JP3786884B2 - Ferrule for optical connector, optical connector, and optical connector assembling method - Google Patents

Description

【００１８】
上式（１）から分かるように、段数ｋが大きくなれば大きくなるほど、上記ズレ量Ｇｋは大きくなる。このように、２段目以降の各段のファイバ挿入穴の中心軸の段方向に沿った位置と多心光ファイバテープ心線５３ａｋの段方向に沿った中心位置との間にズレ量Ｇｋが生じている状態で、各段のファイバ挿入穴５１ａ１〜５１ａ５に各多心光ファイバテープ心線５３ａ１〜５３ａ５の各光ファイバ５４ａ１〜５４ａ５を挿入すると、図１１に示すように、２段目以降の各段に対応する各光ファイバ５４ａ２〜５４ａ５に特に曲がりが生じる。すなわち、２段目以降の各段に対応する各光ファイバ５４ａ２〜５４ａ５は曲がった状態で固定される。
【００１９】
この光ファイバ（裸ファイバ）の曲がりは、光学特性の面から見ると、接続損失を上昇させる恐れがある。また、強度特性の面から見ると、上記曲がり部分が、温度変化や吸湿等に起因したフェルール内の膨張収縮により変形すると、裸ファイバの断線を誘発することも考えられる。
【００２０】
本発明は上述した事情に鑑みてなされたもので、光ファイバ（裸ファイバ）の曲がりを、その光ファイバの光学特性および強度特性に対して影響を及ぼさない範囲内に設定することができる光コネクタ用フェルール、光コネクタおよび光コネクタ組立方法を提供することにより、上記ファイバ曲がりに起因したフェルール全体および光コネクタ全体の光学特性・強度特性の劣化を防止することをその目的とする。
【００２１】
【課題を解決するための手段】
【００２２】
上述した目的を達成するための本発明の第１の態様によれば、端部の被覆が除去され光ファイバが露出した光ファイバテープ心線を支持する光コネクタ用フェルールであって、複数の段状に配置され、前記光ファイバが挿入される複数のファイバ挿入穴と、前記各ファイバ挿入穴のファイバ挿入側端部に対して一端部が連通するように形成されており、当該各ファイバ挿入穴の中心軸方向に沿って延びる光ファイバ挿入ガイド用のガイド部と、前記各ファイバ挿入穴のファイバ挿入側端部とは反対側の開口側端部から前記ファイバ挿入穴の中心軸方向に沿って所定距離を隔てて形成されており、前記各段の各ファイバ挿入穴に前記光ファイバテープ心線の各光ファイバが挿入された際に、当該光ファイバテープ心線のテープ状部材のファイバ露出側端部が当接する当接部と備えている。
【００２３】
本発明の第１の態様において、前記各ファイバ挿入穴の開口側端部から前記当接部までの前記ファイバ挿入穴の中心軸方向に沿った所定距離を、前記各段の各ファイバ挿入穴に前記光ファイバテープ心線の各光ファイバが挿入された時の当該各段における各光ファイバの曲がりの曲率半径ｒ１〜ｒｍ（但し、ｍは２以上の整数であり、段数に対応する）が所定値以上となるように設定している。
【００２４】
上述した目的を達成するための本発明の第２の態様によれば、端部の被覆が除去され光ファイバが露出した光ファイバテープ心線と、前記光ファイバテープ心線支持用のフェルールとを備え、前記フェルールは、複数の段状に配置され、前記光ファイバが挿入される複数のファイバ挿入穴と、前記各ファイバ挿入穴のファイバ挿入側端部に対して一端部が連通するように形成されており、当該各ファイバ挿入穴の中心軸方向に沿って延びる光ファイバ挿入ガイド用のガイド部と、前記各ファイバ挿入穴のファイバ挿入側端部とは反対側の開口側端部から前記ファイバ挿入穴の中心軸方向に沿って所定距離を隔てて形成されており、前記各段の各ファイバ挿入穴に前記光ファイバテープ心線の各光ファイバが挿入された際に、当該光ファイバテープ心線のテープ状部材のファイバ露出側端部が当接する当接部とを備えている。
【００２５】
上述した目的を達成するための本発明の第３の態様によれば、端部の被覆が除去され光ファイバが露出した光ファイバテープ心線を用いて光コネクタを組み立てる光コネクタ組立方法であって、複数の段状に配置され、前記光ファイバが挿入される複数のファイバ挿入穴、前記各ファイバ挿入穴のファイバ挿入側端部に対して一端部が連通するように形成されており、当該各ファイバ挿入穴の中心軸方向に沿って延びる光ファイバ挿入ガイド用のガイド部および前記各ファイバ挿入穴のファイバ挿入側端部とは反対側の開口側端部から前記ファイバ挿入穴の中心軸方向に沿って所定距離を隔てて形成された当接部をそれぞれ有するフェルールを用意するステップと、前記各段の各ファイバ挿入穴に前記光ファイバテープ心線の各光ファイバを、当該光ファイバテープ心線のテープ状部材のファイバ露出側端部が前記当接部に当接する位置まで挿入するステップとを備えている。
【００２６】
【発明の実施の形態】
以下、本発明の実施の形態について図面を参照して説明する。
【００２７】
図１は、本発明の実施の形態に係わる光コネクタＣを構成する光コネクタ用フェルール（以下、単にフェルールとする）１の概略構成およびこのフェルール１内に挿入されて固定支持される複数（本実施形態では、５個）の光ファイバテープ心線２ａ１〜２ａ５の概略構成とをそれぞれ示す斜視図である。
【００２８】
また、図２は、図１に示すフェルール１を、ファイバ挿入穴３の中心を通り段方向（高さ方向）に沿って切った場合の縦断面図であり、後掲図３に示すＩＩ−ＩＩ矢視縦断面図である。
【００２９】
図１および図２に示すように、フェルール１は方形体状を成しており、例えばプラスチック材料樹脂による成形により一体に形成されている。
【００３０】
すなわち、フェルール１は、その長手方向に沿って複数（複数心；本実施形態では、１２心とする）のファイバ挿入穴３を有している。この複数のファイバ挿入穴３は、フェルール高さ方向に沿って複数段（本実施形態では、第１段〜第５段とする）に配置されている。また、各段の複数のファイバ挿入穴３は、フェルール１の短手方向に沿って一定間隔（ピッチ）を空けて互いに並置されており、また、段方向に沿ったファイバ挿入穴３の間隔（ピッチ）も一定となっている。
【００３１】
以下、本実施形態においては、第１段のファイバ挿入穴３の１２心のファイバ挿入穴３を３Ｎ１とし、同様に、第２段〜第５段の複数のファイバ挿入穴３を３Ｎ２〜３Ｎ５とも記載する。
【００３２】
各光ファイバテープ心線２ａ１〜２ａ５は、図１に示すように、各段の複数（１２心）のファイバ挿入穴３に対応する複数（１２心）の光ファイバと、この複数の光ファイバをテープ状に被覆するテープ状部材２ｃ１〜２ｃ５とを備えてている。
【００３３】
第１段目に対応する光ファイバテープ心線２ａ１の端部においては、その端部におけるテープ状部材２ｃ１が除去されて１２心の光ファイバ（この場合裸ファイバ）２ｂ１が露出されている。同様に、第２段〜第５段の光ファイバテープ心線２ａ２〜２ａ５の端部においては、１２心の光ファイバ２ｂ２〜２ｂ５が露出されている。
【００３４】
各ファイバ挿入穴３Ｎ１〜３Ｎ５の穴径は、対応する光ファイバ２ｂ１〜２ｂ５が挿入できる程度に当該光ファイバ２ｂ１〜２ｂ５の線径と略等しくなっている。
【００３５】
さらに、フェルール１は、複数段に配置された複数のファイバ挿入穴３の開口側端部を含む開口面を有する第１のハウジング部５を備え、この第１のハウジング部５の上記開口面が光コネクタや光モジュール等の他の光部品との接続端面５ａとなる。また、フェルール１は、この第１のハウジング部５から前記ファイバ挿入穴中心軸方向に沿って延在した第２のハウジング部６を備えている。
【００３６】
第２のハウジング部６は、第１のハウジング部５における接続端面５ａの段方向に沿った端部からファイバ穴の軸方向に沿って連接する上面７を有し、この上面７には、各段のファイバ挿入穴３に対する各光ファイバテープ心線２の光ファイバ挿入時における光ファイバ固定用の部材（例えば、接着剤）を注入するための窓穴８が形成されている。
【００３７】
そして、フェルール１は、図１および図２に示すように、各段の各ファイバ挿入穴３Ｎ１〜３Ｎ５の下半周縁部に対して一端部が連通するように形成されており、ファイバ挿入穴の中心軸方向に沿って同軸状に延びる光ファイバ挿入ガイド用のガイド溝１０Ｎ１〜１０Ｎ５を備えている。
【００３８】
第１段〜第５段のファイバ挿入穴３Ｎ１〜３Ｎ５は、その隣接する上段のファイバ挿入穴のガイド溝の光ファイバ挿入方向とは反対側の端部位置まで延びており、この結果、第１段〜第５段のガイド溝１０Ｎ１〜１０Ｎ５およびファイバ挿入穴３Ｎ１〜３Ｎ５全体は、図２に示す断面視において上段から下段に向かって広がる階段状を成している。したがって、各段のファイバ挿入穴３Ｎ１〜３Ｎ５の光ファイバ挿入側端部の位置は、上段から下段に向かって次第に接続端面５ａから離間している。
【００３９】
図３は、図２に示すフェルール１を、３段目のファイバ挿入穴３Ｎ３に対応するガイド溝１０Ｎ３の周縁部上端面に沿って切った場合のＩＩＩ−ＩＩＩ矢視横断面図である。
【００４０】
図２および図３に示すように、第２のハウジング部６は、第１のハウジング部５の開口面５ａに対向する光ファイバテープ心線２を挿入するための挿入口１２と、この挿入口１２形成部分の外周部に形成されたフランジ部１３とを備えている。
【００４１】
そして、第２のハウジング部６は、図２および図３に示すように、接続端面５ａからファイバ挿入穴中心軸方向に沿って所定距離Ｄを隔てて形成された当接部１５を備えている。
【００４２】
図３に示すように、当接部１５は、第２のハウジング部６における互いに対向する挿入口内周縁部６ａおよび６ｂから対向方向へ段状にそれぞれ突出する突出部１５ａ、１５ｂとして形成されている。
【００４３】
突出部１５ａおよび突出部１５ｂの間の距離Ｄ１０は、光ファイバテープ心線２ａ１〜２ａ５のテープ状部材２ｃ１〜２ｃ５におけるファイバ露出側端部（端面）２ｄ１〜２ｄ５の横幅Ｗ１０よりも短い長さとなっている。
【００４４】
また、突出部１５ａおよび突出部１５ｂの間の距離Ｄ１０は、光ファイバテープ心線２ａ１〜２ａ５の光ファイバ２ｂ１〜２ｂ５の挿入時の妨げになることを防止するため、その光ファイバテープ心線２ａ１〜２ａ５のにおける両端の光ファイバ２ｂ１およびｂ５間の横幅（以下、光ファイバ幅とする）Ｗ１１よりも長くなっている。
【００４５】
この当接部１５は、各段のファイバ挿入穴３Ｎ１〜３Ｎ５に光ファイバテープ心線２ａ１〜２ａ５の各光ファイバ２ｂ１〜２ｂ５が挿入された際に、光ファイバテープ心線２ａ１〜２ａ５のテープ状部材２ｃ１〜２ｃ５におけるファイバ露出側端部（端面）２ｄ１〜２ｄ５が当接する位置に形成されている。
【００４６】
また、フェルール１は、階段状を成す各ガイド溝１０Ｎ１〜１０Ｎ５を含むファイバ挿入穴３Ｎ１〜３Ｎ５と挿入口８との間に形成されており、各段のファイバ挿入穴３Ｎ１〜３Ｎ５に挿入された光ファイバ２ｂ１〜２ｂ５を収容するための収容部１６を備えている。
【００４７】
さらに、フェルール１は、ファイバ挿入穴３の並列方向に沿った両側に当該挿入穴と平行に配設されており、位置あわせ用のガイドピンを挿入するための２つのガイドピン穴１７ａ１、１７ａ２を有している。
【００４８】
このように構成されたフェルール１に対して、挿入口１２を介して１段目に対応するファイバテープ心線２ａ１を収容部１６内に挿入する。
【００４９】
そして、光ファイバテープ心線２ａ１の光ファイバ２ｂ１を、ガイド溝１０Ｎ１に沿って対応する１段目のファイバ挿入穴３Ｎ１内に挿入する。
【００５０】
このとき、光ファイバテープ心線２ａ１の各光ファイバ２ｂ１は、そのテープ状部材２ｃ１におけるファイバ露出側端部２ｄ１が当接部１５に当接する位置まで、対応する各ファイバ挿入穴３Ｎ１内に挿入され、その各ファイバ挿入穴３Ｎ１に支持される。
【００５１】
上記ファイバ２ｂ１のファイバ挿入穴３Ｎ１に対する挿入時において、当接部１５である突出部１５ａおよび突出部１５ｂの間の距離Ｄ１０がファイバ露出側端部（端面）２ｄ１〜２ｄ５の横幅Ｗ１０よりも短いため、光ファイバテープ心線２ａ１のテープ状部材２ｃ１におけるファイバ露出側端部２ｄ１は、当接部１５に当接し、その当接状態で固定される。
【００５２】
以下、第２段目〜第５段目の光ファイバテープ心線２ａ２〜２ａ５を、第２段目から昇順に段毎に収容部１６内に挿入し、光ファイバテープ心線２ａ２〜２ａ５の光ファイバ２ｂ２〜２ｂ５を、ガイド溝１０Ｎ２〜１０Ｎ５に沿って対応する２段目〜５段目のファイバ挿入穴３Ｎ２〜３Ｎ５内に挿入する。
【００５３】
このとき、１段目と同様に、光ファイバテープ心線２ａ２〜２ａ５の各光ファイバ２ｂ２〜２ｂ５は、そのテープ状部材２ｃ２〜２ｃ５におけるファイバ露出側端部２ｄ２〜２ｄ５が当接部１５に当接する位置まで、対応する各ファイバ挿入穴３Ｎ２〜３Ｎ５内にそれぞれ挿入され、その各ファイバ挿入穴３Ｎ２〜３Ｎ５に支持される。また、光ファイバテープ心線２ａ２〜２ａ５のテープ状部材２ｃ２〜２ｃ５におけるファイバ露出側端部２ｄ２〜２ｄ５は当接部１５に当接した状態で固定される。
【００５４】
図４は、フェルール１の第１段〜第５段のファイバ挿入穴３Ｎ１〜３Ｎ５に対して光ファイバテープ心線２ａ１〜２ａ５の光ファイバ２ｂ１〜２ｂ５が挿入された状態のフェルール１および光ファイバテープ心線２ａ１〜２ａ５を、ファイバ挿入穴３Ｎ１〜３Ｎ５の中心を通り段方向（高さ方向）に沿って切った場合の図２に対応する縦断面図である。
【００５５】
また、図５は、図４に示す光ファイバテープ心線２ａ１〜２ａ５の光ファイバ２ｂ１〜２ｂ５が挿入された状態のフェルール１を、３段目のファイバ挿入穴３Ｎ３に対応するガイド溝１０Ｎ３の周縁部上端面に沿って切った場合のＶ−Ｖ矢視横断面図である。
【００５６】
図４および図５に示すように、全ての光ファイバテープ心線２ａ１〜２ａ５の光ファイバ２ｂ１〜２ｂ５は、そのテープ状部材２ｃ１〜２ｃ５におけるファイバ露出側端部２ｄ１〜２ｄ５が当接部１５に当接・固定される位置まで挿入されることになる。
【００５７】
このように、光ファイバ２ｂ１〜２ｂ５がファイバ挿入穴３Ｎ１〜３Ｎ５に挿入・支持された状態で、窓穴８を介して接着剤をフェルール１内に注入して光ファイバ２ｂ１〜２ｂ５を固定することにより、光コネクタＣが作成される。
【００５８】
次に、本実施形態のフェルール１およびコネクタＣの構成に基づく作用について説明する。
【００５９】
図６は、従来の第１段目〜第３段目のファイバ挿入穴５１ａ１〜５１ａ３に各多心光ファイバテープ心線５３ａ１〜５３ａ３の各光ファイバ５４ａ１〜５４ａ３を挿入した状態での光ファイバ５４ａ２および５４ａ３の曲がりを示す図である。
【００６０】
すなわち、ｋ段目（ｋは１以上の整数）の光ファイバ５４ａｋの曲がりは、その光ファイバ５４ａｋの曲率半径ｒとして表すことができる。そして、光ファイバ５４ａｋの曲率半径ｒは、ｋ段目の光ファイバテープ心線５３ａｋの剥き際端部（光ファイバ露出側端部）５３ｂｋと、対応するファイバ挿入穴５１ａｋのガイド溝５２との間の距離Ｄｋ´、およびｋ段目におけるファイバ挿入穴５１ａｋの中心軸の段方向に沿った位置と多心光ファイバテープ心線５３ａｋの段方向に沿った中心位置との間のズレ量Ｇｋをパラメータとして表すことができる。
【００６１】
次に、曲がりの曲率半径ｒを近似的に示す方法について説明する。
【００６２】
図７に示すように、両端（固定点ａ）が位置ズレした状態（上記ズレ量Ｇｋに対応する位置ズレ量：Ｇ）で固定された光ファイバの軌跡を、まず、固定点ａを原点とするｘｙ座標系においてｓｉｎカーブ近似する。すなわち、図７に示す光ファイバの軌跡は、固定点間の距離をＤ（上記距離Ｄｋ´に対応）とすると、固定点ａを原点とするｃｏｓ関数（ｙ＝ｃｏｓ ｘ）の波長を２Ｄとして反転したカーブとして近似できる。
【００６３】
すなわち、
【式２】

【００６４】
（２）式の原点を固定点に合わせると、（２）式は、次式のように表せる。
【式３】

【００６５】
図７に示すように、振幅がＧに対応するため、最終的に、光ファイバの軌跡は、次式
【式４】

として表すことができる。
【００６６】
さらに、ｘｙ座標系で表せる軌跡のｘ地点での曲率半径ｒは、次式（５）で表せる。
【式５】

【００６７】
曲率半径は両端で最小（すなわち、曲がりが最大）となるので、（４）式を２階微分して（５）式に代入し、さらにｘ＝０を代入して（５）式を計算すると、次式（６）が導出される。
【００６８】
【式６】

【００６９】
すなわち、光ファイバの曲がりの大きさは、曲率半径ｒに反比例するため、（６）式から分かるように、距離Ｄを長くとれば、曲率半径ｒを大きくして曲がりを小さくできる。
【００７０】
この点、従来のフェルール５０においては、図６に示すように、１段目の光ファイバテープ心線５３ａ１の各光ファイバ５４ａ１を、その光ファイバ露出側端部５３ｂ１が対応する各ファイバ挿入穴５１ａ１のガイド溝５２に当接する位置まで当該各ファイバ挿入穴５１ａ１に挿入し、２段〜５段の各光ファイバ５４ａ２〜５４ａ５を、対応する光ファイバ露出側端部５３ｂ２〜５３ｂ５のファイバ穴中心軸方向に沿った位置が上記１段目の光ファイバ露出側端部５３ｂ１のファイバ穴中心軸方向に沿った位置と同一になるように、対応する各ファイバ挿入穴５１ａ２〜５１ａ５に挿入している。
【００７１】
このため、２段目以降（ｋ≧２）におけるｋ段目の光ファイバテープ心線５３ａｋの光ファイバ露出側端部５３ｂｋとファイバ挿入穴５１ａｋのガイド溝５２との間の距離Ｄｋ´は、対応するｋ段目のガイド溝５２のファイバ穴中心軸方向の長さをＬとすると、次式（７）として表すことができる。
【式７】

【００７２】
すなわち、上記距離Ｄｋ´は、対応するｋ段目のガイド溝５２のファイバ穴中心軸方向の長さＬに依存するため非常に短く、大きな曲がり（歪）が発生することになる。
【００７３】
従来のフェルール５０を用いて光ファイバテープ心線２ａ１〜２ａ５の光ファイバ２ｂ１〜２ｂ５を挿入・固定して組み立てられた光コネクタＣにおいては、２段目以降の光ファイバ２ｂ２〜２ｂ５に大きな曲がり（歪）が発生することになる。
【００７４】
しかしながら、本実施形態の構成においては、図４、図５および図８等に示すように、ガイド溝１０Ｎ１〜１０Ｎ５のファイバ挿入穴とは反対側の他端部Ｅ１〜Ｅ５から各段のファイバ挿入穴３Ｎ１〜３Ｎ５の中心軸方向に沿って所定距離Ｄｋ（Ｄ１〜Ｄ５）を隔てて形成された当接部１５を設けている。このため、各段のファイバ挿入穴３Ｎ１〜３Ｎ５に光ファイバテープ心線２ａ１〜２ａ５の各光ファイバ２ｂ１〜２ｂ５が挿入された際に、光ファイバテープ心線２ａ１〜２ａ５のテープ状部材２ｃ１〜２ｃ５におけるファイバ露出側端部（端面）２ｄ１〜２ｄ５は、当接部１５に当接して固定されることになる。
【００７５】
すなわち、本実施形態の構成においては、ｋ段目のファイバテープ心線２ａｋの光ファイバ露出側端部２ｄｋと対応するファイバ挿入穴３Ｎｋのガイド溝１０Ｎｋの他端部Ｅｋとの間の距離Ｄｋを、当接部１５のファイバ挿入穴中心軸方向に沿った配設位置、言い換えれば、当接部１５のガイド溝１０Ｎｋの他端部Ｅｋからのファイバ挿入穴３Ｎｋの中心軸方向に沿った距離Ｄｋ（Ｄ１〜Ｄ５）として表すことができる。
【００７６】
したがって、上記当接部１５の距離に対応するｋ段目のファイバテープ心線２ａｋの光ファイバ露出側端部２ｄｋと対応するファイバ挿入穴３Ｎｋのガイド溝１０Ｎｋの他端部Ｅｋとの間の距離Ｄｋを十分長く設定して、各光ファイバ２ｂ１〜２ｂ５の曲率半径ｒを大きくすれば、各光ファイバ２ｂ１〜２ｂ５に生じる曲がり（歪）を最小限度に抑制することができる。
【００７７】
一般に、各光ファイバ２ｂ１〜２ｂ５に生じる曲がりは、その曲率半径ｒが３０ｍｍ以上であれば、各光ファイバの光学特性および強度特性に対して影響を及ぼさないことが知られている。
【００７８】
したがって、本実施形態では、ｋ段目のファイバテープ心線２ａｋの光ファイバ露出側端部２ｄｋと対応するファイバ挿入穴３Ｎｋのガイド溝１０Ｎｋの他端部Ｅｋとの間の距離Ｄｋを、各光ファイバ２ｂ１〜２ｂ５の曲率半径ｒが３０ｍｍ以上となるように設定している。
【００７９】
例えば、本実施形態において、ｋ（１≦ｋ≦５）段目のファイバ位置ズレ量Ｇｋは、段方向のファイバピッチとテープ状部材の厚みとの差０．０５を用いて上式（１）｛Ｇｋ＝０．０５（ｋ−１）＋α｝で表すことができる。そして、各段のガイド溝１０Ｎ１〜１０Ｎ５のファイバ挿入穴中心軸方向に沿った長さをＬ＝０．３（ｍｍ）とし、上記式（６）を用いて、ｒ≧３０ｍｍ以上となる距離Ｄｋを求めると、表１に示す結果が得られた。
【００８０】
【表１】

【００８１】
ここで、本実施形態のフェルール１において、接続端面５ａからファイバ挿入穴中心軸方向に沿った５段目のガイド溝１０Ｎ５の他端部Ｅ５までの距離を２．０（ｍｍ）とすると、接続端面５ａからファイバ挿入穴中心軸方向に沿った４段目のガイド溝１０Ｎ４の他端部Ｅ４までの距離は２．３（ｍｍ）、接続端面５ａからファイバ挿入穴中心軸方向に沿った３段目のガイド溝１０Ｎ３の他端部Ｅ３までの距離は２．６（ｍｍ）、接続端面５ａからファイバ挿入穴中心軸方向に沿った２段目のガイド溝１０Ｎ２の他端部Ｅ２までの距離は２．９（ｍｍ）、接続端面５ａからファイバ挿入穴中心軸方向に沿った１段目のガイド溝１０Ｎ１の他端部Ｅ１までの距離は３．２（ｍｍ）となる。
【００８２】
したがって、各段（１段〜５段）のフェルール端面５ａと第１段目〜第５段目のファイバテープ心線２ａ１〜２ａ５の光ファイバ露出側端部２ｄ１〜２ｄ５との間の距離Ｄｓ１〜Ｄｓ５は、次の表２のように求められる。
【表２】

【００８３】
すなわち、フェルール端面５ａから第１段目〜第５段目のファイバテープ心線２ａ１〜２ａ５の光ファイバ露出側端部２ｄ１〜２ｄ５までの距離Ｄｓ１〜Ｄｓ５を、各段毎に個別に、表２に示す値Ｄｓ１＝３．２０（ｍｍ）〜Ｄｓ５＝７．４４（ｍｍ）に設定すれば、光ファイバ２ｂ１〜２ｂ５の曲がりの曲率半径ｒ≧３０ｍｍ以上にすることが可能になる。
【００８４】
しかしながら、第１段目〜第５段目のファイバテープ心線２ａ１〜２ａ５の光ファイバ露出側端部２ｄ１〜２ｄ５の距離Ｄｓ１〜Ｄｓ５を各段毎に個別に設定することは困難である。
【００８５】
そこで、本実施形態では、第１段目〜第５段目のファイバテープ心線２ａ１〜２ａ５の光ファイバ露出側端部２ｄ１〜２ｄ５の距離Ｄｓ１〜Ｄｓ５の中で、最も長い段（第５段）の距離Ｄｓ５を、各段（１段〜５段）のフェルール端面５ａと第１段目〜第５段目のファイバテープ心線２ａ１〜２ａ５の光ファイバ露出側端部２ｄ１〜２ｄ５との間の共通の距離として設定している。
【００８６】
すなわち、接続端面５ａとファイバ挿入穴中心軸方向に沿った当接部１５との間の距離Ｄを、上記Ｄｓ５＝７．４４（ｍｍ）に設定している。
【００８７】
この結果、本実施形態では、全てのファイバテープ２ａ１〜２ａ５のテープ状部材２ｃ１〜２ｃ５におけるファイバ露出側端部２ｄ１〜２ｄ５が当接部１５に当接・固定されているため、上記ファイバ露出側端部（剥きぎわ端部）２ｄ１〜２ｄ５を、対応する各光ファイバ２ｂ１〜２ｂ５の曲率半径ｒが３０ｍｍ以上となる位置に固定することができる。
【００８８】
したがって、各光ファイバ２ｂ１〜２ｂ５の曲がりを、その各光ファイバ２ｂ１〜２ｂ５の光学特性および強度特性に対して影響を及ぼさない最小限度に抑制することができる。
【００８９】
この結果、成形歪、温度変化、吸湿による歪等の影響による光ファイバ２ｂ１〜２ｂ５の曲がりに起因した光学特性および強度特性の劣化を抑止し、フェルール１全体および光コネクタＣ全体の信頼性を高く維持することができる。
【００９０】
なお、上述した接続端面５ａとファイバ挿入穴中心軸方向に沿った当接部１５との間の距離Ｄ＝７．４４（ｍｍ）はあくまで具体例であり、この数値自体に限定されないことは当然である。
【００９１】
また、本実施形態では、各光ファイバ２ｂ１〜２ｂ５に生じる曲がりの曲率半径ｒの信頼性許容範囲を３０ｍｍ以上とし、接続端面５ａとファイバ挿入穴中心軸方向に沿った当接部１５との間の距離Ｄを、上記曲率半径ｒが３０ｍｍ以上となるように設定したが、本発明はこれに限定されるものではない。
【００９２】
すなわち、信頼性を多少犠牲にしてフェルール自体を小型化する等の理由から、上記曲率半径ｒを３０ｍｍ未満を許容する場合でも、その曲率半径ｒを満足するように接続端面５ａとファイバ挿入穴中心軸方向に沿った当接部１５との間の距離Ｄを設定すればよい。
【００９３】
さらに、本実施形態では、１２心のファイバ挿入穴が第１段〜第５段に亘って配置された６０心フェルールおよびこの６０心フェルールを用いた光コネクタについて説明したが、本発明はこれに限定されるものではなく、複数心のファイバ挿入穴が複数段状に配置されたフェルールおよびこのフェルールを用いた光コネクタであればよい。
【００９４】
【発明の効果】
以上述べたように、本発明に係わる光コネクタ用フェルール、光コネクタおよび光コネクタ組立方法によれば、各ファイバ挿入穴のファイバ挿入側端部とは反対側の開口側端部からファイバ挿入穴の中心軸方向に沿って所定距離を隔てて形成され、各段の各ファイバ挿入穴にテープ心線端部の各光ファイバが挿入された際に、当該テープ心線のテープ状部材のファイバ露出側端部が当接する当接部を設けているため、上記当接部の所定距離を、各光ファイバの曲がりが影響を与えない値（曲がりの曲率半径が３０ｍｍ以上）に設定することができる。
【００９５】
したがって、各光ファイバの曲がりを、その各光ファイバの光学特性および強度特性に対して影響を及ぼさない最小限度に抑制することができる。この結果、光ファイバの曲がりに起因した光学特性および強度特性の劣化を抑止し、フェルール全体および光コネクタ全体の信頼性を高く維持することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係わる光コネクタを構成する光コネクタ用フェルールの概略構成およびこのフェルール内に挿入されて固定支持される複数の光ファイバテープ心線の概略構成とをそれぞれ示す斜視図。
【図２】図１に示すフェルールを、ファイバ挿入穴の中心を通り段方向（高さ方向）に沿って切った場合の縦断面図であり、図３に示すＩＩ−ＩＩ矢視縦断面図。
【図３】図２に示すフェルールを、３段目のファイバ挿入穴に対応するガイド溝の周縁部上端面に沿って切った場合のＩＩＩ−ＩＩＩ矢視横断面図。
【図４】フェルールの第１段〜第５段のファイバ挿入穴に対して光ファイバテープ心線の光ファイバが挿入された状態のフェルールおよび光ファイバテープ心線を、ファイバ挿入穴の中心を通り段方向（高さ方向）に沿って切った場合の図２に対応する縦断面図。
【図５】図４に示す光ファイバテープ心線の光ファイバが挿入された状態のフェルールを、３段目のファイバ挿入穴に対応するガイド溝の周縁部上端面に沿って切った場合のＶ−Ｖ矢視横断面図。
【図６】従来の第１段目〜第３段目のファイバ挿入穴に各多心光ファイバテープ心線の各光ファイバを挿入した状態での光ファイバおよびの曲がりを拡大して示す図。
【図７】両端が位置ズレ固定された光ファイバの軌跡を表す図。
【図８】本実施形態の第１段目〜第３段目のファイバ挿入穴に各多心光ファイバテープ心線の各光ファイバを挿入した状態での光ファイバおよびの曲がりを拡大して示す図。
【図９】従来の光コネクタ用フェルールの概略構成を示す斜視図。
【図１０】図９に示すフェルールを、ファイバ挿入穴の中心を通り段方向に沿って切った場合の縦断面図。
【図１１】図１０に示すフェルールに対して、ファイバテープの光ファイバを挿入した状態を表す縦断面図。
【符号の説明】
１ フェルール
２ａ１〜２ａ５ 光ファイバテープ
２ｂ１〜２ｂ５ 光ファイバ（裸ファイバ）
２ｃ１〜２ｃ５ テープ状部材
２ｄ１〜２ｄ５ ファイバ露出側端部
３、３Ｎ１〜３Ｎ５ ファイバ挿入穴
５ 第１のハウジング部
５ａ 接続端面
６ 第２のハウジング部
７ 上面
８ 窓穴
１０Ｎ１〜１０Ｎ５ ガイド溝
１２ 挿入口
１３ フランジ部
１５ 当接部
１５ａ、１５ｂ 突出部
１６ 収容部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ferrule for an optical connector, an optical connector, and an optical connector assembling method used at a connection portion between optical fibers in optical communication, a connection portion of an optical module such as an optical semiconductor, or the like.
[0002]
[Prior art]
With the development of information networks including optical fiber networks, transmission capacity has been rapidly increasing. Therefore, high density is required for the ferrule for optical connectors used in the connection between optical fibers, the connection of an optical module such as an optical semiconductor, and the like.
[0003]
In order to achieve the above high density, optical connector ferrules have been increased in number so that a large number of optical fibers can be connected together while maintaining the appearance and size of the conventional optical fiber. Yes.
[0004]
In particular, in recent years, a multi-stage multi-core pursuing higher density from a single-stage multi-core {1 stage × n-core} ferrule having one stage of multi-fiber insertion holes (fine holes) for supporting a large number of optical fibers ( (m stage x n core) The ferrule has been moved.
[0005]
FIG. 9 is a diagram showing an example of an optical connector ferrule 50 having multi-core (n-core) fiber insertion holes provided in multiple stages (m-stage). Ie, figure 9 In the optical connector ferrule 50 shown in FIG. 1, for example, n (= 12) core fiber insertion holes 51 arranged in the horizontal direction in the figure are provided in m (= 5) stages in the vertical direction (5 stages × 12 cores) and 60 core ferrules.
[0006]
The optical connector ferrule 50 includes a multi-fiber optical fiber ribbon corresponding to the multi-fiber insertion hole. 53 The exposed optical fiber (bare fiber in this case) is fixedly supported through the multi-fiber insertion hole, thereby facilitating connection to the optical connector or optical module of the connection partner.
[0007]
The outer diameter of the optical fiber and the inner diameter of the fiber insertion hole of the ferrule are very small. Therefore, in order to improve the workability of inserting each optical fiber into each fiber insertion hole, the ferrule includes a guide groove for guiding insertion of each optical fiber into each fiber insertion hole.
[0008]
FIG. 10 is a longitudinal sectional view of the ferrule 50 shown in FIG. 9 cut along the step direction passing through the center of the fiber insertion hole 51. As shown in FIG. 10, a ferrule for a multi-fiber optical connector 50 The guide groove 52 of each step is extended along the axial direction from the terminal position along the axial direction of the guide groove 52 on the upper step.
[0009]
Ferrules for such multi-fiber optical connectors 50 When assembling an optical connector using a plurality of (5) multi-fiber optical fiber ribbons 53a1 to 53a5 corresponding to the number of stages are prepared. And each optical fiber (in this case bare fiber) 54a1 which the tape part of the multi-fiber optical fiber ribbon 53a1 corresponding to the 1st step in the prepared multi-core optical fiber ribbon 53a1-53a5 was peeled off and exposed, It inserts in each fiber insertion hole 51a1 of the lowest step (1st step).
[0010]
At this time, each optical fiber 54a1 is made to contact the guide groove 52 of each first-stage fiber insertion hole 51a1 corresponding to the end portion (end portion when the tape is peeled off) 53b1 of the multi-fiber ribbon fiber 53a1. It inserts in each said fiber insertion hole 51a1 to the position which contact | connects (refer FIG. 11).
[0011]
Next, the optical fibers 54a2 of the multi-core optical fiber ribbons 53a2 to 53a5 are sequentially applied toward the upper stage side with respect to the fiber insertion holes 51a2 to 51a5 of the second stage and subsequent stages (2 to 5 stages). 54a5 is inserted.
[0012]
At this time, the optical fibers 54a2 to 54a5 of the 2nd to 5th stages are connected to the center of the fiber holes of the optical fiber exposed side ends (ends when the tape is peeled off) 53b2 to 53b5 in the corresponding multi-core optical fiber ribbons 53a2 to 53a5 It inserts into each corresponding fiber insertion hole 51a2-51a5 so that the position along an axial direction may become the same as the position along the fiber-hole center axial direction of the said 1st step | paragraph optical fiber exposure side edge part 53b1 (FIG. 11).
[0013]
In this way, with the optical fibers 54a1 to 54a5 of the multi-core optical fiber ribbons 53a1 to 53a5 being inserted into the fiber insertion holes 51a1 to 51a5, fiber fixing members such as adhesives are passed through the window holes 55. The optical connector is assembled by injecting and fixing the optical fibers 54a1 to 54a5.
[0014]
[Problems to be solved by the invention]
In an optical connector ferrule 50 having a multi-core (n-core) fiber insertion hole provided in multiple stages (m stages) (m-stage × n-core), the step direction in the fiber insertion holes 51a1 to 51a5 (hereinafter also referred to as the longitudinal direction). The pitch between the holes adjacent to each other (the vertical pitch between the central axes of the adjacent holes) is generally 0.25 mm. On the other hand, the thickness along the longitudinal direction of each of the multi-fiber optical fiber ribbons 53a1 to 53a5 is generally 0.3 mm.
[0015]
Therefore, between the position along the step direction of the central axis of the fiber insertion holes 51a2 to 51a5 of the second and subsequent steps and the center position along the step direction of the corresponding multi-core optical fiber ribbons 53a2 to 53a5. In FIG. 2, a deviation occurs in the vertical direction by the difference between the vertical pitch between the fiber insertion holes and the thickness of the multi-core optical fiber ribbon.
[0016]
Here, the deviation between the position along the step direction of each fiber insertion hole 51a1 at the lowest stage (first stage) and the position along the step direction of the corresponding multi-fiber optical fiber ribbon 53a1 is the internal structure of the ferrule. It depends on. For this reason, when the above deviation is α, the position along the step direction of the central axis of the fiber insertion hole 51ak at the k {1 ≦ k ≦ m (= 5)} step from the lowest step and the multi-core optical fiber ribbon The amount of deviation Gk between the center position along the step direction of 53ak is expressed by the following equation (1) using a difference of 0.05 mm between the longitudinal pitch between the fiber insertion holes and the thickness of the multi-core optical fiber ribbon. Can be expressed as
[0017]
[Formula 1]

[0018]
As can be seen from the above equation (1), the larger the number k of stages, the larger the deviation amount Gk. As described above, the deviation amount Gk is between the position along the center direction of the center axis of the fiber insertion hole of each stage after the second stage and the center position along the stage direction of the multi-fiber optical fiber ribbon 53ak. When the optical fibers 54a1 to 54a5 of the multi-core optical fiber ribbons 53a1 to 53a5 are inserted into the fiber insertion holes 51a1 to 51a5 in the respective stages in the generated state, as shown in FIG. In particular, the optical fibers 54a2 to 54a5 corresponding to the respective stages are bent. That is, the optical fibers 54a2 to 54a5 corresponding to the second and subsequent stages are fixed in a bent state.
[0019]
This bending of the optical fiber (bare fiber) may increase the connection loss from the viewpoint of optical characteristics. Further, from the viewpoint of strength characteristics, if the bent portion is deformed due to expansion and contraction in the ferrule due to temperature change, moisture absorption, or the like, it may be considered that the bare fiber is disconnected.
[0020]
The present invention has been made in view of the above-described circumstances, and an optical connector that can set the bending of an optical fiber (bare fiber) within a range that does not affect the optical characteristics and strength characteristics of the optical fiber. It is an object of the present invention to provide a ferrule, an optical connector, and an optical connector assembling method for preventing deterioration of optical characteristics and strength characteristics of the entire ferrule and the entire optical connector due to the bending of the fiber.
[0021]
[Means for Solving the Problems]
[0022]
According to the first aspect of the present invention for achieving the above-mentioned object, there is provided an optical connector ferrule for supporting an optical fiber ribbon in which an end portion is removed and an optical fiber is exposed. Are formed in such a manner that one end thereof communicates with a plurality of fiber insertion holes into which the optical fibers are inserted and end portions of the fiber insertion holes on the fiber insertion side. A guide portion for an optical fiber insertion guide extending along the central axis direction of the optical fiber, and an opening side end opposite to the fiber insertion side end of each fiber insertion hole along the central axis direction of the fiber insertion hole When each optical fiber of the optical fiber ribbon is inserted into each fiber insertion hole of each stage, the fiber of the tape-like member of the optical fiber ribbon is formed at a predetermined distance The outlet end is provided with abutment portion abutting.
[0023]
1st aspect of this invention WHEREIN: The predetermined distance along the center-axis direction of the said fiber insertion hole from the opening side edge part of each said fiber insertion hole to the said contact part is made into each fiber insertion hole of each said step | level. The curvature radii r1 to rm of the bending of each optical fiber at each stage when each optical fiber of the optical fiber ribbon is inserted (where m is an integer of 2 or more and corresponds to the number of stages) are predetermined. It is set to be greater than or equal to the value.
[0024]
According to the second aspect of the present invention for achieving the above-described object, an optical fiber tape core wire from which an end portion is removed and an optical fiber is exposed, and a ferrule for supporting the optical fiber tape core wire are provided. The ferrule is arranged in a plurality of steps, and is formed so that one end portion thereof communicates with a plurality of fiber insertion holes into which the optical fibers are inserted, and fiber insertion side ends of the respective fiber insertion holes. A guide portion for an optical fiber insertion guide extending along the central axis direction of each fiber insertion hole, and the fiber from the opening side end opposite to the fiber insertion side end of each fiber insertion hole. The optical fiber tape is formed when each optical fiber of the optical fiber ribbon is inserted into each fiber insertion hole of each stage. Fiber exposed end of the tape-like member flop core wire and an abutment portion abutting.
[0025]
According to the third aspect of the present invention for achieving the above-described object, there is provided an optical connector assembling method for assembling an optical connector using an optical fiber ribbon having an end portion removed and an optical fiber exposed. A plurality of fiber insertion holes that are arranged in a plurality of steps, and are formed so that one end thereof communicates with a fiber insertion side end of each of the fiber insertion holes, A guide part for an optical fiber insertion guide extending along the central axis direction of the fiber insertion hole and an opening side end opposite to the fiber insertion side end of each fiber insertion hole in the direction of the central axis of the fiber insertion hole Preparing a ferrule having a contact portion formed at a predetermined distance along the optical fiber tape, and inserting each optical fiber of the optical fiber ribbon into each fiber insertion hole of each stage. And a step of fiber exposed end of the tape-like member of the optical fiber ribbon is inserted to a position abutting the abutting portion.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0027]
FIG. 1 shows a schematic configuration of an optical connector ferrule (hereinafter simply referred to as a ferrule) 1 that constitutes an optical connector C according to an embodiment of the present invention, and a plurality of (this book) inserted and fixedly supported in the ferrule 1. In an embodiment, it is a perspective view showing a schematic structure of each of five optical fiber tape cores 2a1-2a5.
[0028]
FIG. 2 is a longitudinal sectional view of the ferrule 1 shown in FIG. 1 cut along the step direction (height direction) through the center of the fiber insertion hole 3, and II- It is an II arrow longitudinal cross-sectional view.
[0029]
As shown in FIGS. 1 and 2, the ferrule 1 has a rectangular shape, and is integrally formed by molding with, for example, a plastic material resin.
[0030]
That is, the ferrule 1 has a plurality of (multiple cores; in this embodiment, 12 cores) fiber insertion holes 3 along the longitudinal direction thereof. The plurality of fiber insertion holes 3 are arranged in a plurality of stages (in the present embodiment, the first to fifth stages) along the ferrule height direction. In addition, the plurality of fiber insertion holes 3 at each stage are juxtaposed with each other at a constant interval (pitch) along the short direction of the ferrule 1, and the distance between the fiber insertion holes 3 along the step direction ( The pitch is also constant.
[0031]
Hereinafter, in the present embodiment, the 12 fiber insertion holes 3 of the first-stage fiber insertion holes 3 are defined as 3N1, and similarly, the second to fifth-stage fiber insertion holes 3 are defined as 3N2 to 3N5. Describe.
[0032]
As shown in FIG. 1, each of the optical fiber ribbons 2 a 1 to 2 a 5 includes a plurality (12 cores) of optical fibers corresponding to a plurality (12 cores) of fiber insertion holes 3 at each stage, and the plurality of optical fibers. Tape-shaped members 2c1 to 2c5 that are coated in a tape shape are provided.
[0033]
At the end of the optical fiber ribbon 2a1 corresponding to the first stage, the tape-like member 2c1 at the end is removed, and the 12-fiber optical fiber (bare fiber in this case) 2b1 is exposed. Similarly, 12 optical fibers 2b2 to 2b5 are exposed at the ends of the second to fifth optical fiber ribbons 2a2 to 2a5.
[0034]
The hole diameter of each of the fiber insertion holes 3N1 to 3N5 is substantially equal to the wire diameter of the optical fibers 2b1 to 2b5 to such an extent that the corresponding optical fibers 2b1 to 2b5 can be inserted.
[0035]
Further, the ferrule 1 includes a first housing portion 5 having an opening surface including opening side end portions of a plurality of fiber insertion holes 3 arranged in a plurality of stages, and the opening surface of the first housing portion 5 is It becomes a connection end surface 5a with other optical components such as an optical connector and an optical module. In addition, the ferrule 1 includes a second housing portion 6 that extends from the first housing portion 5 along the central axis direction of the fiber insertion hole.
[0036]
The second housing portion 6 has an upper surface 7 connected along the axial direction of the fiber hole from the end portion of the first housing portion 5 along the step direction of the connection end surface 5a. A window hole 8 for injecting an optical fiber fixing member (for example, an adhesive) at the time of inserting the optical fiber of each optical fiber ribbon 2 into the stepped fiber insertion hole 3 is formed.
[0037]
As shown in FIGS. 1 and 2, the ferrule 1 is formed so that one end thereof communicates with the lower half peripheral edge of each stage of the fiber insertion holes 3N1 to 3N5. Guide grooves 10N1 to 10N5 for optical fiber insertion guides extending coaxially along the central axis direction are provided.
[0038]
The first to fifth-stage fiber insertion holes 3N1 to 3N5 extend to the end positions of the adjacent upper-stage fiber insertion holes on the side opposite to the optical fiber insertion direction. The step to fifth step guide grooves 10N1 to 10N5 and the fiber insertion holes 3N1 to 3N5 as a whole have a stepped shape extending from the upper step toward the lower step in the cross-sectional view shown in FIG. Therefore, the positions of the optical fiber insertion side end portions of the fiber insertion holes 3N1 to 3N5 of each stage are gradually separated from the connection end surface 5a from the upper stage toward the lower stage.
[0039]
3 is a cross-sectional view taken along arrow III-III when the ferrule 1 shown in FIG. 2 is cut along the peripheral edge upper end surface of the guide groove 10N3 corresponding to the third-stage fiber insertion hole 3N3.
[0040]
As shown in FIGS. 2 and 3, the second housing portion 6 includes an insertion port 12 for inserting the optical fiber ribbon 2 facing the opening surface 5 a of the first housing portion 5, and the insertion port. 12 and a flange portion 13 formed on the outer peripheral portion of the forming portion.
[0041]
2 and 3, the second housing portion 6 includes a contact portion 15 formed at a predetermined distance D from the connection end surface 5a along the center axis direction of the fiber insertion hole. .
[0042]
As shown in FIG. 3, the contact portion 15 is formed as projecting portions 15 a and 15 b that project stepwise from the inner peripheral edge portions 6 a and 6 b of the second housing portion 6 facing each other in the facing direction. .
[0043]
The distance D10 between the protrusion 15a and the protrusion 15b is shorter than the lateral width W10 of the fiber exposed side ends (end faces) 2d1 to 2d5 of the tape-like members 2c1 to 2c5 of the optical fiber ribbons 2a1 to 2a5. ing.
[0044]
Moreover, in order to prevent the distance D10 between the protrusion part 15a and the protrusion part 15b from interfering when the optical fibers 2b1 to 2b5 of the optical fiber tape cores 2a1 to 2a5 are inserted, the optical fiber tape core 2a1 is used. The lateral width between the optical fibers 2b1 and b5 at both ends in ˜2a5 (hereinafter referred to as optical fiber width) W11 is longer.
[0045]
The contact portion 15 is formed in a tape shape of the optical fiber ribbons 2a1 to 2a5 when the optical fibers 2b1 to 2b5 of the optical fiber ribbons 2a1 to 2a5 are inserted into the fiber insertion holes 3N1 to 3N5 of each stage. Fiber exposed side end portions (end faces) 2d1 to 2d5 of the members 2c1 to 2c5 are formed at positions where they abut.
[0046]
Further, the ferrule 1 is formed between the fiber insertion holes 3N1 to 3N5 including the respective guide grooves 10N1 to 10N5 having a stepped shape and the insertion port 8, and is inserted into the fiber insertion holes 3N1 to 3N5 of each step. A housing portion 16 for housing the optical fibers 2b1 to 2b5 is provided.
[0047]
Further, the ferrule 1 is disposed on both sides of the fiber insertion hole 3 along the parallel direction in parallel with the insertion hole, and has two guide pin holes 17a1 and 17a2 for inserting alignment guide pins. Have.
[0048]
With respect to the ferrule 1 configured as described above, the fiber tape core wire 2a1 corresponding to the first stage is inserted into the accommodating portion 16 through the insertion port 12.
[0049]
Then, the optical fiber 2b1 of the optical fiber ribbon 2a1 is inserted into the corresponding first-stage fiber insertion hole 3N1 along the guide groove 10N1.
[0050]
At this time, each optical fiber 2b1 of the optical fiber ribbon 2a1 is inserted into the corresponding fiber insertion hole 3N1 until the fiber exposed side end 2d1 of the tape-like member 2c1 contacts the contact portion 15. These fiber insertion holes 3N1 are supported.
[0051]
When the fiber 2b1 is inserted into the fiber insertion hole 3N1, the distance D10 between the protruding portion 15a that is the contact portion 15 and the protruding portion 15b is shorter than the lateral width W10 of the fiber exposed side end portions (end surfaces) 2d1 to 2d5. The fiber-exposed-side end 2d1 of the tape-like member 2c1 of the optical fiber ribbon 2a1 contacts the contact portion 15 and is fixed in the contact state.
[0052]
Hereinafter, the second to fifth stage optical fiber ribbons 2a2 to 2a5 are inserted into the housing portion 16 in ascending order from the second stage, and the optical fibers of the optical fiber ribbons 2a2 to 2a5 are inserted. The fibers 2b2 to 2b5 are inserted into the corresponding second to fifth fiber insertion holes 3N2 to 3N5 along the guide grooves 10N2 to 10N5.
[0053]
At this time, as in the first stage, the optical fiber 2b2 to 2b5 of the optical fiber ribbons 2a2 to 2a5 has the fiber exposed side end portions 2d2 to 2d5 of the tape-like members 2c2 to 2c5 abutting against the contact portion 15. Each of the fiber insertion holes 3N2 to 3N5 is inserted into the corresponding fiber insertion hole 3N2 to 3N5 and supported by the fiber insertion hole 3N2 to 3N5. Further, the fiber exposed side end portions 2d2 to 2d5 of the tape-like members 2c2 to 2c5 of the optical fiber ribbons 2a2 to 2a5 are fixed in a state of being in contact with the contact portion 15.
[0054]
4 shows the ferrule 1 and the optical fiber tape in a state where the optical fibers 2b1 to 2b5 of the optical fiber ribbons 2a1 to 2a5 are inserted into the first to fifth fiber insertion holes 3N1 to 3N5 of the ferrule 1. It is a longitudinal cross-sectional view corresponding to FIG. 2 at the time of cutting the core wires 2a1 to 2a5 along the step direction (height direction) through the centers of the fiber insertion holes 3N1 to 3N5.
[0055]
5 shows the ferrule 1 in a state where the optical fibers 2b1 to 2b5 of the optical fiber ribbons 2a1 to 2a5 shown in FIG. 4 are inserted into the periphery of the guide groove 10N3 corresponding to the third-stage fiber insertion hole 3N3. It is a VV arrow cross-sectional view at the time of cutting along a part upper end surface.
[0056]
As shown in FIGS. 4 and 5, the optical fibers 2b1 to 2b5 of all the optical fiber ribbons 2a1 to 2a5 have fiber exposed side end portions 2d1 to 2d5 in the tape-like members 2c1 to 2c5 at the contact portions 15. It is inserted to the position where it abuts and is fixed.
[0057]
In this manner, with the optical fibers 2b1 to 2b5 inserted and supported in the fiber insertion holes 3N1 to 3N5, the adhesive is injected into the ferrule 1 through the window holes 8 to fix the optical fibers 2b1 to 2b5. Thus, the optical connector C is created.
[0058]
Next, the operation based on the configuration of the ferrule 1 and the connector C of the present embodiment will be described.
[0059]
FIG. 6 shows an optical fiber 54a2 in a state where the optical fibers 54a1 to 54a3 of the multicore optical fiber ribbons 53a1 to 53a3 are inserted into the conventional first to third fiber insertion holes 51a1 to 51a3. It is a figure which shows the curve of 54a3.
[0060]
That is, the bend of the optical fiber 54ak in the k-th stage (k is an integer of 1 or more) can be expressed as the radius of curvature r of the optical fiber 54ak. The radius of curvature r of the optical fiber 54ak is between the end portion (optical fiber exposed side end) 53bk of the k-th stage optical fiber ribbon 53ak and the guide groove 52 of the corresponding fiber insertion hole 51ak. And a deviation amount Gk between the position along the step direction of the central axis of the fiber insertion hole 51ak at the k-th stage and the center position along the step direction of the multi-fiber optical fiber ribbon 53ak at the k-th stage are parameters. Can be expressed as
[0061]
Next, a method for approximately indicating the curvature radius r of the bend will be described.
[0062]
As shown in FIG. 7, the locus of the optical fiber fixed in a state where both ends (fixed point a) are displaced (positional deviation amount G corresponding to the above-described deviation amount Gk) is first set with the fixed point a as the origin. The sin curve is approximated in the xy coordinate system. That is, in the locus of the optical fiber shown in FIG. 7, when the distance between the fixed points is D (corresponding to the distance Dk ′), the wavelength of the cos function (y = cos x) having the fixed point a as the origin is 2D. It can be approximated as an inverted curve.
[0063]
That is,
[Formula 2]

[0064]
When the origin of equation (2) is set to a fixed point, equation (2) can be expressed as the following equation.
[Formula 3]

[0065]
As shown in FIG. 7, since the amplitude corresponds to G, the trajectory of the optical fiber finally becomes
[Formula 4]

Can be expressed as
[0066]
Further, the radius of curvature r at the point x of the locus that can be expressed in the xy coordinate system can be expressed by the following equation (5).
[Formula 5]

[0067]
Since the radius of curvature is minimum at both ends (that is, the curve is maximum), the equation (4) is second-order differentiated and substituted into the equation (5), and further, x = 0 is substituted and the equation (5) is calculated. The following equation (6) is derived.
[0068]
[Formula 6]

[0069]
That is, since the bend of the optical fiber is inversely proportional to the radius of curvature r, as can be seen from equation (6), if the distance D is increased, the radius of curvature r can be increased to reduce the bend.
[0070]
In this regard, in the conventional ferrule 50, as shown in FIG. 6, each optical fiber 54a1 of the first-stage optical fiber ribbon 53a1 is connected to each fiber insertion hole 51a1 corresponding to the optical fiber exposed side end 53b1. Are inserted into the fiber insertion holes 51a1 up to the position where they abut against the guide grooves 52, and the optical fibers 54a2 to 54a5 of the second to fifth stages are inserted into the corresponding optical fiber exposed side end portions 53b2 to 53b5 in the axial direction of the fiber hole. Are inserted into the corresponding fiber insertion holes 51a2 to 51a5 so that the positions along the fiber hole center axis direction of the first-stage optical fiber exposed side end portion 53b1 are the same.
[0071]
Therefore, the distance Dk ′ between the optical fiber exposed side end portion 53bk of the k-th stage optical fiber ribbon 53ak and the guide groove 52 of the fiber insertion hole 51ak in the second and subsequent stages (k ≧ 2) corresponds to If the length of the k-th guide groove 52 in the fiber hole central axis direction is L, it can be expressed as the following equation (7).
[Formula 7]

[0072]
In other words, the distance Dk ′ is the corresponding k-th guide groove 52 in the fiber hole central axis direction. Because it depends on the length L Very short and large bending (distortion) will occur.
[0073]
In the optical connector C assembled by inserting and fixing the optical fibers 2b1 to 2b5 of the optical fiber ribbons 2a1 to 2a5 using the conventional ferrule 50, the optical fibers 2b2 to 2b5 in the second and subsequent stages are greatly bent ( Distortion) will occur.
[0074]
However, in the configuration of the present embodiment, as shown in FIGS. 4, 5, and 8, etc., fiber insertion at each stage is performed from the other ends E1 to E5 on the opposite side of the fiber insertion holes of the guide grooves 10N1 to 10N5. A contact portion 15 formed at a predetermined distance Dk (D1 to D5) is provided along the central axis direction of the holes 3N1 to 3N5. For this reason, when the optical fibers 2b1 to 2b5 of the optical fiber ribbons 2a1 to 2a5 are inserted into the fiber insertion holes 3N1 to 3N5 of each stage, the tape-like members 2c1 to 2c5 of the optical fiber tapes 2a1 to 2a5 are inserted. The fiber exposed side end portions (end surfaces) 2d1 to 2d5 are fixed to contact the contact portion 15.
[0075]
That is, in the configuration of the present embodiment, the distance Dk between the optical fiber exposed side end 2dk of the k-th stage fiber tape core 2ak and the corresponding other end Ek of the guide groove 10Nk of the corresponding fiber insertion hole 3Nk is set. The arrangement position of the contact portion 15 along the center axis direction of the fiber insertion hole, in other words, the distance Dk along the center axis direction of the fiber insertion hole 3Nk from the other end Ek of the guide groove 10Nk of the contact portion 15 It can be expressed as (D1-D5).
[0076]
Therefore, the distance between the optical fiber exposed side end 2dk of the k-th stage fiber tape core 2ak corresponding to the distance of the contact portion 15 and the other end Ek of the guide groove 10Nk of the corresponding fiber insertion hole 3Nk. If Dk is set sufficiently long and the radius of curvature r of each of the optical fibers 2b1 to 2b5 is increased, the bending (distortion) occurring in each of the optical fibers 2b1 to 2b5 can be suppressed to the minimum.
[0077]
In general, it is known that the bending that occurs in each of the optical fibers 2b1 to 2b5 does not affect the optical characteristics and strength characteristics of each optical fiber if the curvature radius r is 30 mm or more.
[0078]
Therefore, in this embodiment, the distance Dk between the optical fiber exposed side end 2dk of the k-th stage fiber tape core 2ak and the corresponding other end Ek of the guide groove 10Nk of the corresponding fiber insertion hole 3Nk is set to each light. The radius of curvature r of the fibers 2b1 to 2b5 is set to be 30 mm or more.
[0079]
For example, in the present embodiment, the k (1 ≦ k ≦ 5) stage fiber position deviation amount Gk is expressed by the above equation (1) using the difference 0.05 between the fiber pitch in the stage direction and the thickness of the tape-shaped member. {Gk = 0.05 (k−1) + α}. A length Dk of the guide grooves 10N1 to 10N5 of each step along the center axis direction of the fiber insertion hole is L = 0.3 (mm), and a distance Dk that satisfies r ≧ 30 mm or more using the above formula (6). The results shown in Table 1 were obtained.
[0080]
[Table 1]

[0081]
Here, in the ferrule 1 of this embodiment, when the distance from the connection end surface 5a to the other end E5 of the fifth-stage guide groove 10N5 along the fiber insertion hole central axis direction is 2.0 (mm), the connection The distance from the end face 5a to the other end E4 of the fourth-stage guide groove 10N4 along the fiber insertion hole central axis direction is 2.3 (mm), and the distance from the connection end face 5a to the fiber insertion hole central axis direction is three stages. The distance from the guide groove 10N3 of the eye to the other end E3 is 2.6 (mm), and the distance from the connection end surface 5a to the other end E2 of the second-stage guide groove 10N2 along the center axis direction of the fiber insertion hole is The distance from the connection end surface 5a to the other end E1 of the first-stage guide groove 10N1 along the center axis direction of the fiber insertion hole is 3.2 (mm).
[0082]
Therefore, the distances Ds1 between the ferrule end face 5a of each stage (1 stage to 5 stages) and the optical fiber exposed side ends 2d1 to 2d5 of the first to fifth stage fiber tape cores 2a1 to 2a5. Ds5 is obtained as shown in Table 2 below.
[Table 2]

[0083]
That is, the distances Ds1 to Ds5 from the ferrule end face 5a to the optical fiber exposed side ends 2d1 to 2d5 of the first to fifth stage fiber tape cores 2a1 to 2a5 are individually shown in Table 2 for each stage. If the values Ds1 = 3.20 (mm) to Ds5 = 7.44 (mm) are set, the radius of curvature r of the optical fibers 2b1 to 2b5 can be set to r ≧ 30 mm or more.
[0084]
However, it is difficult to set the distances Ds1 to Ds5 of the optical fiber exposed side ends 2d1 to 2d5 of the first to fifth stage fiber tape cores 2a1 to 2a5 individually for each stage.
[0085]
Therefore, in the present embodiment, the longest stage (fifth stage) among the distances Ds1 to Ds5 of the optical fiber exposed side ends 2d1 to 2d5 of the first to fifth stage fiber tape cores 2a1 to 2a5. ) Between the ferrule end face 5a of each stage (1st to 5th stage) and the optical fiber exposed side ends 2d1 to 2d5 of the first to fifth stage fiber tape cores 2a1 to 2a5. Is set as a common distance.
[0086]
That is, the distance D between the connection end surface 5a and the contact portion 15 along the fiber insertion hole central axis direction is set to Ds5 = 7.44 (mm).
[0087]
As a result, in this embodiment, since the fiber exposed side end portions 2d1 to 2d5 of the tape-like members 2c1 to 2c5 of all the fiber tapes 2a1 to 2a5 are in contact with and fixed to the contact portion 15, the fiber exposed side Ends (peeling ends) 2d1 to 2d5 can be fixed at positions where the corresponding radii of curvature r of the optical fibers 2b1 to 2b5 are 30 mm or more.
[0088]
Therefore, the bending of each optical fiber 2b1-2b5 can be suppressed to the minimum that does not affect the optical characteristics and strength characteristics of each optical fiber 2b1-2b5.
[0089]
As a result, deterioration of optical characteristics and strength characteristics due to bending of the optical fibers 2b1 to 2b5 due to the influence of molding distortion, temperature change, distortion due to moisture absorption, etc. is suppressed, and the reliability of the entire ferrule 1 and the entire optical connector C is increased. Can be maintained.
[0090]
The distance D = 7.44 (mm) between the connection end surface 5a and the abutment portion 15 along the fiber insertion hole central axis direction is merely a specific example, and is not limited to this numerical value itself. It is.
[0091]
Further, in the present embodiment, the reliability allowable range of the curvature radius r of the bend generated in each of the optical fibers 2b1 to 2b5 is set to 30 mm or more, and between the connection end surface 5a and the contact portion 15 along the fiber insertion hole central axis direction. The distance D is set so that the radius of curvature r is 30 mm or more, but the present invention is not limited to this.
[0092]
That is, even if the radius of curvature r is less than 30 mm for reasons such as reducing the size of the ferrule itself at the expense of some reliability, the connection end face 5a and the center of the fiber insertion hole are satisfied so as to satisfy the radius of curvature r. What is necessary is just to set the distance D between the contact parts 15 along an axial direction.
[0093]
Furthermore, in the present embodiment, a 60-fiber ferrule in which 12 fiber insertion holes are arranged from the first stage to the fifth stage and an optical connector using the 60-core ferrule have been described. The present invention is not limited, and any ferrule having a plurality of fiber insertion holes arranged in a plurality of stages and an optical connector using the ferrule may be used.
[0094]
【The invention's effect】
As described above, according to the ferrule for optical connector, the optical connector, and the optical connector assembling method according to the present invention, the fiber insertion hole is formed from the opening side end opposite to the fiber insertion side end of each fiber insertion hole. When the optical fiber at the end of the tape core is inserted into each fiber insertion hole of each stage formed at a predetermined distance along the central axis direction, the fiber exposed side of the tape-shaped member of the tape core Since the abutting portion with which the end abuts is provided, the predetermined distance of the abutting portion can be set to a value that does not affect the bending of each optical fiber (the radius of curvature of the bending is 30 mm or more).
[0095]
Therefore, the bending of each optical fiber can be suppressed to the minimum that does not affect the optical characteristics and strength characteristics of each optical fiber. As a result, it is possible to suppress deterioration of the optical characteristics and strength characteristics due to the bending of the optical fiber, and to maintain high reliability of the entire ferrule and the entire optical connector.
[Brief description of the drawings]
FIG. 1 shows a schematic configuration of an optical connector ferrule that constitutes an optical connector according to an embodiment of the present invention, and a schematic configuration of a plurality of optical fiber ribbons that are inserted and fixedly supported in the ferrule. Perspective view.
2 is a longitudinal sectional view when the ferrule shown in FIG. 1 is cut along the step direction (height direction) through the center of the fiber insertion hole, and is a longitudinal sectional view taken along the line II-II shown in FIG. 3; .
3 is a cross-sectional view taken along arrow III-III when the ferrule shown in FIG. 2 is cut along the upper end surface of the peripheral edge portion of the guide groove corresponding to the third-stage fiber insertion hole.
FIG. 4 shows the ferrule and optical fiber ribbon in a state where the optical fiber of the optical fiber tape is inserted into the fiber insertion holes of the first to fifth stages of the ferrule, passing through the center of the fiber insertion hole. The longitudinal cross-sectional view corresponding to FIG. 2 at the time of cutting along a step direction (height direction).
5 is a view showing a case where the ferrule with the optical fiber of the optical fiber ribbon shown in FIG. 4 inserted therein is cut along the upper end surface of the peripheral edge of the guide groove corresponding to the third-stage fiber insertion hole. -V arrow cross-sectional view.
FIG. 6 is an enlarged view showing bending of an optical fiber and a state where each optical fiber of each multi-core optical fiber ribbon is inserted into a conventional first to third stage fiber insertion hole.
FIG. 7 is a diagram illustrating a trajectory of an optical fiber in which both ends are fixed to misalignment.
FIG. 8 is an enlarged view of the bending of the optical fiber in a state where each optical fiber of each multi-fiber optical fiber ribbon is inserted into the first to third-stage fiber insertion holes of the present embodiment. Figure.
FIG. 9 is a perspective view showing a schematic configuration of a conventional ferrule for an optical connector.
FIG. 10 is a longitudinal sectional view of the ferrule shown in FIG. 9 cut along the step direction through the center of the fiber insertion hole.
11 is a longitudinal sectional view showing a state where an optical fiber of a fiber tape is inserted into the ferrule shown in FIG.
[Explanation of symbols]
1 Ferrule
2a1-2a5 Optical fiber tape
2b1-2b5 optical fiber (bare fiber)
2c1-2c5 Tape-shaped member
2d1-2d5 Fiber exposed side end
3, 3N1-3N5 Fiber insertion hole
5 First housing part
5a Connection end face
6 Second housing part
7 Top surface
8 Window holes
10N1-10N5 guide groove
12 insertion slot
13 Flange
15 Contact part
15a, 15b Projection
16 containment

Claims (5)

A plurality of fiber insertion holes are formed at a predetermined step pitch on the connection end surface of the ferrule, and an optical fiber tape core is formed at an opening side end opposite to the connection end surface at a step pitch larger than the predetermined step pitch. An optical connector ferrule in which a plurality of wires are arranged, and the optical fiber of each stage exposed by removing the coating of the end portion of the optical fiber ribbon is arranged in the fiber insertion hole of each stage for each stage. And
Are arranged in a plurality of stepped, and the plurality of fiber insertion hole in which the optical fiber is inserted,
One end portion is formed to communicate with the fiber insertion side end portion of each fiber insertion hole, and a guide portion for an optical fiber insertion guide extending along the central axis direction of each fiber insertion hole,
Wherein the said connecting end face of each fiber insertion holes along from the opening side end opposite the center axis direction of the fiber insertion hole, the optical fiber tape center to the each fiber insertion hole of the optical fiber tapes each stage The radius of curvature r1-rm (where m is an integer greater than or equal to 2 and corresponds to the number of stages) of the bending of each optical fiber at each stage when each optical fiber of the wire is inserted is 30 mm or more. When the respective optical fibers of the optical fiber ribbon are inserted into the respective fiber insertion holes of the respective stages, the fibers of the tape-like member of the optical fiber ribbon are formed at a set predetermined distance. A contact portion with which the exposed side end abuts,
An optical connector ferrule characterized by comprising: A plurality of fiber insertion holes are formed, a first housing part having an opening surface including an opening side end part of the plurality of fiber insertion holes, and the fiber insertion hole central axis direction from the first housing part And a second housing part including an insertion port for inserting the optical fiber ribbon, facing the opening surface,
2. The ferrule for an optical connector according to claim 1 , wherein the contact portion is a protruding portion that protrudes stepwise in the opposing direction from the inner peripheral edge portions of the second housing portion that face each other. The distance between the projection projecting respectively from the insertion mouth periphery of the facing each other, wherein characterized in that said optical fiber ribbon tape-like fiber exposed end shorter than the width length of the member Item 3. An optical connector ferrule according to Item 2 . A plurality of fiber insertion holes are formed at a predetermined inter-step pitch on the connection end face of the ferrule, and an optical fiber tape core is formed at an opening side end opposite to the connection end face at an inter-step pitch larger than the predetermined inter-step pitch. An optical connector in which a plurality of wires are arranged, and an optical fiber for each step exposed by removing the coating at the end of the optical fiber ribbon is arranged in each fiber insertion hole for each step ,
With said optical fiber ribbon is coated end is removed optical fiber is exposed, and the ferrule of the optical fiber ribbon supporting,
The ferrule is
Are arranged in a plurality of stepped, and the plurality of fiber insertion hole in which the optical fiber is inserted,
One end portion is formed to communicate with the fiber insertion side end portion of each fiber insertion hole, and a guide portion for an optical fiber insertion guide extending along the central axis direction of each fiber insertion hole,
Along said central axis of said fiber insertion hole from the opening side end portion opposite to the fiber insertion side end portion of each of the fiber insertion hole, the optical fiber to the each fiber insertion hole of the optical fiber tapes each stage The curvature radii r1 to rm of the bending of each optical fiber in each stage when each optical fiber of the tape core is inserted (where m is an integer of 2 or more and corresponds to the number of stages) is 30 mm or more. When the optical fibers of the optical fiber ribbon are inserted into the fiber insertion holes of the respective stages, the tape-like member of the optical fiber ribbon is formed at a predetermined distance set as described above. A contact portion with which the fiber exposed side end of the
An optical connector comprising: An optical connector assembling method for assembling an optical connector using an optical fiber ribbon with an end portion removed and an optical fiber exposed.
A plurality of fiber insertion holes in the connection end face of the ferrule is a plurality of stages formed in a predetermined interstage pitch, said plurality of fiber insertion hole in which the optical fiber is inserted, the one end with respect to the fiber insertion side end portion of each of the fiber insertion hole The optical fiber insertion guide guide portion extending along the central axis direction of each fiber insertion hole and the opening-side end opposite to the connection end face are formed between the predetermined steps. A plurality of the optical fiber ribbons are arranged at a step-to-step pitch larger than the pitch, and each fiber insertion hole of each step of the optical fiber tape extends from the opening side end along the central axis direction of the fiber insertion hole. The radius of curvature r1 to rm of each optical fiber at each stage when each optical fiber of the optical fiber ribbon is inserted (where m is an integer of 2 or more, Comprising the steps of: providing a ferrule having abutments corresponding to the number) are formed at a predetermined distance set to be equal to or greater than the 30mm respectively,
Inserting each optical fiber of the optical fiber ribbon into each fiber insertion hole in each stage to a position where a fiber exposed side end of a tape-like member of the optical fiber ribbon is in contact with the contact portion When,
An optical connector assembling method comprising:

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