JP2004117656A - Method for selecting ferrule, and method for manufacturing optical connector plug - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ferrule selection method by which a low-loss ferrule can relatively easily be selected, and to provide a method for manufacturing an optical connector adapter. <P>SOLUTION: A 2nd ferrule is connected opposite to a 1st ferrule in which a core of an optical fiber is at a specified reference position and the 2nd ferrule is rotated on its axis to measure insertion loss; and the position in a reference direction where the insertion loss value is minimum is determined as an eccentricity reference direction and coordinates of an estimated position of the core 2 at each rotational position based upon the reference position as the center of coordinates is estimated while it is considered that the distance between the estimated position and coordinate center is correlated with the insertion loss value; and the center of rotation of the 2nd ferrule is calculated from the coordinates of the estimated position for each rotational position and the estimated position of the core 2 of the 2nd ferrule for the center of rotation is calculated as core position information. Then a ferrule is selected based upon a shift angle from the eccentricity reference direction of the core 2 of the 2nd ferrule and the quantity of a shift from the center of rotation which are calculated from the eccentricity reference direction and core position information. <P>COPYRIGHT: (C)2004,JPO

Description

【００４６】
表１に示すように、実施例１の換算値であるコア偏心量と、比較例１の実測値であるコア偏心量との差は、非常に小さいことが分かった。
【００４７】
したがって、逆に、上記式（１）を予め求めておけば、挿入損失値Ｌ_１〜Ｌ_４を求めることにより、実測値に近いコア偏心量を求めることができることが確認できた。
【００４８】
なお、上記式（１）のような換算式は、個々のアジャスト用フェルール７０を基準とした場合の相関関数であるため、基準として使用するアジャスト用フェルール毎に求める必要がある。
【００４９】
次に、図４に示す上述した方法で推定したフェルール４０のコア２位置座標
（Ｘ_１〜４，Ｙ_１〜４）と、アジャスト用フェルール７０のコア位置座標（Ｘ_０，Ｙ_０）から、軸ズレ量ｄ_１〜ｄ_４を求め、挿入損失値Ｌ_１〜Ｌ_４との関係を検証した。
【００５０】
ここで、軸ズレ量ｄと挿入損失値Ｌとの関係を示した下記式（２）が一般的に知られており、実測した各軸ズレ量ｄ_１〜ｄ_４を下記式（２）に代入すれば挿入損失値Ｌ_１′〜Ｌ_４′が算出できる。なお、本実施形態では、Ｌ_０＝４．３４（係数）、ω＝５．０μｍとした。
Ｌ＝Ｌ_０×（ｄ／ω）^２　　　　　　　（２）
Ｌ：挿入損失（ｄＢ）
Ｌ_０：軸ズレのみを考慮した場合の係数
ｄ：軸ズレ量（μｍ）
ω：モードフィールド半径（μｍ）
そして、挿入損失値Ｌ_１〜Ｌ_４（測定値）と、挿入損失値Ｌ_１′〜Ｌ_４′（推定値）とが相関関係を有しているか否かの検証を行った。その結果を図７に示す。なお、図７は、挿入損失値と軸ズレ量との関係を示すグラフである。
【００５１】
図７に示すように、挿入損失値Ｌ_１〜Ｌ_４（測定値）と挿入損失値Ｌ_１′〜Ｌ_４′（推定値）とは、非常に近い相関関係があることは明らかである。この結果、測定した挿入損失値Ｌ_１〜Ｌ_４（測定値）は、実際の各軸ズレ量ｄ_１〜ｄ_４と相関した値を示していることが検証でき、上述したフェルール４０の選別が有効であることが確認された。
【００５２】
また、図７に示すように、挿入損失値Ｌ_１〜Ｌ_４（測定値）と挿入損失値Ｌ_１′〜Ｌ_４′（推定値）とも非常に近い相関関係を示しているから、逆に、測定した挿入損失値Ｌ_１〜Ｌ_４（測定値）から直接、各軸ズレ量ｄ_１〜ｄ_４を推定できることも明らかである。したがって、このように推定した各軸ズレ量ｄ_１〜ｄ_４からは、コア偏心量及びコア偏心方向を数学的に算出でき、これを用いてフェルール４０の選別をすることができる。すなわち、測定した挿入損失値Ｌ_１〜Ｌ_４から軸ズレ量ｄ_１〜ｄ_４を推定し、これからコア偏心量及びコア偏心方向を算出することができ、これに基づいてフェルール４０の選別することができる。なお、この場合には、上記式（１）は不要となる。
【００５３】
以上説明したように、本実施形態では、アジャスト用フェルール７０とフェルール４０との光ファイバ１同士の各回転位置毎の挿入損失値Ｌ_１〜Ｌ_４からフェルール４０の回転中心とアジャスト用フェルール７０のコア座標（Ｘ_０、Ｙ_０）を基準としたコア座標とを特定し、且つこれら回転中心とコア座標とからコア偏心量及びコア偏心方向を求めるようにしたので、フェルール４０のコア位置の偏心基準方向Ａに対するズレ角が、例えば、９０°より小さい所定角度範囲のものを選別することができる。さらに、これに加えてコア偏心量が所定量以下のフェルール４０を選別することができる。これにより、低損失、例えば、０．１ｄＢ以下のフェルール４０の選別が可能となる。
【００５４】
ここで、フェルール４０の選別方法の具体例を挙げれば、例えば、９０°より小さい所定角度範囲をコア偏心量及びコア偏心方向の何れか一方により規定した範囲で選別してもよく、または、両者を適宜組み合わせて規定した範囲で選別してもよい。
【００５５】
また、コア偏心量やコア偏心方向が所定量より大きいもの同士を集めて低損失のフェルール４０のグループを作ることもできる。例えば、より低い挿入損失値Ｌのフェルール４０を選別するには、上述したフェルール４０の偏心基準方向Ａとコア偏心方向とのズレ角を小さく、例えば、６０°とすればよい。なお、実際には、低損失のフェルール４０を所定角度範囲毎にグループに分けし、同一のグループ同士のフェルール４０を組み合わせて使用するようにした。
【００５６】
このようなフェルール４０の選別は、フェルール４０のコア偏心量の相対値と実測値とは非常に近い相関が得られていることから、アジャスト用フェルール７０に対するフェルール４０の各回転位置毎の挿入損失値Ｌ_１〜Ｌ_４により求めた光ファイバ１のコア偏心量の相対値によって低損失のフェルール４０を選別することができる。
【００５７】
また、これらコア偏心量の相対値をアジャスト用フェルール毎に求めた相関関数、例えば、本実施形態では、上記式（１）で換算したコア偏心量の換算値から実際に近いコア位置情報を取得し、このコア位置情報に基づいてフェルール４０を選別してもよい。このコア位置情報は、実測値に近いものであるため、選別したフェルール４０の規格値として使用することができる。
【００５８】
このように、本実施形態のフェルール４０の選別方法では、従来の偏心方向位置合わせ工程、いわゆるアジャスト工程に準じて行うことができるので、工程数を増やすことなく低損失のフェルール４０を選別することができる。また、コア偏心測定装置等を用いてマスタ用のフェルール４０の選別していた工程も、本実施形態の選別方法に置き換えが可能となり、マスタ用のフェルール４０を選別する工程数を少なくできる。しかも、マスタ用のフェルール４０を選別するのは勿論のこと、従来のコア偏心測定器等に比べて安定したコア偏心量の算出が可能であるため、標準のフェルール４０の選別にも適用できる。したがって、マスタ用や標準用といったフェルール４０の用途に関係なく、０．１ｄＢ以下というマスタ並みの低い挿入損失のフェルール４０を選別できる。
【００５９】
また、上述したように、アジャスト用フェルール７０とフェルール４０とを光接続用スリーブ８０を介して光接続するようにしたので、コア偏心測定装置等で回転毎にＶ溝と押え部材との間にフェルール４０を固定する作業を省略できるため、作業性を向上できると共に、フェルール４０の端面にごみ等が付着することもない。これらのことから、比較的安定した挿入損失値を測定することができる。したがって、コア偏心量やコア偏心方向を測定する作業効率を向上でき、製造コストを低く抑えることができるという効果もある。
【００６０】
ここで、上述した方法により選別された低損失のフェルール４０は、その後、図８（ａ）に示すように、光ファイバ１のコア位置の偏心方向を示すキー溝４８のマーク（図示なし）を基準にしてプラグフレーム３０に嵌合させる。次に、このプラグフレーム３０の外周にプラグハウジング２０を嵌合する。これにより、図８（ｂ）に示すような光コネクタプラグ１０が完成する。
【００６１】
このように、本実施形態では、コア偏心の基準方向に対応するキー溝４８に基づいてフェルール４０をプラグフレーム３０へ位置決め固定して光コネクタプラグ１０を製造するようにしたので、この光コネクタプラグ１０を用いて対向接続させた際には、光ファイバ１のコア位置が略一致し、低損失での光接続を行うことができる。
【００６２】
また、上述したように、光ファイバ１のコアを所定量偏心させたアジャスト用フェルール７０を基準とした低損失のフェルール４０を選別し、且つ大量生産できるため、このフェルール４０を用いて光コネクタプラグ１０を製造することにより、常に安定した挿入損失での光接続が行える光コネクタプラグ１０を実現できる。
【００６３】
また、本実施形態の製造方法によれば、コア偏心測定装置等を用いて光ファイバのコア位置を画像処理により特定する工程を省略でき、且つマスタ並みの低い挿入損失での光接続が行えるフェルール４０を選別して光コネクタプラグ１０を製造できるため、光コネクタプラグ１０をマスタ用として製造する際の工程数を実質的に少なくできる。これにより、大幅なコストの削減を図ることができる。
【００６４】
さらに、マスタ用の光コネクタプラグの製造だけでなく、標準用の光コネクタプラグ１０の製造にも採用できるため、マスタ並の低損失の光コネクタプラグ１０を実現できる。
【００６５】
（他の実施形態）
以上、本発明の各実施形態を説明したが、フェルールの選別方法及び光コネクタプラグの製造方法の基本的構成は上述したものに限定されるものではない。
【００６６】
例えば、上述した実施形態１では、ＳＣ型の光コネクタプラグを例示したが、シングルモード（ＳＭ）の光ファイバ１を有する光コネクタプラグであれば限定されず、例えば、ＭＵ型、ＦＣ型又はＳＴ型等の光コネクタプラグであってもよい。
【００６７】
また、上述した実施形態１では、フェルール４０を９０°毎に回転した際の挿入損失値Ｌ_１〜Ｌ_４を測定したが、これに限定されず、フェルール４０を少なくとも３回、すなわち、１２０°毎に回転した際の挿入損失値を測定するようにしてもよい。
【００６８】
【発明の効果】
以上説明したように、本発明によれば、第１のフェルール（アジャスト用フェルール）のコア位置を座標中心とした各回転位置毎のコアの推定座標を、その推定座標と座標中心との距離が挿入損失値に相関するものとして推定し、コアの回転位置毎の推定座標から第２のフェルールの回転中心を算出すると共にその回転中心に対する第２のフェルールのコアの推定位置の座標をコア位置情報として算出するようにしたので、キー溝４８の偏心方向とコア位置情報とからコア偏心量及びコア偏心方向を算出できる。そして、これらコア偏心量及びコア偏心方向に基づいて低損失の第２のフェルールを比較的容易に選別することができる。
【図面の簡単な説明】
【図１】本発明の実施形態１に係る光コネクタプラグの分解斜視図である。
【図２】本発明の実施形態１に係るフェルールの概略図であって、（ａ）が斜視図であり、（ｂ）が断面図であり、（ｃ）が光ファイバの端面側の平面図である。
【図３】本発明の実施形態１に係るフェルールの選別方法を説明する図である。
【図４】本発明の実施形態１に係るフェルールの選別方法を説明する図である。
【図５】本発明の実施形態１に係るフェルールの選別方法を説明する図である。
【図６】コア偏心量（相対値）とコア偏心量（実測値）との関係を示す図である。
【図７】挿入損失値と軸ズレ量との関係を示すグラフである。
【図８】本発明の実施形態１に係る光コネクタプラグの製造方法を説明する図である。
【図９】本発明の実施形態１に係るフェルールの選別方法を説明する図である。
【符号の説明】
１　光ファイバ
２　コア
３　クラッド
４　回転中心
１０　光コネクタプラグ
２０　プラグハウジング
３０　プラグフレーム
４０　フェルール
４１　フェルール用筒状体
４２　つば部材
４８　キー溝
５０　ストップリング
６０　付勢ばね
７０　アジャスト用フェルール
８０　光接続用スリーブ
９０　光源
９１　光パワーメータ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for selecting a ferrule, which is a component on a plug side of an optical connector, and a method for manufacturing an optical connector plug.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, detachable optical connectors have been used for connection of optical fiber cables and optical fiber cords used for wiring in buildings and wiring to equipment, that is, for optical connection between optical fibers.
[0003]
Such an optical connector generally includes an optical connector plug to which a ferrule for inserting and holding an end of an optical fiber is fixed, and an optical connector adapter to which the optical connector plug is fitted from both sides facing each other. .
[0004]
The ferrule for inserting and holding the optical fiber is usually provided at the rear end of the ferrule cylindrical body having an optical fiber insertion hole formed of hard ceramic such as zirconia or glass, or the like, and the ferrule cylindrical body. And a brim member made of metal such as stainless steel, plastic, ceramics or the like having a hollow hole communicating with the rear end of the optical fiber insertion hole. Then, an optical fiber from which the coating of the tip of the optical fiber core has been removed is inserted into the optical fiber insertion hole provided inside the ferrule cylindrical body, and the optical fiber and the ferrule are bonded with, for example, an adhesive. Adhere and fix.
[0005]
In recent years, when the optical fibers of the above-described optical connector plug are connected to each other via an optical connector adapter, optical connection with relatively low insertion loss is desired.
[0006]
Here, the loss factors at the time of optical connection between optical fibers include, for example, axis shift, angle shift, gap, optical fiber end face quality, and end face reflection between optical fibers. It is generally known that the misalignment causes the largest insertion loss.
[0007]
For example, in the case of an optical connector plug having a single mode (SM) optical fiber, the axial displacement between the optical fibers is determined by the position of the center of the cross section with respect to the outer diameter of the ferrule cylindrical body which is a reference at the time of optical connection. This is caused by a positional deviation between the optical fiber and the core eccentricity of the optical fiber.
[0008]
For this reason, conventionally, in order to guarantee a low-loss optical connector plug, the core eccentricity of each optical connector plug is measured using a measuring device such as a core eccentricity measuring device or a core eccentricity measuring system, and the core eccentricity is measured. The amount of eccentricity is provided to the user as a standard value (see Non-Patent Documents 1 and 2).
[0009]
In such a core eccentricity measuring device, first, light is passed through the ferrule cylindrical body in a state where the ferrule cylindrical body is fixed between the V groove and the holding member, and the core position of the optical fiber is adjusted. Is enlarged by a lens and taken into an image processing apparatus. Next, the ferrule cylindrical body is removed from the V-groove, rotated by a predetermined angle, and fixed to the V-groove again, and the optical fiber core position is again enlarged by a lens and taken into the image processing apparatus. Usually, by performing such an operation four times and performing image processing on the core position of the optical fiber for each rotation using an image processing apparatus, the core position of the optical fiber is estimated, and the core position is determined from the core position. The eccentricity is measured.
[0010]
[Non-Patent Document 1]
NTT-AFTY, "Optical connector polished surface measuring device PSI-101 type", [online], [searched on August 27, 2002], Internet <URL: http // www. ntt-afri. co. jp / meka / si — 101. html>
[0011]
[Non-patent document 2]
NTT-AT, "Core eccentricity measurement system CENTROC", [online], [searched on August 27, 2002], Internet <URL: http: // www. keytech. ntt-at. co. jp / optic1 / prd_0028. html>
[0012]
[Problems to be solved by the invention]
However, in the above-described method of measuring the amount of core eccentricity, the workability is extremely poor because the ferrule cylindrical body is fixed and measured between the V-groove and the holding member at each rotation, and the workability is extremely poor. It is very troublesome to obtain a stable core eccentricity due to the attachment of dust and the like.
[0013]
That is, conventionally, in order to measure a stable core eccentricity, the core eccentricity is measured only when the core position for each rotation of the ferrule cylindrical body falls within a predetermined estimation range. However, as described above, it often happens that the core position for each rotation does not fall within the predetermined estimation range due to poor workability when measuring the core eccentricity. In such a case, the measurement must be repeatedly performed until the core position falls within the estimated range, and it takes a lot of time to measure a stable core eccentricity.
[0014]
Therefore, there is a problem that the work efficiency of measuring the core eccentricity is low, and the manufacturing cost is high. For this reason, there is a problem that even if it is cost-effective to select an expensive master ferrule, it is not economically profitable to select an inexpensive standard ferrule.
[0015]
As described above, since it takes time and effort to measure a stable core eccentricity, there is also a problem that it is relatively difficult to estimate the core position of the optical fiber.
[0016]
In view of such circumstances, it is an object of the present invention to provide a method of selecting a ferrule and a method of manufacturing an optical connector plug which can relatively easily select a low-loss ferrule.
[0017]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a ferrule including a ferrule tubular body for holding an optical fiber, and a ferrule fixed to the ferrule tubular body and capable of determining a plurality of reference directions. In the selection method, the second ferrule is connected to the first ferrule in which the core position of the optical fiber is at a predetermined reference position, and the second ferrule is rotated around its axis to rotate the plurality of reference ferrules. Measuring the insertion loss for each direction, determining the position of the reference direction in which the insertion loss value is the minimum as an eccentric reference direction, and a core for each rotation position with the reference position as the coordinate center. The second ferrule is estimated from the coordinates of the estimated position assuming that the distance between the estimated position and the coordinate center is proportional to the insertion loss value, and from the coordinates of the estimated position for each rotational position. Calculating a center of rotation and calculating an estimated position of the core of the second ferrule with respect to the center of rotation as core position information; and calculating a second ferrule calculated from the eccentricity reference direction and the core position information. A step of selecting based on a shift angle of the core with respect to the eccentricity reference direction and a shift amount from the rotation center.
[0018]
According to a second aspect of the present invention, in the first aspect, the coordinates of the estimated position of the core of the second ferrule are relatively determined from the reference position and the minimum value of the insertion loss value. There is a method of sorting ferrules.
[0019]
According to a third aspect of the present invention, in the first or second aspect, the second ferrule is selected in a predetermined angle range in which a shift amount of the core position of the second ferrule with respect to the reference direction is smaller than 90 °. In the method of sorting ferrules.
[0020]
A fourth aspect of the present invention is the ferrule according to any one of the first to third aspects, wherein the first ferrule and the second ferrule are optically connected to each other via an optical connection sleeve. In the sorting method.
[0021]
According to a fifth aspect of the present invention, there is provided a method for manufacturing an optical connector plug, comprising assembling using a ferrule selected by the ferrule selecting method according to any one of the first to fourth aspects.
[0022]
According to the present invention, the rotation center and the core coordinates of the second ferrule are specified from the insertion loss value at each rotation position between the optical fibers of the first ferrule (adjustment ferrule) and the second ferrule, and By determining the core eccentricity and the core eccentric direction from the rotation center and the core coordinates, it is possible to select the second ferrule having a deviation angle of the core position with respect to the reference direction within a predetermined angle range. In addition, the second ferrule having the core eccentricity equal to or less than the predetermined amount can be selected. Thus, it is possible to select the second ferrule having a low loss, for example, 0.1 dB or less.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments.
[0024]
(Embodiment 1)
FIG. 1 is an exploded perspective view of an optical connector plug according to Embodiment 1 of the present invention. FIG. 2 is a schematic view of a ferrule, where (a) is a perspective view and (b) is a cross-sectional view. FIG. 2C is a plan view of the end face side of the optical fiber.
[0025]
As shown in the figure, the optical connector plug 10 holds a plug housing 20 fitted in an SC type optical connector adapter, a plug frame 30 fitted in the plug housing 20, and an optical fiber 1 for optical connection. A ferrule 40 inserted from the rear of the plug frame 30, a stop ring 50 whose leading end engages with the rear end of the plug frame 30, and the ferrule 40 held between the ferrule 40 and the stop ring 50 in the axial direction. An urging spring 60 for urging toward the distal end side. In the present embodiment, the ferrule 40 includes a ferrule tubular body 41 that holds the optical fiber 1 and a collar member 42 fixed to one end of the ferrule tubular body 41.
[0026]
The ferrule cylindrical body 41 has a substantially cylindrical shape, and an optical fiber insertion hole 43 that penetrates in the axial direction and inserts and holds the optical fiber 1 is provided therein. At the rear end of the optical fiber insertion hole 43, a tapered portion 44 whose inner diameter gradually increases toward the opening side is provided. By providing such a tapered portion 44, when the optical fiber 1 is inserted into the optical fiber insertion hole 43, the tip of the optical fiber 1 comes into contact with the end face of the ferrule tubular body 41, so that it is chipped or broken. Can be prevented.
[0027]
Examples of the material of the ferrule cylindrical body 41 include a ceramic material such as zirconia, a plastic material, and a glass material such as crystallized glass, borosilicate glass, and quartz. The outer diameter of the ferrule cylindrical body 41 is 2.5 mm in the present embodiment.
[0028]
Here, the above-described optical fiber 1 is single mode (SM) in the present embodiment, and includes a core 2 of the optical fiber 1 and a clad 3 covering the core 2 as shown in FIG. It is configured. The opposing connection between the optical fibers 1 is performed by bringing the cores 2 into contact with each other.
[0029]
On the other hand, the collar member 42 has a fitting hole 45 into which one end of the ferrule cylindrical body 41 is fitted, and an optical fiber core insertion for inserting and holding the optical fiber core 4 coated on the outer periphery of the optical fiber 1. It has a hole 46 and a flange portion 47 provided on the outer periphery on the side where the fitting hole 45 is opened so as to protrude a predetermined amount in the radial direction in the circumferential direction.
[0030]
Further, the collar portion 47 is provided with four key grooves 48 at 90-intervals along the circumferential direction thereof so that the reference direction of the eccentricity of the core of the optical fiber 1 can be determined. Here, the reference direction of the eccentricity of the core of the optical fiber 1 is one direction indicating the position of the key groove 48 closest to the core 2 of the optical fiber 1 in the present embodiment.
[0031]
The number, position, depth, shape, and the like of the key grooves 48 are not particularly limited, and may be appropriately determined according to the plug frame 30 on which the ferrule 40 is positioned. Examples of the material of the collar member 42 include metal materials such as stainless steel, brass, and iron. In the present embodiment, stainless steel is used.
[0032]
Here, the assembly process of the above-described ferrule 40 will be described. First, the ferrule cylindrical body 41 is pressed into the fitting hole 45 of the collar member 42. Next, after passing the stop ring 50, the urging spring 60, and the like through the optical fiber 4, the optical fiber 1 from which the coating on the end of the optical fiber 4 has been removed is placed in the optical fiber insertion hole 43 with an adhesive ( (Not shown). At this time, the optical fiber 4 is also fixed in the optical fiber insertion hole 46 via an adhesive. Thereafter, the end face of the ferrule cylindrical body 41 is polished together with the end face of the optical fiber 1. Thus, the ferrule 40 described above is completed. After that, the ferrule 40 selected by a method for selecting a ferrule 40 described later is fixed to the plug frame 30 and the plug housing 20 to form the optical connector plug 10.
[0033]
Hereinafter, a method for selecting the above-described ferrule 40 will be described with reference to FIGS. 3 to 5 and 9. FIGS. 3 to 5 and FIG. 9 are diagrams illustrating a ferrule selection method according to the present embodiment.
[0034]
First, an adjusting ferrule 70 in which the core position of the optical fiber 1 is at a predetermined reference position is prepared.
[0035]
For example, in this embodiment, an adjustment ferrule 70 having a core eccentricity of 0.99 μm was prepared using a core eccentricity measuring device (NTT-AFTY “PSI-101”). As shown in FIG. 3A, the core position of the adjusting ferrule 70 matches the position A of the key groove 72 of the collar member 71, that is, is aligned with the position A of the closest key groove 72. The direction of the position A of the key groove 72 was set as a reference direction.
[0036]
Next, the adjusting ferrule 70 connected to the light source 90 is fixed at a predetermined position where the position A of the key groove 72 is in a predetermined direction, for example, in the present embodiment, vertically upward. Then, as shown in FIG. 3B, the adjusting ferrule 70 is inserted into one opening of the optical connection sleeve 80, and then connected to the optical power meter 91 through the other opening of the optical connection sleeve 80. The inserted ferrules 40 connect the end faces of the optical fibers 1 to face each other.
[0037]
Next, the insertion loss when the two are connected to each other via the optical connection sleeve 80, that is, the magnitude (light intensity) of the light amount at the time of optical connection is measured by the optical power meter 91, and then the ferrule 40 is set to a predetermined value. The insertion loss is measured by rotating each angle.
[0038]
For example, in the present embodiment, as shown in FIG. 3C, the key grooves 48 are provided at four locations at 90-intervals in the circumferential direction of the collar portion 47. 40 is rotated counterclockwise by 90 °, and the insertion loss value L corresponding to the core position for each rotation is obtained from the optical power meter 91. ₁ , L ₂ , L ₃ , L ₄ Was read.
[0039]
After that, each insertion loss value L read from the optical power meter 91 ₁ ~ L ₄ Is determined, that is, the key groove 48 that matches the reference direction A of the adjusting ferrule 70 when the light intensity becomes maximum, and this key groove 48 is determined as the eccentric reference direction of the ferrule 40.
[0040]
For example, in the present embodiment, since the reference direction of the adjustment ferrule 70 is vertically upward, the core position of the ferrule 40 approaches the core position of the adjustment ferrule 70 when the insertion loss value shows the minimum value. The key groove 48 of the ferrule 40 positioned vertically above when the marking is performed is marked, and the direction of the key groove 48 provided with this mark (not shown), that is, the vertically upper direction is determined as the eccentric reference direction.
[0041]
In the present embodiment, the core eccentricity and the core eccentricity direction are obtained from the core position of the optical fiber 1 specified with reference to the key groove 48 in the eccentricity reference direction described above, and based on the core eccentricity and the core eccentricity direction. The ferrule 40 having a low loss, for example, 0.1 dB or less is selected.
[0042]
First, the position coordinates of the rotation center 4 are estimated on the virtual coordinate system of the ferrule 40.
[0043]
Specifically, as shown in FIG. 9, the insertion loss value L corresponding to the core position for each rotation is shown. ₁ , L ₂ , L ₃ , L ₄ Is the position coordinate of the core 2. The position coordinates (L ₁ , 0), (0, L ₂ ), (-L ₃ , 0), (0, -L ₄ ) To calculate the least squares circle. The radius r of the least-squares circle is relative to the rotation center 4 of the ferrule 40 of the core 2.
The angle θ formed by the rotation center 4 with respect to the virtual coordinate system is the core eccentric direction.
[0044]
Here, the radius r corresponding to the core eccentricity is the insertion loss value L ₁ ~ L ₄ , A conversion formula is needed to convert the actual core eccentricity.
In order to obtain this conversion formula, the radius r corresponding to the core eccentricity, the core eccentricity of the ferrule 40 (actually measured value) measured by a core eccentricity measuring device (NTT-AFTY: “PSI-101 type”) for comparison. Was determined. The results are shown in Table 1 and FIG. FIG. 6 is a diagram illustrating a relationship between the radius r and the amount of core eccentricity (actually measured value).
The following equation (1) was obtained from such a relationship.
y = 2.14x-0.02 (1)
x: radius r
y: Core eccentricity (actual measurement) [μm]
Then, the core eccentricity (converted value) calculated by substituting the radius r calculated by the above-described method into the above equation (1) was compared with the core eccentricity (actually measured value) measured by the core eccentricity measuring device.
[0045]
[Table 1]

[0046]
As shown in Table 1, it was found that the difference between the core eccentricity, which was the converted value of Example 1, and the core eccentricity, which was the measured value of Comparative Example 1, was very small.
[0047]
Therefore, conversely, if the above equation (1) is obtained in advance, the insertion loss L ₁ ~ L ₄ It has been confirmed that by calculating, the core eccentricity close to the actually measured value can be obtained.
[0048]
It should be noted that since the conversion equation such as the above equation (1) is a correlation function based on the individual adjustment ferrules 70, it must be obtained for each adjustment ferrule used as a reference.
[0049]
Next, the core 2 position coordinates of the ferrule 40 estimated by the above-described method shown in FIG.
(X _1-4 , Y _1-4 ) And the core position coordinates (X ₀ , Y ₀ ), The axis deviation d ₁ ~ D ₄ And the insertion loss value L ₁ ~ L ₄ The relationship was verified.
[0050]
Here, the following equation (2) showing the relationship between the axis shift amount d and the insertion loss value L is generally known, and the actually measured axis shift amount d ₁ ~ D ₄ Into the following equation (2), the insertion loss value L ₁ '~ L ₄ 'Can be calculated. In the present embodiment, L ₀ = 4.34 (coefficient) and ω = 5.0 µm.
L = L ₀ × (d / ω) ² (2)
L: insertion loss (dB)
L ₀ : Coefficient when only the axis deviation is considered
d: Axis shift (μm)
ω: mode field radius (μm)
And the insertion loss value L ₁ ~ L ₄ (Measured value) and insertion loss value L ₁ '~ L ₄ '(Estimated value) was verified to have a correlation. FIG. 7 shows the result. FIG. 7 is a graph showing the relationship between the insertion loss value and the amount of misalignment.
[0051]
As shown in FIG. 7, the insertion loss value L ₁ ~ L ₄ (Measured value) and insertion loss value L ₁ '~ L ₄ It is clear that there is a very close correlation with '(estimated value). As a result, the measured insertion loss value L ₁ ~ L ₄ (Measured value) is the actual amount of misalignment d of each axis ₁ ~ D ₄ Can be verified, and it was confirmed that the selection of the ferrule 40 described above was effective.
