JPH0668569B2 - Optical fiber multi-core batch connector - Google Patents

Description

Description: TECHNICAL FIELD The present invention enables high-density and highly-stable connection of optical fiber core wires in a high-density optical cable of 1000 cores or more for public communication, and can easily perform connection replacement. The present invention relates to the structure of an optical fiber connector.

(Prior art and its problems) Examples of a conventional optical fiber multi-fiber batch connector are shown in FIGS.
Shown in FIG. 5 and FIG. 5, the drawbacks of each are described below.

First, FIG. 3 shows an optical fiber multi-core batch connector (Example 1) developed at Bell Laboratories in the United States, in which a 12-fiber optical fiber 1 is sandwiched on a silicon V-groove substrate (positive chip) 3. Connector plugs are manufactured by sandwiching the plugs in a circular shape, then the index matching agents are applied to the end faces of the two plugs, the plugs are sandwiched by the negative V-groove chips 4, and the metal clip 6 is inserted via the metal back plate 5. Has a structure for fixing the axial alignment of the optical fiber 1. The dimension of the connecting portion including the metal clip 6 in a section perpendicular to the optical axis is about 3 mm × 5 mm.

We will clarify the drawbacks of this connector by comparing it with the following three requirements that are indispensable for connecting cables of 1000 cores or more.

(1) Sealing function of the connection part: A refractive index matching agent is applied between the connection end faces of the connector plug, but the connector is connected to prevent this from flowing out and to prevent the ingress of water etc. from the outside. The part requires a housing with a sealing function.

(2) Stability against external force ...... The connector connection part needs measures to ensure the stability of connection quality even when external force is applied in two directions, a direction perpendicular to the optical axis and a direction parallel to the optical axis. Is.

(3) Connection / detachment function ...... In optical communication as well as conventional metal cable communication, it is necessary to adapt the core wire of the cable according to the demand of the user terminal.
It is necessary to change the connection twice. Moreover, since the installation location of the connection part is a place where the work environment is bad, such as on a telephone pole or in an underground manhole, it is essential that the connection replacement work can be performed easily.

When the connector of Example 1 is evaluated from the above three conditions, (1) there is a possibility that the matching agent and the like may flow out from the end face of the connector because it does not have the sealing function of the connection portion, and the reliability is poor.

(2) A leaf spring is used to align the connector, but if external force is applied, the alignment will change. In addition, since it has no function of pressing the end faces of the fibers together, when the fiber is pulled by an external force, a gap is produced between the end faces, and the connection loss increases, resulting in a lack of stability.

(3) When changing the connection of the connector, insert two plugs with a positive tip 3 having a V groove having a width of about 0.1 mm and a width of about the same, and use two leaf springs 6. It is necessary to fix this. According to published materials (described later), the thickness of the plug is about 1 mm, the width is about 4 mm, and the length is about 10 mm, and the thickness of the negative tip and the leaf spring is at least 0.
It is considered to be 5 mm or more. In order to assemble the connection part, it is necessary to combine these small plugs with the two negative V-groove chips 4 and the two leaf springs 6. Considering the necessity of handling a large number of minute parts, work on a pillar or the like. It has the drawback of being difficult to do.

Having described the drawbacks of the example of FIG. 3 above, the drawbacks of the example of FIG. 4 will now be described.

The example in FIG. 4 is a splicing multi-core connector manufactured by CNET of France. The connection method is as follows. First, a group of 10-core fibers facing two V-grooved substrates 9 obtained by dividing one substrate into two in the longitudinal direction is aligned, and fixed with an adhesive and a holding plate 10. After polishing the end face, the clamp leaf spring 8 and the guide pin 7 are axially aligned. After that, although not shown in the figure, a method of accommodating and sealing the connecting portion in a circular pipe after clamping with a leaf spring that presses the end face in the axial direction is adopted. Its outer diameter is about 20 mm and its length is about 110 mm. In this connector, the two V-grooved substrates 9 are originally
Since one board is divided into two, arbitrary connectors cannot be connected to each other. Therefore, it has a drawback that the connection cannot be changed. In addition, the connected state is unstable because the structure is held by the leaf spring 8, and it is said that the leaf spring is also used for the pressing force in the axial direction. It also has the drawback of being considered unstable.

