JPH07174937A - Ceramic capillary for optical fiber juncture and its production connection - Google Patents

Abstract

PURPOSE:To provide a capillary which permits omission of reboring of a small-diameter straight pipe part, lessens bending of the small-diameter straight pipe part and sufficiently withstands thermal shock by specifying the total length of the small-diameter straight pipe part and tapered pipe part of the fired body of the ceramic capillary and producing by an injection molding. CONSTITUTION:This ceramic capillary 1 is mounted at the front end of an optical fiber 10 and has a large-diameter straight pipe part 2 for housing a coated fiber 11, the small-diameter straight pipe part 3 for housing the fiber 12 and the tapered pipe part 4 for smoothly connecting the large-diameter straight pipe part 2 and the small- diameter straight pipe part 3. The sum L1 of the length L3 of the small-diameter straight pipe part 3 and the length L4 of the tapered pipe part 4 is set at 6.0 mm<=L1<=8.5mm. This ceramic capillary 1 is produced by an injection molding method. The degree of freedom in determining the length and shape of the tapered pipe part 4 is increased if the straight pipe part is included in the tapered pipe part 4. Further, the firm adhesion of the capillary 1 and the coated fiber 11 by the tapered pipe part 4 is possible and the length L3 of the small-diameter straight pipe part 3 is made shorter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic capillary used in an optical fiber connecting portion and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a method for manufacturing a capillary for an optical fiber connector, for example, a technique disclosed in Japanese Patent Publication No. 1-45042 is known. FIG. 9 is a cross-sectional view of a conventional capillary,
Corresponding to FIG. 2 of the above publication, the ceramic capillary 10
0 is a flange 10 made of stainless steel or plastic
1, a ceramic capillary 100 is provided with a sufficiently long minute hole 102 (corresponding to a small diameter straight pipe portion), and a large hole 103 (corresponding to a large diameter straight pipe portion) is formed in a flange. Then, according to the above publication, the ceramic molded body having the prepared hole is fired, and the prepared hole of the fired body is polished with a wire and a diamond paste.

[0003]

The above-mentioned technique is a general method for manufacturing a ceramic capillary, but it has the following disadvantages. Since the prepared hole is reprocessed, the number of processing steps is increased and the processing time and cost are increased. Although not specified in the above publication, there are extrusion molding methods and injection molding methods as molding methods, and since extrusion molding methods can only produce symmetrical cylindrical shapes, the taper portion for fiber insertion is cut after firing. Need to be formed. Therefore, the processing cost is increased, and an edge is easily formed at the intersection of the fine hole portion and the tapered portion, which may cause fiber breakage. Therefore, an injection molding method having a flexible shape and suitable for mass production is desirable.

FIG. 10 is a cross-sectional view of an example of a conventional injection molding die. For example, a cavity 112 for a capillary is engraved in a first die 111, and a conical portion 114 is provided in a second die 113.
And a pin 115 is projected and gates 116, 116
Is provided, the second mold 113 is matched with the first mold 111, and at this time, the tip of the pin 115 is inserted into the concave portion 111a of the first mold 111.
A ceramic powder (not shown) containing a binder is injected into the cavity 112 at high pressure via the.

At this time, a slight but non-uniform lateral pressure acts on the pin 115 to bend the pin 115, which may deteriorate the linearity of the prepared hole. The bending or bending of the pin 115 increases as the length of the pin 115 increases, and decreases as the diameter of the pin 115 increases. Therefore, the thicker the pin, the better, but in the conventional example, it is necessary to set the pin to a small diameter in order to secure a cutting allowance, and the pin is easily bent. Since excessive repetitive bending stress is generated in the pin during each molding, the life of the pin leading to breakage is shortened. Further, even in a capillary molded and fired by injection molding, in the conventional example, since the inner diameter is processed, the pores and the taper portion are likely to have edges, which may be broken when the fiber is inserted. Therefore, the capillary 1 of FIG.
The production of 00 by the injection molding method is not advantageous in cost and performance as compared with the extrusion molding method.

Also, in FIG. 2 of the above publication, the thick fiber core wire is supported only by the flange, but such a structure does not sufficiently withstand thermal cold shock (heating and cooling and shock are repeatedly applied). I can't say. A specific example will be described below. FIG. 11 is a graph showing the splice loss of an optical fiber splicing part produced using a conventional ferrule, in which the abscissa shows the number of thermal cold shock cycles and the ordinate shows the splice loss. The conditions for creating the above graph are as follows. Capillary; Capillary material; ZrO ₂ (Yttria partial stabilization;
The ratio of Y ₂ O ₃ to ZrO ₂ is 5.3 wt%) Outer diameter of fired body: 2.499 ± 0.0005 mm Length of fired body: 10.5 mm Length of small diameter straight pipe section: 10.0 mm Straightness of small diameter Diameter of tube part: 125.5-126.0 μm Processing method of tip part; PC polishing (spherical surface processing) Thermal-cold shock cycle; Room temperature → 75 ° C 100 mm drop → 75 ° C 30
Hold for minutes → Room temperature → Drop from a height of 100 mm at −40 degrees → −
Hold at 40 ° C for 30 minutes → normal temperature as one cycle.

Control value (allowable value) of connection loss in this class
Is ± 0.2 dB. When 10 cycles of 100 samples were tested, 8 samples were good, but 2 samples showed that the connection loss began to increase to the negative side after 20 cycles and exceeded the control value at 30 cycles. That is, n = 10 and the number of samples is small, but 2
It can be said that the conventional connector in which a defect of 0% is recognized and the fiber core wire is held by the flange has extremely poor reliability.

Therefore, an object of the present invention is to eliminate the re-hole machining of the small diameter straight pipe portion and to reduce the bending of the small diameter straight pipe portion,
Another object of the present invention is to provide a ceramic capillary that sufficiently withstands thermal shock and a method for manufacturing the same.

[0009]

In order to achieve the above object, the present invention provides a large-diameter straight pipe portion for accommodating a fiber core wire, a small-diameter straight pipe portion for accommodating a fiber element wire, and these large-diameter straight pipe portions. In a ceramic capillary that is provided with a taper pipe part that smoothly connects a small diameter straight pipe part, and this ceramic capillary has a sum of the length of the small diameter straight pipe part and the length of the taper pipe part of 6 mm to 8.5 mm. It is characterized by having a range of. Further, the tapered pipe portion may include at least one straight pipe portion.

[0010]

The above-mentioned ceramic capillary is manufactured by the injection molding method. According to this method, it is not necessary to re-hole the small diameter straight pipe portion formed during injection molding after firing.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view of a ceramic capillary manufactured by the method of the present invention.
A large-diameter straight pipe part 2 for accommodating the fiber core wire 11, a small-diameter straight pipe part 3 for accommodating the fiber element wire 12, which is attached to the tip of the optical fiber 10, and these large-diameter straight pipe part 2 and small The ceramic capillary 1 (fired body) has a structure including a taper pipe portion 4 that smoothly connects the diameter pipe portion 3, and the ceramic capillary 1 (fired body) has a length of the small diameter pipe portion 3 of L3 and a length of the taper pipe portion 4. Where L4 is L4 and L3 + L4 is Lt, the following relationship is characterized.

Inner diameter of large-diameter straight pipe portion 2; 1.0 to 1.2 mm
(After firing) Inner diameter of small-diameter straight pipe portion 3; 125.5-126.0 μm (after firing) Inner diameter of small-diameter straight pipe portion 3; about 176 μm (molded body) Total length of small-diameter straight pipe and tapered pipe portion; 6 .0 ≦ Lt ≦ 8.
5 mm (after firing)

The above-mentioned ceramic capillary 1 can be manufactured by a die press molding method, but in the present invention, it is manufactured by an injection molding method. At that time, a 176 μm pin is interposed in the mold. Since the molded body shrinks when fired, a thick pin is used so that the final diameter of the small-diameter straight pipe portion 3 is 125.5 to 126.0 μm. In the injection molding method, an eccentric load may act on the pin.

FIG. 2 is a model diagram for obtaining the deflection of the pin. In this model, an eccentric load acts on the pin 5 with an evenly distributed load w, one end of the pin 5 is fixed, and the other end is simply supported. ymax and the maximum inclination αmax are given by the following equations and equations (see the Mechanical Engineering Handbook, Revised 5th Edition, page 47).

[0015]

[Equation 1]

Comparative Example: The diameter of the small diameter straight pipe part of the finished product is 126
μm, the pore size of the fired product is 100 μ
When m, the diameter of the small diameter straight pipe part 3 of the molded body before firing is 1
It is 35-141 micrometers. Therefore, the outer diameter of the pin 5 is 138
μm and the length of the small diameter straight pipe portion 3 is 14.5 mm,
The maximum deflection of the manufactured injection molding was 27 μm. The distributed load w could be obtained from this data and the above equation, and at the same time, the maximum inclination αmax could be obtained from the equation.

Example: The diameter of the small diameter straight pipe portion of the finished product is set to 126.
μm, if the diameter of the small-diameter straight pipe part of the fired product that does not allow for the cutting margin is 126 μm, the small-diameter straight pipe part 3 of the molded product before firing
Has a diameter of 173 to 182 μm. Therefore, the second moment of area I is given by setting the outer diameter of the pin 5 to 176 μm, and the length of the small diameter straight pipe portion 3 is 4.1, 8.3, 12.4, 14.5.
mm (3,6,9,10.5 mm after firing) is given and L is applied mutatis mutandis, the maximum deflection of the example is calculated from the formula, and the maximum inclination of the example is calculated from the formula. The (deflection angle) was calculated and shown in FIGS.

FIG. 3 is a graph showing the relationship between the maximum deflection and the length of the small diameter straight pipe portion of the capillary fired body. According to this graph, it is exponential when the length of the small diameter straight pipe portion 3 of the capillary fired body decreases. It can be seen that the deflection y is small. The comparative examples are indicated by Δ. FIG. 4 is a graph showing the relationship between the length of the small-diameter straight pipe portion of the capillary fired body and the maximum inclination. According to this graph, when the length of the small-diameter straight pipe portion 3 of the capillary fired body decreases, the exponentially inclined α It turns out that becomes smaller. The magnitude of this inclination α is directly related to the angular displacement when the ceramic capillaries 1 and 1 are butted and connected to each other.

In the above comparative example, the diameter of the pin was 0.138 mm, and the life of the pin was 20000 (injection) times on average. On the other hand, in the example, the pin diameter was as thick as 0.176 mm, and there was no problem even if it exceeded 20000 (injection) times.

Furthermore, the following is clear from FIG. When the length of the small diameter straight pipe is 10.5 mm, the maximum deflection is 10 ^-2.
mm = 10 μm When the length of the small diameter straight pipe is 6 mm, the maximum deflection is 10 ^-3 mm =
When the length of the straight pipe part with a small diameter of 1 μm is 3 mm, the maximum deflection is 10 ^-4 mm =
0.1 μm Naturally, the bending of the small diameter straight pipe portion 3 is drastically reduced by shortening the length of the pin. However, it is impossible to make the small diameter straight pipe portion 3 as short as possible for the following reason.

FIG. 5 is a graph showing the relationship between the length of the small diameter straight pipe portion and the adhesive strength of the fiber. The horizontal axis represents the length of the small diameter straight pipe portion and the vertical axis represents the adhesive strength. The longer the length of the small diameter straight pipe part 3, the greater the adhesive strength when the fiber is pulled in the longitudinal direction. From this point, if the small diameter straight pipe portion 3 is made too short, the service life may be shortened. Therefore, a thermal shock cycle test was carried out and its limit was investigated.

FIG. 6 is a graph showing the splice loss of the optical fiber splicing part produced by using the ferrule of this embodiment.
The horizontal axis represents the number of thermal shock cycles and the vertical axis represents the connection loss. The conditions for creating the above graph are as follows. Capillary of Example 1; Capillary material; ZrO ₂ (Yttria partial stabilization;
The ratio of Y ₂ O ₃ to ZrO ₂ is 5.3 wt%) Outer diameter of fired body: 2.499 ± 0.0005 mm Length of fired body: 10.5 mm Length of small diameter straight pipe part L3: 6 mm Straight pipe of small diameter Diameter of part: 125.5 to 128.5 μm Length of tapered tube part L4; 1 mm Lt; 7 mm Processing method of tip part; PC polishing (spherical surface processing)

Thermal-cold shock cycle; normal temperature → falls from 100 mm height at 75 ° C. → 30 at 75 ° C.
Hold for minutes → Room temperature → Drop from a height of 100 mm at −40 degrees → −
Hold at 40 ° C for 30 minutes → normal temperature as one cycle. In the example, after 100 cycles, all 10 samples had good connection loss within ± 0.2 dB.

