JP2002062432A - Optical fiber head part and its treating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber head part which is assembled without requiring special working or a special tool and to provide its treating method. SOLUTION: In the terminating structure of this optical fiber, when an metallic tube 28 is inserted into a third pore part 24, it is easily positioned by the tip end being a butted against a step 26. Thus, application of resin coating or flare working to the metallic tube is not required as in a conventional practice and the tool preparation is not required either, and thereby manufacturing cost is controlled. When the optical fiber 10 is inserted, the element fiber 11 of the optical fiber 10 is guided by a tapered part 25 formed in a first pore part 22, and hence the optical fiber 10 is easily inserted into the metallic tube 28 even if it is thin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical fiber head and a processing method therefor.

[0002]

2. Description of the Related Art For example, when an object to be detected in a narrow place is detected by a sensor having an optical element, an optical fiber is connected to the optical element, and the tip of the optical fiber is connected to a light projecting section (or a light receiving section). Section). As such an optical fiber head, for example, the following conventional examples 1 to 3 are known.

[0003] First, Conventional Example 1 is shown in FIG. 3, in which a large-diameter hole 2 and a small-diameter hole 3 are formed inside a cylindrical housing 1. Taper part 4 between
The base end of the metal tube 5 is inserted and fixed in the small diameter hole 3. The optical fiber 6 is inserted from the cylindrical housing 1 into the metal tube 5.

[0004] The method of manufacturing this is as follows. That is, first, a resin coating 5A is applied to the base end of the metal tube 5. Then, after inserting the strand 8 of the optical fiber 6 from which the outer skin 7 has been peeled off, the optical fiber 6 and the metal tube 5 are bonded and fixed. Thereafter, the metal tube 5 is moved from the large-diameter hole 2 side of the cylindrical housing 1 to the small-diameter hole 3.
Insert into. Then, the resin coating 5 </ b> A applied to the metal tube 5 abuts against the tapered portion 4 and is positioned.
It is in the state extended from. In this state, the large-diameter hole portion 2 is filled with resin, and the cylindrical housing 1, the optical fiber 6, and the metal tube 5 are fixed.

Conventional example 2 is shown in FIG. 4, and is different from prior art example 1 only in that a flare processing portion 5B obtained by expanding the base end of metal tube 5 in a rocket shape is provided. And
The guide of the flare processing portion 5B facilitates the work of inserting the optical fiber 6. Other structures and manufacturing methods are the same as those of the conventional example 1.

FIG. 5 shows a conventional example 3 in which the amount of protrusion of the metal tube 5 from the cylindrical housing 1 is adjusted by using a jig 9 instead of the resin coating 5A of the conventional example 1. It is. More specifically, the wire 8 of the optical fiber 6 is inserted into the metal tube 5 and fixed. Next, the cylindrical housing 1
With the metal tube 5 inserted therein, it is set on a jig 9, and the jig 9 is used to set the cylindrical housing 1 of the metal tube 5.
After setting the amount of protrusion from
Is filled with resin and fixed.

[0007]

However, the above-mentioned conventional examples 1 to 3 have the following problems. That is, in the first conventional example, an operation of applying the resin coating 5A to the metal tube 5 is required, so that the manufacturing cost is increased. If the optical fiber 6 and the metal tube 5 have small diameters, it is difficult to simply insert the optical fiber 6 into the cylindrical metal tube 5, so that the manufacturing cost is high. Further, there is a possibility that the optical fiber 6 may be damaged without being inserted smoothly.

On the other hand, in the conventional example 2, the operation of inserting the optical fiber 6 into the metal tube 5 can be easily performed, but the metal tube 5 needs to be flared, so that the manufacturing cost is increased.

In the third conventional example, as in the first conventional example, a difficult operation of inserting the optical fiber 6 into a simple tubular metal tube 5 is required, so that the manufacturing cost is increased and the optical fiber 6 may be damaged. In addition to this, the cost is increased due to the necessity of the jig.

The present invention has been made in view of the above circumstances, and has as its object to provide an optical fiber head that can be assembled without requiring special processing or a jig, and a method of processing the same.

[0011]

In order to achieve the above object, an optical fiber head according to the first aspect of the present invention has a thinner than the cylindrical housing at the tip of a through hole formed inside the cylindrical housing. In the optical fiber head where the base end of the metal tube is inserted and fixed and the optical fiber is inserted and fixed from the cylindrical housing toward the metal tube, the through hole inside the cylindrical housing has a distal end from the base end side. Towards the side,
The first hole, the second hole, and the third hole are provided side by side, and the first hole has a tapered portion tapered toward the distal end, and the second hole has a second hole.
The hole has a diameter substantially equal to or larger than the outer diameter of the cladding of the optical fiber and a diameter substantially equal to or smaller than the inner diameter of the metal tube,
The third hole has substantially the same diameter as the outer diameter of the metal tube. The metal tube is inserted into the third hole, and the third hole and the second hole are connected to each other.
It is characterized in that the end of the metal tube is abutted and fixed to the step formed between the hole and the hole.

According to a second aspect of the present invention, there is provided a method for processing an optical fiber head, comprising: a first hole, a second hole, and a third hole inside a cylindrical housing from a base end to a tip end; Are formed in the first hole, a tapered portion tapered toward the distal end is formed, and the second hole is formed to have a diameter substantially equal to or larger than the outer diameter of the cladding of the optical fiber. The diameter is formed to be substantially the same as or smaller than the inner diameter of the metal tube, and the third hole is further formed by:
The metal tube is formed to have substantially the same diameter as the outer diameter of the metal tube, and the metal tube is inserted into the third hole, and the metal tube is inserted into the step formed between the third hole and the second hole. After fixing the optical fiber in a state where the ends of the optical fiber are abutted, the optical fiber is guided by the tapered portion of the first hole, inserted into the metal tube, and further, the optical fiber is filled with the resin filled in the first hole. It is characterized by being fixed to a cylindrical housing.

[0013]

According to the first and second aspects of the present invention, when the metal pipe is inserted into the third hole, the end of the metal pipe is abutted against the step and positioned easily. This eliminates the need to apply resin coating or flare processing to the metal tube as in the conventional case, and eliminates the need to provide a jig, thereby making it possible to reduce the manufacturing cost as compared with the conventional case. Then, when inserting the optical fiber, the first
Since the optical fiber is guided by the tapered portion formed in the hole, even if the optical fiber is thin, it can be easily inserted into the metal tube.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to, for example, a light emitting section of a photoelectric sensor will be described below with reference to FIGS. In this photoelectric sensor, an optical fiber 10 is extended from a controller (not shown), and the tip of the optical fiber 10 is fixed by a reinforcing member 20, and an optical fiber head 30 (see FIG. 1) as a light projecting unit is formed. Is formed.

The optical fiber 10 has a wire-like element wire 11 which is covered around a central portion called a core having a high refractive index with a clad having a lower refractive index than the core. The outer surface of the element wire 11 is covered with a skin 12 made of non-translucent resin.

As shown in FIG. 2, the reinforcing member 20 is formed by inserting and fixing the base end of a metal tube 28 thinner than the cylindrical housing 21 to the distal end of the cylindrical housing 21.

The metal tube 28 has a cylindrical shape having a predetermined length.
It extends straight. The inner diameter of the metal tube 28 is larger than the outer diameter of the strand 11 of the optical fiber 10, that is, the outer diameter of the clad.

The cylindrical housing 21 is made of, for example, a cylindrical metal member, and its outer peripheral edge is chamfered (reference numeral 21C in FIG. 2).

The first hole 22 and the second hole 23 are provided inside the cylindrical housing 21 from the base end toward the front end.
And a third hole portion 24 are provided.
The hole 22 is opened to the base end surface of the cylindrical housing 21 and extends to the middle part in the longitudinal direction of the cylindrical housing 21 with the same diameter. Tapered portion 25 tapered toward the front end of housing 21
Are formed.

The second hole 23 is formed so as to be continuous with the tapered portion 25 of the first hole 22 and has a diameter substantially the same as or larger than the outer diameter of the element wire 11 of the optical fiber 10. 24, and the first and third holes 2
It is shorter than 2,24. The second hole 23
Is slightly smaller than the inner diameter of the metal tube 28,
This is preferable in the work of inserting the optical fiber 10 described later.

The third hole 24 is formed so as to be continuous with the second hole 23 and is open to the front end surface of the cylindrical housing 21, and has substantially the same diameter as the outer diameter of the metal tube 28. . Further, between the second and third holes 23 and 24, both holes 2 are provided.
A step 26 is formed by the difference between the inner diameters of the base plates 3 and 24.

Next, the optical fiber head 3 of the present embodiment
0 will be described. First, the base end of the metal tube 28 is inserted into the third hole 24 of the cylindrical housing 21. Then, when the metal tube 28 is inserted into the third hole portion 24, the end face of the metal tube 28 abuts against the step 26 between the second and third hole portions 23 and 24 and is positioned. Then, the metal tube 28 projects from the distal end surface of the cylindrical housing 21 by a predetermined length, and is fixed by the above-mentioned adhesive.