Next, the example in Fig. 5 is an example of NTT Corporation, which is a rectangular core 1
3 is a circular core housing 14 and a pin sandwiched between them is used as a plug, and two pins are used to axially align the plug 11, and the axial pressure is applied by the coil spring 12, which has a highly stable structure and is detachable. However, the housing has a large outer diameter of about 15 mm, which is not suitable for high-density mounting.

The above conventional examples are mainly based on the following documents and the like.

Fig. 3 example HJFRIEDRICHSEN and PFGAGEN, “OPTICAL CABLE FIE
LD REPAIR USING ARRAY FABRICATION ", 7th ECOC, P.7.2,
Copenhagen, September1981. Fig. 4 example FRENCH ADMINISTRATION, “FLAT MASS SPLICING PROCESS
FOR CYLINDRICAL V-GROOVED CABLES "CCITT, AD HOC WOR
KING GROUP ON Q.15-18 / VI, GenOeva, 10-13 October 198
3. Example of Fig. 5 Satake, Kashima, Nagasawa, “Basic characteristics of plastic multi-fiber optical connectors” Proceedings of the 1994 IEICE General Conference, March 1984. (Object of the Invention) An object of the present invention is to eliminate these drawbacks, to provide a high-density, highly stable, highly reliable optical fiber multi-fiber collective connector with easy connection replacement.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention has a pair of connector plugs in which the connecting portions of a plurality of optical fibers are collectively attached, and a tip portion of the connector plug is provided inside. And a housing adapted to be fitted, the abutting end surface of the connector plug having at least two guide holes extending along the axial direction of the optical fiber, and the outer peripheral surface of the rear end portion of the connector plug. In the state in which a concavo-convex portion that goes around the outer peripheral surface is provided in a part of the above, and the pair of connector plugs are joined by inserting the two guide pins into the guide holes and fitting them into the housing, the whole shrinks. It is characterized in that the heat-shrinkable tube is covered with a tube, the portion corresponding to the uneven portion of the heat-shrinkable tube is heated and shrunk, and then the other portion of the heat-shrinkable tube is heated and shrunk by heat transfer from the housing.

(Operation) According to the present invention, the guide pin fits into the guide hole and the plug fits into the housing, and the heat shrink tube bites into the uneven portion and shrinks in the axial direction of the plug, so that the plug is securely Be combined with.

(Embodiment) FIG. 1 shows an embodiment of the present invention.
(a) is a cross-sectional view of the connector when the connection is completed, Fig. 1 (b) is an exploded perspective view of the connector before covering the shrinkable tube, Fig. 1
(c) is a sectional view showing a state before heating the shrinkable tube.
In the figure, 101 is an optical fiber 10-fiber ribbon, 102 is a connector plug, 103 is a rectangular cross-section housing made of a copper-nickel pipe, 104 is an uneven portion provided on the outer peripheral surface of the connector plug 102, 105 is a guide pin, and 106 is a guide. It is a pin receiving hole. Reference numeral 107 denotes a heat shrink tube, and A denotes a heated portion of the heat shrink tube.

The housing 103 was obtained by drawing a rectangular cross-section pipe having a wall thickness of about 0.2 mm from a circular pipe defined by JIS H3300 containing copper and nickel as main components by a drawing method. The heat-shrinkable tube 107 has a wall thickness of about 3 mm. The cross section of the plug is 2.
5 mm x 5.4 mm, the height of the convex portion of the concave and convex portion 104 is 0.2 m
m and width were 0.5 mm. The pin diameter is 0.7 mm and the pin interval is 3.6 mm. As a result, the cross-sectional dimension of the connection portion was 3.5 mm × 6.4 mm.

In order to connect a 10-fiber optical fiber according to this embodiment,
First, the 10-core tape core wire 101 and the connector plug 102
, Then insert the two guide pins 105 into one plug 102, and further insert the rectangular cross-section housing 103
The plug 102 is fitted inside, and then the end face of the other plug 102 is coated with a refractive index matching agent. After this, Fig. 1
As shown in (b), the heat-shrinkable tube 107 is covered, and then the portion shown in (A) is heated. Heat shrink tube 107
First, it contracts in the direction perpendicular to the optical axis of the fiber so as to bite into the concave-convex portion 104 at the rear end portion of the plug and make close contact therewith. Next, heat is transferred to the housing 103, and the contraction tube 107 contracts in the optical axis direction. At this time, since the contraction tube 107 holds the rear end of the plug,
It works so as to press the end faces of the two plugs 102. Further, at this time, since there is no uneven portion on the outer peripheral surface of the housing 103 on the tip end side, the contracting force of the tube 107 acts so as to almost press the end surfaces of the two plugs 102.

The connection work is completed by the above.

In this embodiment, the clearance between the outer peripheral surface of the connector plug 102 and the inner surface of the housing 103 is about 20 μm.
And The reason for this is that the plug 102 into the housing 103
Since the clearance at the time of inserting the plug is small, the positions of the guide holes 106 of the two plugs 102 can be aligned by about ± 20 μm, and the tip of the guide pin 105 is slightly tapered so that the two This is aimed at the effect that the guide pin 105 of the plug 102 can be easily coupled.

In the above connection work, the clearance between the guide pin and the guide pin hole is about 1 μm, but the tip of the guide pin is tapered and the two plugs are connected using the metal housing as a guide. , And can be easily and accurately combined in a working time of 1 to 3 seconds.

The connection loss of this 10-core connector is GI type core diameter 50
It was 0.17 dB (N = 50) on average under the condition of steady-state excitation of the fiber of μm. From this, it is understood that the axis alignment within 1 μm can be easily performed by using the housing 103 as a guide.

The heating of the heat-shrinkable tube 107 that was packaged was performed in about 3 minutes using an electric heater. The total connection time was 5 connections (50 cores) completed in about 5 minutes by connecting a plurality of connectors at the same time.

From this, it can be seen that the connection work time is short. Also, regarding the stability of the connecting portion, the guide pin 10
Since the clearance between the guide hole 5 and the guide hole 106 is within 1 μm, the stability against the axial deviation is high, and the compression force is constantly applied by the contraction tube 107 to the pressing force in the axial direction, so that the connector is pulled from the outside. A stable connection is maintained even when force is applied, temperature fluctuations, and vibration conditions.

As described above, in the embodiments of the present invention, there are drawbacks of the conventional multi-fiber optical fiber connector, such as instability with respect to axial misalignment, instability due to an end face gap caused by an external force, and a sealed connection state. We solved the large external shape and realized a stable connector with a small cross section.

Further, regarding the disassembly of the connector, the heat shrinkable tube 10
When a material such as polyethylene is used as the material of 7, the shrink tube can be easily cut and removed by a knife. At this time, since the housing 103 is made of metal, the shrink tube 107 is not damaged on the outer peripheral surface of the plug.
Can be cut into pieces. Therefore, it is possible to easily and safely perform the work of changing the connection of the connector. The reconnection can be done in a short time as with the initial connection.

As described above, the connector of the present invention has a small cross section, has stable characteristics, and can be easily reconnected. Therefore, it is possible to connect a multi-fiber optical fiber cable having more than 1000 fibers such as an optical cable for public communication. Can be applied to the department.

FIG. 2 shows a second embodiment of the present invention. The structure is different from that of the first embodiment only in that the ten-core tape core wire 1 is mounted in five layers on the connector plug, and the other parts have the same structure.