FIG. 7 is a graph showing the splice loss of the optical fiber splicing part produced by using the ferrule of the comparative example, in which the horizontal axis represents the thermal shock cycle number and the vertical axis represents the splice loss. The conditions for creating the above graph are as follows. Capillary of Comparative Example 1; Capillary material; ZrO ₂ (Yttria partial stabilization;
The ratio of Y ₂ O ₃ to ZrO ₂ is 5.3 wt%) Outer diameter of fired body: 2.499 ± 0.0005 mm Length of fired body: 10.5 mm Length of small diameter straight pipe part L3; 3 mm Straight pipe of small diameter Diameter of part: 125.5-126.0 μm Length of taper tube part L4; 1 mm Lt; 4 mm Processing method of tip part; PC polishing (spherical surface processing)

Thermal cold shock cycle; normal temperature → falls from 100 mm height at 75 ° C. → 30 at 75 ° C.
Hold for minutes → Room temperature → Drop from a height of 100 mm at −40 degrees → −
Hold at 40 ° C for 30 minutes → normal temperature as one cycle. In the comparative example, after 70 cycles, 4 samples out of −0.2 dB out of 10 samples, and 1 sample out of 6 remaining samples are not good. Therefore, Lt is 4mm
The following is not preferable in terms of life. The thermal cold shock cycle test was also tried on other examples, and the results are shown in Table 1.

[0026]

[Table 1]

Table 1 is a table in which Lt was changed from 4 mm to 10.5 mm and the connection loss of each was examined. Comparative Example 2
Since (Lt = 4 mm) has already exceeded 0.3 dB in 30 cycles, the determination is x, and in Comparative Example 3 (Lt = 10.5 mm), the determination is x because it is 0.3 dB or more in 50 cycles.

Examples 2 and 3 (Lt = 6 mm), Examples 4, 5 and 6 (Lt = 7 mm) and Example 7 (Lt =
(8.5 mm) was good, and the judgment was ◯. Furthermore,
Example 4 in which both Lt = 7 mm (L3 = 1 mm),
Example 5 (L3 = 3 mm), Example 6 (L3 = 6 mm)
In each of the cases, since the judgment was ◯, it was found that good results can be obtained if Lt is 6 to 8.5 mm without being influenced by the size of L3 or L4.

Estimating the reason why the above connection loss remains at a low level, the following two can be considered. First, the more the portion where the fiber and the ferrule are directly adhered to each other, the higher the adhesive strength is, and since the inorganic substances are bonded to each other, internal stress is generated by the thermal cycle, but thermal deterioration is less likely to occur. Therefore, when the thickness is 4 mm, the adhesive strength is not so large as to resist the repeated internal stress, so that it is useless, and when 6 mm or more, a good result is obtained. Secondly, when the ferrule has a diameter of 8.5 mm or less, since it has a sufficient large-diameter straight pipe portion, the fiber core wire can be reliably held, and it is considered to have an impact resistant structure.

Therefore, it can be said that the adhesive strength of the optical fiber is related to the sum Lt of the length L3 of the small diameter straight pipe portion and the length L4 of the taper pipe portion, and this Lt is in the range of 6.0 to 8.5 mm. If so, it is possible to provide a ceramic capillary capable of withstanding a thermal shock test. Further, by making the tapered pipe part longer, the structure is such that it can withstand the thermal shock even if the small diameter straight pipe part is shortened, the deformation of the hole during the injection molding process is small, and the life of the molding pin is extended.

FIG. 8 is a sectional view of another embodiment of the ceramic capillary of the present invention.
Is a small diameter straight pipe portion 23, a taper pipe portion 24 (taper pipe portion 24
Is composed of a first taper pipe part 25, a straight pipe part 26 and a second taper pipe part 27. ), The large-diameter straight pipe portion 22 is provided in order, the small-diameter straight pipe portion 23 and the taper pipe portion 24 contribute to the improvement of the adhesive strength, and the small-diameter straight pipe portion 23 can be sufficiently shortened. That is, the tapered pipe portion 24 is the small diameter pipe portion 2
3 and the large-diameter pipe portion 22 are tapered portions (in this example, 25, 2
It suffices that the taper pipe portion including 7) be included, and that one or more straight pipe portions be included therein.

