JP3207092B2 - Optical connector sleeve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sleeve used for connecting ferrules having optical fibers in an optical connector.

[0002]

2. Description of the Related Art In the field of optical communication, connectors are used when optical fibers are connected to each other. As shown in FIG. 3, one end of the optical fiber 30 is inserted and fixed in the central through hole 21 of the ceramic ferrule 20, and two ferrules 20 are inserted from both ends of the sleeve 10 to abut the end faces inside. Thus, an optical signal can be transmitted between the two optical fibers 30.

The sleeve 10 is a cylindrical body made of ceramics such as zirconia. There are two types of sleeves, a split sleeve having a slit formed in the axial direction and a precision sleeve having no slit. 20
Has been polished to a smooth surface so that it can be held with high precision.

On the other hand, as shown in FIG. 4, three protrusions 11 extending in the axial direction are provided on the inner peripheral surface of the sleeve 10 at symmetrical positions, and the ferrule 20 is provided only at the tip of the protrusion 11.
One that supports a point has been proposed (Japanese Unexamined Patent Publication No. Hei 6-2732).
No. 8). Such a three-point support type sleeve 10
The polishing process can be simplified because only the tip of the convex portion 11 supporting the ferrule 20 needs to be polished, and a gap is formed between the convex portions 11.
This has the effect of preventing air from accumulating at the time of insertion and removing foreign substances existing between the ferrule 20 and the sleeve 10 from the gap.

[0005]

However, in the case of a three-point support type using a precision sleeve having no slit, there is a problem that the holding accuracy of the ferrule 20 to be inserted cannot be increased.

That is, in a precision sleeve without a slit,
Since the inner diameter of the sleeve 10 is slightly larger than the outer diameter of the ferrule 20 and there is a clearance between the two, the holding position of the ferrule 20 varies by the clearance. For example, as shown in FIG. 5A, the holding position of the ferrule 20 in the sleeve 10 varies by the clearance c between the solid line position and the broken line position.

On the other hand, as shown in FIG.
The point support type sleeve 10 has a disadvantage that the clearance c is larger than that of the sleeve without the protrusion 11 due to the phenomenon that the ferrule 20 falls into the space between the protrusions 11.

For example, in a precision sleeve having an inner diameter of 2.501 mm, the clearance c of the sleeve 10 without the convex portion 11 shown in FIG.
The clearance c of the three-point support type sleeve 10 shown in FIG. 5B is 3.05 μm, and the three-point support type sleeve 1
In the case of 0, the clearance c was larger by 0.55 μm.

If the clearance c is large, when used as an optical connector, the center positions of the optical fibers connected to each other are shifted and the optical transmission loss increases, so that the inner diameter of the three-point support type sleeve 10 is particularly severe. There was a problem that had to be managed.

In the case of a split sleeve having a slit, since the ferrule is held by the elasticity of the sleeve itself, the above-mentioned problem does not occur even with a three-point support type. The above-mentioned problem is a problem peculiar to a case where a precision sleeve having no slit is a three-point support type.

[0011]

Accordingly, the present invention is characterized in that four or more axial projections are formed on the inner peripheral surface of the precision sleeve.

That is, the number of projections supporting the ferrule is 4
By increasing the number of the protrusions to more than three, the distance between the protrusions was reduced, and the clearance of the ferrule held inside was reduced.

In addition, the angle formed on the circumference of each projection is 18
By making it as small as 0 / n ° or less, it is possible to easily perform the polishing process to make the front end surfaces of the respective convex portions on the same circumference.

[0014]

Embodiments of the present invention will be described below.

As shown in a perspective view in FIG. 1 and a sectional view in FIG. 2 (a), a sleeve 10 is a cylindrical body made of zirconia ceramics and is a precision sleeve having no slit, and a shaft is provided on an inner peripheral surface thereof. The projections 11 in the directions are provided at six contrasting locations on the circumference. When the sleeve 10 is used, as shown in FIG.
An optical connector can be formed by inserting 0 and abutting the end surfaces inside each other. At this time,
The ferrule 20 is supported by the distal end surfaces 12 of the six convex portions 11 formed on the inner peripheral surface of the sleeve 10.

In another embodiment, as shown in FIG. 2B, the projections 11 are provided at four contrasting positions, and the ferrule 20 is supported by the distal end surfaces 12 of the four projections 11. it can.

As described above, by setting the number of the protrusions 11 to four or more, the interval between the protrusions 11 is reduced, and FIG.
It is possible to prevent the ferrule 20 from dropping as shown in (b) and reduce the clearance of the ferrule 20.

The number of the convex portions 11 is not particularly limited as long as the number is four or more, but as a result of various experiments, six optimal ones as shown in FIG. If the number of the protrusions 11 is six or more, the clearance can be substantially the same as that without the protrusions 11, and even if the number of the protrusions is more than six, no particularly excellent effect is produced. That's why.

When the ferrule 20 is held, a gap is formed in the space between the protrusions 11, so that the sleeve 10
This prevents air traps in the interior and allows good discharge of dust and the like. Moreover, since the ferrule 20 is supported only by the distal end surface 12 of the projection 11, only the distal end surface 12 needs to be polished, so that the polishing step can be simplified.

