JP4117876B2 - Write-once optical recording medium and recording / reproducing method thereof - Google Patents

Description

【００３９】
実施例１
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、変形形状補償層としてＤＶＤ−Ｒに利用できる上記〔化１〕の色素からなる色素層を厚さ約６０ｎｍ、その上に光吸収機能を有する変形層としてＳｉＣを厚さ１０ｎｍ、更にその上に変形受容層としてポリスチレン樹脂を厚さ約２μｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、ポリスチレン樹脂層側から９．７ｍＷのレーザ光を照射し、ランド部（入射レーザ光側から見て、手前側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで８−１６変調の信号を記録した。
その結果、変調度が約６１％で、記録極性がＨｉｇｈ ｔｏ Ｌｏｗであり、比較例１と同様に明瞭なアイパターンが得られ、ジッタ（σ／Ｔｗ）は８．０％となった。
また、記録パワーに対するジッタ特性は、図２４の■で示した線のようになり、比較例１のディスクに比べて（図２４の◆で示した線）、記録パワーマージンが広いことが確認できた（変形受容層の効果が確認できた）。
この時、ポリスチレン樹脂層を剥がし、変形層の変形状態をＡＦＭによって確認したところ、図２３に示すように、変形層は入射光側（ポリスチレン樹脂層側）に変形しており、またその変形形状の対称性は良好であった。なお、図２３中の白い点線はマーク中心を示す線である。
【００４０】
比較例２
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、光吸収機能を有する変形層としてＳｉＣを厚さ１０ｎｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、ＳｉＣ側から８．０ｍＷのレーザ光を照射し、ランド部（入射レーザ光側から見て、手前側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで８−１６変調の信号を記録した。
その結果、変調度が約７０％で、記録極性がＨｉｇｈ ｔｏ Ｌｏｗであり、図１８に示すような、比較的良好なアイパターンが得られたが、ジッタ（σ／Ｔｗ）は１０．４％と大きくなった。
また、記録パワーに対するジッタ特性は、図２０の●で示した線のようになり、前述した比較例１に比べて、ジッタの値が悪く、また記録パワーマージンも狭いことが確認できた。
この時、変形層の変形状態をＡＦＭによって確認したところ、図２１に示すように、変形層は入射光側に変形しているが、その変形形状の対称性が大きく崩れていた。なお、図２１中の白い点線はマーク中心を示す線である。
以上、比較例１と比較例２の結果から、変形形状補償層の有効性が示され、比較例１と実施例１の結果から、変形受容層の有効性が示された。
【００４１】
実施例２
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、変形形状補償層として青色レーザ波長に吸収を持つ下記〔化２〕からなる色素層を厚さ約２０ｎｍ、光吸収機能を有する変形層としてＳｉＣを厚さ約５ｎｍ、変形受容層としてポリスチレン樹脂からなる層を厚さ約８０ｎｍ、反射層としてＡｇを厚さ約１００ｎｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、基板側から９．５ｍＷのレーザ光を照射し、ランド部（入射レーザ光側から見て、奥側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで８−１６変調の信号を記録した。
その結果、記録パワーに対するジッタ特性は、図２５の■で示した線のようになり、後述する比較例３に比べて、ジッタの値が良いことが確認できた。
また、繰り返し再生による再生劣化が殆どなく、記録部の色素層は分解・変質を起していることが確認できた。
【００４２】
【化２】

【００４３】
比較例３
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、光吸収機能を有する変形層としてＳｉＣを厚さ約１０ｎｍ、変形受容層としてポリスチレン樹脂からなる層を厚さ約８０ｎｍ、反射層としてＡｇを厚さ約１００ｎｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、基板側から９．８ｍＷのレーザ光を照射して、ランド部（入射レーザ光側から見て、奥側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで８−１６変調の信号を記録した。
その結果、記録パワーに対するジッタ特性は、図２５の◆で示した線のようになり、前述の実施例２に比べて、ジッタの値が悪かった。
【００４４】
以上、実施例において、本発明の変形形状補償層と変形受容層の効果を確認したが、本発明では、光吸収層に記録に必要な光吸収機能を持たせることにより、色素層（例えば変形形状補償層）に大きな光吸収機能を持たせる必要がなくなるため、色素層の膜厚を薄膜化でき、従って、浅溝基板の利用が可能であることを確認した。
また、上記実施例では、何れも記録をランド部に行ったが、これは、変形層の変形形状を観察し易くするためであって、本発明はランド記録に限定されるものではない。
【００４５】
次に、参考例１〜８により、変形層とその隣接層の界面が主反射界面となる場合において、変形層を入射光側に変形させることの重要性を示すが、これらの参考例では、変形層の変形の作用を明確にするため、変形形状補償層を設けない光記録媒体で実験を行った（変形形状補償層を設けた場合も、これらの参考例と同様な現象となる）。
なお、図１０〜図１７は、それぞれ参考例１〜８の記録結果を示す図である。
図１０（ａ）〜図１７（ａ）は、参考例１〜８の再生信号（ＲＦレベル）の記録マーク長（Ｍａｒｋ Ｌｅｎｇｔｈ）依存性を測定した結果を示す図であり、各図中の、Ｕｎｒｅｃは未記録時の再生信号（ＲＦレベル）を、Ｔｏｐはマーク列を記録した時の最大再生信号レベル（即ちスペース部）を、Ｂｏｔｔｏｍはマーク列を記録した時の最小再生信号レベルを、ＭＡは（Ｔｏｐ−Ｂｏｔｔｏｍ）／Ｔｏｐで計算される変調度を示す。
また、図１０（ｂ）〜図１６（ｂ）には、３Ｔマークを連続して記録した場合の再生信号、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを、図１０（ｃ）〜図１６（ｃ）には、６Ｔマークを連続して記録した場合の再生信号、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを、図１０（ｄ）〜図１７（ｄ）には、３Ｔマークを連続して記録した場合の再生信号、１４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示した。
【００４６】
参考例１
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、光吸収機能を有する変形層としてＳｉＣを厚さ１０ｎｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、基板側から５．０ｍＷのレーザ光を照射し、グルーブ部（入射レーザ光側から見て、手前側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで３Ｔ〜１４Ｔマークをそれぞれ単独で記録した。
なお、ＳｉＣは入射光とは反対側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１０（ａ）の結果から、記録マーク長によらずＨｉｇｈ ｔｏ Ｌｏｗ記録が行えている可能性があることが確認できる。
更に、図１０（ｂ）〜図１０（ｄ）の結果から、３Ｔ、４Ｔ、６Ｔ、８Ｔ、１４Ｔとも、マーク長記録が可能な再生信号波形を示すことが分る。
【００４７】
参考例２
記録パワーを６．０ｍＷとした点以外は参考例１と全く同様の実験を行った。なお、ＳｉＣは入射光とは反対側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１１（ａ）の結果から、記録マーク長によって記録極性が変化すること、即ち、短マークではＨｉｇｈ ｔｏ Ｌｏｗ記録であるが、長マークではＨｉｇｈ ｔｏ Ｌｏｗ記録とＬｏｗ ｔｏ Ｈｉｇｈ記録が混在したような信号が発生し、マーク長記録が困難となることが分る。
更に、図１１（ｂ）〜図１１（ｄ）の結果から、３Ｔ、４Ｔはマーク長記録が可能な再生信号波形を示すが、６Ｔ、８Ｔ、１４Ｔはマーク中央部のＲＦレベルが大きく上昇した再生信号波形を示し〔６Ｔ、８Ｔでは、再生信号の周期が本来の再生信号の倍に見える。このことは図１０（ｃ）と比べるとよく分る〕、マーク長記録が困難となることが分る。
【００４８】
参考例３
基板側から６．０ｍＷのレーザ光を照射してランド部（入射レーザ光側から見て奥側にある溝位置）に記録した点以外は参考例１と全く同様の実験を行った。なお、ＳｉＣは入射光とは反対側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１２（ａ）の結果から、記録マーク長によって記録極性が変化する傾向、即ち、短マークではＨｉｇｈ ｔｏ Ｌｏｗ記録であるが、長マークではＨｉｇｈ ｔｏ Ｌｏｗ記録とＬｏｗ ｔｏ Ｈｉｇｈ記録が混在したような信号が発生する傾向が見られ、マーク長記録が困難となる可能性があることが分る。更に、図１２（ｂ）〜図１２（ｄ）の結果から、３Ｔ、４Ｔ、６Ｔ、８Ｔは、マーク長記録が可能な再生信号波形を示すが、１４Ｔはマーク中央部のＲＦレベルが大きく上昇した再生信号波形を示し、マーク長記録が困難となることが分る。
【００４９】
参考例４
基板側から７．０ｍＷのレーザ光を照射してランド部（入射レーザ光側から見て奥側にある溝位置）に記録した点以外は参考例１と全く同様の実験を行った。
なお、ＳｉＣは入射光とは反対側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１３（ａ）の結果から、記録マーク長によって記録極性が変化すること、即ち、短マークではＨｉｇｈ ｔｏ Ｌｏｗ記録であるが、長マークではＨｉｇｈ ｔｏ Ｌｏｗ記録とＬｏｗ ｔｏ Ｈｉｇｈ記録が混在したような信号が発生し、マーク長記録が困難となることが分る。
更に、図１３（ｂ）〜図１３（ｄ）の結果から、３Ｔ、４Ｔは、マーク長記録が可能な再生信号波形を示すが、６Ｔ、８Ｔ、１４Ｔはマーク中央部のＲＦレベルが大きく上昇した再生信号波形を示し〔例えば６Ｔでは再生信号の周期が本来の再生信号の倍に見える。このことは図１０（ｃ）と比べるとよく分る〕、マーク長記録が困難となることが分る。
【００５０】
以上、参考例１〜４の結果から、変形層とその隣接層の界面が主反射界面となり、基板上に光吸収機能を有する変形層を設けたような単純層構成で、変形層を入射光と反対側に変形させる場合は（今の場合、基板側から記録再生する方式では）、マーク長による記録再生が困難である場合が多く、また記録極性がＬｏｗｔｏ Ｈｉｇｈ化する場合が多いことが確かめられた。
【００５１】
参考例５
溝深さ５５ｎｍの案内溝を有するポリカーボネート基板上に、光吸収機能を有する変形層としてＳｉＣを厚さ１０ｎｍ設けた光記録媒体を作製した。
この光記録媒体に対して、パルステック工業製の光ディスク評価装置、ＤＤＵ−１０００（波長：４０５ｎｍ、ＮＡ：０．６５）を用いて、ＳｉＣ側から８．０ｍＷのレーザ光を照射し、ランド部（入射レーザ光側から見て、手前側にある溝位置）に、記録周波数６５．４ＭＨｚ、記録線速度６．０ｍ／ｓで３Ｔ〜１４Ｔマークをそれぞれ単独で記録した。
なお、ＳｉＣは入射光側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１４（ａ）の結果から、記録マーク長によらずＨｉｇｈ ｔｏ Ｌｏｗ記録が行えている可能性があることが確認できる。
更に、図１４（ｂ）〜図１４（ｄ）の結果から、３Ｔ、４Ｔ、６Ｔ、８Ｔ、１４Ｔとも、マーク長記録が可能な再生信号波形を示すことが分る。
【００５２】
参考例６
記録パワーを９．０ｍＷとした点以外は参考例５と全く同様の実験を行った。
なお、ＳｉＣは入射光側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１５（ａ）の結果から、記録マーク長によらずＨｉｇｈ ｔｏ Ｌｏｗ記録が行えている可能性があることが確認できる。
更に、図１５（ｂ）〜図１５（ｄ）の結果から、３Ｔ、４Ｔ、６Ｔ、８Ｔ、１４Ｔとも、マーク長記録が可能な再生信号波形を示すことが分る。
【００５３】
参考例７
ＳｉＣ側から７．０ｍＷのレーザ光を照射してグル−ブ部（入射レーザ光側から見て奥側にある溝位置）に記録した点以外は、参考例５と全く同様の実験を行った。なお、ＳｉＣは入射光側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１６（ａ）の結果から、記録マーク長によらずＨｉｇｈ ｔｏ Ｌｏｗ記録が行えている可能性があることが確認できる。
更に、図１６（ｂ）〜図１６（ｄ）の結果から、３Ｔ、４Ｔ、６Ｔ、８Ｔ、１４Ｔとも、マーク長記録が可能な再生信号波形を示すことが分る。
【００５４】
参考例８
基板側から８．０ｍＷのレーザ光を照射してグル−ブ部（入射レーザ光側から見て奥側にある溝位置）に記録した点以外は参考例５と全く同様の実験を行った。なお、ＳｉＣは入射光側（反基板側）に変形していることをＡＦＭにより確認した。
また、図１７（ａ）の結果から、記録マーク長によらずＨｉｇｈ ｔｏ Ｌｏｗ記録が行えている可能性があることが確認できる。
更に、図１７（ｄ）の結果から、最短及び最長マークとも、マーク長記録が可能な再生信号波形を示すことが分る。
【００５５】
以上、参考例５〜８に示したように、変形層とその隣接層の界面が主反射界面となり、基板上に光吸収機能を有する変形層を設けただけの単純な光記録媒体であって、変形層を入射光側に変形させる場合は（今の場合、反基板側から記録再生する方式では）、マーク長記録が可能で、Ｈｉｇｈ ｔｏ Ｌｏｗ記録が行える可能性があることが実験によって証明された。
【００５６】
【発明の効果】
本発明１〜２２によれば、単純層構成で安価に製造可能であり、記録再生波長に大きな制限がなく、記録特性の波長依存性が少なく、有機材料を用いる場合でも有機材料に対して従来のような厳しい光学的条件が不要であり、変形を主体とする記録原理を用いているにも関わらず良好なジッタと広い記録パワーマージンを実現でき、表面記録或いは高ＮＡレンズによる記録に対応でき高密度化が達成できるという特性を有する追記型光記録媒体及びその記録再生方法を提供できる。
【図面の簡単な説明】
【図１】変形層の変形形状の対称性を説明する図。
（ａ） 対称性が悪化した変形形状の例。
（ｂ） 理想的な変形形状の例。
【図２】マーク長記録の記録マークを再生した場合の再生信号の波形を説明する図。
（ａ） 一般的な場合
（ｂ） 記録マークの前後エッジ近傍で変極点を持つ微分波形
（ｃ） 記録マークの中心近傍で変極点を持つ微分波形
【図３】変形層に変形形状補償層と変形受容層を隣接させた構造を有する例を示す図。
【図４】図３の構造を有し、主反射界面が変形層と変形受容層の界面にある場合の、変形層の変形方向と再生方向を示した図。
【図５】図４の構造と機能を有する層構成を、実際の追記型光記録媒体に適用した例、即ち、基板上に図４の層構成を積層した例を示す図。
【図６】図４の構造と機能を有する層構成を、実際の追記型光記録媒体に適用した別の例、即ち、基板上に図４の層構成を積層し、更に変形受容層上にカバー層を設けた例を示す図。
【図７】図４の構造と機能を有する層構成を、実際の追記型光記録媒体に適用した更に別の例、即ち、基板上に図４の層構成を積層し、更に変形受容層上に接着層を介してカバー層を設けた例を示す図。
【図８】図３の構造を有し、変形受容層の変形層とは反対側の隣接層として反射層を有する構造であって、主反射界面が変形受容層と反射層の界面にある場合の、変形層の変形方向と再生方向を示した図。
【図９】図８の構造と機能を有する層構成を、実際の追記型光記録媒体に適用した例、即ち、基板上に図８の層構成を積層した例を示す図。
【図１０】参考例１の記録結果を示す図。
（ａ） 記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ） ３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ） ６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ） ３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１１】参考例２の記録結果を示す図。
（ａ） 記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ） ３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ） ６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ） ３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１２】参考例３の記録結果を示す図。
（ａ） 記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ） ３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ） ６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ） ３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１３】参考例４の記録結果を示す図。
（ａ） 記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ） ３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ） ６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ） ３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１４】参考例５の記録結果を示す図。
（ａ） 記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ） ３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ） ６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ） ３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１５】参考例６の記録結果を示す図。
（ａ） 記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ） ３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ） ６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ） ３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１６】参考例７の記録結果を示す図。
（ａ） 記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｂ） ３Ｔマーク、４Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｃ） ６Ｔマーク、８Ｔマークを連続して記録した場合の再生信号、及び、未記録時の再生信号レベルを示す。
（ｄ） ３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１７】参考例８の記録結果を示す図。
（ａ） 記録マーク長と再生信号（ＲＦレベル）及び変調度の関係を示す。
（ｄ） ３Ｔマーク、１４Ｔマークを連続して記録した場合の再生信号、及び未記録時の再生信号レベルを示す。
【図１８】比較例２の光記録媒体のアイパターンを示す図。
【図１９】比較例１の光記録媒体のアイパターンを示す図。
【図２０】比較例１及び比較例２の各光記録媒体の記録パワーに対するジッタ特性を示す図。
【図２１】比較例２の光記録媒体の変形層の変形状態をＡＦＭによって測定した図。
【図２２】比較例１の光記録媒体の変形層の変形状態をＡＦＭによって測定した結果を示す図。
【図２３】実施例１の光記録媒体のポリスチレン層を剥がし、変形層の変形状態をＡＦＭによって測定した結果を示す図。
【図２４】比較例１及び実施例１の各光記録媒体の記録パワーに対するジッタ特性を示す図。
【図２５】実施例２及び比較例３の各光記録媒体の記録パワーに対するジッタ特性を示す図。
【図２６】従来のディスクの層構成を示す図。
【符号の説明】
Ａ 変形層と変形形状補償層が剥離した部分、変形形状補償層が膨張した部分、或いは変形層が膨張した部分
Ｍａｒｋ Ｌｅｎｇｔｈ マーク長
Ｔ 基準クロック
ＲＦ Ｌｅｂｅｌ（Ｖ） ＲＦ（再生信号）レベル（ボルト）
Ｍｏｄｕｌａｔｅｄ ａｍｐｌｉｔｕｄｅ 変調度
Ｕｎｒｅｃ 未記録時の再生信号（ＲＦ）レベル
Ｔｏｐ マーク列を記録した時の最大再生信号レベル（即ちスペース部）
Ｂｏｔｔｏｍ マーク列を記録した時の最小再生信号レベル（即ちマーク部）
ＭＡ （Ｔｏｐ−Ｂｏｔｔｏｍ）／Ｔｏｐで計算される変調度
Ｔｉｍｅ０．５（μｓ／ｄｉｖ） 時間（１メモリ０．５マイクロ秒）
σ／Ｔｗ ジッタ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a write once read many (WORM) optical recording medium, and more particularly to a write once optical recording medium capable of high density recording even at a blue laser wavelength of about 350 to 500 nm.
[0002]
[Prior art]
◎ About recordable optical recording media for blue laser
Development of blue lasers capable of ultra-high density recording is rapidly progressing, and write-once type optical recording media corresponding thereto are being developed.
In conventional write-once optical recording media, recording pits are formed by irradiating a recording layer made of an organic material with laser light and causing a change in refractive index mainly due to decomposition and alteration of the organic material. The optical constant and decomposition behavior of the organic material used are important factors for forming good recording pits.
Accordingly, it is necessary to select an organic material used for the recording layer that is suitable for optical properties and decomposition behavior with respect to the blue laser wavelength. In other words, the recording / reproducing wavelength has a large absorption band in order to increase the reflectivity when unrecorded, and to cause a large change in refractive index due to decomposition of the organic material by laser irradiation (this provides a large degree of modulation). It is selected so as to be located at the bottom of the long wavelength side.
[0003]
This is because the skirt on the long wavelength side of the large absorption band of the organic material is a wavelength region having an appropriate absorption coefficient and a large refractive index.
However, an organic material having an optical property with respect to a blue laser wavelength that is the same as the conventional value has not yet been found. This is because in order to obtain an organic material having an absorption band near the blue laser wavelength, it is necessary to reduce the molecular skeleton or shorten the conjugated system, but this leads to a decrease in absorption coefficient, that is, a decrease in refractive index. Because.
That is, there are many organic materials having an absorption band near the blue laser wavelength, and the absorption coefficient can be controlled. However, since there is no large refractive index, a large degree of modulation cannot be obtained.
[0004]
Examples of organic materials compatible with blue lasers are described in JP-A Nos. 2001-181524, 2001-158865, 2000-343824, 2000-343825, and 2000-335110. is there.
However, these publications only measure the spectra of the solution and the thin film even when looking at the examples, and there is no description regarding recording and reproduction.
In JP-A-11-221964, JP-A-11-334206, and JP-A-2000-43423, although there is a description of recording in the examples, the recording wavelength is 488 nm, and the description regarding the recording conditions and recording density is as follows. There is only a statement that a good recording pit was formed.
In Japanese Patent Laid-Open No. 11-58955, although there is a description of recording in the examples, the recording wavelength is 430 nm, and there is no description regarding recording conditions and recording density, and there is a description that a good degree of modulation was obtained. Only.
[0005]
JP 2001-39034, JP 2000-149320, JP 2000-11504, JP 2000-108513, JP 2000-222772, JP 2000-218940, JP 2000-222771, In Japanese Laid-Open Patent Publication Nos. 2000-158818, 2000-280621, and 2000-280620, there are examples of recording with a recording wavelength of 430 nm and NA of 0.65, but the shortest pit is 0.4 μm. Density conditions (recording density equivalent to DVD).
In Japanese Patent Application Laid-Open No. 2001-146074, the recording / reproducing wavelength is 405 to 408 nm, but there is no specific description regarding the recording density, and the recording density is a low recording density condition of 14T-EFM signal recording.
[0006]
Further, the following technologies are disclosed regarding the layer configuration and recording method different from those of conventional CD and DVD optical recording media.
Japanese Patent Application Laid-Open No. 7-304258 discloses a technique for recording by changing the extinction coefficient (absorption coefficient in the present invention) of a saturable absorbing dye in a layer structure of substrate / saturable absorbing dye-containing layer / reflective layer. It is disclosed.
In JP-A-8-83439, recording is performed by discoloring or deforming a metal vapor deposition layer by heat generated by the light absorption layer in a layer configuration of substrate / metal vapor deposition layer / light absorption layer / protective sheet. Techniques to do are disclosed.
In JP-A-8-138245, recording is performed by changing the depth of the groove portion by changing the film thickness of the recording layer in a layer structure of substrate / dielectric layer / recording layer including light absorber / reflective layer. Technology is disclosed.
Japanese Patent Application Laid-Open No. H8-297838 discloses a technique for performing recording by changing the film thickness of the recording layer by 10 to 30% in a layer configuration of substrate / recording layer including a light absorber / metal reflective layer. Yes.
[0007]
Japanese Patent Application Laid-Open No. 9-198714 discloses that a substrate / a recording layer containing an organic dye / a metal reflective layer / a protective layer has a layer structure of 20 to 40% wider than the unrecorded portion. A technique for recording is disclosed.
Japanese Patent No. 2506374 discloses a technique for recording by forming a bubble by deforming a metal thin film with a layer structure of substrate / intermediate layer / metal thin film.
Japanese Patent No. 2591939 discloses a layer structure of substrate / light absorption layer / recording auxiliary layer / light reflecting layer, in which the recording auxiliary layer is deformed into a concave shape, and the light reflecting layer is made concave along the deformation of the recording auxiliary layer. A technique for recording by deforming is disclosed.
Japanese Patent No. 2591940 discloses a recording assist with a layer structure of substrate / light absorbing layer / porous recording auxiliary layer / light reflecting layer or substrate / porous recording auxiliary layer / light absorbing layer / light reflecting layer. A technique is disclosed in which recording is performed by deforming the layer into a concave shape and deforming the light reflecting layer into a concave shape along with the deformation of the recording auxiliary layer.
Japanese Patent No. 2591941 discloses a layer structure of substrate / porous light absorption layer / light reflection layer, in which the light absorption layer is deformed into a concave shape, and the light reflection layer is deformed into a concave shape along with the deformation of the light absorption layer. A technique for recording by performing the above is disclosed.
[0008]
Japanese Patent No. 2998925 discloses that the recording auxiliary layer and the organic dye are compatible with each other and the absorption spectrum of the organic dye is shifted to the short wavelength side in a layer configuration of substrate / recording layer containing organic dye / recording auxiliary layer. A technique for recording with the above is disclosed.
In Japanese Patent Laid-Open No. 9-265660, a composite functional layer having a function of a reflective layer and a recording layer and a protective layer are sequentially formed on a substrate, and recording is performed by forming bumps on the substrate and the composite functional layer. Techniques to do are disclosed. In addition, as a composite functional layer, there exists a prescription | regulation with metals, such as nickel, chromium, titanium, or those alloys.
Japanese Patent Laid-Open No. 10-134415 discloses a layer structure in which a metal thin film layer, a deformable buffer layer, a reflective layer, and a protective layer are sequentially formed on a substrate, and the substrate and the metal thin film layer are deformed at the same time. A technique for recording by reducing the thickness of the buffer layer is disclosed. In addition, as a metal thin film layer, there exists prescription | regulation with metals, such as nickel, chromium, titanium, or those alloys. In addition, as the buffer layer, there is a description that a resin that is easily deformable and has an appropriate fluidity is used, and a pigment may be contained in order to promote deformation.
[0009]
Japanese Patent Laid-Open No. 11-306591 discloses a layer structure in which a metal thin film layer, a buffer layer, and a reflective layer are sequentially laminated on a substrate, and the substrate and the metal thin film layer are deformed at the same time. A technique for recording by changing an optical constant is disclosed. In addition, as a metal thin film layer, there exists a description that metals, such as nickel, chromium, titanium, or those alloys are preferable. The buffer layer is made of a mixture of a dye and an organic polymer, and a dye having a large absorption band near the recording / reproducing wavelength is used.
Japanese Patent Laid-Open No. 10-124926 discloses a layer structure in which a metal recording layer, a buffer layer, and a reflective layer are sequentially laminated on a substrate, and the substrate and the metal recording layer are deformed at the same time. A technique for recording by changing an optical constant is disclosed. In addition, as a metal recording layer, there exists a description that metals, such as nickel, chromium, titanium, or those alloys are preferable. The buffer layer is made of a mixture of a dye and a resin, and a dye having a large absorption band near the recording / reproducing wavelength is used.
[0010]
As described above, the above-described conventional technologies are not aimed at realizing an optical recording medium in the blue laser wavelength region, and are not a layer configuration or a recording method effective in the blue laser wavelength region.
In particular, in the vicinity of 405 nm, which is the center of the oscillation wavelength of a blue semiconductor laser that is currently in practical use, most organic materials have an optical constant comparable to that required for the recording layer of conventional write-once type optical recording media. It does n’t exist. In addition, there are no examples in which recording conditions are clarified near 405 nm and recording is performed at a higher recording density than DVD.
Furthermore, many of the above embodiments in the prior art are experiments with a conventional disk configuration (see FIG. 26), and a configuration different from the conventional disk configuration has been proposed. The same optical characteristics and functions as before are required, and there is no effective proposal for a layer structure, a recording principle, and a recording method that can easily realize a write-once type optical recording medium made of an organic material in the blue laser wavelength region.
[0011]
In addition, in a write-once type optical recording medium using a conventional organic material, a large refractive index and a relatively small absorption coefficient (about 0.05 to 0.07) with respect to the recording / reproducing wavelength from the viewpoint of securing the degree of modulation and the reflectance. ) Can only be used.
That is, since the organic material does not have sufficient absorption capability for the recording light, it is impossible to reduce the film thickness of the organic material, and thus it is necessary to use a substrate having a deep groove. (Organic materials are usually formed by spin coating, so organic materials were buried in deep grooves to increase the thickness). Therefore, it becomes very difficult to form a substrate having a deep groove, which is a factor of deteriorating the quality as an optical recording medium.
Furthermore, in a write-once optical recording medium using a conventional organic material, the main absorption band of the organic material exists in the vicinity of the recording / reproducing wavelength, so the wavelength dependence of the optical constant of the organic material increases (the optical constant depends on the wavelength). Recording characteristics such as recording sensitivity, modulation factor, jitter, error rate, and reflectivity greatly change with respect to fluctuations in recording / reproducing wavelength due to individual differences of lasers, environmental temperature changes, etc. was there.
[0012]
[Problems to be solved by the invention]
An object of the present invention is to provide a write-once type optical recording medium that satisfies the following characteristics a) to e) and a recording / reproducing method thereof.
a) It can be manufactured inexpensively with a simple layer structure.
b) There is no great limitation on the recording / reproducing wavelength, and the wavelength dependence of the recording characteristics is small.
c) Even in the case of using an organic material, strict optical conditions as in the past are not required for the organic material.
d) Good jitter and a wide recording power margin can be realized in spite of using the recording principle mainly composed of deformation.
e) Corresponding to surface recording or recording with a high NA lens, high density can be achieved.
[0013]
[Means for Solving the Problems]
  The above-mentioned problems are solved by the following inventions 1) to 22) (hereinafter referred to as the present invention 1 to 22).
  1) The deformation layer that causes deformation by recording has a structure sandwiched between a deformation shape compensation layer that compensates for the deformation shape of the deformation layer and a deformation receptive layer that receives the deformation of the deformation layer.The deformation shape compensation layer is made of an organic material that generates a pressure toward the deformation layer side by a change in state of at least one of decomposition, explosion, and sublimation due to recording.A write-once optical recording medium characterized by the above.
  2)The write-once type optical recording medium according to 1), wherein the organic material is a dye.
  3)The deformation layer that causes deformation by recording has a structure sandwiched between a deformation shape compensation layer that compensates for the deformation shape of the deformation layer and a deformation reception layer that receives deformation of the deformation layer, and the recording polarity is High to Low. A write-once type optical recording medium characterized by being.
  4) The interface between the deformation layer and the deformation receiving layer is the main reflection interface, and the regeneration is performed from the deformation receiving layer side 1)~ Any one of 3)The write-once type optical recording medium as described.
  5) The recording portion is formed by deformation of the deformation layer toward the deformation-receiving layer side.4)The write-once type optical recording medium as described.
  6)Adjacent to the deformation receptive layerReflective layerSet up1) characterized in that the interface between the deformation-receiving layer and the reflective layer is the main reflective interface, and the reproduction is performed from the deformation shape compensation layer side.Or 2) as describedWrite-once optical recording medium.
  7) The recording portion is formed by deformation of the deformation layer toward the deformation-receiving layer side.6)The write-once type optical recording medium as described.
  8) The deformed portion is formed in the deformable layer by the light absorption function of the deformable layer 1) to7)The write-once type optical recording medium according to any one of the above.
  9) The deformation portion is formed in the deformation layer by the light absorption function of the deformation shape compensation layer.7)The write-once type optical recording medium according to any one of the above.
  10) The deformable layer and the deformed shape compensation layer have a light absorption function with respect to the recording light, the deformed portion is formed in the deformable layer by the light absorption function of both, and the light absorption function of the deformed shape compensation layer is reduced or disappeared by the recording. 1) to characterized by7)The write-once type optical recording medium according to any one of the above.
  11) The write-once type optical recording medium according to any one of 1) to 10), wherein the deformation-receiving layer is made of a polymer compound.
  12) The recordable optical recording medium according to any one of 1) to 11), wherein the deformable layer contains Si or Ge.
  13) The write-once type optical recording medium according to 12), wherein recording and reproduction are possible in a laser wavelength range of 350 to 500 nm.
  14) The deformation layer that causes deformation by recording has a structure sandwiched between a deformation shape compensation layer that compensates the deformation shape of the deformation layer and a deformation receptive layer that receives deformation of the deformation layer,The deformation shape compensation layer is made of an organic material that generates a pressure toward the deformation layer side by a change in state of at least one of decomposition, explosion, and sublimation due to recording.A recording method for a write once optical recording medium, wherein the deformation layer is deformed toward the deformation receiving layer by recording.
  15) The organic material is a pigment14)The recording method of the write-once type optical recording medium as described.
  16) To a write-once type optical recording medium having a structure in which a deformation layer that is deformed by recording is sandwiched between a deformation shape compensation layer that compensates for the deformation shape of the deformation layer and a deformation reception layer that receives deformation of the deformation layer. A recording method for a write-once optical recording medium, wherein the deformation layer is deformed toward the deformation-receiving layer by recording, and the recording polarity is set to High to Low.
  17) The deformation layer that causes deformation by recording has a structure sandwiched between a deformation shape compensation layer that compensates for the deformation shape of the deformation layer and a deformation reception layer that accepts deformation of the deformation layer. A recording method on a write once optical recording medium in which the interface of the receiving layer is a main reflection interface and reproduction is performed from the deformation receiving layer side, wherein the deformation layer is deformed to the deformation receiving layer side by recording. Method of recording optical recording medium.
  18) a deformation shape compensation layer that compensates the deformation shape of the deformation layer, a deformation layer that causes deformation by recording, a deformation receptive layer that accepts deformation of the deformation layer, and a reflective layer; Is a recording method on a write once optical recording medium in which reproduction is performed from the deformation shape compensation layer side, and the deformation layer is deformed to the deformation receiving layer side by recording. Recording method of write-once type optical recording medium.
  19) The deformation of the deformation layer toward the deformation-receiving layer is caused by the expansion force of the deformation layer and / or the pressure accompanying the change in the state of the deformation shape compensation layer.18)A recording method of a write-once type optical recording medium according to any one of the above.
  20) The deformation of the deformation layer toward the deformation receiving layer side is caused by the light absorption function of the deformation layer and / or the light absorption function of the deformation shape compensation layer by irradiation of recording light.18)A recording method of a write-once type optical recording medium according to any one of the above.
  21) Deformation of the deformation layer toward the deformation-receiving layer is caused by the light absorption function of the deformation layer and the light absorption function of the deformation shape compensation layer by irradiation of recording light. 14) to characterized in that the light absorption function is reduced or eliminated18)A recording method of a write-once type optical recording medium according to any one of the above.
  22) The write-once type optical recording medium according to any one of 14) to 21), wherein the deformable layer is composed of a material containing Si or Ge, and recording / reproduction is performed with a laser beam having a wavelength of 350 to 500 nm. Recording method.
[0014]
Hereinafter, the present invention will be described in detail.
The present inventor has found that sufficient recording / reproducing characteristics cannot be obtained with a write-once optical recording medium in which a deformable layer is provided on a substrate. That is, in a write-once type optical recording medium provided with a deformable layer on a substrate, for example, when the deformable layer has a light absorption function, the deformable layer can be deformed by irradiation of recording light, and a certain level of recording / reproduction characteristics can be obtained. Although it can be obtained, it has been found that jitter characteristics similar to CD-R and DVD-R cannot be obtained.
The cause is that, as a result of the examination, in the deformed shape of the deformable layer, the symmetry with respect to the scanning direction of the recording light around the central portion of the recording mark (hereinafter, simply referred to as the deformed shape symmetry) deteriorates. [See Fig. 1 (a). FIG. 1B is an example of an ideal deformed shape.
The deterioration of the symmetry of the deformed shape is likely to occur when the mark length becomes long or the physical properties (film thickness, hardness, etc.) relating to deformation of the deformed layer are not optimal.
[0015]
Therefore, as a result of examining the solution to the above problem, the present inventor provided a deformed shape compensation layer adjacent to the deformed layer in order to correct the deformed shape distortion as shown in FIG. The idea of using pressure due to the state change of the deformed shape compensation layer was confirmed, and its effectiveness was confirmed.
That is, in order to improve jitter characteristics, it has been found that it is important that the deformation shape of the deformation layer has a good symmetry. In the present invention, the deformation shape compensation layer is adjacent to the deformation layer. To compensate (correct) the distortion of the deformed shape.
On the other hand, the present inventor has found that it is important to control the deformation amount in order to widen the recording power margin (jitter fluctuation margin with respect to the recording power change).
In the present invention, in order to reduce the variation in the deformation amount of the deformation layer with respect to the change in recording power, the deformation receiving layer is provided in the adjacent layer on the direction side where the deformation layer causes deformation.
By changing the hardness, film thickness, etc. of the deformation receiving layer, the deformation amount and the deformation increase / decrease amount can be controlled, and the recording power margin can be widened.
[0016]
In the present invention, when the interface between the deformable layer and its adjacent layer becomes the main reflection interface, it is preferable to deform the deformable layer to the incident light side. This is because when the deformation layer is deformed to the side opposite to the incident light, the recording polarity becomes low to high, the recording polarity changes depending on the recording mark length or recording power, or the reproduction signal waveform is differentiated. It is because it is easy to do.
Generally, in mark length recording, when a recorded mark is reproduced, a reproduction signal (RF signal) as shown in FIG. 2A is obtained, whereas as shown in FIGS. 2B and 2C. In the present invention, a signal having an inflection point in the vicinity of the front and rear edges of the recording mark and in the vicinity of the center of the recording mark is referred to as a differential waveform (differential waveform conversion).
In addition, the main reflection interface referred to in the present invention refers to a reflection interface having the largest contribution to the reflected light from the optical recording medium by irradiation of recording / reproducing light, and is usually a reflection interface having the largest reflection coefficient.
[0017]
The deformation layer used in the present invention is not limited as long as it is deformed by recording. This deformation is caused by expansion of the deformation layer or pressure from other layers.
In the present invention, in order to improve the recording / reproduction characteristics, it is preferable to use a material having a large complex refractive index difference from the adjacent layer as the deformation layer.
For example, Au, Ag, Al, Cr, Ni, Al, Fe, Sn etc. are mentioned as a metal with a small refractive index (complex refractive index real part) generally. In general, as a material having a large refractive index (real refractive index real part), a material containing Si or Ge (for example, Si, Ge, Si)_xGe_1-x, Mg₂Ge, Mg₂Si, SiC, etc.); metals such as Nb, Ta, Be, V, or metal oxides thereof (for example, Ta₂O₅, Nb₂O₅Etc.); AlSb, Al_xGa_1-xAs, CdSe, GaSb, Hg_1-xCd_xExamples thereof include semiconductors such as Te, Se, Te, ZnTe, ZnS, PbS, InP, and GaP.
[0018]
When the adjacent layer of the deformation layer has a relatively low refractive index (for example, about 1.8 or less), the material of the deformation layer is Al.₂O₃, MgO, BeO, ZrO₂, UO₂, ThO₂Simple oxide based oxides such as SiO₂2MgO · SiO₂, MgO / SiO₂, CaO · SiO₂, ZrO₂・ SiO₂3Al₂O₃・ 2SiO₂2MgO · 2Al₂O₃・ 5SiO₂, Li₂O ・ Al₂O₃・ 4SiO₂Silicate oxides such as Al₂TiO₅, MgAl₂O₄, Ca₁₀(PO₄)₆(OH)₂, BaTiO₃LiNbO₃, PZT, PLZT (PbTiO₃-PbZrO₃Oxides), double oxide oxides such as ferrite; Si₃N₄, Si_6-ZAl_ZO_ZN_8-ZNon-oxides of nitrides such as AlN, BN, TiN; SiC, B₄Non-oxides of carbides such as C, TiC and WC; LaB₆TiB₂, ZrB₂Non-oxides of borides such as CdS, MoS₂Sulfide non-oxide such as MoSi₂Silicide-based non-oxides such as amorphous carbon, graphite, diamond and other carbon-based non-oxides; or their contents can be used.
[0019]
When the light absorbing function is imparted to the deformable layer, the deformable layer has a relatively large absorption coefficient with respect to the recording wavelength (the absorption coefficient here is an imaginary part of the complex refractive index, preferably 0.2 or more, for example). There is no limitation as long as the material has. Examples include materials containing Si or Ge (eg, Si, Ge, Si_xGe_1-x, Mg₂Ge, Mg₂Si, SiC, etc.); metals such as Nb, Ta, Be, V, or metal oxides thereof (for example, Ta₂O₅, Nb₂O₅Etc.); AlSb, Al_xGa_1-xAs, CdSe, GaSb, Hg_1-xCd_xTe, Se, Te, ZnTe, ZnS, PbS, InP, GaP, and other semiconductors; or metals such as Ni, Cr, Ti, Ta, Fe, etc., which have lower thermal conductivity than Ag, etc., and Cu / Al, Ni / An alloy such as Fe can be used.
[0020]
In the present invention, when the interface between the deformable layer and the adjacent layer becomes the main reflection interface, the deformable layer is deformed to the incident light side, so that the deformed shape of the deformable layer is compensated (the symmetry of the deformed shape is improved). It is preferable that the deformation shape compensation layer for this is an adjacent layer on the back side of the deformation layer as viewed from the incident light side.
This is because, in the present invention, in order to compensate for the deformation shape of the deformation layer, a pressure based on a change in the state of the material constituting the deformation shape compensation layer, for example, a pressure accompanying expansion, decomposition, explosion, sublimation, or the like is used. (If the deformed shape compensation layer is an adjacent layer on the near side of the deformed layer when viewed from the incident light side, the deformed layer is opposite to the incident light due to the pressure accompanying the change in the state of the material constituting the deformed shape compensated layer. The recording polarity is changed to Low to High, the recording polarity changes depending on the recording mark length and recording power, or the reproduction signal waveform is differentiated).
Among the pressures based on the state change of the material constituting the deformed shape compensation layer, it is particularly preferable to use the pressure accompanying decomposition, explosion, sublimation and the like.
[0021]
The deformation shape compensation layer needs to be made of a material that generates pressure toward the deformation layer side as described above, and an organic material is preferably used. This is because organic materials cause decomposition, explosion, sublimation, etc. within an appropriate recording power range.
Preferred organic materials include polymethine, naphthalocyanine, phthalocyanine, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (indanthrene), xanthene, triphenylmethane, azulene, tetrahydrocholine , Phenanthrene-based, triphenothiazine-based dyes, metal complex compounds, and the like.
The dye layer can be formed by ordinary means such as vapor deposition, sputtering, CVD, and solvent coating. In the case of using the coating method, the above-described pigment or the like may be dissolved in an organic solvent and applied by a conventional coating method such as spraying, roller coating, dipping, or spin coating.
[0022]
As the organic solvent to be used, alcohols such as methanol, ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; amides such as N, N-dimethylacetamide and N, N-dimethylformamide; sulfoxide such as dimethyl sulfoxide Ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether; esters such as methyl acetate and ethyl acetate; aliphatic halogenated carbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride and trichloroethane; Aromatics such as benzene, xylene, monochlorobenzene and dichlorobenzene; cellosolves such as methoxyethanol and ethoxyethanol; hexane, pentane, Cyclohexane, and hydrocarbons such as methylcyclohexane.
The film thickness of the dye layer (deformation shape compensation layer) is 10 nm to 10 μm, preferably 10 to 200 nm.
[0023]
In addition to the above, the deformation shape compensation layer may be composed of a gas generating compound that decomposes by heat.
As specific examples of the gas generating compound, it is necessary to appropriately select a decomposition temperature, a decomposition rate, and the like. For example, as an organic compound, dinitrosopentamethylenetetramine (DPT), N, N′-dimethyl-N, Nitroso compounds such as N′-dinitrosoterephthalamide (DMDNTA); benzenesulfonyl hydrazite (BSH), p-toluenesulfonyl hydrazite (TSH), diphenylsulfone-S, S′-disulfonylhydrazide (DPSDSH), 4 Sulfonylhydrazide compounds such as 4,4'-oxybisbenzenesulfonylhydrazide (OBSH); azodicarboxylic acid amide (ADCA), azobisisobutyronitrile (AIBN), diazoaminobenzene (DAB), barium-azodicarboxylate Azo and diazo compounds such as trihydra Bruno triazine, p- toluenesulfonyl semicarbazide, include 4,4'-oxybisbenzenesulfonyl semicarbazide etc., sodium bicarbonate as inorganic compounds, ammonium carbonate, ammonium bicarbonate, ammonium nitrite, include peroxides.
[0024]
Any of the above organic compounds and inorganic compounds can be used alone or in admixture of two or more.
Among the above-mentioned gas generating compounds, the decomposition behavior of organic compounds becomes an exothermic reaction, so when the temperature reaches a certain temperature, the amount of generated gas tends to be constant because it decomposes rapidly, so the relationship between the amount added and the amount of gas generated is expected. It is easy to do and preferable.
In general, some inorganic compounds have many endothermic reactions and gradually decompose. In such cases, it is desirable to control gas generation and the like.
In addition, an auxiliary may be appropriately added to the gas generating compound, particularly an organic compound, in order to adjust the decomposition temperature.
[0025]
As an auxiliary agent, for example, as an auxiliary agent for lowering the decomposition temperature, zinc compounds such as zinc white, zinc caprylate, zinc nitrate, zinc fatty acid soap; lead carbonate, lead phthalate, lead phosphite, lead stearate, etc. Lead compounds; cadmium compounds such as cadmium caprylate, cadmium caproate, cadmium laurate, cadmium myristate, cadmium fatty acid soap; urea, borax, ethanolamine and the like. On the other hand, as an auxiliary for suppressing decomposition, organic acids such as maleic acid and fumaric acid; halogenated organic acids such as stearoyl chloride and phthaloyl chloride; anhydrous organic acids such as maleic anhydride and phthalic anhydride; hydroquinone and naphthalene Polyhydric alcohols such as diols; Hydrocarbons such as d-maltose; Nitrogen containing aliphatic amines, heterocyclic amines, amides, oximes, etc .; Sulfur containing thiols, mercaptans, sulfides, sulfonic acids, sulfoxides, isocyanates, etc. Products; ketones such as cyclohexanone and acetylacetone; aldehydes; phosphates and phosphite compounds; 6,6-dimethylfulvene, hexachlorocyclopentadiene, dibutyltin maleate and the like. The decomposition behavior can be corrected by appropriately using these auxiliaries.
[0026]
In the present invention, the organic material layer is used as a constituent layer of the optical recording medium. However, since the pressure to the deformed layer based on the change in the state of the organic material is used, severe optical conditions as in the past are imposed on the organic material. There is nothing.
Therefore, in order to increase the reflectance when not recorded, it is possible to use an organic material having a small absorption coefficient with respect to the recording / reproducing wavelength, and when the reflectance when not recorded is not much concerned, The absorption coefficient of the organic material layer can be adjusted in accordance with the light absorption function of the deformable layer so that recording can be performed with an appropriate recording power.
As described above, in the present invention, basically, it is not necessary to use the complex refractive index change of the organic material, so that strict optical conditions are not imposed on the organic material, and a very large number of materials can be used as the organic material. It becomes.
As a result, in the conventional recording / reproducing method in which the absorption band is positioned on the short wavelength side with respect to the recording / reproducing wavelength, for example, when the recording / reproducing wavelength is 450 nm or less, basically a conjugated system of an organic material or Deterioration of stability of organic materials (crystallization and aggregation occur over time), deterioration of solubility, deterioration of wavelength control (decrease in the number of substituent introduction sites, substituent However, in the present invention, these problems do not occur.
That is, the physical properties of the organic material can be changed very widely and flexibly according to the purpose, and the recording / reproducing characteristics can be improved.
[0027]
For example, in the write-once type optical recording medium of the present invention, although it is an optical recording medium corresponding to a blue wavelength or less, for example, a dye used for CD-R or DVD-R can be used, so that recording can be performed at a blue wavelength or a red wavelength. An optical recording medium that can be reproduced can be provided.
In the present invention, basically, it is not necessary to use a change in the optical constant (complex refractive index) of the organic material for recording and reproduction, but of course, a change in the optical constant of the organic material may be used.
In the above, a preferred material example has been described in the case of using the pressure accompanying explosion, decomposition, and sublimation of the material constituting the deformation shape compensation layer in order to compensate the deformation shape of the deformation layer. When the expansion pressure of the material to be used is used, for example, a polymer material can be used.
Examples of such a polymer material include polynorbornene, polyisoprene, styrene / butadiene copolymer, polyurethane, polyolefin resin, fluorine-containing resin, polycaprocraton resin, and polyamide resin. Moreover, the polymeric material which can be used as a deformation | transformation receiving layer mentioned later can also be used. Furthermore, these polymer materials can also be used by mixing with a pigment.
[0028]
In the present invention, a deformation receiving layer is provided as an adjacent layer on the side opposite to the deformation shape compensation layer among the adjacent layers of the deformation layer.
This deformation receptive layer is provided in order to reduce the variation of the deformation amount of the deformation layer with respect to the change in recording power, and is very effective in expanding the recording power margin. Accordingly, it is preferable that the deformation receiving layer is made of a material that hardly generates pressure on the deformation layer side due to the state change by recording, contrary to the deformation shape compensation layer. That is, the deformation receiving layer is made of a material and a film thickness that do not easily cause large decomposition, explosion, sublimation, etc. by recording, or a material and a film thickness that do not increase the pressure on the deformation layer even if decomposition, explosion, sublimation, etc. occur. Is preferred.
Therefore, it is preferable to use a high-molecular compound that is easy to form a film and is inexpensive as the deformation receiving layer.
Examples of the polymer compound include acrylic resin, polycarbonate resin, polyester resin, polyamide resin, vinyl chloride resin, polyvinyl ester resin, polystyrene resin, polyolefin resin, and polyethersulfone resin.
[0029]
Specific examples include polystyrene, poly (α-methylstyrene), polyindene, poly (4-methyl-1-pentene), polyvinylpyridine, polyvinyl formal, polyvinyl acetal, polyvinyl butyral, polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride. , Polyvinylidene chloride, polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl benzyl ether, polyvinyl methyl ketone, poly (N-vinyl carbazole), poly (N-vinyl pyrrolidone), methyl polyacrylate, polyethyl acrylate, polyacrylic acid , Polyacrylonitrile, polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polybenzyl methacrylate, polycyclohexyl methacrylate, polymethacrylic acid, poly Tacrylic acid amide, polymethacrylonitrile, polyacetaldehyde, polychloral, polyethylene oxide, polypropylene oxide, polyethylene terephthalate, polybutylene terephthalate, polycarbonates (bisphenols + carbonic acid), poly (diethylene glycol bisallyl carbonates), 6-nylon , 6,6-nylon, 12-nylon, 6,12-nylon, polyethyl aspartate, ethyl polyglutamate, polylysine, polyproline, poly (γ-benzyl-L-glutamate), methylcellulose, ethylcellulose, benzylcellulose, hydroxy Ethyl cellulose, hydroxypropyl cellulose, acetyl cellulose, cellulose triacetate, cellulose tributyrate, polyurethane Resins such as fats; the like, or a copolymer or co-polycondensate thereof; organic polygermane; poly (phenyl methyl silane) organic polysilane such.
[0030]
Furthermore, it is also possible to use a dye having characteristics that do not cause large decomposition, explosion, sublimation, etc. as the deformation receiving layer. In this case, it is preferable that the decomposition temperature of the pigment is sufficiently lower or sufficiently higher than the deformation temperature of the deformation layer.
The thickness of the deformation receiving layer is arbitrary, but when a material with high hardness is provided adjacent to the deformation receiving layer, it is preferable to determine the film thickness according to the balance between recording sensitivity and recording power margin.
The deformation receptive layer referred to in the present invention can be any layer as long as the deformation receptive layer is not composed of a material that completely inhibits deformation of the deformable layer or a material that deteriorates the symmetry of the deformed shape. For example, an air layer, an adhesive layer, a protective layer, a cover layer, or the like may be used.
[0031]
In the present invention, information is recorded / reproduced by deformation of the deformation layer. The deformation of the deformation layer can be either a single layer having a light absorption function or a deformation shape compensation layer having a single light absorption function. Alternatively, this can be achieved by providing both the deformation layer and the deformation shape compensation layer with a light absorption function.
However, in order to improve the reproduction stability and storage stability after recording, it is preferable that the light absorption function is lowered in the recording portion.
Therefore, in the present invention, it is particularly preferable that both the deformation layer and the deformation shape compensation layer have a light absorption function, and the light absorption function of the deformation shape compensation layer is reduced or eliminated by recording.
This is because, in the present invention, the deformable layer is preferably composed of a material that does not decompose or sublimate due to recording, and it is generally difficult to reduce or eliminate the light absorption function of the deformable layer by recording. On the other hand, the deformed shape compensation layer is preferably composed of a material that easily undergoes decomposition, sublimation or the like by recording, and it is easy to reduce or eliminate the light absorption function of the deformed shape compensating layer by recording.
As a result, the light absorption function of the recording part after recording can be lowered, deterioration due to reproduction can be prevented, and stability is improved.
[0032]
In the present invention, a “write-once type optical recording medium and a recording / reproducing method thereof that can be manufactured at a low cost with a simple layer configuration” can be provided because the simplest recording principle of deformation is used.
In addition, the reason why the “write-once type optical recording medium and recording / reproducing method thereof with no significant limitation on the recording / reproducing wavelength and with less wavelength dependency of the recording characteristics” can be provided is, for example, using a deformation layer having a light absorption function for recording light In this case, Si or Ge-containing materials such as SiC, Si, and Ge are preferably used as the deformable layer, and the complex refractive index of these materials has a large wavelength as in organic materials used in conventional write-once optical recording media. This is because there is no dependency.
The reason why the “write-once type optical recording medium and recording / reproducing method thereof that can cope with surface recording or recording with a high NA lens and can achieve high density” is provided on the basis of the structure and recording principle of the optical recording medium of the present invention. This is because there is no restriction in the recording / reproducing direction (and any layer structure corresponding to the recording / reproducing direction can be easily realized). Further, in the present invention, the deformation direction of the deformation layer with respect to the incident light is defined. However, as described above, this is for making the polarity of the reproduction signal High to Low and preventing the differential waveform. When there is no problem such as recording polarity or differential waveform, or when there is no problem, the relationship between the deformation direction of the deformation layer and the incident light may be arbitrary.
[0033]
In the present invention, a reflective layer may be provided.
As the material of the reflective layer, a substance having a high reflectance with respect to laser light is suitable. For example, Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Metals such as Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi, and the like Mention may be made of metals or stainless steel.
Among these, Cr, Ni, Pt, Cu, Ag, Au, Al, and stainless steel are preferable.
These substances may be used alone, in combination of two or more kinds or as an alloy.
The reflective layer can be formed, for example, by vapor deposition, sputtering or ion plating of the above substance.
The thickness of the reflective layer is usually 10 to 500 nm, preferably 10 to 300 nm.
[0034]
Embodiments of the present invention are as shown in FIGS.
FIG. 3 is an example having a structure in which the deformation shape compensation layer of the present invention and the deformation receiving layer are adjacent to the deformation layer (essential layer structure of the present invention).
FIG. 4 is a diagram showing the deformation direction and the reproduction direction of the deformation layer when the main reflection interface is at the interface between the deformation layer and the deformation receiving layer, having the structure of FIG. In FIG. 4, the deformation layer is deformed to the deformation receiving layer side by the light absorption function of the deformation layer and / or the deformation shape compensation layer.
FIG. 5 is a diagram showing an example in which the layer configuration having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, an example in which the layer configuration of FIG. 4 is stacked on a substrate.
FIG. 6 shows another example in which the layer structure having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, the layer structure of FIG. 4 is laminated on a substrate, and further on the deformation receiving layer. It is a figure which shows the example which provided the cover layer.
FIG. 7 shows another example in which the layer structure having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, the layer structure of FIG. 4 is laminated on a substrate, and further on the deformation receiving layer. It is a figure which shows the example which provided the cover layer through the contact bonding layer.
[0035]
FIG. 8 is a structure having the structure of FIG. 3 and having a reflective layer as an adjacent layer on the opposite side of the deformation receiving layer, and the main reflection interface is at the interface between the deformation receiving layer and the reflection layer. It is the figure which showed the deformation | transformation direction and reproduction | regeneration direction of a deformation | transformation layer.
In FIG. 8, the deformation layer is deformed to the deformation receiving layer side by the light absorption function of the deformation layer and / or the deformation shape compensation layer.
FIG. 9 is a diagram showing an example in which the layer configuration having the structure and function of FIG. 8 is applied to an actual write-once optical recording medium, that is, an example in which the layer configuration of FIG. 8 is stacked on a substrate.
“A” in FIGS. 3 to 9 indicates a portion where the deformation layer and the deformation shape compensation layer are peeled, a portion where the deformation shape compensation layer is expanded, or a portion where the deformation layer is expanded.
3 to 9, the deformation shape compensation layer in the portion where the deformation of the deformation layer has occurred may cause an optical constant change.
The above FIGS. 3 to 9 show examples having the minimum layers that exhibit the effects of the present invention. In practice, in addition to the layer configuration shown in FIGS. A substrate, an undercoat layer, an overcoat layer, a protective layer, an adhesive layer, a cover layer, and the like are provided.
[0036]
【Example】
EXAMPLES Hereinafter, although an Example, a comparative example, and a reference example are shown and this invention is demonstrated concretely, this invention is not limited by these Examples.
[0037]
Comparative Example 1
On a polycarbonate substrate having a guide groove with a groove depth of 55 nm, a dye layer composed of the following [Chemical Formula 1] that can be used in a DVD-R as a deformation shape compensation layer is about 60 nm thick, and further has a light absorption function thereon. An optical recording medium having SiC as a layer having a thickness of 10 nm was produced.
The optical recording medium was irradiated with 9.0 mW laser light from the SiC side using an optical disk evaluation device, DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulse Tech Industry, and the land portion A signal of 8-16 modulation was recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s at the groove position on the near side as viewed from the incident laser beam side.
As a result, the modulation degree is about 70%, the recording polarity is High to Low, a very clear eye pattern as shown in FIG. 19 is obtained, and the jitter (σ / Tw) is 7.8%. became.
Further, the jitter characteristic with respect to the recording power is as shown by the line marked with ♦ in FIG. 20, and it was confirmed that the jitter value was good and the recording power margin was wide as compared with Comparative Example 2 described later.
FIG. 20 also shows the measurement results (lines indicated by ■) when the film thickness of the dye layer is 50 nm in this comparative example.
At this time, when the deformation state of the deformation layer was confirmed by AFM (atomic force microscope), as shown in FIG. 22, the deformation layer was deformed to the incident light side, and the symmetry of the deformation shape was good. there were.
[0038]
[Chemical 1]

[0039]
Example 1
On a polycarbonate substrate having a guide groove with a groove depth of 55 nm, a dye layer composed of the dye of the above [Chemical Formula 1] that can be used in a DVD-R as a deformation shape compensation layer is about 60 nm thick, and has a light absorption function thereon. An optical recording medium was prepared in which SiC was formed as a deformable layer with a thickness of 10 nm and a polystyrene resin was formed thereon as a deformable receiving layer with a thickness of about 2 μm.
This optical recording medium was irradiated with 9.7 mW of laser light from the polystyrene resin layer side using an optical disk evaluation apparatus, DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial, A signal of 8-16 modulation was recorded at a land frequency (groove position on the near side when viewed from the incident laser beam side) at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s.
As a result, the degree of modulation was about 61%, the recording polarity was High to Low, a clear eye pattern was obtained as in Comparative Example 1, and the jitter (σ / Tw) was 8.0%.
In addition, the jitter characteristic with respect to the recording power is shown by the line indicated by ■ in FIG. 24, and it can be confirmed that the recording power margin is wider than the disk of Comparative Example 1 (line indicated by ◆ in FIG. 24). (The effect of the deformation receptive layer was confirmed).
At this time, when the polystyrene resin layer was peeled off and the deformation state of the deformation layer was confirmed by AFM, the deformation layer was deformed to the incident light side (polystyrene resin layer side) as shown in FIG. The symmetry of was good. The white dotted line in FIG. 23 is a line indicating the mark center.
[0040]
Comparative Example 2
An optical recording medium in which SiC was formed to a thickness of 10 nm as a deformable layer having a light absorption function on a polycarbonate substrate having a guide groove with a groove depth of 55 nm was produced.
The optical recording medium was irradiated with 8.0 mW of laser light from the SiC side using an optical disk evaluation device, DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial Co., Ltd. A signal of 8-16 modulation was recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s at the groove position on the near side as viewed from the incident laser beam side.
As a result, the degree of modulation was about 70%, the recording polarity was High to Low, and a relatively good eye pattern as shown in FIG. 18 was obtained, but the jitter (σ / Tw) was 10.4%. It became bigger.
Further, the jitter characteristic with respect to the recording power is as shown by the line indicated by ● in FIG. 20, and it was confirmed that the jitter value was worse and the recording power margin was narrower than that of the comparative example 1 described above.
At this time, when the deformation state of the deformation layer was confirmed by AFM, as shown in FIG. 21, the deformation layer was deformed to the incident light side, but the symmetry of the deformation shape was greatly broken. The white dotted line in FIG. 21 is a line indicating the mark center.
As described above, the results of Comparative Example 1 and Comparative Example 2 showed the effectiveness of the deformed shape compensation layer, and the results of Comparative Example 1 and Example 1 showed the effectiveness of the deformation receiving layer.
[0041]
Example 2
On a polycarbonate substrate having a guide groove with a groove depth of 55 nm, a dye layer consisting of the following [Chemical Formula 2] having absorption at the blue laser wavelength as a deformation shape compensation layer is about 20 nm thick, and SiC as a deformation layer having a light absorption function. An optical recording medium having a thickness of about 5 nm, a layer made of polystyrene resin as a deformation receiving layer about 80 nm thick, and Ag as a reflection layer about 100 nm thick was prepared.
The optical recording medium is irradiated with 9.5 mW laser light from the substrate side using an optical disk evaluation device, DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulse Tech Industry, and the land portion A signal of 8-16 modulation was recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s at the groove position on the back side as viewed from the incident laser beam side.
As a result, the jitter characteristic with respect to the recording power is as indicated by the line indicated by the black square in FIG. 25, and it was confirmed that the jitter value was better than that of Comparative Example 3 described later.
In addition, it was confirmed that there was almost no reproduction deterioration due to repeated reproduction, and that the dye layer in the recording area was decomposed and altered.
[0042]
[Chemical 2]

[0043]
Comparative Example 3
On a polycarbonate substrate having a guide groove with a groove depth of 55 nm, SiC is about 10 nm thick as a deformation layer having a light absorption function, a layer made of polystyrene resin is about 80 nm thick as a deformation receiving layer, and Ag is thick as a reflection layer. An optical recording medium having a thickness of about 100 nm was produced.
This optical recording medium was irradiated with 9.8 mW of laser light from the substrate side using an optical disk evaluation device, DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial. A signal of 8-16 modulation was recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s in a portion (a groove position on the back side as viewed from the incident laser beam side).
As a result, the jitter characteristic with respect to the recording power is as indicated by the line marked with ♦ in FIG. 25, and the jitter value was worse than that in Example 2 described above.
[0044]
As described above, in the examples, the effects of the deformed shape compensation layer and the deformable receiving layer of the present invention were confirmed, but in the present invention, the light absorbing layer has a light absorbing function necessary for recording, so that the dye layer (for example, the deformed layer) Since it is not necessary to give the shape compensation layer a large light absorption function, it has been confirmed that the film thickness of the dye layer can be reduced, and that a shallow groove substrate can be used.
In the above embodiments, the recording is performed on the land portion, but this is for easy observation of the deformation shape of the deformation layer, and the present invention is not limited to the land recording.
[0045]
Next, reference examples 1 to 8 show the importance of deforming the deformation layer to the incident light side when the interface between the deformation layer and its adjacent layer is the main reflection interface. In these reference examples, In order to clarify the deformation effect of the deformable layer, an experiment was performed on an optical recording medium without a deformable shape compensation layer (the same phenomenon as in these reference examples is also obtained when a deformable shape compensation layer is provided).
10 to 17 are diagrams showing recording results of Reference Examples 1 to 8, respectively.
10 (a) to 17 (a) are diagrams showing the results of measuring the recording mark length (Mark Length) dependence of the reproduction signals (RF levels) of Reference Examples 1 to 8, and in each figure, Unrec is a reproduction signal (RF level) when not recorded, Top is a maximum reproduction signal level (that is, a space portion) when a mark row is recorded, Bottom is a minimum reproduction signal level when a mark row is recorded, MA Indicates the degree of modulation calculated by (Top-Bottom) / Top.
FIGS. 10B to 16B show a reproduction signal when 3T marks are continuously recorded, a reproduction signal when 4T marks are continuously recorded, and a reproduction signal when no recording is performed. FIGS. 10 (c) to 16 (c) show the levels of the reproduction signal when the 6T mark is continuously recorded, the reproduction signal when the 8T mark is continuously recorded, and the reproduction when not recorded. The signal levels in FIGS. 10D to 17D are the reproduction signal when the 3T mark is continuously recorded, the reproduction signal when the 14T mark is continuously recorded, and the unrecorded signal. The reproduction signal level is shown.
[0046]
Reference example 1
An optical recording medium in which SiC was formed to a thickness of 10 nm as a deformable layer having a light absorption function on a polycarbonate substrate having a guide groove with a groove depth of 55 nm was produced.
This optical recording medium was irradiated with 5.0 mW of laser light from the substrate side using an optical disk evaluation apparatus, DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial Co., Ltd. 3T to 14T marks were individually recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s at the groove position on the near side as viewed from the incident laser beam side.
It was confirmed by AFM that SiC was deformed to the side opposite to the incident light (on the side opposite to the substrate).
Further, from the result of FIG. 10A, it can be confirmed that there is a possibility that High to Low recording can be performed regardless of the recording mark length.
Furthermore, it can be seen from the results of FIGS. 10B to 10D that 3T, 4T, 6T, 8T, and 14T all show reproduced signal waveforms that allow mark length recording.
[0047]
Reference example 2
The same experiment as in Reference Example 1 was performed except that the recording power was 6.0 mW. It was confirmed by AFM that SiC was deformed to the side opposite to the incident light (on the side opposite to the substrate).
Further, from the result of FIG. 11A, the recording polarity changes depending on the recording mark length, that is, the high mark is high to low recording in the short mark, but the high to low recording and the low to high recording are mixed in the long mark. It can be seen that such a signal is generated and it becomes difficult to record the mark length.
Further, from the results shown in FIGS. 11B to 11D, 3T and 4T show reproduction signal waveforms that can be recorded in the mark length, but 6T, 8T, and 14T have greatly increased the RF level at the center of the mark. Reproduction signal waveform is shown [In 6T and 8T, the period of the reproduction signal appears to be double that of the original reproduction signal. This can be clearly seen when compared with FIG. 10 (c)], indicating that it is difficult to record the mark length.
[0048]
Reference example 3
Except that the laser beam of 6.0 mW was irradiated from the substrate side and recorded in the land portion (groove position on the back side when viewed from the incident laser beam side), the same experiment as in Reference Example 1 was performed. It was confirmed by AFM that SiC was deformed to the side opposite to the incident light (on the side opposite to the substrate).
Further, from the result of FIG. 12A, the recording polarity tends to change depending on the recording mark length, that is, the short mark is High to Low recording, but the long mark is a mixture of High to Low recording and Low to High recording. It can be seen that such a signal tends to be generated and mark length recording may be difficult. Further, from the results shown in FIGS. 12B to 12D, 3T, 4T, 6T, and 8T show reproduction signal waveforms that allow mark length recording, while 14T shows a significant increase in the RF level at the center of the mark. It can be seen that it is difficult to record the mark length.
[0049]
Reference example 4
Except that the laser beam of 7.0 mW was irradiated from the substrate side and recorded in the land portion (groove position on the back side when viewed from the incident laser beam side), the same experiment as in Reference Example 1 was performed.
It was confirmed by AFM that SiC was deformed to the side opposite to the incident light (on the side opposite to the substrate).
Further, from the result of FIG. 13A, the recording polarity changes depending on the recording mark length, that is, the short mark is High to Low recording, but the long mark is a mixture of High to Low recording and Low to High recording. It can be seen that such a signal is generated and it becomes difficult to record the mark length.
Further, from the results shown in FIGS. 13B to 13D, 3T and 4T show the reproduction signal waveforms that can be recorded in the mark length, but 6T, 8T, and 14T show a significant increase in the RF level at the center of the mark. [For example, at 6T, the period of the reproduced signal appears to be double that of the original reproduced signal. This can be clearly seen when compared with FIG. 10 (c)], indicating that it is difficult to record the mark length.
[0050]
As described above, from the results of Reference Examples 1 to 4, the interface between the deformed layer and its adjacent layer is the main reflective interface, and the deformed layer is made incident light with a simple layer structure in which a deformable layer having a light absorption function is provided on the substrate. (In this case, recording / reproduction from the substrate side), it is often difficult to perform recording / reproduction by the mark length, and the recording polarity often becomes Low to High. It was.
[0051]
Reference Example 5
An optical recording medium in which SiC was formed to a thickness of 10 nm as a deformable layer having a light absorption function on a polycarbonate substrate having a guide groove with a groove depth of 55 nm was produced.
The optical recording medium was irradiated with 8.0 mW of laser light from the SiC side using an optical disk evaluation device, DDU-1000 (wavelength: 405 nm, NA: 0.65) manufactured by Pulstec Industrial Co., Ltd. 3T to 14T marks were individually recorded at a recording frequency of 65.4 MHz and a recording linear velocity of 6.0 m / s at the groove position on the near side as viewed from the incident laser beam side.
In addition, it was confirmed by AFM that SiC was deformed to the incident light side (non-substrate side).
Further, from the result of FIG. 14A, it can be confirmed that High to Low recording may be performed regardless of the recording mark length.
Further, from the results of FIGS. 14B to 14D, it can be seen that all of 3T, 4T, 6T, 8T, and 14T show reproduction signal waveforms that allow mark length recording.
[0052]
Reference Example 6
Except for the point that the recording power was 9.0 mW, the same experiment as in Reference Example 5 was performed.
In addition, it was confirmed by AFM that SiC was deformed to the incident light side (non-substrate side).
Further, from the result of FIG. 15A, it can be confirmed that there is a possibility that High to Low recording can be performed regardless of the recording mark length.
Further, from the results of FIGS. 15B to 15D, it can be seen that all of 3T, 4T, 6T, 8T, and 14T show reproduced signal waveforms that allow mark length recording.
[0053]
Reference Example 7
Exactly the same experiment as Reference Example 5 was performed, except that 7.0 mW laser light was irradiated from the SiC side and recorded in the groove portion (groove position on the back side when viewed from the incident laser light side). . In addition, it was confirmed by AFM that SiC was deformed to the incident light side (non-substrate side).
Further, from the result of FIG. 16A, it can be confirmed that there is a possibility that High to Low recording can be performed regardless of the recording mark length.
Further, from the results of FIGS. 16B to 16D, it can be seen that all of 3T, 4T, 6T, 8T, and 14T show reproduced signal waveforms that allow mark length recording.
[0054]
Reference Example 8
Exactly the same experiment as in Reference Example 5 was performed except that 8.0 mW laser beam was irradiated from the substrate side and recorded in the groove portion (groove position on the back side when viewed from the incident laser beam side). In addition, it was confirmed by AFM that SiC was deformed to the incident light side (non-substrate side).
Further, from the result of FIG. 17A, it can be confirmed that there is a possibility that High to Low recording can be performed regardless of the recording mark length.
Further, from the result of FIG. 17 (d), it can be seen that both the shortest and longest marks show reproduction signal waveforms that allow mark length recording.
[0055]
As described above, as shown in Reference Examples 5 to 8, a simple optical recording medium in which the interface between the deformable layer and its adjacent layer is the main reflective interface, and the deformable layer having the light absorption function is provided on the substrate. In the case where the deformation layer is deformed to the incident light side (in the present case, recording / reproduction from the non-substrate side), it is proved by experiments that mark length recording is possible and High to Low recording is possible. It was done.
[0056]
【The invention's effect】
According to the present invention 1 to 22, it can be manufactured at a low cost with a simple layer configuration, the recording / reproducing wavelength is not greatly limited, the wavelength dependence of recording characteristics is small, and even when an organic material is used, it is conventional with respect to the organic material. It is possible to realize good jitter and a wide recording power margin despite the use of the recording principle mainly composed of deformation, and can cope with surface recording or recording with a high NA lens. It is possible to provide a write-once type optical recording medium having a characteristic that high density can be achieved and a recording / reproducing method thereof.
[Brief description of the drawings]
FIG. 1 is a view for explaining the symmetry of a deformed shape of a deformable layer.
(A) An example of a deformed shape whose symmetry has deteriorated.
(B) An example of an ideal deformed shape.
FIG. 2 is a diagram for explaining a waveform of a reproduction signal when a mark length recording mark is reproduced.
(A) General case
(B) Differential waveform having an inflection point near the front and rear edges of the recording mark.
(C) Differential waveform with an inflection point near the center of the recording mark
FIG. 3 is a view showing an example having a structure in which a deformation shape compensation layer and a deformation receiving layer are adjacent to a deformation layer;
4 is a diagram showing the deformation direction and the reproduction direction of the deformation layer when the main reflection interface is at the interface between the deformation layer and the deformation reception layer, having the structure of FIG. 3;
5 is a diagram showing an example in which the layer configuration having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, an example in which the layer configuration of FIG. 4 is stacked on a substrate.
6 is another example in which the layer structure having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, the layer structure of FIG. 4 is laminated on a substrate, and further on the deformation receiving layer. The figure which shows the example which provided the cover layer.
7 is another example in which the layer configuration having the structure and function of FIG. 4 is applied to an actual write-once optical recording medium, that is, the layer configuration of FIG. 4 is laminated on a substrate, and further on the deformation receiving layer. The figure which shows the example which provided the cover layer through the contact bonding layer.
8 is a structure having the structure of FIG. 3 and having a reflective layer as an adjacent layer on the opposite side of the deformation receiving layer, and the main reflection interface is at the interface of the deformation receiving layer and the reflection layer. The figure which showed the deformation | transformation direction and reproduction | regeneration direction of a deformation | transformation layer.
9 is a diagram showing an example in which the layer configuration having the structure and function of FIG. 8 is applied to an actual write-once optical recording medium, that is, an example in which the layer configuration of FIG. 8 is stacked on a substrate.
10 is a diagram showing a recording result of Reference Example 1. FIG.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the modulation degree is shown.
(B) Reproduction signal when 3T mark and 4T mark are continuously recorded, and reproduction signal level when not recorded.
(C) Reproduction signal when 6T mark and 8T mark are continuously recorded, and reproduction signal level when not recorded.
(D) A reproduction signal when 3T mark and 14T mark are continuously recorded, and a reproduction signal level when not recorded.
FIG. 11 is a diagram showing a recording result of Reference Example 2.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the modulation degree is shown.
(B) Reproduction signal when 3T mark and 4T mark are continuously recorded, and reproduction signal level when not recorded.
(C) Reproduction signal when 6T mark and 8T mark are continuously recorded, and reproduction signal level when not recorded.
(D) A reproduction signal when 3T mark and 14T mark are continuously recorded, and a reproduction signal level when not recorded.
12 is a view showing a recording result of Reference Example 3. FIG.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the modulation degree is shown.
(B) Reproduction signal when 3T mark and 4T mark are continuously recorded, and reproduction signal level when not recorded.
(C) Reproduction signal when 6T mark and 8T mark are continuously recorded, and reproduction signal level when not recorded.
(D) A reproduction signal when 3T mark and 14T mark are continuously recorded, and a reproduction signal level when not recorded.
13 is a diagram showing a recording result of Reference Example 4. FIG.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the modulation degree is shown.
(B) Reproduction signal when 3T mark and 4T mark are continuously recorded, and reproduction signal level when not recorded.
(C) Reproduction signal when 6T mark and 8T mark are continuously recorded, and reproduction signal level when not recorded.
(D) A reproduction signal when 3T mark and 14T mark are continuously recorded, and a reproduction signal level when not recorded.
14 is a diagram showing a recording result of Reference Example 5. FIG.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the modulation degree is shown.
(B) Reproduction signal when 3T mark and 4T mark are continuously recorded, and reproduction signal level when not recorded.
(C) Reproduction signal when 6T mark and 8T mark are continuously recorded, and reproduction signal level when not recorded.
(D) Reproduction signal when 3T mark and 14T mark are continuously recorded, and reproduction signal level when not recorded.
15 is a diagram showing a recording result of Reference Example 6. FIG.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the modulation degree is shown.
(B) Reproduction signal when 3T mark and 4T mark are continuously recorded, and reproduction signal level when not recorded.
(C) Reproduction signal when 6T mark and 8T mark are continuously recorded, and reproduction signal level when not recorded.
(D) A reproduction signal when 3T mark and 14T mark are continuously recorded, and a reproduction signal level when not recorded.
FIG. 16 is a view showing a recording result of Reference Example 7;
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the modulation degree is shown.
(B) Reproduction signal when 3T mark and 4T mark are continuously recorded, and reproduction signal level when not recorded.
(C) Reproduction signal when 6T mark and 8T mark are continuously recorded, and reproduction signal level when not recorded.
(D) A reproduction signal when 3T mark and 14T mark are continuously recorded, and a reproduction signal level when not recorded.
FIG. 17 is a view showing a recording result of Reference Example 8.
(A) The relationship between the recording mark length, the reproduction signal (RF level), and the modulation degree is shown.
(D) A reproduction signal when 3T mark and 14T mark are continuously recorded, and a reproduction signal level when not recorded.
18 is a diagram showing an eye pattern of the optical recording medium of Comparative Example 2. FIG.
19 is a diagram showing an eye pattern of the optical recording medium of Comparative Example 1. FIG.
20 is a diagram showing jitter characteristics with respect to recording power of optical recording media of Comparative Example 1 and Comparative Example 2. FIG.
FIG. 21 is a diagram in which the deformation state of the deformation layer of the optical recording medium of Comparative Example 2 is measured by AFM.
FIG. 22 is a view showing a result of measuring the deformation state of the deformation layer of the optical recording medium of Comparative Example 1 by AFM.
FIG. 23 is a diagram showing the results of measuring the deformation state of the deformation layer by AFM after peeling off the polystyrene layer of the optical recording medium of Example 1.
24 is a graph showing jitter characteristics with respect to recording power of optical recording media of Comparative Example 1 and Example 1. FIG.
FIG. 25 is a diagram showing jitter characteristics with respect to recording power of optical recording media of Example 2 and Comparative Example 3;
FIG. 26 is a diagram showing a layer structure of a conventional disk.
[Explanation of symbols]
A A part where the deformed layer and the deformed shape compensation layer are separated, a part where the deformed shape compensation layer is expanded, or a part where the deformed layer is expanded
Mark Length Mark Head
T Reference clock
RF Level (V) RF (reproduction signal) level (volts)
Modulated amplitude modulation degree
Playback signal (RF) level when Unrec is not recorded
Top playback signal level (ie space part) when Top mark row is recorded
Bottom Minimum playback signal level when a mark row is recorded (ie, mark portion)
Degree of modulation calculated by MA (Top-Bottom) / Top
Time0.5 (μs / div) Time (1 memory 0.5 microsecond)
σ / Tw jitter

Claims (22)

Deformable layer causing deformation by recording a deformed shape compensation layer to compensate for the deformation shape of the deformation layer, deformation sandwiched between receiving layer configured for receiving deformation of the deformable layer have a, deformation shape compensation layer, A write-once type optical recording medium comprising an organic material that generates pressure toward the deformation layer side by at least one state change among decomposition, explosion, and sublimation by recording.   The write-once type optical recording medium according to claim 1, wherein the organic material is a dye.   The deformation layer that causes deformation by recording has a structure sandwiched between a deformation shape compensation layer that compensates for the deformation shape of the deformation layer and a deformation reception layer that receives deformation of the deformation layer, and the recording polarity is High to Low. A write-once type optical recording medium characterized by being. The write-once type optical recording medium according to any one of claims 1 to 3, wherein the interface between the deformation layer and the deformation receiving layer is a main reflection interface, and reproduction is performed from the deformation receiving layer side. The write-once type optical recording medium according to claim 4, wherein the recording portion is formed by deformation of the deformation layer toward the deformation receiving layer. Claims reflective layer adjacent to the deformed receptive layer has a set vignetting structure, the interface deformation receptive layer and the reflective layer as a main reflection interface, characterized in that the reproduction is performed from the deformed shape compensation layer side Item 3. The write-once type optical recording medium according to item 1 or 2 . The write-once type optical recording medium according to claim 6, wherein the recording portion is formed by deformation of the deformation layer toward the deformation receiving layer. Write-once optical recording medium according to any one of claims 1 to 7, characterized in that deformable portion to deform layer by light absorption function active layer is formed. Write-once optical recording medium according to any one of claims 1 to 7, characterized in that deformable portion to deform layer by light absorption function deformed shape compensation layer is formed. The deformable layer and the deformed shape compensation layer have a light absorption function with respect to the recording light, the deformed portion is formed in the deformable layer by the light absorption function of both, and the light absorption function of the deformed shape compensation layer is reduced or eliminated by recording The write-once type optical recording medium according to any one of claims 1 to 7 .   The write-once type optical recording medium according to claim 1, wherein the deformation receiving layer is made of a polymer compound.   The write-once type optical recording medium according to claim 1, wherein the deformable layer contains Si or Ge.   13. The write-once type optical recording medium according to claim 12, wherein recording / reproduction is possible in a laser wavelength range of 350 to 500 nm. The deformation layer that causes deformation by recording has a structure sandwiched between a deformation shape compensation layer that compensates for the deformation shape of the deformation layer and a deformation reception layer that receives deformation of the deformation layer , and the deformation shape compensation layer comprises: A recording method for a write-once optical recording medium made of an organic material that generates pressure toward the deformation layer by at least one state change of decomposition, explosion, and sublimation by recording. A recording method for a write-once type optical recording medium, characterized by being deformed to the layer side. Recording method of the write once optical recording medium according to claim 14, wherein the organic material is dye. Recording method to write-once type optical recording medium, wherein deformation layer causing deformation by recording is sandwiched between deformation shape compensation layer for compensating deformation shape of deformation layer and deformation receiving layer for receiving deformation of deformation layer A recording method for a write-once type optical recording medium, wherein the deformation layer is deformed to the deformation receiving layer side by recording, and the recording polarity is set to High to Low.   The deformation layer that causes deformation by recording has a structure sandwiched between a deformation shape compensation layer that compensates the deformation shape of the deformation layer and a deformation reception layer that receives deformation of the deformation layer, and the deformation layer and the deformation reception layer Is a recording method on a write-once optical recording medium in which reproduction is performed from the deformation-receiving layer side, and the deformation layer is deformed to the deformation-receiving layer side by recording. Recording method of recording medium.   A deformation shape compensation layer that compensates for the deformation shape of the deformation layer, a deformation layer that causes deformation by recording, a deformation reception layer that receives deformation of the deformation layer, and a reflection layer are provided in order, and the deformation reception layer and the reflection layer A recording method on a write once optical recording medium in which the interface of the layer is a main reflection interface, and reproduction is performed from the deformation shape compensation layer side, wherein the deformation layer is deformed to the deformation receiving layer side by recording. Method of recording optical recording medium. The additional writing according to any one of claims 14 to 18 , wherein the deformation of the deformation layer toward the deformation receiving layer is caused by an expansion force of the deformation layer and / or a pressure accompanying a state change of the deformation shape compensation layer. Method of recording optical recording medium. The deformation of the deformable receiving layer side of the deformable layer, any one of claims 14 to 18, characterized in that to produce the light absorption function of the active layer due to irradiation with recording light and / or light absorption function of the deformed shape compensation layer The recording method of the write-once type optical recording medium described in 1. The deformation of the deformation layer toward the deformation receiving layer is caused by the light absorption function of the deformation layer and the light absorption function of the deformation shape compensation layer by irradiation of the recording light, and after the light irradiation of the recording light, the light absorption of the deformation shape compensation layer recording method of the write-once optical recording medium according to any one of claims 14 to 18, characterized in that reducing or eliminating the function.   The recording on the write-once type optical recording medium according to any one of claims 14 to 21, wherein the deformable layer is made of a material containing Si or Ge, and recording / reproducing is performed with a laser beam having a wavelength of 350 to 500 nm. Method.

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