The cross-sectional dimension of the multi-core connector plug 108 according to this embodiment is 2.5 mm × 5.4 mm, which is the same as that of the plug 102 of the embodiment of FIG. 1, and the number of fiber cores per cross-sectional area of the connecting portion is shown in FIG. 5 times as many as 50 cores / 3.5 mm × 6.4 mm =
It becomes 2.3 cores / mm ² .

Table 1 shows a comparison of the mounting densities of this connector and other examples. When the connector having the hermetic structure and this connector are compared with each other, the mounting density is 10 to 50 times larger, and it is clear that the effect of the present invention is great.

(Effects of the Invention) As described above, according to the present invention, the outer shape of the housing can be made into a small cross section, so that there is an advantage that it can be mounted at a high density, and the connection portion with a cable or the like having more than 1000 cores can be made small. effective. Even when a cable with a connector is laid in an underground cable burying pipe, if the connector of the present invention is attached to the cable end, the cable pulling end can be realized with a small cross-sectional diameter, so that the cable with a connector can be easily realized. There is also an advantage that you can. Furthermore,
Axial pressing force is applied to both connector plugs by heating and shrinking the heat-shrinkable tube, so a stable connection state is maintained even when external pulling force is applied to the connector plugs, temperature fluctuations and vibration conditions. There is also an effect that you can.

[Brief description of drawings]

FIGS. 1 (a), (b) and (c) show a first embodiment of the present invention. FIG. 1 (a) is a partially longitudinal front view of the connector of the present invention.
(b) is an exploded perspective view of the shrinkable tube before coating, FIG.
Is a partial vertical sectional front view before heating the shrinkable tube, FIG. 2 is a partial vertical sectional side view showing another embodiment of the present invention, and FIGS. 3 (a) and 3 (b).
(c) shows a conventional optical fiber multi-fiber batch connector. (a) is a partially longitudinal front view, (b) is a partial front view, and (c) is a partially cutaway view. FIG. 4 (a) and FIG. 4 (b) are vertical perspective views showing another conventional multi-fiber optical fiber connector,
1A is a side view, FIG. 1B is an exploded perspective view, and FIG. 5 is a perspective view of essential parts showing another conventional multi-fiber optical fiber connector. 101 is a 10-fiber ribbon, 102 is a connector plug,
103 is a rectangular cross-section housing made of copper-nickel alloy,
Reference numeral 104 denotes an uneven portion provided on the outer peripheral surface of the connector plug, and 105
Is a guide pin, 106 is a guide pin receiving hole, 107 is a heat shrink tube, (A) is a heating portion of the heat shrink tube, 10
8 is a 50-core connector plug

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryosuke Arioka 162 Shirahane, Shikataji, Tokai-mura, Naka-gun, Ibaraki Prefecture, Nippon Telegraph and Telephone Corporation, Ibaraki Telecommunications Research Laboratory (72) Inventor Masayuki Oki, Naka-gun, Ibaraki Prefecture Tokai-mura, Oita, Shirahoji, Shirane 162, Nippon Telegraph and Telephone Corporation, Ibaraki Telecommunications Research Laboratories (56) Reference JP-A-56-30112 (JP, A) JP-A-51-140745 (JP, A) JP 53-148456 (JP, A) Actual opening 51-139641 (JP, U) Actual opening 57-160115 (JP, U) Actual opening Sho-58-128408 (JP, U)

Claims (1)

[Claims] 1. A connector plug comprising: a pair of connector plugs in which a plurality of optical fiber connection portions are collectively mounted; and a housing in which a tip portion of the connector plug can be fitted inside. Has at least two guide holes extending along the axial direction of the optical fiber, and a concave-convex portion that makes a round of the outer peripheral surface is provided on a part of the outer peripheral surface of the rear end of the connector plug. In a state in which the pair of connector plugs are coupled by inserting the two guide pins into the guide holes and fitting the housing, the whole is covered with a heat shrink tube, and the portion corresponding to the uneven portion of the heat shrink tube A multi-fiber optical fiber connector that heats and shrinks the core, and then heats and contracts the other parts of the heat shrink tube by heat transfer from the housing.