JP5557866B2 - Heater for heating optical fiber base material - Google Patents

Heater for heating optical fiber base material Download PDF

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JP5557866B2
JP5557866B2 JP2012078556A JP2012078556A JP5557866B2 JP 5557866 B2 JP5557866 B2 JP 5557866B2 JP 2012078556 A JP2012078556 A JP 2012078556A JP 2012078556 A JP2012078556 A JP 2012078556A JP 5557866 B2 JP5557866 B2 JP 5557866B2
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heat generating
connection
optical fiber
heater
fiber preform
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JP2013209225A (en
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宗久 藤巻
数成 斉藤
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Fujikura Ltd
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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
    • C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
    • C03B37/029—Furnaces therefor
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2205/00—Fibre drawing or extruding details
    • C03B2205/60—Optical fibre draw furnaces
    • C03B2205/62—Heating means for drawing
    • C03B2205/63—Ohmic resistance heaters, e.g. carbon or graphite resistance heaters

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacture, Treatment Of Glass Fibers (AREA)

Description

本発明は、光ファイバ母材を加熱して光ファイバの紡糸を行う紡糸炉や、光ファイバ母材を細径化する延伸炉に使用できる光ファイバ母材加熱用ヒータに関する。   The present invention relates to an optical fiber preform heating heater that can be used in a spinning furnace for spinning an optical fiber by heating an optical fiber preform and a drawing furnace for reducing the diameter of an optical fiber preform.

図９は、光ファイバ母材加熱用ヒータの一例を示すもので、ここに示すヒータ３０は、概略円筒状の発熱部１と、電極（図示略）に接続された一対の給電部２と、発熱部１と給電部２とを接続する接続部３３とを備えている（特許文献１参照）。
発熱部１には、周方向に所定間隔ごとにスリット４が形成されている。スリット４は、発熱部１の上端から下端近くまで切り込まれたスリット４Ａと、発熱部１の下端から上端近くまで切り込まれたスリット４Ｂとを有する。
スリット４Ａ、４Ｂは、発熱部１の周方向に交互に形成されているため、発熱部１は、直線部５と折返し部６とが繰返される蛇行構造となっている。 FIG. 9 shows an example of a heater for heating an optical fiber preform. A heater 30 shown here includes a substantially cylindrical heat generating portion 1, a pair of power feeding portions 2 connected to electrodes (not shown), A connecting portion 33 that connects the heat generating portion 1 and the power feeding portion 2 is provided (see Patent Document 1).
In the heat generating portion 1, slits 4 are formed at predetermined intervals in the circumferential direction. The slit 4 has a slit 4A cut from the upper end of the heat generating unit 1 to near the lower end, and a slit 4B cut from the lower end of the heat generating unit 1 to near the upper end.
Since the slits 4A and 4B are alternately formed in the circumferential direction of the heat generating portion 1, the heat generating portion 1 has a meandering structure in which the straight portion 5 and the folded portion 6 are repeated.

給電部２、２は、発熱部１の径方向外方に延出する板状とされ、発熱部１の中心軸Ｃ１に対して互いに回転対称となる位置に形成されている。給電部２は、接続部３３を介して発熱部１に給電できる。
接続部３３、３３は、発熱部１の下端から下方に延出し、それぞれ給電部２の径方向内方の端部２ａに達しており、互いに回転対称となる位置にある。 The power feeding units 2 and 2 have a plate shape extending outward in the radial direction of the heat generating unit 1, and are formed at positions that are rotationally symmetric with respect to the central axis C <b> 1 of the heat generating unit 1. The power supply unit 2 can supply power to the heat generating unit 1 via the connection unit 33.
The connecting portions 33, 33 extend downward from the lower end of the heat generating portion 1, reach the radially inner end 2 a of the power feeding portion 2, and are in positions that are rotationally symmetric with each other.

光ファイバ母材を発熱部１内に導入するとともに、給電部２からの給電により発熱部１を発熱させると、光ファイバ母材は加熱により軟化し、線引き等が可能となる。   When the optical fiber preform is introduced into the heat generating portion 1 and the heat generating portion 1 is heated by power feeding from the power feeding portion 2, the optical fiber preform is softened by heating, and drawing or the like becomes possible.

特開平８−１１９６６２号公報JP-A-8-119662

図１０に示すように、光ファイバ母材加熱用ヒータ３０では、発熱部１は高温となって熱膨張するが、その際、給電部２および接続部３３の位置は変化しない。
そのため、発熱の際に、接続部３３が形成された箇所での発熱部１の径は変化しない一方、接続部３３から離れた箇所での発熱部１の径は大きくなり、その結果、発熱部１の平面視形状が真円形（図１０（ａ）参照）から、非円形（楕円形）（図１０（ｂ）参照）となるおそれがあった。
発熱部１が非円形化すると、光ファイバ母材に対する距離が周方向に均一でなくなる結果、加熱温度が不均一となり、光ファイバが非円形となり、光ファイバの特性、例えば偏波モード分散（ＰＭＤ）等に影響が及ぶ可能性がある。
近年では、光ファイバ母材の大型化・太径化に対応して、径が大きい発熱部１が用いられるため、前述の発熱部１の非円化による加熱特性の不均一化が起こりやすくなっていた。
本発明は、上記事情に鑑みてなされたもので、発熱部に非円化が生じない光ファイバ母材加熱用ヒータを提供することを目的とする。 As shown in FIG. 10, in the optical fiber preform heating heater 30, the heat generating portion 1 becomes hot and thermally expands, but at that time, the positions of the power feeding portion 2 and the connecting portion 33 do not change.
Therefore, when heat is generated, the diameter of the heat generating portion 1 at the location where the connecting portion 33 is formed does not change, while the diameter of the heat generating portion 1 at the location away from the connecting portion 33 is increased, and as a result, the heat generating portion. There is a possibility that the shape of the plan view of 1 is changed from a perfect circle (see FIG. 10A) to a non-circular shape (ellipse) (see FIG. 10B).
When the heat generating portion 1 is made non-circular, the distance to the optical fiber preform becomes non-uniform in the circumferential direction. As a result, the heating temperature becomes non-uniform, the optical fiber becomes non-circular, and characteristics of the optical fiber, such as polarization mode dispersion (PMD) ) May be affected.
In recent years, since the heat generating part 1 having a large diameter is used in response to the increase in size and diameter of the optical fiber preform, the heating characteristics are likely to be non-uniform due to the non-circularization of the heat generating part 1 described above. It was.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a heater for heating an optical fiber base material that does not cause non-circularity in a heat generating portion.

本発明は、光ファイバ母材が導入される円筒状の発熱部と、前記発熱部に給電する２つの給電部と、前記発熱部と前記給電部とを連結する接続部と、を備え、前記発熱部に対する前記接続部の接続箇所である第１接続箇所と、前記給電部に対する前記接続部の接続箇所である第２接続箇所とは、前記発熱部の周方向の位置が互いに異なり、前記接続部は、前記第１接続箇所から前記第２接続箇所にかけて延在して形成された延在部を有し、前記延在部は、前記第１接続箇所と前記第２接続箇所との間で、平面視において前記発熱部の周方向に沿って形成され、前記第１接続箇所が前記発熱部の中心軸から離間する方向の弾性的な曲げ変形が可能である光ファイバ母材加熱用ヒータを提供する。
前記第１接続箇所に対する前記第２接続箇所の前記周方向の角度は、４５度以上、１８０度以下であることが好ましい。
前記延在部は、前記発熱部に比べて電気抵抗が小さいことが好ましい。
前記延在部は、発熱部の径方向の寸法が、発熱部の中心軸方向の寸法より小さいことが好ましい。
The present invention comprises a cylindrical heat generating part into which an optical fiber preform is introduced, two power supplying parts for supplying power to the heat generating part, and a connecting part for connecting the heat generating part and the power supplying part, The first connection location that is the connection location of the connection portion with respect to the heat generating portion and the second connection location that is the connection location of the connection portion with respect to the power feeding portion are different from each other in the circumferential position of the heat generation portion. The portion has an extending portion formed to extend from the first connecting location to the second connecting location, and the extending portion is between the first connecting location and the second connecting location. An optical fiber preform heating heater that is formed along a circumferential direction of the heat generating portion in a plan view and is capable of elastic bending deformation in a direction in which the first connection portion is separated from the central axis of the heat generating portion. provide.
The circumferential angle of the second connection location with respect to the first connection location is preferably 45 degrees or more and 180 degrees or less.
The extending part preferably has a smaller electrical resistance than the heat generating part.
The extension part preferably has a radial dimension of the heat generating part smaller than a dimension of the heat generating part in the central axis direction.

本発明によれば、第１接続箇所と第２接続箇所との周方向の位置が異なるため、接続部は十分な長さを有し、第１接続箇所が外方移動する方向に容易に変形する。このため、温度上昇時において、発熱部には移動規制は加えられず、発熱部は真円形を保ったまま径が大きくなる。
発熱部の非円化が生じないため、光ファイバ母材に対する発熱部の距離は周方向に均一となり、均一な加熱が可能となる。
従って、光ファイバの非円率を小さくでき、光ファイバの特性（偏波モード分散（ＰＭＤ）等）の悪化を防ぐことができる。 According to the present invention, since the circumferential positions of the first connection location and the second connection location are different, the connection portion has a sufficient length and is easily deformed in the direction in which the first connection location moves outward. To do. For this reason, when the temperature rises, no movement restriction is applied to the heat generating portion, and the diameter of the heat generating portion increases while maintaining a true circle.
Since the non-circularization of the heat generating portion does not occur, the distance of the heat generating portion with respect to the optical fiber preform is uniform in the circumferential direction, and uniform heating is possible.
Therefore, the non-circularity of the optical fiber can be reduced, and deterioration of the optical fiber characteristics (polarization mode dispersion (PMD), etc.) can be prevented.

本発明の光ファイバ母材加熱用ヒータの第１実施形態を示す斜視図である。1 is a perspective view showing a first embodiment of a heater for heating an optical fiber preform of the present invention. 図１の光ファイバ母材加熱用ヒータの延長部を示す断面図である。It is sectional drawing which shows the extension part of the heater for optical fiber preform | base_material heating of FIG. 図１の光ファイバ母材加熱用ヒータを模式的に示す平面図である。It is a top view which shows typically the heater for optical fiber preform | base_material heating of FIG. 図１の光ファイバ母材加熱用ヒータの高温時の状態を示す模式図である。It is a schematic diagram which shows the state at the time of high temperature of the heater for optical fiber preform | base_material heating of FIG. 本発明の光ファイバ母材加熱用ヒータの第２実施形態を示す平面図である。It is a top view which shows 2nd Embodiment of the heater for optical fiber preform | base_material heating of this invention. 実施例のヒータ内の温度分布を示す図である。It is a figure which shows the temperature distribution in the heater of an Example. 実施例のヒータ内の温度分布を示す図である。It is a figure which shows the temperature distribution in the heater of an Example. 比較例のヒータ内の温度分布を示す図である。It is a figure which shows the temperature distribution in the heater of a comparative example. 従来の光ファイバ母材加熱用ヒータを示す斜視図である。It is a perspective view which shows the conventional heater for optical fiber preform | base_material heating. （ａ）前図の光ファイバ母材加熱用ヒータを模式的に示す平面図である。（ｂ）前図の光ファイバ母材加熱用ヒータの高温時の状態を示す模式図である。(A) It is a top view which shows typically the heater for optical fiber preform | base_material heating of a previous figure. (B) It is a schematic diagram which shows the state at the time of the high temperature of the heater for optical fiber preform | base_material heating of a front figure.

以下、本発明の光ファイバ母材加熱用ヒータの実施形態を詳しく説明する。
＜第１実施形態＞
図１は、本発明の光ファイバ母材加熱用ヒータ（以下、単にヒータということがある）の第１実施形態であるヒータ１０を示す斜視図である。図２は、接続部３の延長部８の断面図である。図３は、このヒータ１０を模式的に示す平面図である。
図１に示すように、ヒータ１０は、概略円筒状の発熱部１と、一対の給電部２、２と、これら発熱部１と給電部２とをそれぞれ接続する一対の接続部３、３とを備えている。
以下の説明において、「上」および「下」とは図１における上および下であり、発熱部１の中心軸Ｃ１に沿う方向である。また、周方向とは発熱部１の周方向である。 Hereinafter, embodiments of the heater for heating an optical fiber preform of the present invention will be described in detail.
<First Embodiment>
FIG. 1 is a perspective view showing a heater 10 which is a first embodiment of a heater for heating an optical fiber preform (hereinafter simply referred to as a heater) according to the present invention. FIG. 2 is a cross-sectional view of the extension portion 8 of the connection portion 3. FIG. 3 is a plan view schematically showing the heater 10.
As shown in FIG. 1, the heater 10 includes a substantially cylindrical heat generating portion 1, a pair of power feeding portions 2, 2, and a pair of connecting portions 3, 3 that connect the heat generating portion 1 and the power feeding portion 2, respectively. It has.
In the following description, “upper” and “lower” are the upper and lower in FIG. 1 and are directions along the central axis C1 of the heat generating portion 1. Further, the circumferential direction is the circumferential direction of the heat generating portion 1.

発熱部１は、例えば導電性のカーボン材料からなり、抵抗値を大きくして発熱量を多くするために、周方向に所定間隔ごとにスリット４が形成されている。
スリット４は、発熱部１の上端から下方に向けて下端近くまで切り込まれたスリット４Ａと、発熱部１の下端から上方に向けて上端近くまで切り込まれたスリット４Ｂとを有する。
スリット４Ａ、４Ｂは、発熱部１の周方向に交互に形成されているため、発熱部１は、上下方向に直線的に延在する直線部５と、折返し部６とが繰返される蛇行構造となっている。
具体的には、発熱部１では、直線部５A下端と、これに隣接する直線部５B下端とが折返し部６Aにより連結され、直線部５B上端と、これに隣接する直線部５C上端とが折返し部６Bにより連結される構造が周方向に繰り返されている。
直線部５および折返し部６の断面形状は特に限定されないが、例えば矩形とすることができる。 The heat generating portion 1 is made of, for example, a conductive carbon material, and slits 4 are formed at predetermined intervals in the circumferential direction in order to increase the resistance value and increase the heat generation amount.
The slit 4 has a slit 4A cut from the upper end of the heat generating part 1 downward to near the lower end and a slit 4B cut from the lower end of the heat generating part 1 upward to near the upper end.
Since the slits 4A and 4B are alternately formed in the circumferential direction of the heat generating portion 1, the heat generating portion 1 has a meandering structure in which a straight portion 5 linearly extending in the vertical direction and a folded portion 6 are repeated. It has become.
Specifically, in the heat generating portion 1, the lower end of the straight portion 5A and the lower end of the straight portion 5B adjacent thereto are connected by the turn-up portion 6A, and the upper end of the straight portion 5B and the upper end of the straight portion 5C adjacent thereto are turned up. The structure connected by the part 6B is repeated in the circumferential direction.
Although the cross-sectional shape of the straight part 5 and the folding | returning part 6 is not specifically limited, For example, it can be set as a rectangle.

給電部２、２は、例えば導電性のカーボン材料からなり、平面視において発熱部１の径方向外方に延出する板状とされ、互いに周方向の位置を違えて設けられている。図示例の給電部２、２は、発熱部１の中心軸Ｃ１に対して互いに回転対称となる位置に形成されている。
給電部２は電極（図示略）に接続されており、接続部３を介して発熱部１に給電できる。
給電部２の数は、３以上の任意の数としてよく、これらのうち少なくとも２つは周方向に位置を違えて設けられる。 The power feeding units 2 and 2 are made of, for example, a conductive carbon material, have a plate shape extending outward in the radial direction of the heat generating unit 1 in a plan view, and are provided at different positions in the circumferential direction. The power feeding units 2 and 2 in the illustrated example are formed at positions that are rotationally symmetric with respect to the central axis C1 of the heat generating unit 1.
The power supply unit 2 is connected to an electrode (not shown) and can supply power to the heat generating unit 1 via the connection unit 3.
The number of the power feeding units 2 may be an arbitrary number of 3 or more, and at least two of them are provided at different positions in the circumferential direction.

接続部３は、例えば導電性のカーボン材料からなり、発熱部１の下端から下方に延出する基部７と、基部７の下端７ｂから発熱部１の周方向に沿って延在する延長部８（延在部）とを有する。
基部７は、隣り合う２つの直線部５、５および折返し部６から下方に延出して形成されている。図示例の基部７は、直線部５、５および折返し部６を、厚さおよび幅を変えずにそのまま下方に延長した形状であって、発熱部１と一体に形成されている。
基部７の上端７ａは、発熱部１の下端に接続された第１接続箇所である。以下、上端７ａを第１接続箇所７ａということがある。 The connecting portion 3 is made of, for example, a conductive carbon material, and includes a base portion 7 that extends downward from the lower end of the heat generating portion 1 and an extension portion 8 that extends from the lower end 7 b of the base portion 7 along the circumferential direction of the heat generating portion 1. (Extending part).
The base portion 7 is formed to extend downward from two adjacent linear portions 5 and 5 and the folded portion 6. The base portion 7 in the illustrated example has a shape in which the straight portions 5 and 5 and the folded portion 6 are extended downward as they are without changing the thickness and width, and are formed integrally with the heat generating portion 1.
The upper end 7 a of the base portion 7 is a first connection location connected to the lower end of the heat generating portion 1. Hereinafter, the upper end 7a may be referred to as a first connection location 7a.

図１および図３に示すように、延長部８は、平面視において発熱部１の周方向に沿う円弧状に形成されている。
延長部８の一端８ａは、基部７の下端７ｂに対し一体に接合して形成されている。基部７は上下方向に沿う形状であるため、延長部８の一端８ａと、基部７の上端７ａ（第１接続箇所７ａ）との周方向の位置はほぼ同じである。
この例の延長部８では、平面視において内縁８ｃの径方向位置が発熱部１の外縁１ａの径方向位置にほぼ一致しており、発熱部１に対して外方に張り出して形成されている。 As shown in FIGS. 1 and 3, the extension portion 8 is formed in an arc shape along the circumferential direction of the heat generating portion 1 in plan view.
One end 8 a of the extension portion 8 is integrally joined to the lower end 7 b of the base portion 7. Since the base portion 7 has a shape along the vertical direction, the circumferential positions of the one end 8a of the extension portion 8 and the upper end 7a (first connection portion 7a) of the base portion 7 are substantially the same.
In the extension portion 8 of this example, the radial position of the inner edge 8 c substantially coincides with the radial position of the outer edge 1 a of the heat generating portion 1 in plan view, and is formed to project outward from the heat generating portion 1. .

延長部８の他端８ｂは、給電部２の径方向内方の端部２ａに一体に接続された第２接続箇所である。以下、他端８ｂを第２接続箇所８ｂということがある。
延長部８は、一端８ａが中心軸Ｃ１に対して接近および離間するような弾性的な曲げ方向の変形が可能である。このため、延長部８は、一端８ａが外方移動する方向の弾性変形が可能である（図３および図４を参照）。 The other end 8 b of the extension portion 8 is a second connection location that is integrally connected to the radially inner end portion 2 a of the power feeding portion 2. Hereinafter, the other end 8b may be referred to as a second connection location 8b.
The extension portion 8 can be deformed in an elastic bending direction such that one end 8a approaches and separates from the central axis C1. For this reason, the extension part 8 can be elastically deformed in the direction in which the one end 8a moves outward (see FIGS. 3 and 4).

図２に示すように、延長部８の横断面形状は矩形とすることができる。
延長部８は、発熱部１の径方向（図２の左右方向）の寸法Ｗ１を、高さ方向（図２の上下方向。中心軸Ｃ１方向）の寸法Ｈ１より小さくすると、前述の曲げ方向の変形が起こりやすくなるため好ましい。
この例の延長部８の横断面形状は矩形であるが、延長部８の横断面形状はこれに限らず、多角形（台形等）、円形、楕円形など、任意としてよい。
なお、接続部３は、全長にわたって図２に示す形状であってもよい。 As shown in FIG. 2, the cross section of the extension 8 can be rectangular.
When the dimension W1 in the radial direction (left-right direction in FIG. 2) of the heating part 1 is made smaller than the dimension H1 in the height direction (vertical direction in FIG. 2, direction of the central axis C1), the extension part 8 This is preferable because deformation easily occurs.
The cross-sectional shape of the extension 8 in this example is a rectangle, but the cross-sectional shape of the extension 8 is not limited to this, and may be arbitrary, such as a polygon (such as a trapezoid), a circle, or an ellipse.
In addition, the shape shown in FIG. 2 may be sufficient as the connection part 3 over the full length.