[0052]
In addition, as shown in FIG. ₁ ~ L ₄ (Measured value) and insertion loss value L ₁ '~ L ₄ '(Estimated value) shows a very close correlation, and conversely, the measured insertion loss value L ₁ ~ L ₄ (Measured value) directly from each axis deviation d ₁ ~ D ₄ It is clear that can be estimated. Therefore, each axis shift amount d thus estimated ₁ ~ D ₄ From, the core eccentric amount and the core eccentric direction can be mathematically calculated, and the ferrule 40 can be selected using the calculated values. That is, the measured insertion loss value L ₁ ~ L ₄ To axis shift d ₁ ~ D ₄ Can be estimated, and the core eccentric amount and the core eccentric direction can be calculated from this, and the ferrule 40 can be selected based on this. In this case, the above equation (1) becomes unnecessary.
[0053]
As described above, in the present embodiment, the insertion loss value L at each rotational position of the optical fiber 1 between the adjusting ferrule 70 and the ferrule 40 is determined. ₁ ~ L ₄ From the center of rotation of the ferrule 40 and the core coordinates (X ₀ , Y ₀ ) Is specified, and the core eccentricity and the core eccentric direction are determined from the rotation center and the core coordinates. Therefore, the deviation angle of the core position of the ferrule 40 with respect to the eccentric reference direction A is: For example, those having a predetermined angle range smaller than 90 ° can be selected. Further, in addition to this, it is possible to select the ferrule 40 whose core eccentricity is equal to or less than a predetermined amount. Thus, the ferrule 40 having a low loss, for example, 0.1 dB or less can be selected.
[0054]
Here, as a specific example of the method of selecting the ferrule 40, for example, a predetermined angle range smaller than 90 ° may be selected in a range defined by one of the core eccentric amount and the core eccentric direction, or both may be selected. May be selected in a specified range by appropriately combining.
[0055]
Further, a group of ferrules 40 having a low loss can be formed by collecting cores having a core eccentricity or a core eccentricity direction larger than a predetermined amount. For example, in order to select a ferrule 40 having a lower insertion loss value L, the deviation angle between the eccentric reference direction A of the ferrule 40 and the core eccentric direction may be small, for example, 60 °. In practice, the low-loss ferrules 40 are divided into groups for each predetermined angle range, and the ferrules 40 of the same group are used in combination.
[0056]
In the selection of the ferrule 40, since the correlation between the relative value of the core eccentricity of the ferrule 40 and the measured value is very close, the insertion loss at each rotation position of the ferrule 40 with respect to the adjusting ferrule 70 is obtained. Value L ₁ ~ L ₄ The ferrule 40 with low loss can be selected based on the relative value of the core eccentricity of the optical fiber 1 obtained by the above.
[0057]
In addition, in the present embodiment, core position information that is close to the actual value is obtained from the converted value of the core eccentricity calculated by the above equation (1). Then, the ferrule 40 may be selected based on the core position information. Since the core position information is close to the measured value, it can be used as the standard value of the selected ferrule 40.
[0058]
As described above, according to the method for selecting the ferrule 40 of the present embodiment, the ferrule 40 can be selected according to the conventional eccentric alignment step, that is, the adjustment step. Therefore, the ferrule 40 having a low loss can be selected without increasing the number of steps. Can be. Also, the step of selecting the master ferrule 40 using the core eccentricity measuring device or the like can be replaced with the selection method of the present embodiment, and the number of steps of selecting the master ferrule 40 can be reduced. In addition, since it is possible to calculate the core eccentric amount more stably than the conventional core eccentricity measuring device as well as to select the master ferrule 40, the present invention can be applied to the selection of the standard ferrule 40. Therefore, regardless of the use of the ferrule 40 such as the master or standard, the ferrule 40 having an insertion loss as low as 0.1 dB or less, which is as low as that of the master, can be selected.
[0059]
Further, as described above, since the adjustment ferrule 70 and the ferrule 40 are optically connected via the optical connection sleeve 80, the core eccentricity measuring device or the like may be provided between the V-groove and the holding member for each rotation. Since the work of fixing the ferrule 40 can be omitted, workability can be improved, and no dust or the like adheres to the end face of the ferrule 40. From these, a relatively stable insertion loss value can be measured. Therefore, the working efficiency of measuring the core eccentric amount and the core eccentric direction can be improved, and the manufacturing cost can be reduced.
[0060]
Here, the low-loss ferrule 40 selected by the above-described method is then marked with a keyway 48 mark (not shown) indicating the eccentric direction of the core position of the optical fiber 1 as shown in FIG. The plug frame 30 is fitted on the basis of the reference. Next, the plug housing 20 is fitted on the outer periphery of the plug frame 30. Thus, the optical connector plug 10 as shown in FIG. 8B is completed.
[0061]
As described above, in the present embodiment, the optical connector plug 10 is manufactured by positioning and fixing the ferrule 40 to the plug frame 30 based on the key groove 48 corresponding to the reference direction of the core eccentricity. When the optical fiber 1 is used for the opposing connection, the core positions of the optical fibers 1 substantially coincide with each other, and the optical connection can be performed with low loss.
[0062]
Further, as described above, since the low-loss ferrule 40 based on the adjusting ferrule 70 in which the core of the optical fiber 1 is decentered by a predetermined amount can be selected and mass-produced, the optical connector plug using this ferrule 40 can be selected. By manufacturing the optical connector 10, it is possible to realize the optical connector plug 10 that can always perform optical connection with stable insertion loss.
[0063]
Further, according to the manufacturing method of the present embodiment, the step of specifying the core position of the optical fiber by image processing using the core eccentricity measuring device or the like can be omitted, and the ferrule can perform optical connection with insertion loss as low as that of the master. Since the optical connector plug 10 can be manufactured by selecting the 40, the number of steps for manufacturing the optical connector plug 10 for a master can be substantially reduced. As a result, significant cost reduction can be achieved.
[0064]
Furthermore, since the present invention can be employed not only for manufacturing the optical connector plug for the master but also for manufacturing the optical connector plug 10 for the standard, it is possible to realize the optical connector plug 10 having the same low loss as the master.
[0065]
(Other embodiments)
The embodiments of the present invention have been described above, but the basic configurations of the ferrule selection method and the optical connector plug manufacturing method are not limited to those described above.
[0066]
For example, in the first embodiment described above, the SC type optical connector plug is exemplified, but the optical connector plug having the single mode (SM) optical fiber 1 is not limited. For example, the MU type, the FC type, or the ST type An optical connector plug such as a mold may be used.
[0067]
Further, in the first embodiment described above, the insertion loss value L when the ferrule 40 is rotated every 90 degrees. ₁ ~ L ₄ However, the present invention is not limited thereto, and the insertion loss value when the ferrule 40 is rotated at least three times, that is, every 120 ° may be measured.
[0068]
【The invention's effect】
As described above, according to the present invention, the estimated coordinates of the core at each rotation position with the core position of the first ferrule (adjustment ferrule) as the coordinate center are determined by calculating the distance between the estimated coordinate and the coordinate center. It is estimated as correlating with the insertion loss value, the rotation center of the second ferrule is calculated from the estimated coordinates for each rotation position of the core, and the coordinates of the estimated position of the core of the second ferrule with respect to the rotation center are core position information. , The core eccentric amount and the core eccentric direction can be calculated from the eccentric direction of the key groove 48 and the core position information. The second ferrule having low loss can be relatively easily selected based on the core eccentric amount and the core eccentric direction.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of an optical connector plug according to Embodiment 1 of the present invention.
FIGS. 2A and 2B are schematic views of a ferrule according to Embodiment 1 of the present invention, wherein FIG. 2A is a perspective view, FIG. 2B is a cross-sectional view, and FIG. It is.
FIG. 3 is a diagram illustrating a ferrule selection method according to the first embodiment of the present invention.
FIG. 4 is a diagram illustrating a ferrule selection method according to the first embodiment of the present invention.
FIG. 5 is a diagram illustrating a ferrule selection method according to the first embodiment of the present invention.
FIG. 6 is a diagram illustrating a relationship between a core eccentricity (relative value) and a core eccentricity (actually measured value).
FIG. 7 is a graph showing a relationship between an insertion loss value and an axis shift amount.
FIG. 8 is a diagram illustrating a method for manufacturing the optical connector plug according to the first embodiment of the present invention.
FIG. 9 is a diagram illustrating a ferrule selection method according to the first embodiment of the present invention.
[Explanation of symbols]
1 Optical fiber
2 core
3 clad
4 Center of rotation
10 Optical connector plug
20 Plug housing
30 Plug frame
40 Ferrule
41 Tubular body for ferrule
42 brim member
48 keyway
50 Stop Ring
60 biasing spring
70 Adjusting Ferrule
80 Optical connection sleeve
90 light source
91 Optical Power Meter

Claims (5)

A ferrule cylindrical body for holding an optical fiber, and a method of selecting a ferrule including a collar member fixed to the ferrule cylindrical body and a plurality of reference directions can be determined,
The second ferrule is connected to the first ferrule in which the core position of the optical fiber is at the predetermined reference position, and the second ferrule is rotated around its axis to insert the second ferrule in each of the plurality of reference directions. Measuring the position of the reference direction in which the insertion loss value is the minimum value as the eccentric reference direction, and the coordinates of the estimated position of the core for each rotation position with the reference position as the coordinate center Is estimated as the distance between the estimated position and the coordinate center correlates with the insertion loss value, the rotation center of the second ferrule is calculated from the coordinates of the estimated position for each rotation position, and the rotation center is calculated. Calculating the estimated position of the core of the second ferrule with respect to the core position information, and calculating the core of the second ferrule calculated from the eccentricity reference direction and the core position information. Selection method of the ferrule, characterized by comprising the step of selecting, based on the amount of deviation from the deviation angle and the rotation center relative to the eccentric reference direction. 2. The ferrule selection method according to claim 1, wherein the core position information is obtained by estimating a distance between the coordinates of the estimated position of the core of the second ferrule and the coordinate center from the insertion loss value. 3. The ferrule selection method according to claim 1, wherein a deviation of the core position of the second ferrule from the reference direction in a predetermined angle range smaller than 90 [deg.] Is selected. The ferrule selection method according to any one of claims 1 to 3, wherein the first ferrule and the second ferrule are optically connected via an optical connection sleeve. A method for manufacturing an optical connector plug, comprising assembling using a ferrule selected by the ferrule selection method according to claim 1.

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