JPH0380206A - Hermetic terminal of optical fiber - Google Patents

Abstract

PURPOSE:To obtain airtightness by inserting an optical fiber into the insertion hole of a holding member fixed through a vessel wall and packing a packing material around a coated fiber formed in this insertion hole. CONSTITUTION:The elastic member 10 comes into tight contact with the outer peripheral surface of the optical fiber 3a and the coated optical fiber 3c and the inner peripheral surface of the insertion hole 9 of the holding member 8 when a bolt 11 is screwed to the internal threads at the atm. side B end of the insertion hole 9 of the holding member 8 and the elastic member 10 is compressed. Since the elastic member 10 is in tight contact with the coated optical fiber 3c and the holding member 8, the airtightness between the holding member 8 and the optical fiber 3c is assured. The high airtightness is maintained in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an airtight terminal used for passing an optical fiber into and out of an airtight container.

[Conventional technology]

FIG. 5 is a side view showing an example of the structure of a conventional airtight terminal. In FIG. 0, (1) is an optical connector adapter, (2)
are optical connector plugs, (3a) and (3b) are optical fibers, (4) is the container wall of the airtight container (A), (5) is the bolt for attaching the optical connector adapter (1) to the container wall (4), ( 6) is a terminal plate, and (7) is an annular packing provided between this terminal plate (6) and the container wall (4).

The structure of a conventional airtight terminal is as described above, and includes, for example, the temperature, pressure, voltage, current, magnetic field,
For optical signals of information such as vibrations from sensor parts (not shown), connect the optical connector plug (2) to the optical connector adapter (1).
The signal is transmitted to a measuring device (not shown) on the atmospheric side (n). The airtightness inside the airtight container (A) is maintained by an annular packing (7) provided between the terminal plate (6) and the container wall (4).

[Problem to be solved by the invention]

As mentioned above, conventional airtight terminals are optical connector adapters (
1), and there was a problem in that the airtightness was not necessarily sufficient.

This invention was made to solve the above-mentioned problems, and an object of the present invention is to obtain an airtight terminal for an optical fiber that can maintain high airtightness.

[Means and effects for solving the problem] The airtight terminal for an optical fiber according to the present invention has a holding member provided with an insertion hole through which the optical fiber is inserted, which is fixed through a container wall, and the light inside the insertion hole is fixed. The coating of the fiber is removed, and a filling member is filled around the core wire to ensure airtightness within the insertion hole.

The optical fiber passing through the inside and outside of the airtight container is kept airtight by a filling member in the core portion of the optical fiber.

In addition, in other cases, the optical fiber in the insertion hole of the holding member is an indoor optical fiber made of a core wire, and the above-mentioned optical connector adapter is used to connect this indoor optical fiber to an outdoor optical fiber outside the airtight container. It is fixed to the holding member.

Airtightness inside and outside the airtight container is ensured by a filling member placed around the indoor optical fiber in the insertion hole2, and weather resistance outside the airtight container is ensured by employing the outdoor optical fiber.

〔Example〕

1 and 2 are cross-sectional views showing one embodiment of the present invention, and (1) to (4) are the same as the structure of the conventional airtight terminal described above. (81 is the container m of the airtight container (A) (
The holding member (9) provided in the through hole (4a) of 4) is provided coaxially with the holding member (8), and is attached to the optical fiber (3a).
The insertion hole αω, through which the holding member (8) is inserted, is provided with a female thread at both ends, and αω is an elastic member as a filling member, for example, an elastic material such as silicone rubber is used to hold the holding member (8). The insertion hole (9) is filled with the required length, and as shown in FIG.
It is in contact with the entire periphery of the optical fiber (3c) except for the coating made of protective fibers etc. applied to a). (11)
is a locking member, and in this embodiment, a bolt is used, which is screwed into the female thread at the end of the insertion hole (9) and moves forward and backward, compressing the elastic member and tightening the optical fiber (3C). and the holding member (8), respectively, to ensure airtightness between them.

(12) is a rubber bush attached to the heads of bolts (11) and (13), (14) is a nut used to tighten the holding member (8) to the container wall (4), and (15)
is an annular packing, and in this embodiment, an O-ring is used. Note that the bolt (13) may not be provided separately, but may be manufactured integrally with the holding member (8) to reduce the number of parts.

In the airtight terminal configured as described above, the bolt (11) is screwed into the female thread at the atmosphere side (B) end of the insertion hole (9) of the holding member (81) and moved forward to compress the elastic member. Then, this elastic member αω comes into close contact with the outer peripheral surfaces of the optical fiber (3a) and the optical fiber core wire (3c) and the inner peripheral surface of the insertion hole (9) of the holding member 6). Conventionally, there was a risk of air leaking between the core wire and the coating of this optical fiber, but
As described above, since the elastic member is in close contact with the optical fiber core wire (3c) and the holding member 8), airtightness between the holding member (8) and the optical fiber (3a) is ensured, and light It is possible to prevent local pressure from being applied to the fiber.

