JPH1184172A - Production of ferrule made of quartz glass and apparatus for production of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ferrule consisting of quartz glass as a material which is difficult to be produced heretofore. SOLUTION: This process consists in introducing a pipe-like preform (quartz glass tube) 1 consisting of the quartz glass into a heating furnace 11, melting and drawing this preform to reduce the diameter and to form a quartz glass capillary 2 and introducing this quartz glass capillary 2 to a bore measuring section 12. The bore thereof is measured and the drawing speed of a endless tracked vehicle 14 is regulated in accordance with the measured value of the bore, by which the bore of the quartz glass capillary 2 is regulated. After the quartz glass capillary 2 is cooled, the capillary cut to a prescribed length and the outside surface thereof is ground, by which the ferrule 3 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferrule of an optical connector used for connecting a connector such as an optical fiber cable or an optical fiber cord, and an apparatus for manufacturing the ferrule.

[0002]

2. Description of the Related Art A ferrule of an optical connector is a component for firmly and accurately holding and fixing a bare optical fiber portion such as an optical fiber core wire or an optical fiber cord to be connected. Ferrules usually have an outer diameter of 2.
5 mm in length, 5 to 15 mm in length in the shape of a cylinder, a fine hole having a small diameter of 125 μm is bored at the center thereof, and the bare optical fiber portion is inserted into the fine hole, and an adhesive is used. It is fixed.

[0003] The ferrule of this optical connector is in contact with another ferrule at an end thereof via an adapter,
An optical connection is made between the two, and it is required that the connection loss is small and that the connection loss does not fluctuate even after repeated attachment / detachment, and an extremely high level of dimensional accuracy is required. For example, the outer diameter of the ferrule is required to have an accuracy of exactly 2499 ± 0.5 μm, the center axis of the microhole exactly matches the center axis of the ferrule, and the inner diameter of the microhole (the inner diameter of the ferrule) is Exactly 125-1
It needs to be 26 μm.

In order to satisfy such high dimensional accuracy and dimensional stability, a conventional ferrule is made of zirconia (zirconium oxide) as a raw material. This zirconia ferrule is tough, has excellent dimensional accuracy, dimensional stability, high reliability, and excellent characteristics.However, since it is made of ceramic, it requires labor such as firing and grinding, making it difficult to manufacture and expensive. There is a disadvantage that it is. In addition, zirconia ferrules have significantly different polishing characteristics compared to silica-based glass, which is the material for optical fibers.
Polishing the end face of the connector for optical connection requires an expensive polishing material such as diamond and a long polishing time, and has a disadvantage that the polishing cost is high. Further, since the linear expansion coefficient of zirconia is 8.3 × 10 ⁻⁶ / ° C., which is much larger than the linear expansion coefficient of quartz glass as the material of the optical fiber, 5.4 × 10 ⁻⁷ / ° C. There is also a drawback that the optical fiber is likely to protrude or retract due to the change of the optical fiber.

[0005]

For this reason, as a relatively inexpensive ferrule, a glass ferrule having high manufacturability obtained by melt drawing is manufactured. What is currently used as a glass ferrule is made of a multi-component glass such as borosilicate glass. The multi-component glass has good moldability, and the dimensional control of the ferrule at the time of manufacture is relatively easy.

[0006] On the other hand, a ferrule made of quartz glass as in the case of the optical fiber is still in a proposal stage.
Quartz-based glass has more stable material and higher surface hardness than multi-component glass, and therefore has excellent wear resistance, chemical resistance, ultraviolet resistance, and radiation resistance. For this reason, the ferrule made of quartz glass has few problems of long-term reliability. In addition, since the quartz glass ferrule has the same polishing characteristics as the optical fiber, the optical fiber and the ferrule can be polished at once using the same polishing material in polishing the connector end face for optical connection. Further, since the coefficient of linear expansion is equal to that of the optical fiber, the optical fiber is unlikely to protrude or retract due to a change in the operating environment temperature of the connector. On the other hand, since quartz glass has poor moldability, precise control of dimensions is difficult. Especially the bare optical fiber is inserted,
The microholes of the ferrule to be fixed are very small, and it is difficult to precisely control the inner diameter of a ferrule made of quartz glass, so that the ferrule made of quartz glass has excellent characteristics as described above. Has not been put to practical use. Therefore, an object of the present invention is to obtain a ferrule using quartz glass as a material.

[0007]

Means for Solving the Problems In order to solve such problems, the present invention proposes the following solutions. According to a first aspect of the present invention, a quartz glass thin tube is formed by melting and drawing a pipe-shaped base material made of quartz glass while adjusting a drawing speed based on a measured value of the inner diameter thereof. This is a method of manufacturing a ferrule. Second
According to the invention, the outer surface, the roundness, and the eccentricity of the quartz glass ferrule can be adjusted by grinding the outer surface of the quartz glass thin tube. Also, when grinding the outer surface in this way, grooves and protrusions are formed on this outer surface, and a structure that can be more firmly fixed to a ferrule holder that fixes a quartz glass ferrule when incorporating it into an optical connector etc. It can also be. According to a third aspect, in the first or second aspect, a measurement container made of a material having a refractive index equal to that of the quartz glass thin tube is filled with a liquid having a refractive index equal to the quartz glass thin tube, The quartz glass thin tube is inserted into the measurement container, and the quartz glass thin tube is irradiated with laser light from the outside of the measurement container through the measurement container and the liquid to reduce the inner diameter of the quartz glass thin tube. This is a method for producing a quartz glass ferrule, which is characterized by measuring. Further, a fourth invention is characterized in that it comprises a drawing means for melting and drawing a pipe-shaped base material made of quartz glass into a quartz glass thin tube, and a means for measuring the inner diameter of the quartz glass thin tube. This is a manufacturing device for glass ferrules. In a fifth aspect based on the fourth aspect, the inner diameter measuring means comprises a measuring container made of a material having a refractive index equal to that of the quartz glass thin tube, and the quartz glass thin tube filled in the measuring container. A liquid having a refractive index equal to and a laser beam is radiated from the outside of the measuring container to the quartz glass thin tube inserted into the measuring container through the measuring container and the liquid, and the inner diameter of the quartz glass thin tube And a laser measuring device for measuring

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
A ferrule made of quartz glass (hereinafter, sometimes simply referred to as a ferrule) of the present invention is a ferrule for connecting an optical fiber to a connector, and uses quartz glass as a constituent material. The ferrule has only to have a cylindrical fine hole, and its outer shape is not limited. Ferrules made of quartz-based glass have the advantage of being easy to manufacture, relatively inexpensive to supply, stable in material, high in surface hardness, and free from problems of wear and long-term reliability due to insertion and removal. Having.

FIG. 1 is a schematic diagram showing an example of a ferrule manufacturing apparatus according to the present invention. FIG. 2 is a schematic diagram showing a state where the inner diameter measuring unit of the manufacturing apparatus is viewed from above. Here, an example in which a cylindrical single-core ferrule is manufactured using a pipe-shaped base material made of quartz glass will be described. In the drawing, reference numeral 1 denotes a quartz glass tube (pipe-shaped base material), 2 denotes a quartz glass thin tube, 3 denotes a ferrule, 11 denotes a heating furnace, 12 denotes an inner diameter measuring unit, 13 denotes a wiping device, 14
Is a caterpillar.

The drawing means used in the present invention is obtained by heating and melting the quartz glass tube 1 as a starting base material to reduce the diameter, and the heating furnace 11 to reduce the diameter. And a caterpillar 14 for taking out the quartz glass thin tube 2. The heating furnace 11 is a quartz glass tube 1
Can be configured appropriately as long as it has a mechanism of heating the melted tip to a temperature higher than the melting point and dropping the melted tip.

The caterpillar 14 includes a belt 14 a for holding the quartz glass thin tube 2 melt-drawn in the heating furnace 11,
The belt 14a is configured to be driven in a direction for moving the quartz glass thin tube 2 downward. The belt 14a is made of a material that does not damage the surface of the quartz glass thin tube 2. For example, a rubber belt or the like is suitably used.

The caterpillar 14 is provided at a position after at least the surface of the quartz glass thin tube 2 is solidified.
Further, by changing the driving speed of the belt 14a of the caterpillar 14, it is possible to control the drawing speed of the quartz glass thin tube 2, that is, the drawing speed. In addition,
The device for pulling out the quartz glass thin tube 2 is not limited to the caterpillar 14 but may be any device having an appropriate configuration.

In this embodiment, the heating furnace 11 of the drawing means is used.
An inner diameter measuring unit 12 and a wiping device 13 are sequentially provided between and the caterpillar 14. Inner diameter measuring unit 12
Is for measuring the inner diameter of the quartz glass thin tube 2 melted and reduced in the heating furnace 11 as shown in FIG. 2 while the temperature is high. If the driving speed of the caterpillar 14 provided below the inner diameter measuring unit 12 is adjusted based on the measured value of the inner diameter, the drawing speed of the quartz glass thin tube 2 is changed, and the quartz glass The inner diameter of the thin tube 2 can be adjusted.

In the inner diameter measuring section 12, the measuring vessel 12a
Is a hollow with a bottom made of quartz glass whose refractive index is the same as that of the quartz glass thin tube 2.
A hole for inserting the quartz glass thin tube 2 is formed at the bottom of. The measurement container 12a is not limited to quartz glass, and may be any material formed of a material having the same refractive index as the quartz glass thin tube 2. Then, at least, when the measurement container 12a is arranged between the laser light emitting unit 12e and the laser light receiving unit 12f of the laser measuring device 12d as described later, the side face facing the laser light emitting unit 12e and the laser light receiving unit 12f The opposing side surfaces may be made of a material having the same refractive index as the quartz glass thin tube 2. The inside of the measurement container 12a is filled with a liquid 12b having a refractive index equal to that of the quartz glass thin tube 2. This liquid 1
2b is generally called matching oil. A quartz glass thin tube 2 is movably inserted into a hole at the bottom of the measurement container 12a, and a ring-shaped tube 12c made of silicone rubber or the like for closing the hole in a watertight manner is attached. In the present invention, the refractive index equal to that of the quartz glass thin tube 2 indicates that the refractive index is within ± 1.0% based on the refractive index of the material of the quartz glass thin tube 2 at a wavelength of 0.589 μm. And

A laser measuring device 12d is provided outside the measuring container 12a. This laser measuring machine 1
2d has a laser emitting section 12e and a laser receiving section 12f facing the laser emitting section 12e. And as shown in FIG.
Laser light generated from the laser light emitting section 12e passes through the portion including the fine hole 2a of the quartz glass thin tube 2 inserted through the measuring container 12a through the measuring container 12a and the liquid 12b, and is transmitted to the laser receiving portion 12f. The measurement container 12a is disposed between the laser light emitting unit 12e and the laser light receiving unit 12f so as to receive light.

In the inner diameter measuring section 12, the measuring vessel 1
2a, the liquid 12b and the quartz glass thin tube 2 are made of quartz glass or those having the same refractive index as the quartz glass.
From the laser emitting unit 12e to the measurement container 12a
When the quartz glass thin tube 2 in the inside is irradiated with a laser beam, the inner diameter of the fine hole 2a (the inner diameter of the quartz glass thin tube 2) which is a cylindrical cavity in the quartz glass thin tube 2 can be measured. The wavelength of the laser beam at this time is usually 0.78 μm.
m. Specifically, for example, KL152E (product name) manufactured by Anritsu Corporation can be suitably used as the laser measuring device 12d.

The position of the inner diameter measuring section 12 is located below the heating furnace 11 and in a state where the temperature of the quartz glass thin tube 2 coming out of the heating furnace 11 is high and the molding is possible. The measuring position of the inner diameter of the quartz glass thin tube 2 can be adjusted by changing the distance between the heating furnace 11 and the inner diameter measuring unit 12, the arrangement positions of the laser emitting unit 12e and the laser receiving unit 12f, and the like.

The wiping device 13 is for wiping liquid adhering to the surface of the quartz glass thin tube 2 after passing through the inner diameter measuring section 12, and for example, a felt, an air wiper or the like is used.

A method of manufacturing a ferrule using the apparatus having such a configuration will be described. First, a quartz glass tube 1 as a starting base material is prepared. As the quartz glass tube 1, a tube made of pure quartz, a tube obtained by adding an appropriate additive to quartz (a quartz glass mainly containing quartz), or the like can be used. Then, the quartz glass tube 1 is inserted vertically into the heating furnace 11 and is melted and drawn to reduce the diameter. Since the ratio between the outer diameter and the inner diameter of the quartz glass thin tube 2 thus obtained basically depends on the ratio between the outer diameter and the inner diameter of the pipe-shaped base material (quartz glass tube) 1, for example, Diameter 2.5mm ± 0.001mm, inner diameter 125 (~ 12
6) When manufacturing a ferrule of μm, the inner diameter is 3 m.
m, quartz glass tube 1 with outer diameter 60mm ± 0.024mm
Can be suitably used.

Subsequently, the quartz glass capillary 2 coming out of the heating furnace 11 is introduced into the inner diameter measuring section 12 while the temperature is high, the inner diameter is measured, and the caterpillar 14 is measured based on the measured value of the inner diameter. Is adjusted so that the measured value of the inner diameter of the quartz glass thin tube 2 becomes a desired value.
At this time, control means for adjusting and controlling the drawing speed of the caterpillar 14 based on the measured value of the inner diameter may be provided.

After adjusting the inner diameter of the quartz glass thin tube 2,
The quartz glass thin tube 2 is introduced into the wiping device 13 from the inner diameter measuring unit 12 and passed therethrough to remove the liquid adhering to the surface. And the silica glass thin tube 2
After cooling down to the inside, this is cut into a predetermined length of ferrule 3 by a cutting device (not shown), and the outer surface is ground using a grinder or the like to adjust its outer diameter, roundness, and eccentricity. Then, an appropriate process such as chamfering the tip portion is performed to obtain a target cylindrical ferrule 3. Here, the length when cutting the quartz glass thin tube 2 is usually a length obtained by adding an appropriate length for polishing the end face to the length of the ferrule 3 to be obtained. The operation of grinding the outer surface can be omitted or simplified if the desired outer diameter, roundness, eccentricity, and the like are obtained at the time of cutting the quartz glass thin tube 2. Since the inner diameter of the ferrule 3 thus obtained is adjusted at the time of manufacture,
It has a desired inner diameter.

In the above-described manufacturing method, the inner diameter of the quartz glass thin tube 2 is measured at the time of melting drawing, and the drawing speed is adjusted based on the measured value so that a desired inner diameter can be obtained. Since the outer diameter, roundness, and eccentricity are adjusted by grinding the surface, the dimensional control of the quartz glass ferrule 3 is easy, and the product yield can be improved.

Further, for example, the ferrule is housed in a housing for a plug or the like and incorporated in an optical connector. At this time, the ferrule is fixed to the ferrule hold, and the ferrule hold is fixed to a predetermined position in the plug housing of the optical fiber connector. Therefore, when the thin silica glass tube is cut and its outer surface is ground to form a ferrule, if the outer surface is processed as shown in FIGS. 3 and 4, for example, the ferrule can be fixed more firmly. be able to.

FIGS. 3 and 4 are partial cross-sectional views in the axial direction showing examples of the shape of the ferrule, respectively, showing a state in which the ferrule is fixed to a ferrule hold.

In FIG. 3, reference numeral 23 denotes a ferrule, 2
4 is a ferrule hold, 20a is an optical fiber core. The optical fiber core 20a has a coating layer 20b at the tip thereof.
Is removed, and the bare optical fiber 20c is exposed.
A front end 23a of the ferrule 23 is chamfered and processed into a tapered shape, and a ring-shaped groove 23c having a width of about 1 mm and a depth of about 1 mm is provided on an outer surface of a side surface on a rear end 23b side. At the center of the ferrule 23, a fine hole into which the bare optical fiber 20c is inserted and fixed is provided.

On the other hand, in the center of the ferrule hold 24, there is provided a through hole 24a into which the optical fiber core 20a is inserted from the rear end side of the ferrule hold 24, and the coating layer portion of the optical fiber core 20a is fixed. ing. The through-hole 24a has a large-diameter portion 24b whose diameter is enlarged on the distal end side.
The rear end 23b side is inserted and fixed. A ring-shaped protrusion 24c corresponding to the groove 23c provided in the ferrule 23 is provided on the inner wall of the large diameter portion 24b.

That is, the coating layer portion on the tip side of the optical fiber core wire 20a is fixed to the through hole 24a of the ferrule hold 24, and the bare optical fiber 20c extending from this coating layer portion is inserted into the fine hole in the ferrule 23. At the rear end 23 of the ferrule 23.
The b side is a large diameter portion 2 provided in the ferrule hold 24.
4b, the groove 23c provided in the ferrule 23 is incorporated into the ring-shaped protrusion 24c provided on the inner wall of the large-diameter portion 24b so that the ferrule 23 and the ferrule hold 24 are firmly fixed. Has become.

As shown in FIG. 4, a ring-shaped protrusion 33c is provided at the end of the rear end 33b of the ferrule 33 so as to protrude in a direction perpendicular to the axis thereof, and corresponds to the ring-shaped protrusion 33c. As described above, the ferrule hold 34 may be configured such that the large diameter portion 34b of the through hole 34a is provided with the groove 34c. That is, when inserting and fixing the rear end portion 33b of the ferrule 33 to the large diameter portion 34b of the ferrule hold 34, the ring-shaped protrusion provided on the ferrule 33 is formed in the groove 34c provided on the inner wall of the large diameter portion 34b of the ferrule hold 34. The part 33c is incorporated so that the ferrule 33 and the ferrule hold 34 are firmly fixed. In this example, the outer diameter a of the ferrule 33 main body is 2500 μm, the outer diameter b including the ring-shaped protrusion 33c is about 2600 μm, and the width c of the ring-shaped protrusion 33c is about 1 mm.