However, since the number of the convex portions 11 is four or more, the number of polished portions is larger than that of the three-point support type, and the tip surfaces 12 of all the convex portions 11 are precisely polished so as to be on the same circumference. Therefore, in the present invention, as described in detail below, the width of each projection 11 is reduced.

That is, in the sectional view shown in FIG.
Since each projection 11 exists on the circumference, the width of the distal end surface 12 of each projection 11 can be represented by the angle θ occupied on the circumference. In the case of the six-point support type shown in FIG. 2A, the angle θ occupied by the convex portion 11 is 30 ° or less.
In the case of the four-point support type shown in (b), it is preferable that the angle θ occupied by the protrusion 11 is 45 ° or less. In general, when the number of the convex portions 11 is n, the angle θ of each convex portion 11 may be 180 / n ° or less, and more preferably 90 / n ° or less. In this case, even if the number of the convex portions 11 is increased, the total amount of the area of the distal end surface 12 does not increase, so that the polishing can be easily performed.

The tip surface 12 of each projection 11 is polished so as to be on the same circumference, and has a shape along the outer peripheral surface of the ferrule 20. Further, the boundary between each convex portion 11 and the inner peripheral surface of the sleeve 10 is formed as an R surface 13 having a radius of curvature of 0.05 mm or more to prevent cracks from being generated at these portions. The height of the convex portion 11 is 2 μm.
m or more.

The material of the sleeve 10 is Y ₂ O
_3. A partially stabilized zirconia ceramic containing at least one of MgO, CaO, CeO _{2 and the} like as a stabilizer is used. Since the partially stabilized zirconia ceramics have extremely high bending strength and toughness, there is no possibility of breakage even when used as the sleeve 10. Among these, in particular,
It contains 5 mol% of Y ₂ O ₃ , contains 80% or more of a tetragonal crystal phase, has an average crystal grain size of 2 μm or less, and has a transverse rupture strength of 10%.
A partially stabilized zirconia ceramic of 0 kg / mm ² or more is suitable.

When the sleeve 10 is manufactured, the above-mentioned ceramic raw material is extruded from a mold to form a cylindrical body having a convex portion 11 on the inner peripheral surface, which is fired under predetermined conditions. After that, it can be obtained by polishing the tip end surface 12 of each projection 11.

Since extrusion is performed in this manner, molding can be easily performed even if the number of projections 11 is increased, and polishing after firing can be easily performed only on the tip end surface 12 of projections 11. Can be polished.

[0026]

Here, a partially stabilized zirconia ceramic having an inner diameter of 2.501 mm and a number n of convex portions 11 on the inner periphery was used.
Were produced. 2.4 outside diameter each
The clearance c when the 985 mm ferrule 20 was inserted was measured.

The results are as shown in Table 1. From this result, it is understood that the clearance c can be reduced by setting the number n of the protrusions 11 to 4 or more, and the clearance c can be reduced as the number n increases. In particular, when the number n of the projections 11 was 6, the difference from the one without the projections 11 was 0.2 μm. Generally, since the tolerance of the gauge for performing the inner diameter inspection is 0.2 μm, if the number n of the protrusions 11 is 6 or more, the clearance is substantially the same as that without the protrusions 11.

[0028]

[Table 1]

[0029]

As described above, according to the present invention, an axially extending convex portion is formed on the inner peripheral surface of a precision sleeve for an optical connector.
By forming at more than one place, the clearance with the ferrule can be reduced and the holding precision can be increased, so that the transmission loss of the optical connector can be reduced. Also,
Since it is sufficient to polish only the tip end surface of the convex portion, the polishing process can be simplified, air accumulation at the time of inserting the ferrule can be prevented, and dust and the like can be discharged well.

Further, according to the present invention, the angle occupied on the circumference of each of the convex portions is 180 when the number of the convex portions is n.
By setting the ratio to / n ° or less, even if the number of convex portions is increased, the total amount of the area of the front end surface does not increase, and polishing can be facilitated.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an optical connector sleeve of the present invention.

2A is a cross-sectional view taken along line XX of FIG. 1, and FIG. 2B is a cross-sectional view illustrating another embodiment.

FIG. 3 is a sectional view showing a schematic structure of a general optical connector.

FIG. 4 is a sectional view showing a conventional three-point support type precision sleeve.

FIGS. 5A and 5B are cross-sectional views showing clearances between a conventional precision sleeve and a ferrule.

[Explanation of symbols]

 10: Sleeve 11: Convex part 12: Tip surface 13: R surface 20: Ferrule 30: Optical fiber

Claims (1)

(57) [Claims] A ferrule having an optical fiber is inserted from both ends to abut end faces of the ferrule .
A precision sleeve without a slit, wherein at least four convex portions extending in the axial direction are formed on the inner peripheral surface of the ceramic cylindrical body, and when the number of the convex portions is n, the axial direction of the sleeve is
The angle occupied on the circumference of each protrusion in a cross section perpendicular to the direction is
180 ° / n or less, and the tip surface of each projection is on the same circumference
Polished so that each protrusion and the inner peripheral surface of the sleeve
The optical connector sleeve as claimed in claim 1, wherein a boundary between the first and second surfaces is an R surface having a radius of curvature of 0.05 mm or more .