In addition, when the nut (summer 4) is tightened to attach the holding member (8) to the container wall (4), the O-ring (15) provided between them is compressed and the holding member (8) and the container are tightened. The airtightness inside the airtight container (A) is ensured by being in close contact with the wall (4). In addition, the rubber bush (12) is connected to the optical fiber (3a
) are bent at the heads of the bolts (11) and (13) so that they are less likely to break.

In addition, all the filling members are initially in liquid form and filled with the insertion hole (
If a resin material or the like is used that hardens after being filled into the hole (9) and is fixed in the insertion hole (9), the bolt (11) for compressing the filling member αα can be omitted.

Then, the optical connector adapter (1) and the optical connector plug (
2) and optical fibers (3a) and (3b) are connected to transmit light between a sensor section (not shown) and a measurement section installed in the airtight container (A) and the atmosphere side (B), respectively. transmit signals.

FIG. 3 is a partial sectional view showing another embodiment of the invention. Install the holding member (8) so that the O-ring (15) contacts the inner surface of the container wall (4), and tighten with the nut (!4).
is placed on the atmosphere side (B), and the holding member (
8) to the container wall (4) and attach it to the container wall (4).
(11) is provided inside the airtight container (A), and the elastic member α■ is tightened and compressed from inside the airtight container (A).

The rest of the configuration of the embodiment shown in FIG. 3 is the same as the embodiment shown in FIG. 1, so the other explanations will be omitted.

In each of the above embodiments, the optical fiber (3a
), only a portion of which is coated is removed to form an optical fiber core (3C). However, depending on the environmental conditions outside the airtight container (A), that is, outdoors, the coated portion of the optical fiber may account for a large proportion. The coating becomes large, has high strength, and has a complex structure, and as mentioned above, it may not be possible to easily remove a part of the coating. In this case, for example, if all the optical fibers (3a) in FIG. 1 are optical fiber cores (3C), especially the optical connector plug (2)
It is easy to break at the exposed part leading to the end, resulting in a lack of safety and reliability.

Figure 4 is a cross-sectional view showing an embodiment that improves the above points. The end portion is coupled to an optical connector plug (2b). (3a) has an optical connector plug (2a) at its end.
), and is introduced into the airtight container (A) through the insertion hole (9) in the holding member (8). Then, install both optical connector plugs (2
Optical connector adapter (1) connecting a) and (2b)
) is fixed to the atmosphere side (B) end of the holding member (8). Other structures are similar to those of the above embodiment.

Therefore, since the end of the indoor optical fiber (3a), which has poor mechanical strength, is integrally supported and fixed with the holding member (8) via the optical connector adapter (1), there is no risk of damage. . Further, since there is no need to partially remove the coating of the optical fiber, assembly work is also simplified.

As described above, in addition to ensuring airtightness, this embodiment has high mechanical stability and reliability, and is easy to assemble.

In the above description, an example of the arrangement in which the sensor section is located inside the airtight container (A) and the measurement section is located on the atmosphere side (B) has been described, but the opposite arrangement may be used.

In addition, the tightening for attaching the holding member (8) to the container wall (4) was described using the bolt (11) that compresses the elastic member α0) on the opposite side of the nut (14).
1) may be any opening, and the holding member (
8) may be provided with bolts (11) on both sides so as to be compressed from both sides of the elastic member that reaches both ends.

〔Effect of the invention〕

As described above, in the present invention, the optical fiber is inserted into the insertion hole of the holding member fixed through the container wall, and the filling member is filled around the core wire formed in the insertion hole. , reliable airtightness can be obtained.

Furthermore, if the optical fiber in the insertion hole is a cored indoor optical fiber and an optical connector adapter for connection with the outdoor optical fiber is fixed to a holding member, the easily broken optical fiber core cannot be held securely. Therefore, in addition to ensuring airtightness, mechanical stability and reliability are also high, and assembly is easy.

[Brief explanation of drawings]

1 is a sectional view showing an airtight terminal for an optical fiber according to an embodiment of the invention; FIG. 2 is an enlarged sectional view showing the contact portion between the optical fiber core wire and the elastic member in FIG. 3 and 4 are sectional views showing other embodiments, and FIG. 5 is a side view showing a conventional airtight terminal. In the figure, (1) is an optical connector adapter, (3a) is an indoor optical fiber, (3b) is an outdoor optical fiber, (3
(c) is an optical fiber core, (4) is a container wall, (8) is a holding member, (9) is an insertion hole, (3) is an elastic member as a filling member, and (A) is an airtight container. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) In an airtight terminal for an optical fiber that airtightly penetrates the container wall of an airtight container, a holding member provided with an insertion hole through which the optical fiber is inserted is fixed through the container wall, and the light inside the insertion hole is fixed. 1. An airtight terminal for an optical fiber, characterized in that the coating of the fiber is removed and a filling member is filled around the core wire to ensure airtightness within the insertion hole. (2) The optical fiber in the insertion hole of the holding member is a cored indoor optical fiber, and an optical connector adapter for connecting this indoor optical fiber to an outdoor optical fiber outside the airtight container is attached to the holding member. The hermetic terminal for an optical fiber according to claim 1, wherein the terminal is fixed.