The ferrule hold 24 shown in FIGS.
The material 34 is preferably a plastic because it can enhance the adhesion to the ferrules 23 and 33 made of hard quartz glass. Specifically, a polycarbonate liquid crystal polymer or the like is preferable because of good moldability and dimensional stability. In addition, the operation of providing a ring-shaped protrusion or groove on the outer surface of the ferrule can be performed simultaneously when cutting the quartz glass thin tube and grinding the outer surface to adjust the outer diameter, etc. Does not increase.

In the above-described example, a single-core ferrule has been described as an example. However, the shape of the ferrule is not limited to this, and the method and apparatus of the present invention include:
The present invention can be applied to a ferrule having any shape as long as it is manufactured by melting and drawing a pipe-shaped base material made of quartz glass.

[0031]

As described above, in the present invention,
The inner diameter of the quartz glass thin tube is measured at the time of melting drawing, and the drawing speed can be adjusted based on the measured value to obtain a desired inner diameter. For this reason, precise dimensional control of the inner diameter of the quartz glass ferrule, which has been considered difficult in the past, becomes possible, and a quartz glass ferrule excellent in wear resistance, chemical resistance, ultraviolet resistance, radiation resistance, It can be provided with high product yield. In addition, since the quartz glass ferrule has the same material properties as the optical fiber, the optical fiber and the quartz glass ferrule can be polished at the same time using the same abrasive at the time of the end face treatment, and the linear expansion coefficient can be increased. Therefore, it is difficult for the optical fiber to protrude or retract due to a change in the use environment temperature of the connector.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a manufacturing apparatus for a ferrule made of quartz-based glass of the present invention.

FIG. 2 is a schematic diagram showing a state in which an inner diameter measuring section of the quartz glass ferrule manufacturing apparatus shown in FIG. 1 is viewed from above.

FIG. 3 is a partial cross-sectional view taken along an axis showing an example of a ferrule obtained in the present invention and a ferrule hold corresponding thereto.

FIG. 4 is a partial cross-sectional view taken along an axis showing another example of a ferrule obtained in the present invention and a ferrule hold corresponding thereto.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Quartz glass tube (pipe-shaped base material), 2 ... Quartz glass thin tube, 3 ... Quartz glass ferrule, 11 ... Heating furnace (drawing means), 12 ... Inner diameter measuring part (inner diameter measuring means), 1
2a: measuring container, 12b: liquid, 12d: laser measuring machine, 14: caterpillar (drawing means).

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Tsumanuma 1440 Mutsuzaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Plant (72) Inventor Yoshiaki Takeuchi 3-19-2 Nishishinjuku, Shinjuku-ku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Inside (72) Inventor Ryo Nagase 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation Inside (72) Inventor Shigeyuki Mitachi 3-2-1-2, Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph Telephone Co., Ltd.

Claims (5)

[Claims] 1. A pipe-shaped base material made of quartz glass,
A method for manufacturing a quartz glass-based ferrule, wherein a molten glass is drawn by adjusting the drawing speed based on the measured value of the inner diameter to form a quartz-based glass thin tube. 2. A pipe-shaped base material made of quartz glass,
Manufacturing a quartz-based glass ferrule, characterized in that, after adjusting the drawing speed based on the measured value of the inner diameter, melting and drawing into a quartz-based glass thin tube, the outer surface of the quartz-glass thin tube is ground. Method. 3. The method of manufacturing a ferrule made of quartz glass according to claim 1 or 2, wherein a refractive index equal to the quartz glass thin tube is placed in a measuring container made of a material having a refractive index equal to the quartz glass thin tube. Filled with a liquid having the same, a quartz glass thin tube is inserted into the measuring container, and the quartz glass thin tube is irradiated with laser light from outside the measuring container via the measuring container and the liquid to form a quartz glass. A method for manufacturing a ferrule made of quartz glass, comprising measuring an inner diameter of a thin tube. 4. A quartz-based glass having a drawing means for melting and drawing a pipe-shaped base material made of a quartz-based glass into a quartz-based glass thin tube, and a means for measuring the inner diameter of the quartz-based glass thin tube. Ferrule manufacturing equipment. 5. The measuring apparatus according to claim 1, wherein the inner diameter measuring means includes a measuring container made of a material having a refractive index equal to that of the quartz glass thin tube, and a liquid filled in the measuring container having a refractive index equal to the quartz glass thin tube. A laser measuring device that irradiates a laser beam to the quartz glass thin tube inserted into the measurement container through the measurement container and the liquid from outside the measurement container to measure the inner diameter of the quartz glass thin tube. 5. The apparatus for manufacturing a ferrule made of quartz-based glass according to claim 4, comprising: