JPH0690331B2 - Flexible optical fiber bundle with reinforced ends - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flexible optical fiber bundle having reinforced end portions, and more specifically, each optical fiber is partly integrated, particularly at the end portions. The present invention relates to an optical fiber bundle that is fixed to the other end of the optical fiber bundle and has other portions that are flexible, and is reinforced and strengthened at the boundary between the fixed portion and the flexible portion.

[Conventional technology]

Optical fiber bundles for endoscopes and the like are used as image guides and light guides, but when used as image guides, in order to transmit a clear and regular image, each optical fiber bundle is paired at both ends of the optical fiber bundle. It is necessary to arrange regularly so as to correspond to one. In addition, in the case of an endoscope or the like, since it is necessary to observe every part of the body cavity, it is flexible except for its end portion, and the distal end portion is freely bent at a sharp angle. There is a need.

For this reason, many optical fibers have been conventionally used as shown in FIG.
An optical fiber bundle is manufactured in which only the end portions 11 of 12 are integrally fixed and the optical fibers of the intermediate portion 12a are separated to have flexibility. In this manufacturing method, optical fibers coated with acid-eluting glass are regularly aligned to form a bundle, heated and drawn to form a conduit, and both ends are sealed with a heat-shrinkable tube that does not dissolve in acid, and nitric acid, etc. It is soaked in the above acid to dissolve the acid-eluting glass in the middle part, and only both ends of each optical fiber are integrally fixed so that the middle part has flexibility.

However, in the optical fiber bundle manufactured in this manner, since both end portions 11 thereof are firmly fixed with the acid-eluting glass, the fixing portion 11 and the respective optical fibers having flexibility of the intermediate portion 12a are The optical fibers near the boundary were apt to break due to microcracks and cracks at the edges. Therefore, it has been performed to fill the vicinity of the boundary with a plastic having appropriate hardness and flexibility (for example, an epoxy adhesive) and heat-cure it to reinforce the vicinity of the boundary. (Japanese Patent Publication Sho 56
However, it is not possible to keep this flexible plastic only near the boundary, and during the curing time it will flow out in the longitudinal direction of the optical fiber bundle due to its surface tension, At the same time, the reinforcement and reinforcement also become weaker, and the length of the reinforcement increases, resulting in a result far from the purpose of bending the tip of the optical fiber bundle at a steep angle. Further, such an adhesive has a problem that it takes time to cure and its workability is poor.

Also, a photocurable plastic is used as the filled plastic, and the optical fiber bundle is irradiated with light to cure the plastic (Japanese Patent Laid-Open Nos. 59-181305 and 60-12.
1402) is also proposed.

[Problems to be solved by the invention]

However, the type of the photocurable plastic to be filled is not limited to any kind. That is, although the photocurable plastic has a short curing time, it cannot be easily impregnated between optical fiber bundles if the viscosity, shrinkage and hardness are inappropriate,
Micro cracks will occur.

The present invention has been made in view of the above-mentioned problems, and an optical fiber bundle capable of easily filling a photocurable plastic in a boundary portion of the optical fiber bundle and forming a reinforcing portion having a uniform and appropriate hard length. The purpose is to provide.

[Means for solving problems]

The present invention is a photocurable plastic to be filled in a boundary portion between a fixed portion and a flexible portion of an optical fiber bundle manufactured by an acid elution method (a) having a viscosity of 500 ± 300 CPS and a shrinkage ratio of 5% or less,
(B) Viscosity is 500 ± 300 CPS, shrinkage is 5% to 15%,
The hardness is JIS A 45 or less.

[Work]

By filling the boundary portion between the fixed portion and the flexible portion of the optical fiber bundle by the acid elution method with a photocurable plastic, it is possible to uniformly fill it, and when it is cured by irradiation with light, microcracks etc. do not occur easily during curing. .

〔Example〕

An embodiment of a flexible optical fiber bundle having reinforced end portions according to the present invention will be described below with reference to the drawings. First
Figures and 2 show core 1, clad 2, acid-eluting glass 3
Optical fiber composed of, and a conduit of an optical fiber bundle manufactured by regularly aligning and heating about 10,000 fibers, and sealing both ends 11 with a heat-shrinkable tube that does not corrode with acid. FIG. 6 is a side view and a cross-sectional view showing, in an enlarged manner, a part of an optical fiber bundle manufactured by immersing in an acid solution and leaching the acid-eluting glass of the optical fiber of the intermediate portion 12a. Therefore, this optical fiber bundle is firmly fixed integrally at both ends 11, and each optical fiber is disjointed and flexible in the middle flexible portion 12a.

In the present invention, the intermediate portion 12a having the fixed end portions 11 and the flexible portion.
The first step of filling the boundary portion 13 with the photocurable plastic 4 of the elastomer type having a small shrinkage over a width of about 2 mm, and the photocurable plastic filling the boundary portion 13 is irradiated with a high pressure mercury lamp or a metal halide lamp. The second step is to irradiate UV light from a light source for 20 to 30 seconds to cure the photocurable plastic.

In the first step, the fixing portion 11 and the flexible intermediate portion 12a
When impregnating the boundary 13 with the plastic with
As shown in the figure, the filling is performed using a coating jig 14 made of a thin metal wire, but if the viscosity is high, it is difficult to fill between the optical fibers of the boundary portion 13 and uniform impregnation cannot be performed. Further, when the viscosity is low, impregnation is likely to occur, but due to the surface tension, the reinforcing fibers 4 flow out in the longitudinal direction of the optical fibers of the flexible intermediate portion 12a until they harden, and the hard length of the reinforcing portion is completed. As a result of (width) widening, reinforcement reinforcement becomes weaker, and the hard length of the reinforcement part also increases,
Bending the tip of the optical fiber bundle at a steep angle, which is the object of the present invention, is far from being achieved.

Therefore, the viscosity of the reinforcing plastic 4 is
It was found that those in the range of 200 CPS to 800 CPS are suitable.

Next, the smaller the shrinkage rate of the reinforcing plastic 4, the better, but the limit is 5% or less. Even if the shrinkage ratio is 5% or more and 15% or less, the hardness is JIS
If it is harder than A 45, the optical fiber will be
It breaks at 13, making it a semi-transparent fiber and unusable as a product. Therefore, the hardness is JIS A 4
It has been found that when it is a relatively soft material having a shrinkage of 5 or less, a shrinkage of 5% or more and 15% or less can be used.

Examples of usable photo-curable plastics include epoxy-modified acrylate photo-curable plastic, urethane-modified acrylate photo-curable plastic, polyethylene-modified acrylate photo-curable plastic, and unsaturated polyester-modified acrylate photo-curable plastic. As an experimental example, an example in which good results were obtained using a urethane-modified acrylate photocurable plastic is shown.

Viscosity (CPS) Shrinkage (%) Hardness A 252.5 6.55 41.0 (shore A) B 450.0 5.16 43.0 (shore A) C 760.0 3.70 64.0 (shore D) Reinforcing plastic with such viscosity, shrinkage and hardness After the first step of filling the boundary portion 13, a second step of irradiating the reinforcing portion 13 with ultraviolet light from a high pressure mercury lamp or a metal halide lamp to cure the filled reinforcing plastic 4 in about 20 to 30 seconds is performed.

It is also possible to irradiate the irradiation light for curing from the end face side of the optical fiber bundle, but in this case, the irradiation light does not reach the filled photocurable plastic due to the acid-eluting glass remaining at the end 11. It has been confirmed. This is because the acid-eluting glass has a transmittance of 0% for UV light having a wavelength of less than 320 nm. In this respect, curing with visible light is considered, but visible light causes a problem in work. However, since the acid-eluting glass has a transmittance of 60 to 70% in the vicinity of a wavelength of 360 nm, it is possible to use a photocurable plastic having one photosensitive band in the vicinity of a photosensitive wavelength of 360 nm ± 20 nm. This photocurable plastic is filled in the boundary between the end 11 and the flexible portion 12a, and then UV is applied from the end face side of the end 11.
When irradiated with light, this UV light is transmitted, so that the plastic can be cured more appropriately and reliably and efficiently, and an end-reinforced optical fiber bundle can be obtained.

For example, the following are used as the photocurable plastic.

I) Cationic polymerization type epoxy photo-curing plastic using strong acid salt type catalyst This strong acid salt type catalyst uses, for example, a polynuclear sulfonium salt and accelerates photodegradation by extending catalyst absorption and wavelength to around 360 nm. .

Strong acid salt catalyst Bis [4- (Diphenylsulfonio) phenyl] Sulfide-Bis
-Hexafluorophosphate That is, the reaction mechanism is that the Lewis acid salt is decomposed by irradiation of ultraviolet rays to generate a strongly acidic substance, and cationically polymerizes the epoxy resin.

II) Cationic polymerization type epoxy resin using non-strong acidic catalyst This non-strong acidic catalyst is decomposed by irradiation of ultraviolet rays with a photolytic silicon compound to purify organic silanol. The organic silanol interacts with the aluminum complex to form an active catalyst and cure the epoxy resin. The effective wavelength is 250 nm to 370 nm.

The non-strong acidic catalyst includes Photo AS (trade name) manufactured by KK Toshiba, and the reaction system is as follows.

The photo-curable plastic as described above is used.

A dye pigment may be added to the photocurable plastic. This is to make it easier to confirm that the boundary is filled with plastic.

〔The invention's effect〕

As described in the above examples, in order to reinforce the boundary portion between the fixed portion and the flexible portion, an elastomer type reinforcing plastic (a) has a viscosity of 500 ± 300 CPS and a shrinkage ratio of 5
%, (B) Viscosity of 500 ± 300 CPS, shrinkage of 5% or more and 15% or less, and hardness of JIS A 45 or less, it is possible to smoothly impregnate the boundary part. The workability can be greatly improved, the hard length (width) can be defined, and a uniform and uniform hardening portion can be formed. Further, the hard length of the reinforcing portion can be defined even if the shrinkage ratio is large, and the reinforcing portion that can prevent the generation of microcracks or cracks with the boundary end portion can be easily formed in the optical fiber.

[Brief description of drawings]

FIG. 1 is an enlarged side view of an essential part showing an enlarged optical fiber bundle to which the present invention is applied, and FIG. 2 is an enlarged cross-sectional view of the essential part of FIG. 1, and FIG. It is a schematic diagram of an optical fiber bundle which has a fixed part in both ends and has a flexible part in the middle. 4 …… Reinforcing plastic (adhesive) 5 …… Fixed part end face 11 …… Fixed part 12 …… Optical fiber bundle 12a …… Flexible part 13 …… Boundary part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 59-181305 (JP, A) JP 60-121402 (JP, A) JP 61-183607 (JP, A)

Claims (2)

[Claims] Claim: What is claimed is: 1. An end portion of a plurality of optical fiber bundles is integrally fixed to form a fixed portion, and a flexible portion is formed at an intermediate portion of the fixed portion of the optical fiber bundle and the flexible portion. In an optical fiber bundle in which a boundary portion is filled with a photocurable reinforcing plastic raw material, and curing light is irradiated to form a reinforcing portion, the photocurable reinforcing plastic raw material is an epoxy photocurable plastic raw material. And the viscosity is 500 ± 300 CPS,
A flexible optical fiber bundle having reinforced end portions, which has a shrinkage ratio of 5% or less. 2. An optical fiber bundle in which the end portions of a plurality of optical fiber bundles are integrally fixed to each other to form a fixed portion, and the middle portion is a flexible portion. In an optical fiber bundle in which a boundary portion is filled with a photocurable reinforcing plastic raw material, and curing light is irradiated to form a reinforcing portion, the photocurable reinforcing plastic raw material is a urethane-modified acrylate. It is a photocurable plastic raw material,
A flexible optical fiber bundle having a reinforced end portion, which has a viscosity of 500 ± 300 CPS, a hardness of JIS A 45 or less, and a shrinkage ratio of 5% or more and 15% or less.