As described above, according to the method of the present invention, the ceramic capillaries can be mass-produced by the injection molding method, and since the small-diameter straight pipe portion has a small bending, it is possible to omit the hole processing after sintering.

The method of the present invention can be applied not only to a ceramic ferrule in which a flange and a capillary are integrally molded, a plastic ferrule, but also to a ferrule in which a capillary is inserted into a metal flange or a metal case.

[0034]

As described above, according to the present invention, the bending of the small-diameter straight pipe portion is achieved by setting the total length of the small-diameter straight pipe portion and the taper pipe portion of the ceramic capillary fired body within the range of 6 to 8.5 mm. It is possible to obtain a ceramic capillary having a small size and sufficiently resistant to thermal shock.

Further, if at least one straight pipe portion is included in the taper pipe portion, the degree of freedom in determining the length and shape of the taper pipe portion increases, and the taper pipe portion further strengthens the capillary and the fiber core wire. Since it can be adhered to, the length of the small diameter straight pipe portion can be further shortened.

Furthermore, if the injection molding method is used, the ceramic capillaries can be mass-produced, and since the re-hole processing of the small diameter straight pipe portion is not required, the manufacturing cost can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a ceramic capillary manufactured by the method of the present invention.

FIG. 2 is a model diagram for obtaining the deflection of a pin.

FIG. 3 is a graph showing the relationship between the maximum deflection and the length of the small diameter straight pipe portion of the capillary fired body.

FIG. 4 is a graph showing the relationship between the maximum inclination and the length of the small diameter straight pipe portion of the capillary fired body.

FIG. 5 is a graph showing the relationship between the length of a small diameter straight pipe section and the adhesive strength of a fiber.

FIG. 6 is a graph showing the connection loss of the optical fiber connection section produced using the ferrule of this example.

FIG. 7 is a graph showing the connection loss of an optical fiber connection section produced using the ferrule of the comparative example.

FIG. 8 is a sectional view of another embodiment of the ceramic capillary of the present invention.

FIG. 9 is a sectional view of a conventional capillary.

FIG. 10 is a sectional view of an example of a conventional injection mold.

FIG. 11 is a graph showing the splice loss of an optical fiber splicing part produced using a conventional ferrule.

[Explanation of symbols]

1, 21 ... Ceramic capillaries, 2, 22 ... Large diameter straight pipe portion, 3, 23 ... Small diameter straight pipe portion, 4, 24 ... Tapered pipe portion, 1
0 ... Optical fiber, 11 ... Fiber core wire, 12 ... Fiber element wire, 26 ... Straight pipe part, L3 ... Length of small diameter straight pipe part, L4 ...
Length of taper tube part, Lt ... Sum of L3 and L4.

Claims (3)

[Claims] 1. A large-diameter straight pipe part for accommodating a fiber core wire, which is attached to the tip of an optical fiber, a small-diameter straight pipe part for accommodating a fiber element wire, and these large-diameter straight pipe part and small-diameter straight pipe part. In a ceramic capillary that is provided with a taper pipe portion that smoothly connects the pipe portion, and the ceramic capillary is fired, the sum of the length of the small diameter straight pipe portion and the length of the taper pipe portion is 6 mm to 8.5 mm. A ceramic capillary for an optical fiber connecting portion, characterized in that 2. The ceramic capillary for an optical fiber connecting section according to claim 1, wherein the tapered tube section includes at least one straight tube section. 3. A large-diameter straight pipe portion for accommodating a fiber core wire, which is attached to the end of an optical fiber, a small-diameter straight pipe portion for housing a fiber element wire, and these large-diameter straight pipe portion and small-diameter straight pipe portion. In the method of manufacturing a ceramic capillary including a taper pipe portion that smoothly connects the pipe portion, in the ceramic capillary, the sum of the length of the small diameter straight pipe portion and the length of the taper pipe portion after firing is 6 mm to 8.5 mm. The method for producing a ceramic capillary for an optical fiber connecting portion, characterized in that the small diameter straight pipe portion formed at the time of injection molding is not re-perforated after being fired by the injection molding method.