接続部３は、少なくとも一部において、発熱部１よりも電気抵抗が小さいと、発熱が小さくなるため好ましい。
例えば、延長部８が発熱部１と同じ材料からなる場合には、延長部８の断面積（図２に示す横断面の面積）を発熱部１の直線部５および折返し部６の断面積（横断面の面積）より大きくすると、発熱部１に比べて電気抵抗が小さくなり、延長部８における発熱を小さくできる。
なお、接続部３は、全長にわたって発熱部１に比べて電気抵抗が小さくてもよい。 It is preferable that at least a part of the connecting portion 3 has an electric resistance smaller than that of the heat generating portion 1 because heat generation is reduced.
For example, when the extension portion 8 is made of the same material as the heat generating portion 1, the cross-sectional area of the extension portion 8 (area of the cross section shown in FIG. 2) is set to the cross-sectional area of the straight portion 5 and the folded portion 6 of the heat generating portion 1 If it is larger than the area of the cross section), the electric resistance is smaller than that of the heat generating portion 1, and the heat generation in the extension portion 8 can be reduced.
Note that the connecting portion 3 may have a smaller electrical resistance than the heat generating portion 1 over the entire length.

図１および図３に示すように、接続部３は、周方向に延在する延長部８を有するため、発熱部１側の第１接続箇所７ａと、給電部２側の第２接続箇所８ｂとの周方向の位置は互いに異なる。
図３に示すように、第１接続箇所７ａに対する第２接続箇所８ｂの周方向の角度θ１は４５度以上が好ましく、９０度以上がさらに好ましい。角度θ１をこの範囲とすることによって、延長部８に十分な長さを与え、後述する温度上昇時の変形を起こりやすくできるため、発熱部１の非円化を防ぐ効果を高めることができる。
角度θ１は、１８０度以下とすると、構造が複雑化してヒータ１０が大型化するのを避けることができる。 As shown in FIG. 1 and FIG. 3, since the connection part 3 has the extension part 8 extended in the circumferential direction, the 1st connection location 7a by the side of the heat generating part 1 and the 2nd connection location 8b by the side of the electric power feeding part 2 are included. The positions in the circumferential direction are different from each other.
As shown in FIG. 3, the angle θ1 in the circumferential direction of the second connection portion 8b with respect to the first connection portion 7a is preferably 45 degrees or more, and more preferably 90 degrees or more. By setting the angle θ1 within this range, the extension portion 8 can be given a sufficient length and can be easily deformed when the temperature rises to be described later, so that the effect of preventing the heat generating portion 1 from becoming non-circular can be enhanced.
If the angle θ1 is 180 degrees or less, it is possible to prevent the heater 10 from becoming large due to a complicated structure.

なお、第１接続箇所７ａと第２接続箇所８ｂとの周方向位置が異なるとは、第１接続箇所７ａに対する第２接続箇所８ｂの周方向の角度θ１が０度を越えることをいう。角度θ１は、３６０度またはその２以上の倍数であってもよい。   In addition, that the circumferential direction position of the 1st connection location 7a and the 2nd connection location 8b differs means that angle (theta) 1 of the circumferential direction of the 2nd connection location 8b with respect to the 1st connection location 7a exceeds 0 degree | times. The angle θ1 may be 360 degrees or a multiple of 2 or more.

延長部８は、周方向に沿って形成されているため、第２接続箇所８ｂが発熱部１に近接した位置にあることから、ヒータ１０の小型化を図ることができる。   Since the extension portion 8 is formed along the circumferential direction, the second connecting portion 8b is located in the vicinity of the heat generating portion 1, and thus the heater 10 can be reduced in size.

接続部３、３は、給電部２、２をそれぞれ発熱部１に接続している。
接続部３、３は、互いに周方向の位置を違えて設けられており、２つの第１接続箇所７ａ、７ａは互いに周方向位置が異なる。
図示例では、給電部２、２が、中心軸Ｃ１に対して互いに回転対称となる位置に形成されているため、接続部３、３も互いに回転対称となる位置に形成されている。このため、２つの第１接続箇所７ａ、７ａも互いに回転対称となる位置にある。
接続部３の数は、３以上の任意の数としてよく、これらのうち少なくとも２つは、第１接続箇所７ａが周方向に位置を違えるように形成される。 The connecting parts 3 and 3 connect the power feeding parts 2 and 2 to the heat generating part 1, respectively.
The connection parts 3 and 3 are provided in different positions in the circumferential direction, and the two first connection locations 7a and 7a have different circumferential positions.
In the illustrated example, since the power feeding portions 2 and 2 are formed at positions that are rotationally symmetric with respect to the central axis C1, the connection portions 3 and 3 are also formed at positions that are rotationally symmetric with respect to each other. For this reason, the two first connection locations 7a and 7a are also in positions that are rotationally symmetric to each other.
The number of the connecting portions 3 may be an arbitrary number of 3 or more, and at least two of them are formed so that the positions of the first connecting portions 7a are different in the circumferential direction.

次に、光ファイバ母材加熱用ヒータ１０を用いて、光ファイバ母材を加熱する方法について説明する。
光ファイバ母材としては、例えば石英ガラス製のものを例示できる。
図３および図４に示すように、光ファイバ母材Ｐ１を発熱部１内に導入するとともに、給電部２からの給電により発熱部１を発熱させる。発熱部１の温度は、例えば１５００℃以上、好ましくは２０００℃以上とすることができる。発熱部１による加熱によって光ファイバ母材は軟化し、線引きや細径化等が可能となる。 Next, a method for heating the optical fiber preform using the optical fiber preform heating heater 10 will be described.
An example of the optical fiber preform is made of quartz glass.
As shown in FIGS. 3 and 4, the optical fiber preform P <b> 1 is introduced into the heat generating unit 1, and the heat generating unit 1 is heated by power supply from the power supply unit 2. The temperature of the heat generating part 1 can be, for example, 1500 ° C. or higher, preferably 2000 ° C. or higher. The optical fiber preform is softened by heating by the heat generating unit 1, and drawing, thinning, and the like are possible.

図４に示すように、発熱部１が高温となると、発熱部１には、熱膨張によって径が大きくなる方向への力が働く。
上述のように、ヒータ１０では、第１接続箇所７ａと第２接続箇所８ｂとの周方向の位置が異なるため、延長部８は十分な長さを有し、一端８ａおよび第１接続箇所７ａが外方移動する方向に容易に弾性変形する。
このため、温度上昇時において、給電部２および第２接続箇所８ｂの位置は変化しないにもかかわらず、発熱部１には移動規制は加えられない。
よって、延長部８の一端８ａおよび第１接続箇所７ａが外方に変位するとともに、発熱部１は真円形を保ったまま径が大きくなる。
発熱部１の非円化が生じないため、光ファイバ母材Ｐ１に対する発熱部１の距離は周方向に均一となり、均一な加熱が可能となる。
従って、光ファイバの非円率（（長径−短径）／長径＊１００（％））を小さくでき、光ファイバの特性（偏波モード分散（ＰＭＤ）等）の悪化を防ぐことができる。 As shown in FIG. 4, when the heat generating portion 1 becomes high temperature, a force is applied to the heat generating portion 1 in a direction in which the diameter increases due to thermal expansion.
As described above, in the heater 10, since the circumferential positions of the first connection portion 7a and the second connection portion 8b are different, the extension portion 8 has a sufficient length, and the one end 8a and the first connection portion 7a. Is easily elastically deformed in the direction of outward movement.
For this reason, no movement restriction is applied to the heat generating portion 1 even though the positions of the power feeding portion 2 and the second connection portion 8b do not change when the temperature rises.
Therefore, the one end 8a of the extension 8 and the first connection portion 7a are displaced outward, and the diameter of the heat generating part 1 is increased while maintaining a perfect circle.
Since the non-circularization of the heat generating portion 1 does not occur, the distance of the heat generating portion 1 to the optical fiber preform P1 is uniform in the circumferential direction, and uniform heating is possible.
Therefore, the non-circularity ((major axis-minor axis) / major axis * 100 (%)) of the optical fiber can be reduced, and deterioration of the optical fiber characteristics (polarization mode dispersion (PMD), etc.) can be prevented.

図５は、本発明の第２実施形態であるヒータ２０は、接続部１３の延長部１８が平面視において直線的に延在して形成されている点で、図３等に示すヒータ１０と異なる。
延長部１８の一端１８ａは、基部７の下端７ｂに接合されており、一端１８ａと第１接続箇所７ａとの周方向の位置はほぼ同じである。延長部１８の他端１８ｂは、給電部２の端部２ａに接続された第２接続箇所である。
延長部１８は、第１接続箇所７ａにおける発熱部１の接線方向に沿う直線状とすることができる。
なお、第１接続箇所７ａと第２接続箇所１８ｂとの周方向の位置は互いに異なっていれば、延長部１８の延在方向は、発熱部１の接線方向に限定されない。 FIG. 5 shows a heater 20 according to the second embodiment of the present invention, in which the extension portion 18 of the connection portion 13 is formed so as to extend linearly in a plan view, and the heater 10 shown in FIG. Different.
One end 18a of the extension portion 18 is joined to the lower end 7b of the base portion 7, and the circumferential positions of the one end 18a and the first connection location 7a are substantially the same. The other end 18 b of the extension 18 is a second connection location connected to the end 2 a of the power feeding unit 2.
The extension part 18 can be made into the linear form along the tangent direction of the heat generating part 1 in the 1st connection location 7a.
In addition, if the position of the circumferential direction of the 1st connection location 7a and the 2nd connection location 18b mutually differs, the extending direction of the extension part 18 is not limited to the tangential direction of the heat generating part 1. FIG.

接続部１３は、延長部１８を有するため、第１接続箇所７ａと第２接続箇所１８ｂとの周方向の位置は互いに異なる。第１接続箇所７ａに対する第２接続箇所１８ｂの周方向の角度θ２は、４５度以上、１８０度以下が好ましい。   Since the connection part 13 has the extension part 18, the position of the circumferential direction of the 1st connection location 7a and the 2nd connection location 18b differs from each other. The angle θ2 in the circumferential direction of the second connection portion 18b with respect to the first connection portion 7a is preferably 45 degrees or more and 180 degrees or less.

ヒータ２０では、図３等に示すヒータ１０と同様に、接続部１３の第１接続箇所７ａと第２接続箇所１８ｂとの周方向の位置が異なるため、延長部１８は十分な長さを有し、一端１８ａおよび第１接続箇所７ａが外方移動する方向に容易に弾性変形する。
このため、高温時において発熱部１の非円化が生じず、光ファイバ母材に対する均一な加熱が可能となることから、光ファイバの特性の悪化を防ぐことができる。 In the heater 20, as in the heater 10 shown in FIG. 3 and the like, since the circumferential positions of the first connection portion 7 a and the second connection portion 18 b of the connection portion 13 are different, the extension portion 18 has a sufficient length. Then, the one end 18a and the first connection portion 7a are easily elastically deformed in the direction of outward movement.
For this reason, the non-circularization of the heat generating portion 1 does not occur at a high temperature, and the optical fiber preform can be uniformly heated, so that deterioration of the characteristics of the optical fiber can be prevented.

ヒータ２０では、延長部１８が直線状に形成されているため曲げ方向の変形が起こりやすい。このため、発熱部１の非円化を防ぐ効果の点で優れている。   In the heater 20, since the extension part 18 is formed in a straight line shape, deformation in the bending direction is likely to occur. For this reason, it is excellent in the point of the effect which prevents non-circularization of the heat generating part 1.

なお、発熱部１、給電部２および接続部３の構成材料としては導電性のカーボン材料を例示したが、前記構成材料は導電性であれば特に限定されず、例えば窒化珪素等のセラミクス材料であってもよい。また、発熱部１、給電部２および接続部３のうち１または２の少なくとも一部に、それ以外の構成とは異なる材料を使用してもよい。
また、図示例の接続部３は、第１接続箇所７ａを有する基部７と、基部７から第２接続箇所８ｂに至る延長部８とを有する構造であるが、第１接続箇所７ａから直接的に第２接続箇所８ｂに達する構造としてもよい。
例えば、接続部は、基部７がなく、延長部８（または延長部１８）が第１接続箇所７ａから第２接続箇所８ｂにわたって形成された構造であってもよい。
本発明は、光ファイバ母材を加熱して光ファイバの紡糸を行う紡糸炉や、光ファイバ母材を細径化する延伸炉に適用できる。 In addition, although the conductive carbon material was illustrated as a constituent material of the heat generating part 1, the electric power feeding part 2, and the connection part 3, if the said constituent material is electroconductive, it will not specifically limit, For example, ceramic materials, such as silicon nitride, are used. There may be. Moreover, you may use the material different from a structure other than that for at least one part of 1 or 2 among the heat generating parts 1, the electric power feeding part 2, and the connection part 3. FIG.
Moreover, although the connection part 3 of the example of illustration is a structure which has the base 7 which has the 1st connection location 7a, and the extension part 8 which extends from the base 7 to the 2nd connection location 8b, it is directly from the 1st connection location 7a. Alternatively, a structure reaching the second connection point 8b may be adopted.
For example, the connection part may have a structure in which the base part 7 is not provided and the extension part 8 (or the extension part 18) is formed from the first connection part 7a to the second connection part 8b.
The present invention can be applied to a spinning furnace for spinning an optical fiber by heating an optical fiber preform and a drawing furnace for reducing the diameter of an optical fiber preform.

（実施例１）
図１〜図３に示すヒータ１０を作製した。
発熱部１は、内径が２８０ｍｍであり、厚さ（直線部５および折返し部６の厚さ）が２０ｍｍであり、平均断面積（直線部５および折返し部６の平均断面積）が４００ｍｍ２であり、高さ１４０ｍｍである。
延長部８の断面積は８００ｍｍ２であり、第１接続箇所７ａに対する第２接続箇所８ｂの角度θ１は１６５度である。
カーボン材料製の管体（炉心管）（図示略）を発熱部１内に設置し、光ファイバ母材を導入していない状態で、発熱部１の温度を１３００℃としたときの内部の温度分布を調べた。温度の測定点は、発熱体１最上部を横切る面に沿う、発熱体１と同心の半径１００ｍｍの円上の各点とした。結果を図６に示す。図中「８ａ」は、延長部８の一端８ａの位置を示す。管体内部の周方向の温度の変動幅は±２℃程度であった。
前記管体内に光ファイバ母材（外径１８０ｍｍ。非円率０．０５％）を導入するとともに、発熱部１の温度を２２００℃として紡糸を行った結果、光ファイバの非円率は０．０８％であった。 Example 1
The heater 10 shown in FIGS. 1 to 3 was produced.
The heat generating portion 1 has an inner diameter of 280 mm, a thickness (thickness of the straight portion 5 and the folded portion 6) of 20 mm, and an average sectional area (average sectional area of the straight portion 5 and the folded portion 6) of 400 mm 2 . Yes, the height is 140 mm.
The cross-sectional area of the extension portion 8 is 800 mm 2 , and the angle θ1 of the second connection location 8b with respect to the first connection location 7a is 165 degrees.
An internal temperature when the temperature of the heat generating part 1 is 1300 ° C. in a state where a tube body (core tube) (not shown) made of carbon material is installed in the heat generating part 1 and the optical fiber preform is not introduced. The distribution was examined. The temperature measurement points were points on a circle having a radius of 100 mm concentric with the heating element 1 along the plane crossing the top of the heating element 1. The results are shown in FIG. “8a” in the drawing indicates the position of one end 8a of the extension 8. The fluctuation range of the temperature in the circumferential direction inside the tube was about ± 2 ° C.
As a result of introducing an optical fiber preform (outer diameter 180 mm, non-circularity 0.05%) into the tube and spinning at a temperature of the heat generating portion 1 of 2200 ° C., the non-circularity of the optical fiber is 0. It was 08%.

（実施例２）
第１接続箇所７ａに対する第２接続箇所８ｂの角度θ１が９０度であること以外は実施例１と同様のヒータ１０を使用して、実施例１と同様にして温度分布を測定した結果を図７に示す。管体内部の周方向の温度の変動幅は±３℃程度であった。
実施例１と同様にして紡糸を行って得た光ファイバの非円率は０．１１％であった。 (Example 2)
The results of measuring the temperature distribution in the same manner as in Example 1 using the same heater 10 as in Example 1 except that the angle θ1 of the second connection point 8b with respect to the first connection point 7a is 90 degrees are shown in FIG. 7 shows. The fluctuation range of the temperature in the circumferential direction inside the tube was about ± 3 ° C.
The non-circularity of the optical fiber obtained by spinning in the same manner as in Example 1 was 0.11%.

（比較例１）
図９および図１０に示すヒータ３０を作製した。実施例１と同様にして温度分布を測定した結果を図８に示す。管体内部の周方向の温度の変動幅は±１０℃程度であった。
給電部２（接続部３３）に相当する箇所と、そこから９０度離れた箇所との温度差は約１０℃であった。
実施例１と同様にして紡糸により得た光ファイバの非円率は約０．３％であった。 (Comparative Example 1)
The heater 30 shown in FIGS. 9 and 10 was produced. The results of measuring the temperature distribution in the same manner as in Example 1 are shown in FIG. The fluctuation range of the temperature in the circumferential direction inside the tube was about ± 10 ° C.
The temperature difference between a portion corresponding to the power feeding unit 2 (connecting unit 33) and a portion 90 degrees away therefrom was about 10 ° C.
The non-circularity of the optical fiber obtained by spinning in the same manner as in Example 1 was about 0.3%.

これらの結果より、実施例１、２のヒータは、発熱部１内の温度分布を均一にすることができ、その結果、非円率が低い光ファイバが得られたことがわかった。   From these results, it was found that the heaters of Examples 1 and 2 were able to make the temperature distribution in the heat generating portion 1 uniform, and as a result, an optical fiber having a low non-circularity was obtained.

１・・・発熱部、２・・・給電部、３・・・接続部、Ｃ１・・・中心軸Ｃ１、７・・・基部、７ａ・・・第１接続箇所、８、１８・・・延長部（延在部）、８ｂ・・・第２接続箇所、１０、２０・・・光ファイバ母材加熱用ヒータ、θ１、θ２・・・第１接続箇所に対する第２接続箇所の周方向角度。 DESCRIPTION OF SYMBOLS 1 ... Heat generating part, 2 ... Power feeding part, 3 ... Connection part, C1 ... Center axis C1, 7 ... Base part, 7a ... 1st connection location, 8, 18 ... Extension part (extension part), 8b ... 2nd connection location, 10, 20 ... Heater for optical fiber preform heating, θ1, θ2 ... Circumferential angle of the 2nd connection location with respect to the 1st connection location .

Claims (4)

光ファイバ母材が導入される円筒状の発熱部と、
前記発熱部に給電する２つの給電部と、
前記発熱部と前記給電部とを連結する接続部と、を備え、
前記発熱部に対する前記接続部の接続箇所である第１接続箇所と、前記給電部に対する前記接続部の接続箇所である第２接続箇所とは、前記発熱部の周方向の位置が互いに異なり、
前記接続部は、前記第１接続箇所から前記第２接続箇所にかけて延在して形成された延在部を有し、
前記延在部は、前記第１接続箇所と前記第２接続箇所との間で、平面視において前記発熱部の周方向に沿って形成され、前記第１接続箇所が前記発熱部の中心軸から離間する方向の弾性的な曲げ変形が可能であることを特徴とする光ファイバ母材加熱用ヒータ。 A cylindrical heat generating part into which the optical fiber preform is introduced;
Two power feeding sections feeding power to the heat generating section;
A connecting part for connecting the heat generating part and the power feeding part,
The first connection location that is the connection location of the connection portion with respect to the heat generating portion and the second connection location that is the connection location of the connection portion with respect to the power feeding portion are different from each other in the circumferential position of the heat generation portion.
The connection part has an extension part formed extending from the first connection part to the second connection part,
The extension portion is formed between the first connection location and the second connection location along a circumferential direction of the heat generating portion in a plan view, and the first connection location extends from a central axis of the heat generating portion. An optical fiber preform heating heater characterized by being capable of elastic bending deformation in a separating direction . 前記第１接続箇所に対する前記第２接続箇所の前記周方向の角度は、４５度以上、１８０度以下であることを特徴とする請求項１に記載の光ファイバ母材加熱用ヒータ。   2. The heater for heating an optical fiber preform according to claim 1, wherein an angle in the circumferential direction of the second connection portion with respect to the first connection portion is 45 degrees or more and 180 degrees or less. 前記延在部は、前記発熱部に比べて電気抵抗が小さいことを特徴とする請求項１または２に記載の光ファイバ母材加熱用ヒータ。 The heater for heating an optical fiber base material according to claim 1 or 2, wherein the extending portion has a smaller electric resistance than the heat generating portion. 前記延在部は、発熱部の径方向の寸法が、発熱部の中心軸方向の寸法より小さいことを特徴とする請求項１〜３のうちいずれか１項に記載の光ファイバ母材加熱用ヒータ。 The optical fiber preform for heating an optical fiber preform according to any one of claims 1 to 3, wherein the extending portion has a radial dimension of the heat generating portion smaller than a dimension in the central axis direction of the heat generating portion. heater.
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JP2561297Y2 (en) * 1992-12-29 1998-01-28 古河電気工業株式会社 Resistance heating element for electric furnace
JPH06227837A (en) * 1993-02-02 1994-08-16 Fujikura Ltd Heating oven for spinning optical fiber
JPH07206464A (en) * 1994-01-24 1995-08-08 Furukawa Electric Co Ltd:The Drawing and heating furnace for optical fiber
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