As described above, in the present embodiment, the metal tube 28
Is simply inserted into the third hole 24, and the end face thereof is
Since the metal tube is easily positioned by abutting the metal tube 6, it is not necessary to apply a resin coating or a flare process to the metal tube as in the related art, and it is not necessary to provide a jig.

Next, the sheath 12 of the optical fiber 10 is peeled off slightly longer than the length of the metal tube 28 to expose the strand 11. Then, the optical fiber 10 is inserted from the first hole 22 of the cylindrical housing 21. Then, the distal end of the element wire 11 of the optical fiber 10 is guided by the tapered portion 25 of the first hole 22, and the second end of the optical fiber 10 located on the back side of the tapered portion 25 is guided.
It is smoothly inserted into the hole 23. Further, when the optical fiber 10 is pushed in, the distal end of the wire 11 passes through the metal tube 28 and slightly protrudes from the distal end surface of the metal tube 28. In this state, the gap between the strand 11 of the optical fiber 10 and the metal pipe 28 and the gap between the metal pipe 28 and the cylindrical housing 21 are fixed with an adhesive. Then, the protruding portion is cut so that the distal end surface of the wire 11 and the distal end surface of the metal tube 28 are flush with each other as shown in FIG.

Next, an adhesive resin 29 is filled from the rear end opening of the first hole 22 and solidified, so that the optical fiber 10 is fixed in the first hole 22 and the optical fiber head 30 is moved. Complete.

As described above, according to the present embodiment, when the optical fiber 10 is inserted, the strand 11 of the optical fiber 10 is guided by the tapered portion 25 formed in the first hole portion 22. Even if the optical fiber 10 is thin, the second hole 23
And can be easily inserted into the metal tube 28. Moreover, since flare processing is not required for guiding the optical fiber as in the related art, the manufacturing cost can be reduced.

<Other Embodiments> The present invention is not limited to the embodiments. For example, the embodiments described below are also included in the technical scope of the present invention. Various changes can be made without departing from the scope of the invention.

(1) In the above embodiment, the cylindrical housing 21 is made of metal, but may be made of synthetic resin.

(2) In the above embodiment, the optical fiber 10
Is provided with an outer skin 12, but an optical fiber having no outer skin may be used.

(3) In the above embodiment, the optical fiber 10
Has a single core structure having one core wire (element wire 11) inside the outer cover 12, but may have a double core structure having a plurality of core wires. In this case, the entire outer diameter of the plurality of core wires is equivalent to the “cladding outer diameter” in the present invention.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an optical fiber head according to an embodiment of the present invention.

FIG. 2 is an exploded sectional view of the optical fiber head.

FIG. 3 is a cross-sectional view of an optical fiber head section of Conventional Example 1.

FIG. 4 is a cross-sectional view of an optical fiber head section of Conventional Example 2.

FIG. 5 is a cross-sectional view of an optical fiber head section according to Conventional Example 3.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Optical fiber 11 ... Element wire 12 ... Outer skin 21 ... Cylindrical housing 22 ... 1st hole 23 ... 2nd hole 24 ... 3rd hole 25 ... Tapered part 26 ... Step part 28 ... Metal tube

Claims (2)

[Claims] 1. A base end of a metal tube thinner than the cylindrical housing is inserted and fixed to a distal end of a through hole formed inside the cylindrical housing, and an optical fiber is removed from the cylindrical housing to the metal. In the optical fiber head portion inserted and fixed toward the tube, the first through hole, the second through hole, and the third through hole are formed in the through hole inside the tubular housing from the base end toward the front end. Are arranged side by side, the first hole portion has a tapered portion tapered toward the distal end side, and the second hole portion has a diameter substantially equal to or larger than the outer diameter of the cladding of the optical fiber. And the third hole has substantially the same diameter as the outer diameter of the metal tube, and the metal tube is inserted into the third hole. And a step formed between the third hole and the second hole,
An optical fiber head portion, wherein ends of the metal tube are abutted and fixed. 2. A through-hole in which a first hole, a second hole, and a third hole are arranged from a base end toward a front end inside the cylindrical housing, wherein the first hole is provided. Forming a tapered portion tapered toward the distal end side, and making the second hole portion substantially the same diameter or large diameter as the outer diameter of the cladding of the optical fiber and substantially the same diameter as the inner diameter of the metal tube. A diameter or a small diameter, and further, the third hole is formed to have substantially the same diameter as the outer diameter of the metal tube, and the metal tube is inserted into the third hole and the third hole is formed. The optical fiber is guided by the tapered portion of the first hole after fixing the metal tube to the step formed between the hole and the second hole in a state where the ends of the metal tube abut against each other. Then, the optical fiber is fixed to the cylindrical housing by resin inserted into the metal tube and further filled in the first hole. A method for treating an optical fiber head, comprising: