JPH02128144A - Water infiltration detector - Google Patents

Abstract

PURPOSE:To detect a water infiltration to an object to be detected accurately by making water fill a gap formed previously between a pair of optical connector plugs when a flooding occurs in the object to be detected. CONSTITUTION:This apparatus comprises a pair of optical connector plugs 14 and 14' facing each other as mounted on optical fiber cores 12 and 12' for monitoring flooding and a storage case 16 and has a gap holding means 18 at opposed parts of the pair of plugs 14 and 14' to hold a gap therebetween. When water infiltrates at a water entry port 16a of the case 16, the water fills an internal space of the case 16 and hence, the water also fills a gap 20 between end faces of the pair of plugs 14 and 14'. This can improve a Fresnel reflection remarkably by a refractive index matching effect to reduce a Fresnel loss. The reduction in the loss is measured with a pulse tester at a light receiving end of the cores 12 and 12' thereby enabling accurate detection of water infiltration.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a water immersion detector used for detecting water immersion in a connecting portion of a non-metallic optical cable for optical communications, for example.

(Prior art) Detecting the presence or absence of water intrusion is required in various fields. For example, in the field of optical communications, in order to ensure the long-term reliability of non-metallic optical cables, it is necessary to detect water intrusion at the joints of optical cables. It is required to be able to promptly detect the

Conventionally, in order to detect water intrusion at the connection part of such optical cables, a water intrusion detection system has been constructed by combining an optical fiber core for monitoring water ingress and a water-absorbing material that expands or contracts due to water absorption and imparts bending to the optical fiber core. A detector has been proposed. This water immersion detector is capable of detecting water immersion because the water absorbing material expands or contracts due to water intrusion, bending the optical fiber, thereby increasing the transmission loss of the optical fiber.

[Invention or problem to be solved]

In this way, conventional water immersion detectors detect water immersion from the increase in transmission loss due to bending of the optical fiber, but the increase in transmission loss due to bending of the optical fiber is small and should not be detected. It was difficult to reliably detect water intrusion into objects.

An object of the present invention is to provide a highly reliable water immersion detector that can avoid the above-mentioned drawbacks and more reliably detect water immersion into an object to be detected.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a pair of optical connector plugs that are attached to optical fiber cores for monitoring water intrusion and face each other, and a pair of optical connectors. The present invention provides a water immersion detector comprising a storage case for storing a plug and having a water inlet hole, and having gap holding means for holding a gap at opposing parts of a pair of optical connector plugs. This gap retaining means may be provided by obliquely polishing one or both end faces of the optical connector plug in advance, or may be a spacer placed between these end faces to avoid the cross section of the optical fiber core. There may be.

[Effect]

According to this configuration, when the object to be detected is flooded with water, the gap between the pair of optical connector plugs is filled with water, and the Fresnel reflection is significantly improved due to the refractive index matching effect, thereby reducing Fresnel loss. This makes it possible to reliably detect flooding.

(Embodiment) An embodiment of the present invention will be described in detail with reference to the drawings. FIGS. 1(A) and 1(B) show a water immersion detector 10 according to the present invention, and this water immersion detector 10 is a water immersion monitor lO. A pair of optical connector plugs 14.14' that are attached to optical fiber cores 12.12' facing each other, and a storage case 16 that houses the pair of optical connector plugs I4.14° and has a water inlet hole 16a. It consists of. A pair of optical connector plugs 14.
A gap holding means 18 for holding the gap 20 is provided at the opposing portion of the gap 14'. In the embodiment shown in FIG. 1, the gap retaining means 18 is constructed by obliquely centering one or both end faces of the optical connector plug 14.14° so that a gap 20 is formed between them. has been done.

Next, the operation of this water immersion detector 10 will be described.

When water enters through the water inlet hole 16a of the storage case 16, water 22
As shown in FIG. 1(B), since the internal space of the storage case 16 is filled, a pair of optical connector plugs 14.14
The gap 20 between the end faces of ' is also filled with water 22. Therefore, the Fresnel reflection is significantly improved between the pair of optical connector plugs 14.14° due to the refractive index matching effect, and the Fresnel loss is reduced.
Water intrusion can be reliably detected by measuring with a pulse tester at the light receiving end of 2°.

FIG. 2 shows another embodiment of the invention, in which:
The gap holding means 18 is a pair of optical connector plugs 14.14.
The optical fiber is placed between the end faces of 12.12''
The embodiment is exactly the same as that of FIG. 1, except that it consists of a spacer 24 which avoids the cross-section of .

In the water immersion detector lO of this embodiment, the space in the storage case 16 including the gap 20 is filled with water 22 due to water intrusion from the water inlet hole 16a, so that the optical fiber core 12 is filled with water 22 as in the embodiment of FIG. .12° connection loss is significantly improved, making it possible to reliably detect water intrusion.

(Effects of the Invention) According to Book 41JJ, as mentioned above, when an object to be detected is submerged in water, the gap previously formed between a pair of optical connector plugs is filled with wood, so there is no Fresnel loss. This is a significant improvement and has the practical benefit of being able to detect flooding more reliably.

[Brief explanation of the drawing]

FIGS. 1A and 1B are cross-sectional views showing the state of a water immersion detector according to an embodiment of the present invention before and after immersion in water, respectively, and FIG. 2 is a sectional view showing a state after immersion in water according to another embodiment of the present invention FIG. 3 is a cross-sectional view showing the state of the detector before it is submerged in water. 10-1111 Water immersion detector, 12.12°-1 optical fiber core, 14.14'--- 1 pair of optical connector plugs, 16--- Storage case,
18---1 Gap holding means, 20---Gap, 2
2---1 Water.

Claims (1)

[Claims] 1 attached to optical fiber core wire for flood monitoring and facing each other
It consists of a pair of optical connector plugs and a storage case that houses the pair of optical connector plugs and has a water inlet hole,
1. A water immersion detector characterized in that opposing portions of a pair of optical connector plugs have gap retaining means for retaining the gap.