcing Plate 10 Protected Connection 11 Adhesive 12 Protective Cover

Claims (2)

[Claims] 1. A reinforcing material is vertically attached to a fusion spliced portion of an optical fiber, and the non-optical fiber spliced portion of the reinforcing material is held by a fixing tool to fix the fusion spliced portion in a fixed position. Fixing structure of optical fiber fusion splicing part. 2. A reinforcing material is provided on the fusion splicing portion by covering the outer circumference of the longitudinally extending portion of the reinforcing material with a heat-melting adhesive tube and a heat-shrinkable tube, and melting the inner tube by heating and shrinking the outer tube by heating. The fixing structure for an optical fiber fusion splicing section according to claim 1, wherein the reinforcing material is sandwiched from the outside of the heat-shrinkable tube with a fixing tool.