JP2995620B2 - Ferrule cylindrical body, ferrule, and optical connector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferrule for fixing an end of an optical fiber and a ferrule cylindrical body.

[0002]

2. Description of the Related Art At present, in an optical connector used for communication, an optical fiber is inserted and fixed in a ferrule in which an inner diameter and an outer diameter are processed with high precision, and an end face of a connection portion is formed into a convex spherical shape. Polishing is performed so that the optical fibers are physically brought into contact with each other and connected. FIG. 11 shows a cross section of a conventional ferrule to which an optical fiber is attached.

[0003] As shown in FIG.
Is generally composed of a cylindrical body 102 made of hard ceramic such as zirconia and a brim 103 made of stainless steel. The cylindrical body 102 has an optical fiber insertion hole 104 formed therein for inserting the optical fiber 201 from which the end of the optical fiber core wire 202 has been removed. The optical fiber insertion hole 104 is generally a diameter having a clearance of about 1 μm with respect to a diameter of 125 μm of the optical fiber 201 from which the coating has been removed, and is a through hole having a length of about 10 mm. In addition, a chamfered portion 107 is formed on the outer peripheral end of the cylindrical body 102 having an outer diameter of 2.5 mm opposite to the side connected to the flange 103. This chamfer 1
Reference numeral 07 denotes a tapered portion usually called a C-plane, which is provided so as to be easily inserted into a cylindrical split sleeve or the like during optical coupling. Since the angle between the chamfered portion 107 and the axis along the outer peripheral surface of the ferrule is about 30 ° ± 5 °, and the minimum tip diameter d is about 1.9 mm, the axial length of the chamfered portion 107 is standardized. The standard is a maximum value of 1.2 mm, and practically 0.5 mm. On the other hand, the collar 103 has a through hole 109 into which the optical fiber 202 is inserted, and
The ferrule 101 is formed by connecting and fixing the ferrule 101.

[0004] The ferrule of such a ferrule 10
3 and the optical fiber 201 is inserted into the optical fiber insertion hole 104, and the optical fiber insertion hole 104 and the through hole 10 are previously inserted.
9 is fixed by the adhesive filled. By polishing the end face of the cylindrical body 102 together with the optical fiber 201, the ferrule 101 thus assembled can be assembled into, for example, an optical connector component to constitute an optical connector.

[0005]

The above-mentioned conventional ferrule 101 is, for example, shown in FIG.
A chamfered portion 107 is provided so as to be easily inserted into the split sleeve 301 as shown in FIG. However,
Due to friction between the boundary between the chamfered portion 107 and the outer peripheral surface 110 of the cylindrical portion and the inner peripheral surface of the split sleeve 301, dust easily accumulates at the corner A, and as a result, the accuracy of the facing position between the ferrules deteriorates. As a result, there is a problem that the connection performance is deteriorated.

In order to prevent such a problem,
The boundary between the chamfered portion 107 and the outer peripheral surface 110 of the cylindrical portion may be rounded by polishing to form an R portion.
There is a problem that the end face polishing is very troublesome because of the extremely hard ceramics. On the other hand, the shape of the tip surface side of the ferrule cylindrical body is, before fixing the optical fiber, polished to a convex spherical shape in advance, and after fixing the optical fiber to this, the optical fiber and the ferrule end surface around it are further convexly spherical. Polishing is generally performed, but there is a problem that these polishing operations are also very troublesome and cause high costs.

The present invention is intended to solve such a problem. Even if insertion into a split sleeve or the like is repeated for optical coupling, dust is less likely to collect between the split sleeve and the cylindrical split sleeve and is easily processed. It is an object to provide an optical connector.

[0008]

According to a first aspect of the present invention, there is provided a ferrule cylindrical body having an optical fiber insertion hole into which an optical fiber is inserted.
A ferrule cylinder, characterized in that the tip of the cylindrical body has a chamfer whose outer diameter gradually decreases toward the tip, and the inclination of the chamfer is formed in two or more steps. In the shape.

According to a second aspect of the present invention, in the first aspect, the multi-stage chamfered portion has three or more chamfered portions, and at least two-stage chamfered portions on the tip end side of the multi-stage chamfered portion. And the inclination angle of the optical fiber protruding part side of the foremost side chamfered part with respect to the axis of the cylindrical body is 85 to 89 degrees, and the optical fiber protruding part of the chamfered part adjacent thereto is formed. The inclination angle of the part side with respect to the axis of the cylindrical body is 45 to 80 degrees.

According to a third aspect of the present invention, in the first or second aspect, the inclination angle of the chamfered portion adjacent to the base end portion side of the chamfered portion of the second step from the distal end portion with respect to the axis of the cylindrical body is provided. Is 15 to 45 °. According to a fourth aspect of the present invention, in any one of the first to third aspects, an inclination angle of the chamfered portion on the base end side with respect to an axis of the cylindrical body is 15 degrees or less. In ferrule cylindrical body.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the boundary between the base end side of the chamfered portion and the outer peripheral surface of the cylindrical portion of the cylindrical body is an R surface. The ferrule tubular body is characterized in that According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the end surface of the cylindrical body on the optical fiber projecting portion side of the final chamfered portion is a flat surface, and the diameter of the flat surface is 0.1 mm. A ferrule tubular body having a length of 25 to 0.3 mm.

According to a seventh aspect of the present invention, there is provided a ferrule cylindrical body according to any one of the first to sixth aspects, and an optical fiber core wire having a base end coated with an outer periphery of the optical fiber is inserted. The ferrule is formed by connecting and fixing a collar member having an optical fiber insertion hole formed therein. According to an eighth aspect of the present invention, there is provided an optical connector comprising the ferrule according to the seventh aspect.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a ferrule equipped with an optical fiber according to an embodiment of the present invention, FIG.
FIG. 1 schematically shows the usage state of the ferrule of the present embodiment. As shown in FIG. 1, the ferrule 11 of the present embodiment
Is composed of a cylindrical body 12 made of ceramic such as zirconia and a brim 13 formed of metal such as stainless steel, plastic, ceramics or the like. An optical fiber insertion hole 14 through which the optical fiber 21 is inserted is formed inside the cylindrical body 12, and a first chamfered portion 17A and a second chamfered portion 17B are formed at the tip of the cylindrical body 12. Is formed. The angle θ1 of the first chamfered portion 17A with respect to the axial direction O of the cylindrical body 12 is about 30 degrees, and the inclination angle θ2 of the second chamfered portion 17B is 5 to 15 degrees.

The first chamfered portion 17A and the second chamfered portion 17B may be formed at the time of forming the ceramics or may be formed by grinding after sintering the ceramics. It is preferable to finish by polishing. The first chamfered portion 17A and the second chamfered portion 17A
The total length of the chamfered portion 17B in the axial direction may be the same as the conventional length, that is, for example, about 0.5 mm, but may be longer than the conventional length by the second chamfered portion 17B. (However, the maximum length is 1.2 mm according to the above-mentioned standard value.) On the other hand, the collar 13 is a fitting hole 1 in which the tubular body 12 is fitted.
8 and a through hole 19 into which the optical fiber core wire 22 is inserted, and the ferrule 11 is configured by fitting the end of the cylindrical body 12 into the fitting hole 18 of the collar 13.
Then, the optical fiber core wire 22 is inserted into the through hole 19 of the collar 13, and the optical fiber 21, from which the end portion of the optical fiber core wire 22 is removed, is inserted through the optical fiber insertion hole 14. The optical fiber 21 and the optical fiber 22 are fixed by the adhesive filled in the hole 14 and the through hole 19. Needless to say, the collar 13 can be applied to a ferrule in which the collar 13 is integrally molded with the cylindrical body 12 with plastic, in addition to the stainless steel or the like.

The ferrule 11 thus assembled can be assembled into an optical connector component by polishing the end face of the cylindrical body 12 together with the optical fiber 21, for example, to constitute an optical connector. With the use of the ferrule 11 described above, for example, as shown in FIG. 2, even if insertion into the split sleeve 25 is repeated, for example, the boundary between the second chamfered portion 17B and the cylindrical outer peripheral surface 17C is not as sharp as before. Therefore, dust due to friction is less likely to be generated, and dust does not accumulate in corners B and the like. Further, there is no possibility of damaging the inner peripheral surface of the split sleeve 25.

FIG. 3 is a sectional view of an example of an optical connector incorporating a ferrule similar to the above-described ferrule. The optical connector shown in FIG. 3 uses a basic plug 30.
A ferrule 31 comprising two and a collar 33;
A compression spring 34 attached to the outer peripheral portion of the rear end of the collar 33, and a stopper 35 when fitted to the rear end of the collar 33 via the compression spring 34. The basic plug 30 is fitted to the ferrule 31 via the compression spring 34 so as to be able to swing mainly in the axial direction by being locked in the locking hole 35 a of 35. Then, the plug frame 36 is fitted to the outside of the basic plug 30, and the locking projection 35b is locked in the locking hole 36a.
The plug frame 36 is fixed, and a knob 37 is fitted and fixed to the outside of the plug frame 36.
The optical connector 40 is configured as described above.

The optical fiber core 22 is inserted into the basic plug 30 while the basic plug 3 is inserted.
The strength member 24 of the optical cord 23 is located at the rear end of the basic plug 30 and is fixed to the outer periphery of the rear end of the stopper 35 of the basic plug 30 by a caulking ring 38. A boot 39 is attached to the rear end of the plug frame 36 so as to cover the connection portion (stopper 35 and caulking ring 38) of the optical cord 23.

FIG. 4 shows a ferrule 41 according to another embodiment. The ferrule 41 is the ferrule 1 described above.
The boundary between the second chamfered portion 17B and the cylindrical outer peripheral surface 17C is rounded by polishing to form an R portion 17D. In this case, wear is less likely to occur when inserted into the split sleeve or the like. Also, in this case, since the R portion 17D is formed at the end of the second chamfered portion 17B having a small inclination angle with respect to the outer peripheral surface of the cylinder, compared with the case where the R portion 17D is formed at the end of the first chamfered portion 17A having a large inclination angle. The work efficiency is very good when the R and R portions are polished.

In the example described above, the chamfered portion is
In the example described above, it is formed in two stages, but it may be formed in three or more stages. That is, when the tip angle is made as small as possible by further increasing the inclination angle θ1, the inclination of the chamfered portion is formed in three or four or more steps, and the inclination angle of the outermost chamfered portion is particularly increased. It is preferable to make it small.

FIG. 5 schematically shows a ferrule for mounting an optical fiber according to an embodiment of the present invention in which the chamfered portion of the ferrule has three inclinations. As shown in FIG. 5, the ferrule 51 of the present embodiment has a third chamfered portion 17E formed on the first chamfered portion 17A of the ferrule 11 described above to have a three-step inclined surface. According to the ferrule 51, since the third chamfered portion 17E is formed, when the end portion is polished after the optical fiber 21 is inserted and fixed, the third chamfered portion 17E is polished starting from the center of the tip end surface of the third chamfered portion 17E. First, the end of the optical fiber can be polished first, and then the convex spherical surface can be successively finished around the tip end surface of the second chamfer. As described above, in the present embodiment, the ferrule 51 is formed into a conical shape by performing multi-step chamfering in advance so that a convex spherical surface as a final shape can be easily formed. Therefore, for example, even after repeated insertion into the split sleeve or the like, the boundary between the third chamfered portion and the outer peripheral surface of the cylinder is less sharp than in the past, so that dust due to friction is less likely to be generated and dust is accumulated in the corners. There is no. In the present embodiment,
θ1 = about 30 °, θ2 = 5 to 15 °, θ3 = 45 to 89
° and an end face diameter of 0.25 to 0.3 mm.

The first chamfered portion 17A, the second chamfered portion 17B, and the third chamfered portion 17E may be formed at the time of molding the ceramics or may be formed by grinding after sintering the ceramics. Then, it is preferable to form by shaping and finish by polishing. 6 is a schematic perspective view of a ferrule according to another embodiment having three chamfers, FIG. 7 is a partially cutaway perspective view of a cylindrical body, and FIG. 8 is an enlarged view of a main part of an end face thereof. . As shown in these drawings, the ferrule 61 of the present embodiment is a
A third chamfered portion 17E is further formed on the chamfered portion 17B and the first chamfered portion 17A to form a three-step inclined surface, and the inclination of the third chamfered portion 17E is made as large as possible to further improve the polishing efficiency of the end face. It is intended to improve.

In the case of the present embodiment, as shown in FIGS. 7 and 8, the third chamfered portion 17E has a flattened truncated conical shape in which the inclination of the third chamfered portion 17E is as large as possible.
Is the top of the truncated cone of the third chamfer 17E. In the ferrule cylindrical body 12 of the present embodiment, the angle of the second chamfered portion 17B is set to θ2 = 30 ° and the first chamfered portion 17A is set.
Is 60.degree., And the angle of the third chamfer 17E is .theta.3 = 86.degree. (.Theta.4 = 4.degree.). When the outer diameter of the cylindrical body 12 is D1 = 2.5 mm, the diameter of the top of the truncated cone of the third chamfer 17E is D2 = 0.25 mm or more.
It is about 0.3 mm.

The angle θ3 of the third chamfer 17E is set to 86
(Θ4 = 4 °) is that when the end face is polished after the optical fiber 21 is inserted, the R
Is set to 10 to 25, and is formed by two chamfered portions having a shape obtained by adding a shaving allowance to the average inclination of 10R to 25R and easy to manufacture. The cross-sectional area of the top portion is preferably as small as possible, for example, 0.5 mm or less, and is preferably set to the minimum value (0.125 mm of the insertion hole diameter) in order to eliminate the apex shift in the convex spherical surface finish. However, the reason why the outer diameter is set to about D2 = 0.25 mm to 0.3 mm is that the insertion hole 14 of the optical fiber 21 is D3 = 0.125.
mm, so that the edge is not chipped. As a result, from the edge of the optical fiber insertion hole 14, D4 =
A flat surface of 0.05 mm will be formed as the actual top of the truncated cone. Although the polished shape after fixing the fiber is shown by a dotted line, it is polished to 20 to 40 μm to form a convex spherical shape in order to remove chipping of the optical fiber, edge dripping of the fiber insertion hole, chipping, and the like.

In the case of this embodiment, the inclination angle of the chamfered portion is not limited to the above, and the angle of the second chamfered portion 17B is set to θ 2 = 5 to 30 °, preferably 5 to 1 °.
5 °, and the angle of the first chamfered portion 17A is θ1 = 45-8.
0 °, the angle of the third chamfer 17E is θ3 = 85-89 °
(Θ4 = 1 to 5 °). In particular, the range of the inclination angles of the three chamfers on the tip side is to obtain a state close to the convex spherical shape which is the final polished shape in the three chamfers, that is, to obtain a polygonal approximation. = 87
In the case of ８９89 ° (θ4 = 1 to 3 °), θ1 = 60 to
80 °, θ2 = 30 ° ± 5 °, θ3 = 85-87 °
(Θ4 = 3-5 °), θ1 = 45-65 °,
It is preferable that θ2 = 30 ° ± 5 °. Thus, the first
The angle θ1 of the chamfer 17A is the angle θ2 of the second chamfer 17B when the angle θ3 of the third chamfer 17E is variable.
This is an important parameter for obtaining a cone by polygon approximation.

By forming such a chamfered portion, a convex spherical surface can be obtained by an easy polishing operation, and the eccentricity at this time is small. Further, since the polishing is easy, the wear of the polishing sheet is small, and the polishing time is shortened. As shown in FIG. 6, using such a tubular body 12, a collar 13 is provided on the outside.
And the optical fiber core wire 22 is inserted into the through hole 1 of the collar 13.
9, the optical fiber 21 is inserted into the optical fiber insertion hole 14, and the optical fiber 21 and the optical fiber core wire 22 are fixed with an adhesive previously filled in the optical fiber insertion hole 14 and the through hole 19, and the ferrule is fixed. Assemble 61.

The ferrule 61 thus assembled can be assembled into, for example, an optical connector component by polishing the end face of the cylindrical body 12 together with the optical fiber 21 to form an optical connector. FIG. 9 shows a case where the ferrule 61 is used to polish the optical fiber 21 after insertion. In FIG. 9, reference numeral 62 denotes a polishing film, and 63 denotes an elastic rubber. As shown in FIG. 9A, when the end face of the ferrule 61 is polished with the polishing film 62, the third chamfered portion 17E and the first chamfered member 17A come into contact with the polishing film 62, but the third chamfered portion 17E Is extremely large (.theta.3 = 86.degree. (.Theta.4 = 4.degree.)) (See FIG. 8), so that the ferrule end face around the optical fiber 21 can be immediately polished.

The inclination of the first chamfer 17A is also θ1 =
Since the angle was set to 60 ° and θ2 = 30 °, the corners became smooth during polishing, and stress concentration was eliminated. As a result,
The polishing time can be reduced, and the life of the polishing film can be improved. When polishing, the polishing film 6
Because there are almost 3 points in the initial stage (in fact,
As shown in FIG. 9 (a), there are four points, but since the top 17F is narrow, it will apparently hit three points). An excellent polishing finish has an advantage that R eccentricity is improved.

As described above, in the present embodiment, since the third chamfered portion 17E and the first chamfered portion 17A are polygonal approximations, the bevel H1 for polishing from a conical shape to a convex spherical surface is used.
Is extremely small, and the polishing time can be shortened. On the other hand, in the conventional polishing, as shown in FIG. 9C, the chamfered portion has only one step, and the angle θ5 of the inclined surface of the end surface of the ferrule 102 is as large as 60 °. It becomes an acute angle, the polishing resistance is concentrated, and it is necessary to first make a corner and then gradually progress to the formation of R, which results in a large amount of removal H3, time and effort in polishing, and significantly lower polishing efficiency.

In the conventional polishing, the ferrule at the initial stage of polishing lacks stability and the R eccentricity is poor in some cases because two points are involved. This point was resolved, and the R eccentricity was improved.
In addition, when the chamfered portion has two steps as shown in FIG.
As compared with FIG. 9 (c), there is an advantage that the corner at the tip becomes gentler from an acute angle to an obtuse angle, so that the concentration of the polishing resistance is eased. There is a problem that stability is impaired and eccentricity of the convex spherical surface is deteriorated. Furthermore, it takes time to form a convex spherical surface around the periphery of θ6 after the corner is formed, and the amount of H2 is large, so that it takes time to polish.

Further, in the present invention, multi-stage conical machining is extremely easy, and the overall machining cost can be reduced, as compared with the conventional case where the ferrule is machined into a convex spherical surface. FIG. 10 shows an end of a ferrule cylindrical body according to an embodiment in which chamfers are formed in four steps.

In the ferrule cylindrical body 12 of the present embodiment, the angle of the second chamfered portion 17B is set to θ2 = 30 °,
The angle of the chamfer 17A is θ1 = 60 °, the angle of the third chamfer 17E is θ3 = 86 ° (θ4 = 4 °), and a fourth chamfer 17G is provided on the base end side. θ5 = 10 °. Also, the outer diameter of the cylindrical body is D1
= 2.5 mm, and the diameter of the flat surface 17F serving as the top of the truncated cone of the third chamfer 17E is D2 = 0.25 mm to 0.3.
mm.

As a result, as compared with the conventional case of processing into a convex spherical surface, the processing is extremely easy, the entire processing cost can be reduced, and after the optical fiber is fixed, for example, a split sleeve is formed. Etc. are repeated,
Since the boundary between the chamfered portion 17G and the outer peripheral surface of the cylinder is less sharp than in the past, dust is less likely to be generated due to friction, and dust is not accumulated at the corners.

In each of the embodiments described above, the ferrule of the present invention has a fiber insertion hole having the same diameter in the longitudinal direction, but the base of the optical fiber insertion hole formed in the cylindrical body. A tapered portion having a gradually increasing diameter may be formed at the end, and an optical fiber insertion hole into which an optical fiber may be inserted may be continuously formed.

[0034]

As described above, in the ferrule and the optical connector according to the present invention, the chamfered portion at the tip of the cylindrical body is formed in a plurality of steps so that the boundary between the outer periphery of the cylindrical portion and the chamfered portion can be sharpened. Since it has been eliminated, for example, dust or the like due to abrasion due to insertion into a split sleeve or the like is less likely to occur, and poor connection and the like can be avoided. In addition, even when the boundary between the chamfered portion and the outer peripheral surface of the cylindrical portion is rounded, there is an effect that the operation is very easy. Furthermore, by increasing the number of chamfers and increasing the inclination of the end face, it is possible to perform polishing without eccentricity when inserting an optical fiber and polishing to a convex spherical surface, thereby reducing polishing time and polishing. This has the effect of improving efficiency.

[Brief description of the drawings]

FIG. 1 is a sectional view of a ferrule to which an optical fiber according to an embodiment of the present invention is attached.

FIG. 2 is a cross-sectional view illustrating a use state of the ferrule of the present embodiment.

FIG. 3 is a diagram illustrating an example of an optical connector incorporating a ferrule according to another embodiment.

FIG. 4 is a cross-sectional view of a ferrule to which an optical fiber according to another embodiment is mounted.

FIG. 5 is a cross-sectional view of a ferrule to which an optical fiber according to another embodiment is mounted.

FIG. 6 is a schematic perspective view of a ferrule according to another embodiment.

FIG. 7 is a partially cutaway perspective view of a cylindrical body according to another embodiment.

8 is an enlarged view of a main part of an end face of the tubular body in FIG. 7;

FIG. 9 is a schematic view of a polishing state.

FIG. 10 is an enlarged view of a main part of a cylindrical body end portion of a cylindrical body according to another embodiment.

FIG. 11 is a sectional view of a conventional ferrule.

FIG. 12 is a sectional view showing a state of use of a conventional ferrule.

[Explanation of symbols]

 11, 21, 31, 41, 51, 61 Ferrule 12 Cylindrical body 13 Collar 14 Optical fiber insertion hole 17A First chamfered portion 17B Second chamfered portion 17C Cylindrical outer peripheral surface 17D R portion 17E Third chamfered portion 17F End face of ferrule 18 Fitting hole 19 Through hole 21 Optical fiber 22 Optical fiber core

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Setsuo Tokaibayashi 6-41-6 Kameido, Koto-ku, Tokyo Inside Nastec Industrial Co., Ltd. (56) References JP-A-63-56618 (JP, A) JP-A-Hei 1-17007 (JP, A) JP-A-8-243930 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 6/36

Claims (8)

(57) [Claims] 1. A ferrule cylindrical body having an optical fiber insertion hole into which an optical fiber is inserted, the cylindrical body having a chamfered portion at the distal end, the outer diameter of which is gradually reduced toward the distal end. A ferrule cylindrical body characterized in that the slope of the chamfered portion is formed in two or more steps. 2. The multi-stage chamfered portion according to claim 1, wherein the multi-stage chamfered portion has three or more stages, and at least two-stage chamfered portions on the tip side of the multi-staged chamfered portion form a substantially convex spherical shape. The angle of inclination of the chamfer on the leading end side with respect to the axis of the cylindrical body on the side of the optical fiber protrusion is 85 to 89 degrees, and the axis of the cylindrical body on the side of the optical fiber protrusion of the chamfer adjacent to this. A ferrule cylindrical body characterized by an inclination angle of 45 to 80 degrees with respect to. 3. The inclination angle of the chamfered portion adjacent to the base end side of the second-stage chamfered portion from the distal end portion with respect to the axis of the cylindrical body according to claim 1 or 2, A ferrule cylindrical body characterized by the following. 4. The angle of inclination of the chamfered portion on the base end side with respect to the axis of the cylindrical body according to any one of claims 1 to 3,
A ferrule cylindrical body characterized by being 15 degrees or less. 5. The ferrule according to claim 1, wherein a boundary between a base end side of the chamfered portion and an outer peripheral surface of the cylindrical portion of the cylindrical body is an R surface. Tubular body. 6. The end surface of the cylindrical body on the optical fiber protruding portion side of the final chamfered portion according to any one of claims 1 to 5, wherein a diameter of the flat surface is 0.5 mm or less. A ferrule cylindrical body characterized by the following. 7. An optical fiber core insertion hole into which a ferrule cylindrical body according to any one of claims 1 to 6 and an optical fiber core having a base end coated with an outer periphery of said optical fiber are inserted. A ferrule characterized by connecting and fixing a brim member formed with. 8. An optical connector comprising the ferrule according to claim 7.