JP3797074B2 - Recording and / or reproducing apparatus and method - Google Patents

Description

上記した（３式）と（４式）との関係については後述する。
【００９８】
次に、図１０及び図１１は、ラジアルプッシュプル信号｛（Ｃ＋Ｄ）−ｋ（Ａ＋Ｂ）｝中のランドプリピット信号を２値化回路９内で確実に２値化するために、（Ｃ＋Ｄ）信号と｛−ｋ（Ａ＋Ｂ）｝信号中のランドプリピット信号のみに注目して、このランドプリピット信号の許容変動幅（スライスウインドウ幅）が所定の係数ｋによりどの様に変化するかをシュミレーションすることで、ハイパワー照射部のランドプリピット信号と、ローパワー照射部のランドプリピット信号との両者を同時に確実に検出することができるスライスウインドウ幅を所定の係数ｋに応じて求めている。この際、ランドプリピット信号に対するスライスウインドウ幅は、２値化回路９内で設定されるものである。
【００９９】
まず、図１０（ａ）〜（ｆ）の場合には、上記図９で説明したａ／ｍ１＝ｂ／ｍ２＝Ｌが成立している特殊な場合であり、ここではＬの値を例えば０．２に設定してシュミレーションをしている。
【０１００】
図１０（ｂ）は所定の係数ｋを「１．０」に設定した場合であり、この場合は従来より行われているラジアルプッシュプル信号｛（Ｃ＋Ｄ）−（Ａ＋Ｂ）｝を得る場合である。この例では、ハイパワー照射部のランドプリピット信号のアンダーレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとが共に同じ基準レベル（以下、０レベルと記す）となり、ここでの図示を省略したウォブリング信号を良好に検出することができるものの、ランドプリピット信号の検出が今一つ良好となり得ない。
【０１０１】
即ち、ハイパワー照射部のランドプリピット信号とローパワー照射部のランドプリピット信号とを検出するための前記スライスウインドウ幅は、ローパワー照射部のランドプリピット信号のピークレベルと、０レベルとのレベル差が４．０となり、このスライスウインドウ幅の値＝４．０はやや小さいので両ランドプリピット信号を確実に検出できない。
【０１０２】
また、上記した図１０（ｂ）に対して図１０（ａ）に示したように、所定の係数ｋを「１．０」より少し小さくして「０．９６」に設定した場合には、ハイパワー照射部のランドプリピット信号のアンダーレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとが共に０レベルより上方に上がり、且つ、両ランドプリピット信号を検出するための前記スライスウインドウ幅は、ローパワー照射部のランドプリピット信号のピークレベルと、ハイパワー照射部のランドプリピット信号のアンダーレベルとのレベル差が０．９２となり、このスライスウインドウ幅の値＝０．９２は図１０（ｂ）よりも極端に小さくなってしまいランドプリピット信号の検出が困難となると共に、図示を省略したウォブリング信号も図１０（ｂ）の場合よりも少し劣る。
【０１０３】
一方、上記した図１０（ｂ）に対して図１０（ｃ）に示したように、所定の係数ｋを「１．０」より少し大きくして「１．１」に設定した場合には、ハイパワー照射部のランドプリピット信号のアンダーレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとが共に０レベルより下方に下がり、且つ、両ランドプリピット信号を検出するための前記スライスウインドウ幅は、ローパワー照射部のランドプリピット信号のピークレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとのレベル差が４．１となり、このスライスウインドウ幅の値＝４．１は図１０（ｂ）よりも僅かに大きいので、ランドプリピット信号の検出が少し向上する。
【０１０４】
この際、図示を省略したウォブリング信号は図１０（ｂ）の場合よりも少し劣るものの、ウォブリング信号の検出が劣化することよりもランドプリピット信号を確実に検出できる方がより重要であり、以下図１０（ｄ）〜図１０（ｆ）の場合でもウォブリング信号の検出が徐々に劣化するものである。
【０１０５】
また、図１０（ｄ）に示したように、所定の係数ｋを図１０（ｃ）よりも大きく「１．２」に設定した場合には、図１０（ｃ）と同じ傾向となるものの、両ランドプリピット信号を検出するための前記スライスウインドウ幅は、ローパワー照射部のランドプリピット信号のピークレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとのレベル差が４．４となり、このスライスウインドウ幅の値＝４．４は両ランドプリピット信号を信頼性良く確実に検出できる良好な値である。
【０１０６】
また、図１０（ｅ）に示したように、所定の係数ｋを図１０（ｄ）よりも更に大きく「１．５」に設定した場合には、ハイパワー照射部のランドプリピット信号のアンダーレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとが共に０レベルより下方に下がった状態で、ハイパワー照射部のランドプリピット信号のピークレベルと、ローパワー照射部のランドプリピット信号のピークレベルとが共に０レベルで一致している。
【０１０７】
また、両ランドプリピット信号を検出するための前記スライスウインドウ幅は、０レベル（＝ハイパワー照射部及びローパワー照射部のランドプリピット信号のピークレベル）と、ローパワー照射部のランドプリピット信号のアンダーレベルとのレベル差が５．０となり、このスライスウインドウ幅の値＝５．０は両ランドプリピット信号を確実に検出できる最大値となるので、後述する理由により、ａ／ｍ１＝ｂ／ｍ２＝Ｌの条件下での所定の係数ｋ＝１．５が理論的上限値となるものである。尚、所定の係数ｋの理論的下限値の求め方については後述する。
【０１０８】
更に、図１０（ｆ）に示したように、所定の係数ｋを図１０（ｄ）よりも更に大きく「１．６」に設定した場合には、ハイパワー照射部のランドプリピット信号のピークレベルとローパワー照射部のランドプリピット信号のピークレベルとが共に０レベルより下方に下り、且つ、ハイパワー照射部のランドプリピット信号のピークレベルの方がローパワー照射部のランドプリピット信号のピークレベルよりも下がった状態となり、且つ、両ランドプリピット信号を検出するための前記スライスウインドウ幅は、ハイパワー照射部のランドプリピット信号のピークレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとのレベル差が２．０となり、このスライスウインドウ幅の値＝２．０は図１０（ｅ）の場合から所定の係数ｋを僅かに０．１だけ増加したにもかかわらず極端に減少してしまい、両ランドプリピット信号の検出が極端に悪化する。
【０１０９】
従って、図１０（ｅ）に示したように所定の係数ｋが「１．５」の場合が理論的上限値となるものであり、この理論的上限値に設定した場合には所定の係数ｋが１．５より大きくなる方向に対して余裕がないため、信頼性及び安全性の面から図１０（ｄ）に示したように、所定の係数ｋが「１．２」〜「１．４」（一部図示省略）の場合がａ／ｍ１＝ｂ／ｍ２＝Ｌの条件下での実用値となる。
【０１１０】
ここで、図１０（ｅ）に示したように、所定の係数ｋがａ／ｍ１＝ｂ／ｍ２＝Ｌの条件下で理論的上限値を取る時の条件は、前述した如く、（３式）による（Ｃ＋Ｄ）信号中のランドプリピット信号の振幅ＬＢ１と、（４式）による｛−ｋ（Ａ＋Ｂ）｝信号中のランドプリピット信号の振幅ＬＢ２とが同じ値になる場合に所定の係数ｋの理論的上限値が得られるものであり、これによって（３式）＝（４式）から所定の係数ｋは以下の５式で算出される値となる。
【０１１１】

更に、上記（５式）中のＬは、前述した（１式）による正規化したＬＰＰｂ信号＝Ｌ１／Ｒ１＝ｋＬ２／ｋＲ２＝Ｌ２／Ｒ２を演算した場合と図７から明らかに等価となるものであるから、上記したＬ値を正規化したＬＰＰｂ信号値に置き換えることができ、即ち、（５式）を下記の（６式）に置き換えることができ、これによりＬＰＰｂ生成回路１４からの出力結果を係数設定回路１６に供給することで（６式）により理論的上限値の所定の係数ｋが得られる。
【０１１２】
ｋ＝（１＋ＬＰＰｂ）／（１−ＬＰＰｂ）……（６式）
次に、図１１（ａ）〜（ｅ）の場合には、上記図９で説明したごとくのａ／ｍ１＝ｂ／ｍ２＝Ｌが成立していなく、即ち、ａ／ｍ１≠ｂ／ｍ２≠Ｌとなる一般的な場合であり、ここではＬの値を例えば略０．２に設定してシュミレーションをしている。
【０１１３】
尚、図１１（ａ）〜（ｅ）も図１０で説明した略同様な考え方で所定の係数Ｋに対してハイパワー照射部のランドプリピット信号及びローパワー照射部のランドプリピット信号を共に確実に検出するためのスライスウインドウ幅を求めている。また、ここで求めたスラウスウインドウ幅の絶対値は、図１０で求めた絶対値とは異なるが、これはもちろん所定の係数ｋ以外の要因が異なるためである。
【０１１４】
即ち、図１１（ａ）は所定の係数ｋを「０．９」に設定した場合なのであるが、この場合、ハイパワー照射部のランドプリピット信号のアンダーレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとが共に０レベルより上方に上がり、且つ、ハイパワー照射部のランドプリピット信号とローパワー照射部のランドプリピット信号とを検出するための前記スライスウインドウ幅は、ローパワー照射部のランドプリピット信号のピークレベルと、ハイパワー照射部のランドプリピット信号のアンダーレベルとのレベル差が３．５となる。この３．５という数値はランドプリピット信号の検出が困難となる小さな値である。
【０１１５】
また、図１１（ｂ）は所定の係数ｋを「１．０」に設定した場合であり、この場合は従来より行われているラジアルプッシュプル信号｛（Ｃ＋Ｄ）−（Ａ＋Ｂ）｝を得る場合である。
【０１１６】
この場合では、ハイパワー照射部のランドプリピット信号のアンダーレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとが共に同じ０レベル（基準レベル）となり、ここでの図示を省略したウォブリング信号を良好に検出することができるものの、ランドプリピット信号の検出が今一つ良好となり得ない。即ち、両ランドプリピット信号を検出するための前記スライスウインドウ幅は、ローパワー照射部のランドプリピット信号のピークレベルと、０レベルとのレベル差が８．０となり、このスライスウインドウ幅の値＝８．０はやや小さいので両ランドプリピット信号を確実に検出できない。
【０１１７】
また、図１１（ｃ）は所定の係数ｋを「１．１」に設定した場合なのであるが、この場合、ハイパワー照射部のランドプリピット信号のアンダーレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとが共に０レベルより下方に下がり、且つ、両ランドプリピット信号を検出するための前記スライスウインドウ幅は、ローパワー照射部のランドプリピット信号のピークレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとのレベル差が８．４となり、このスライスウインドウ幅の値＝８．４は両ランドプリピット信号を信頼性良く確実に検出できる良好な値である。
【０１１８】
また、図１１（ｄ）は所定の係数ｋを「１．２」に設定した場合なのであるが、この場合、ハイパワー照射部のランドプリピット信号のアンダーレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとが共に０レベルより下方に下がった状態で、ハイパワー照射部のランドプリピット信号のピークレベルと、ローパワー照射部のランドプリピット信号のピークレベルとが共に０レベルより上方で一致している。
【０１１９】
そして、両ランドプリピット信号を検出するための前記スライスウインドウ幅は、ハイパワー照射部及びローパワー照射部のランドプリピット信号のピークレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとのレベル差が８．８となり、このスライスウインドウ幅の値＝８．８は両ランドプリピット信号を確実に検出できる最大値となるので、ａ／ｍ１≠ｂ／ｍ２≠Ｌの条件下での所定の係数ｋ＝１．２が理論的上限値となるものである。
【０１２０】
また、図１１（ｅ）は所定の係数ｋを「１．３」に設定した場合なのであるが、この場合、ハイパワー照射部のランドプリピット信号のピークレベルとローパワー照射部のランドプリピット信号のピークレベルとが共に０レベルより下方に下り、且つ、ハイパワー照射部のランドプリピット信号のピークレベルの方がローパワー照射部のランドプリピット信号のピークレベルよりも下がった状態となり、両ランドプリピット信号を検出するための前記スライスウインドウ幅は、ハイパワー照射部のランドプリピット信号のピークレベルと、ローパワー照射部のランドプリピット信号のアンダーレベルとのレベル差が７．０となり、このスライスウインドウ幅の値＝７．０は図１１（ｃ）及び図１１（ｄ）より小さくなってしまい、両ランドプリピット信号の検出が悪化する。
【０１２１】
従って、図１１（ｄ）に示したように所定の係数ｋが「１．２」の場合が理論的上限値となるものであり、この理論的上限値に設定した場合には所定の係数ｋが１．２より大きくなる方向に対して余裕がないため、信頼性及び安全性の面から図１１（ｃ）に示したように、所定の係数ｋが「１．１」近傍の場合がａ／ｍ１≠ｂ／ｍ２≠Ｌの条件下での実用値となる。
【０１２２】
ここで、図１１（ｄ）に示したように、所定の係数ｋがａ／ｍ１≠ｂ／ｍ２≠Ｌの条件下で理論的上限値を取る時の条件は、前記した（５式）及び（６式）から類推できるものであり、下記の（７式）及び（８式）が成立する。
【０１２３】
１．０＜ｋ＜α×｛（１＋Ｌ）／（１−Ｌ）｝……（７式）
１．０＜ｋ＜α×｛（１＋ＬＰＰｂ）／（１−ＬＰＰｂ）｝……（８式）
この際、（７式）及び（８式）中の係数αは、光ピックアップ２の性能、及び、その光ピックアップ２の基での記録パワー、並びに、再生モードにおいては再生パワーによって左右される係数で１．０より小さい値を取るものであり、この係数αの値は予めメモリに格納しておけば良いものである。
【０１２４】
次に、図１２は、ラジアルプッシュプル信号中のランドプリピット信号成分を仮にゼロにしてランドプリピット信号成分を除去し、ラジアルプッシュプル信号中のウォブリング信号のみに着目した図であり、０レベルを境にした正極性側が（Ｃ＋Ｄ）信号のハイパワー照射部のウォブリング信号及びローパワー照射部のウォブリング信号を示し、一方、０レベルを境にした負極性側が｛−ｋ（Ａ＋Ｂ）｝信号のハイパワー照射部のウォブリング信号及びローパワー照射部のウォブリング信号を示している。
【０１２５】
また、｛−ｋ（Ａ＋Ｂ）｝信号は、乗算処理する所定の係数ｋを図９で説明したと同様に可変してシュミレーションしているが、図示の都合上所定の係数ｋ＝１．０，ｋ＝１．１，ｋ＝１．２の場合についてのみ示している。
【０１２６】
また、（Ｃ＋Ｄ）信号は、ローパワー照射部のウォブリング信号の中心レベルを「ｍ１」、ハイパワー照射部のウォブリング信号の中心レベルを「ｍ２」、ローパワー照射部のウォブリング信号の中心レベルから上片側の振幅を「ｃ」、ハイパワー照射部のウォブリング信号の中心レベルから上片側の振幅を「ｄ」とし、ｃ／ｍ１＝ｄ／ｍ２＝Ｗとしたとき、ハイパワー照射部のウォブリング信号波形の頂点からローパワー照射部のウォブリング信号波形の頂点までの振幅である（Ｃ＋Ｄ）信号の振幅ＷＢ１は、以下の（９式）で算出される。
【０１２７】
ＷＢ１＝ｍ２−ｍ１＋ｄ−ｃ＝ｍ２−ｍ１＋Ｗ×ｍ２−Ｗ×ｍ１……（９式）
また、上記と同様に、｛−ｋ（Ａ＋Ｂ）｝信号は、ローパワー照射部のウォブリング信号の中心レベルを「−ｋｍ１」、ハイパワー照射部のウォブリング信号の中心レベルを「−ｋｍ２」、ローパワー照射部のウォブリング信号の中心レベルから上片側の振幅を「ｋｃ」、ハイパワー照射部のウォブリング信号の中心レベルから上片側の振幅を「ｋｄ」とし、−ｋｃ／−ｋｍ１＝−ｋｄ／−ｋｍ２＝Ｗとしたとき、ローパワー照射部のウォブリング信号波形の頂点からハイパワー照射部のウォブリング信号波形の頂点までの振幅である｛−ｋ（Ａ＋Ｂ）｝信号の振幅ＷＢ２は、以下の式（１０式）で算出される。
【０１２８】

上記した（９式）と（１０式）との関係についても後述する。
【０１２９】
次に、図１３は、ラジアルプッシュプル信号｛（Ｃ＋Ｄ）−ｋ（Ａ＋Ｂ）｝中のランドプリピット信号を２値化回路９内で確実に２値化するために、（Ｃ＋Ｄ）信号と｛−ｋ（Ａ＋Ｂ）｝信号中のウォブリング信号のみに注目して、このウォブリング信号が所定の係数ｋによりどの様に変化するかをシュミレーションすることで、ハイパワー照射部のウォブリング信号の振幅と、ローパワー照射部のウォブリング信号の振幅との関係から所定の係数ｋの理論的下限値を決定している。尚、同図中では図１２に合わせて所定の係数ｋが「１．０」，「１．１」，「１．２」である場合を図示している。
【０１３０】
まず、図１３（ａ）〜（ｃ）の場合には、上記図１２で説明したごとくのｃ／ｍ１＝ｄ／ｍ２＝Ｗが成立している特殊な場合であり、ここではＷの値を例えば０．０５に設定してシュミレーションをしている。
【０１３１】
まず、図１３（ａ）は所定の係数ｋを「１．０」に設定した場合であり、この場合は従来より行われているラジアルプッシュプル信号｛（Ｃ＋Ｄ）−（Ａ＋Ｂ）｝を得る場合である。この例では、ハイパワー照射部のウォブリング信号と、ローパワー照射部のウォブリング信号とが共に同一周期であり、且つ、ハイパワー照射部のウォブリング信号の振幅の方がローパワー照射部のウォブリング信号の振幅よりも大きくなっている。この状態は先に説明した図１０（ｂ）と対応しており、ウォブリング信号を良好に検出できるものの、ランドプリピット信号の検出が今一つ良好となり得ない。
【０１３２】
また、図１３（ｂ）は所定の係数ｋを「１．１」に設定した場合であり、この例では、ハイパワー照射部のウォブリング信号と、ローパワー照射部のウォブリング信号とが異なる周期となるものの、ローパワー照射部のウォブリング信号の波形の頂点と、ハイパワー照射部のウォブリング信号の波形の頂点とが中心レベルより上方で一致しており、この状態はｃ／ｍ１＝ｄ／ｍ２＝Ｗの条件下での所定の係数ｋ＝１．１が理論的下限値となるものである。また、この状態は先に説明した図１０（ｃ）と対応しており、ウォブリング信号の検出が図１３（ａ）よりも少し劣るものの、ランドプリピット信号の検出をどうにか検出できるため、所定の係数ｋ＝１．１が理論的下限値となるものである。
【０１３３】
また、図１３（ｃ）は所定の係数ｋを「１．２」に設定した場合であり、この例では、ローパワー照射部のウォブリング信号の波形の頂点の下方に、ハイパワー照射部のウォブリング信号の波形の頂点の交わることなく位置している。この状態は先に説明した図１０（ｄ）と対応しており、ウォブリング信号の検出が更に悪くなる一方、ランドプリピット信号の検出が良好となるものであり、これについては説明済みである。
【０１３４】
ここで、図１３（ｂ）に示したように、所定の係数ｋがｃ／ｍ１＝ｄ／ｍ２＝Ｗの条件下で理論的下限値を取る時の条件は、前述した如く、（９式）による（Ｃ＋Ｄ）信号中のウォブリング信号の振幅ＷＢ１と、（１０式）による｛−ｋ（Ａ＋Ｂ）｝信号中のウォブリング信号の振幅ＷＢ２とが同じ値になる場合に所定の係数ｋの理論的下限値が得られるものであり、これによって（９式）＝（１０式）から所定の係数ｋは以下の式（１１式）で算出される値となる。
【０１３５】

更に、上記（１１式）中のＷは、前述した（２式）による正規化したＷＢＬｂ信号＝Ｗ１／Ｒ１＝ｋＷ２／ｋＲ２＝Ｗ２／Ｒ２を演算した場合と図７から明らかに等価となるものであるから、上記したＷ値を正規化したＷＢＬｂ信号値に置き換えることができ、即ち、（１１式）を下記の（１２式）に置き換えることができ、これによりＷＢＬｂ生成回路１５からの出力結果を係数設定回路１６に供給することで（１２式）により理論的下限値の所定の係数ｋが得られる。
【０１３６】
ｋ＝（１＋ＷＢＬｂ）／（１−ＷＢＬｂ）……（１２式）
また、ここでの図示を省略するものの、図１２で説明したごとくの所定の係数ｋがｃ／ｍ１＝ｄ／ｍ２＝Ｗが成立していなく、即ち、ｃ／ｍ１≠ｄ／ｍ２≠Ｗとなる一般的な場合でも、図１３（ｂ）に示したと略同様に、ローパワー照射部のウォブリング信号の波形の頂点と、ハイパワー照射部のウォブリング信号の波形の頂点とが一致した時に、この状態がｃ／ｍ１≠ｄ／ｍ２≠Ｗの条件下での所定の係数ｋの理論的下限値となるものである。
【０１３７】
この場合には、先に説明した（７式）及び（８式）と対をなす（１３式）及び（１４式）が成立する。
【０１３８】
１．０＜ｋ＜β×｛（１＋Ｗ）／（１−Ｗ）｝……（１３式）
１．０＜ｋ＜β×｛（１＋ＷＢＬｂ）／（１−ＷＢＬｂ）｝……（１４式）
この際、（１３式）及び（１４式）中の係数βは、光ピックアップ２の性能、及び、その光ピックアップ２の基での記録パワー、並びに、再生モードにおいては再生パワーによって左右される係数で１．０より小さい値を取るものであり、この係数βの値は予めメモリに格納しておけば良いものである。
【０１３９】
以上詳述したことを総合すると、所定の係数ｋは、ランドプリピット信号に対して先に説明した（５式），（６式），（７式），（８式）がそれぞれ個別に成立し、また、ウォブリング信号に対して先に説明した（１１式），（１２式），（１３式），（１４式）がそれぞれ個別に成立し、これらをランドプリピット信号側とウォブリング信号とで組み合わせて適用すれば良い。
【０１４０】
従って、所定の係数ｋは、理論的上限値と理論的下限値の範囲内に収まっていればランドドプリピット信号を精度良く確実に検出することができ、これにより以下の（１５式）〜（１８式）が成立するものである。
【０１４１】
即ち、ａ／ｍ１＝ｂ／ｍ２＝Ｌ、且つ、ｃ／ｍ１＝ｄ／ｍ２＝Ｗの条件下では、

一方、ａ／ｍ１≠ｂ／ｍ２≠Ｌ、且つ、ｃ／ｍ１≠ｄ／ｍ２≠Ｗの条件下では、

より具体的には、所定の係数ｋは従来「１．０」に設定されていたものであるが、本発明では、（１）ランドプリピット信号の振幅、又は、ランドプリピット信号の振幅及びウォブリング信号の振幅に基づいて、所定の係数の値を１．０より大きく且つランドプリピット信号を検出可能な範囲の値にフィードバックして設定するとか、もしくは、（２）正規化されたランドプリピット信号の振幅、又は、正規化されたランドプリピット信号の振幅及び正規化されたウォブリング信号の振幅に基づいて、所定の係数の値を１．０より大きく且つランドプリピット信号を検出可能な範囲の値にフィードバックして設定することで、ランドドプリピット信号を精度良く確実に検出することができ、ディスク状記録媒体の記録時又は再生時に、ランド３３に予め形成したランドドプリピットと対応するランドドプリピット信号を精度良く検出することができる。
【０１４２】
更に、当該実施の形態のディスク記録再生装置では、係数設定回路１６が、ＬＰＰ信号，ＷＢＬ信号，ＬＰＰｂ信号，ＷＢＬｂ信号，ランドプリピット信号の検出時のエラーレート，光ピックアップ２の対物レンズのシフト量に基づいて、係数乗算回路６に設定する所定の係数ｋの値を、前記した理論的上限値から理論的下限値の間の値に設定する。より具体的には、所定の係数ｋの値を１．０より大きく且つランドプリピット信号を検出可能な範囲内の値に設定する。
【０１４３】
これにより、記録時にＤＶＤ３１上のハイパワー照射部及びローパワー照射部にかかわらず、ランドプリピット信号を精度良く確実に検出することができ、また、再生時にＤＶＤ３１上の記録ピット形成部位及び未記録部位にかかわらず、ランドプリピット信号を精度良く確実に検出することができる。
【０１４４】
【発明の効果】
請求項１〜請求項８に記載の本発明に係る記録及び／又は再生装置並びに方法によれば、所定の周波数でウォブリングされ且つ情報信号の記録トラックとなるグルーブと、所定のウォブリング周期間隔で少なくともアドレス情報などがランドプリピットとして予め記録されたランドとを螺旋状又は同心円状に交互に形成したディスク状記録媒体に対して情報信号の記録及び／又は再生を行う際に、光ビームをディスク状記録媒体に照射した戻りの反射光をディスク状記録媒体の記録トラックに沿って少なくとも２等分割された第１，第２の受光領域を有する光受光素子で受光し、第１，第２の受光領域から出力された各受光出力のうちでランドプリピットを検出する側として設定した一方の受光出力に対して係数を乗算すると共に、他方の受光出力から前記係数を乗算した結果の出力を差引いた差分をラジアルプッシュプル信号として取り出して、このラジアルプッシュプル信号から前記ランドプリピットと対応したランドプリピット信号を検出するに当たって、前記係数は従来「１．０」に設定されていたものであるが、本発明では、
（１）ランドプリピット信号の振幅、又は、ランドプリピット信号の振幅及びウォブリング信号の振幅とか、
（２）正規化されたランドプリピット信号の振幅、又は、正規化されたランドプリピット信号の振幅及び正規化されたウォブリング信号の振幅とか、
（３）ラジアルプッシュプル信号から得られたエラーレートとか、
（４）光ピックアップの対物レンズの光軸中心からラジアル方向へのレンズシフト量とか
に基づいて、１．０より大きく且つランドプリピット信号を検出可能な範囲内に可変制御した値を係数として係数乗算手段（係数乗算ステップ）にフィードバックして設定する係数設定手段（係数設定ステップ）を備えたため、記録時にディスク状記録媒体上での光ビームによるハイパワー照射部及びローパワー照射部にかかわらず、ランドプリピット信号を精度良く確実に検出することができる。また、再生時にディスク状記録媒体上の記録ピット形成部位及び未記録部位にかかわらず、ランドプリピット信号を精度良く確実に検出することができる。
【図面の簡単な説明】
【図１】本発明に係る記録及び／又は再生装置並びに方法が適用された実施の形態のディスク記録再生装置で記録再生が行われるＤＶＤの構造を説明するための図である。
【図２】前記ＤＶＤのフォーマットを説明するための図である。
【図３】前記ＤＶＤのランド上に記録されているランドプリピットの記録位置を説明するための図である。
【図４】前記実施の形態のディスク記録再生装置のブロック図である。
【図５】前記実施の形態のディスク記録再生装置の光ピックアップに設けられている受光素子の分割受光領域を説明するための図である。
【図６】ラジアルプッシュプル信号を形成するウォブリング信号とランドプリピット信号の波形図である。
【図７】ラジアルプッシュプル信号を検出するための（Ｃ＋Ｄ）信号と｛−ｋ（Ａ＋Ｂ）｝信号をそれぞれ形成するウォブリング信号とランドプリピット信号の波形図である。
【図８】（Ｃ＋Ｄ）信号と｛−ｋ（Ａ＋Ｂ）｝信号のハイパワー照射部及びローパワー照射部の各波形図である。
【図９】乗算する所定の係数ｋの値に応じて変化する｛−ｋ（Ａ＋Ｂ）｝信号のハイパワー照射部及びローパワー照射部の各波形をランドプリピット信号に着目して見た図である。
【図１０】図９に示したａ／ｍ１＝ｂ／ｍ２＝Ｌが成立する場合に、乗算する所定の係数ｋの値に応じて変化する｛−ｋ（Ａ＋Ｂ）｝信号のハイパワー照射部及びローパワー照射部の各波形をランドプリピット信号に着目して見た図である。
【図１１】ａ／ｍ１≠ｂ／ｍ２≠Ｌの場合に、乗算する所定の係数ｋの値に応じて変化する｛−ｋ（Ａ＋Ｂ）｝信号のハイパワー照射部及びローパワー照射部の各波形をランドプリピット信号に着目して見た図である。
【図１２】乗算する所定の係数ｋの値に応じて変化する｛−ｋ（Ａ＋Ｂ）｝信号のハイパワー照射部及びローパワー照射部の各波形をウォブリング信号に着目して見た図である。
【図１３】図１２に示したｃ／ｍ１＝ｄ／ｍ２＝Ｗが成立する場合に、乗算する所定の係数ｋの値に応じて変化する｛−ｋ（Ａ＋Ｂ）｝信号のハイパワー照射部及びローパワー照射部の各波形をウォブリング信号に着目して見た図である。
【符号の説明】
２…光ピックアップ、３…プリアンプ、４…（Ａ＋Ｂ）加算回路、５…（Ｃ＋Ｄ）加算回路、６…係数乗算回路、７…ＲＦ回路、８…ＲＰＰ生成回路、９…２値化回路、１０…ＬＰＰデコード回路、１１…ＣＰＵ、１２…ＬＰＰ振幅検出回路、１３…ＷＢＬ振幅検出回路、１４…ＬＰＰｂ生成回路、１５…ＷＢＬｂ生成回路、１６…係数設定回路、１７…レンズシフト量検出回路、３１…ＤＶＤ、３２…ウォブリンググルーブ、３３…ランド、３４…ランドプリピット[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recording and / or reproducing apparatus and method suitable for application to, for example, a DVD reproducing apparatus, a DVD recording apparatus, a DVD recording / reproducing apparatus, or the like that performs recording and reproduction on an optical disc such as a DVD-R or DVD-RW .
[0002]
[Prior art]
In general, a recordable optical recording medium is prerecorded with address information in order to record desired information, and generates a clock signal for use in recording / reproducing operations. For this purpose, a recording track wobbled at a predetermined frequency is provided.
[0003]
As such an optical recording medium, for example, a DVD-R (Digital Versatile Disc-Recordable) capable of recording information about seven times as large as a CD (Compact Disc) is known. This DVD-R has an address on a convex land which is an area between the pregrooves, together with a concave pregroove which is an area where information to be recorded such as video data and audio data is recorded as recording pits. Information or the like is recorded in advance in the form of land pre-pits (LPP).
[0004]
Land pre-pits (LPP) on the lands are recorded on a straight line perpendicular to the tangential direction of the pre-groove so as not to be adjacent to each other with the pre-groove interposed therebetween. The pregroove is provided so as to slightly wobble at a predetermined frequency in the radial direction of the optical disk at a frequency based on a reference clock used for rotation control of the DVD-R.
[0005]
When performing such DVD-R rotation control, the wobbling frequency is detected from the reproduction output of the wobbling pre-groove (hereinafter referred to as wobbling groove), and the detected wobbling frequency matches the frequency of the reference clock. Feedback control.
[0006]
The land pre-pit (LPP) is a light receiving element that divides the reflected light of the light beam (laser beam) from the semiconductor laser irradiated to the wobbling groove into at least two parts by a dividing line optically parallel to the tangential direction of the wobbling groove. The difference signal is obtained by calculating the difference in the direction perpendicular to the wobbling groove of the output signal from each area (divided individual areas) of the light receiving element, and the difference signal is obtained with a predetermined threshold value. A binarized signal that is binarized in comparison with is detected.
[0007]
When the disc-shaped recording medium is an optical disc, a divided region of the light receiving element is formed along the radial direction (radial direction) of the optical disc by the dividing line, so the difference signal is called a radial push-pull signal. .
[0008]
As described above, the land pre-pit (LPP) can be detected by the binary signal obtained by binarizing the radial push-pull signal (difference signal) with a predetermined threshold value. This is because it is formed so as not to exist in adjacent lands on a straight line that intersects perpendicularly to the tangential direction of the wobbling groove.
[0009]
That is, when irradiating one wobbling groove with a light beam, the reflected light from the lands on both sides does not have a land pre-pit (LPP) reflection component at the same time (only reflected light from one of the lands). Therefore, only the reflected light component of the land pre-pit (LPP) is extracted by performing the above difference calculation.
[0010]
However, normally, a binary signal obtained by comparing only one of the bipolar components obtained by the difference calculation (for example, the positive electrode component) with a predetermined threshold is used as a land pre-pit signal (LPP signal).
[0011]
[Problems to be solved by the invention]
By the way, in an optical disc such as DVD-R or DVD-RW, a land pre-pit (LPP) is detected based on a binarized signal by binarizing a radial push-pull signal (difference signal) with a predetermined threshold value. However, conventionally, the amplitude ratio of two input signals for calculating a radial push-pull signal (difference signal) has been adjusted to be equal, but according to this method, in the land pre-pit (LPP), There is a problem that a laser power modulation component during recording becomes noise or erroneously detects a land pre-pit (LPP) due to the influence of a recording pit in the reproduction mode. Further, when a lens shift by the objective lens occurs in the recording / reproducing mode of the optical disk, the balance of the radial push-pull signal is lost, and there is a problem of erroneously detecting a land pre-pit (LPP).
[0012]
The present invention has been made in view of the above-described problems, and provides a recording and / or reproducing apparatus and method capable of accurately extracting a land prepit signal (LPP signal) with a simple configuration. Objective.
[0013]
[Means for Solving the Problems]
  The recording and / or reproducing apparatus according to the first aspect of the present invention includes a wobbling groove wobbled at a predetermined frequency and serving as a recording track for an information signal, and at least address information at a predetermined wobbling cycle interval. In a recording and / or reproducing apparatus for recording and / or reproducing the information signal with respect to a disk-shaped recording medium in which lands prerecorded as a spiral or concentric circle are alternately formed,
  First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam Receive light atA light receiving element that
  in front1st and 2nd light receiving areaOutput fromOf each received light outputSet as the land pre-pit detection sideFor one received light outputA predetermined initial value is set when the information signal recording and / or reproducing operation is started, and a value changed by variable control is set after the operation is started.Multiply coefficientCalculationCoefficient multiplication means for outputting
  The coefficient multiplying means multiplies the other received light output of the first and second light receiving areas from the other received light output.CalculationPush-pull signal generation means for outputting a difference obtained by subtracting the output of the result as a radial push-pull signal;
  A land pre-pit signal amplitude detecting means for extracting a land pre-pit signal corresponding to the land pre-pit of the land from the radial push-pull signal, detecting the amplitude of the land pre-pit signal, and outputting it;
  A wobbling signal amplitude detecting means for extracting the wobbling signal of the wobbling groove from the radial push-pull signal and detecting and outputting the amplitude of the wobbling signal;
  At the time of starting the recording and / or reproducing operation of the information signal, the initial value is set as the coefficient in the coefficient multiplication means, and after the operation starts,Based on the amplitude of the land pre-pit signal, or the amplitude of the land pre-pit signal and the amplitude of the wobbling signal1. Greater than 0 and within the range where the land pre-pit signal can be detectedThe value that is variably controlled is fed back to the coefficient multiplication means as the coefficient.Coefficient setting means for setting.
[0014]
  According to a second aspect of the present invention, there is provided a recording and / or reproducing apparatus according to the present invention, wherein a wobbling groove wobbled at a predetermined frequency and serving as a recording track of an information signal, and at least address information at a predetermined wobbling cycle interval are landed. In a recording and / or reproducing apparatus for recording and / or reproducing the information signal with respect to a disk-shaped recording medium in which lands prerecorded as prepits are alternately formed in a spiral or concentric shape,
  First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam Receive light atA light receiving element that
  in front1st and 2nd light receiving areaOutput fromOf each received light outputSet as the land pre-pit detection sideFor one received light outputA predetermined initial value is set when the information signal recording and / or reproducing operation is started, and a value changed by variable control is set after the operation is started.Multiply coefficientCalculationCoefficient multiplication means for outputting
  The coefficient multiplying means multiplies the other received light output of the first and second light receiving areas from the other received light output.CalculationPush-pull signal generation means for outputting a difference obtained by subtracting the output of the result as a radial push-pull signal;
  A land pre-pit signal amplitude detecting means for extracting a land pre-pit signal corresponding to the land pre-pit of the land from the radial push-pull signal, detecting the amplitude of the land pre-pit signal, and outputting it;
  A wobbling signal amplitude detecting means for extracting the wobbling signal of the wobbling groove from the radial push-pull signal and detecting and outputting the amplitude of the wobbling signal;
  Sum signal generating means for taking the sum of the light receiving outputs of the first and second light receiving regions and outputting a sum signal;
  Normalizing land pre-pit signal amplitude generating means for outputting the amplitude of the normalized land pre-pit signal by dividing the amplitude of the land pre-pit signal by the sum signal;
  A normalized wobbling signal amplitude generating means for outputting the amplitude of the normalized wobbling signal by dividing the amplitude of the wobbling signal by the sum signal;
  At the time of starting the recording and / or reproducing operation of the information signal, the initial value is set as the coefficient in the coefficient multiplication means, and after the operation starts,Based on the amplitude of the normalized land pre-pit signal, or the amplitude of the normalized land pre-pit signal and the amplitude of the normalized wobbling signal1. Greater than 0 and within the range where the land pre-pit signal can be detectedThe value that is variably controlled is fed back to the coefficient multiplication means as the coefficient.Coefficient setting means for setting.
[0015]
  According to a third aspect of the present invention, there is provided a recording and / or reproducing apparatus according to the present invention, wherein a wobbling groove wobbled at a predetermined frequency and serving as a recording track of an information signal, and at least address information etc. at a predetermined wobbling cycle interval are landed. In a recording and / or reproducing apparatus for recording and / or reproducing the information signal with respect to a disk-shaped recording medium in which lands prerecorded as prepits are alternately formed in a spiral or concentric shape,
  First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam Receive light atA light receiving element that
  in front1st and 2nd light receiving areaOutput fromOf each received light outputSet as the land pre-pit detection sideFor one received light outputA predetermined initial value is set when the information signal recording and / or reproducing operation is started, and a value changed by variable control is set after the operation is started.Multiply coefficientCalculationCoefficient multiplication means for outputting
  The coefficient multiplying means multiplies the other received light output of the first and second light receiving areas from the other received light output.CalculationPush-pull signal generation means for outputting a difference obtained by subtracting the output of the result as a radial push-pull signal;
  An error rate calculating means for calculating and outputting an error rate at the time of detection of a land pre-pit signal included in the radial push-pull signal;
  At the time of starting the recording and / or reproducing operation of the information signal, the initial value is set as the coefficient in the coefficient multiplication means, and after the operation starts,Based on the error rate1. Greater than 0 and within the range where the land pre-pit signal can be detectedThe value that is variably controlled is fed back to the coefficient multiplication means as the coefficient.Coefficient setting means for setting.
[0016]
  According to a fourth aspect of the present invention, there is provided a recording and / or reproducing apparatus according to the present invention, wherein a wobbling groove wobbled at a predetermined frequency and serving as a recording track of an information signal, and at least address information etc. at a predetermined wobbling cycle interval are landed. In a recording and / or reproducing apparatus for recording and / or reproducing the information signal with respect to a disk-shaped recording medium in which lands prerecorded as prepits are alternately formed in a spiral or concentric shape,
  First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam Receive light atA light receiving element that
  in front1st and 2nd light receiving areaOutput fromOf each received light outputSet as the land pre-pit detection sideFor one received light outputA predetermined initial value is set when the information signal recording and / or reproducing operation is started, and a value changed by variable control is set after the operation is started.Multiply coefficientCalculationCoefficient multiplication means for outputting
  The coefficient multiplying means multiplies the other received light output of the first and second light receiving areas from the other received light output.CalculationPush-pull signal generating means for outputting a difference obtained by subtracting the output of the result as a radial push-pull signal;
  A lens shift amount detecting means for detecting a lens shift amount in the radial direction from the optical axis center of the objective lens of the optical pickup that irradiates the light beam onto the disc-shaped recording medium, and outputting the lens shift amount;
  At the time of starting the recording and / or reproducing operation of the information signal, the initial value is set as the coefficient in the coefficient multiplication means, and after the operation starts,Based on the lens shift amount1. Greater than 0 and within the range where the land pre-pit signal can be detectedThe value that is variably controlled is fed back to the coefficient multiplication means as the coefficient.Coefficient setting means for setting.
[0017]
  According to a fifth aspect of the present invention, there is provided a recording and / or reproducing method according to the present invention, wherein a wobbling groove wobbled at a predetermined frequency and serving as a recording track of an information signal, and at least address information at a predetermined wobbling cycle interval are landed. In a recording and / or reproducing method for recording and / or reproducing the information signal on a disk-shaped recording medium in which lands prerecorded as prepits are alternately formed in a spiral shape or a concentric shape,
  First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam Receive light atA light receiving step to
  in front1st and 2nd light receiving areaOutput fromOf each received light outputSet as the land pre-pit detection sideFor one received light outputA predetermined initial value is set when the information signal recording and / or reproducing operation is started, and a value changed by variable control is set after the operation is started.Multiply coefficientCalculationA coefficient multiplication step to be output,
  Of the light receiving outputs of the first and second light receiving regions, the other light receiving output is multiplied by the coefficient multiplication step.CalculationA push-pull signal generation step for outputting a difference obtained by subtracting the output of the result as a radial push-pull signal;
  A land pre-pit signal amplitude detecting step for extracting a land pre-pit signal corresponding to the land pre-pit of the land from the radial push-pull signal and detecting and outputting the amplitude of the land pre-pit signal;
  A wobbling signal amplitude detection step of extracting a wobbling signal of the wobbling groove from the radial push-pull signal and detecting and outputting an amplitude of the wobbling signal;
  At the time of starting the recording and / or reproducing operation of the information signal, the initial value is set as the coefficient in the coefficient multiplication step, and after the operation starts,Based on the amplitude of the land pre-pit signal, or the amplitude of the land pre-pit signal and the amplitude of the wobbling signal1. Greater than 0 and within the range where the land pre-pit signal can be detectedThe value that is variably controlled is fed back to the coefficient multiplication step as the coefficient.A coefficient setting step for setting.
[0018]
  According to a sixth aspect of the present invention, there is provided a recording and / or reproducing method according to the present invention, wherein a wobbling groove wobbled at a predetermined frequency and serving as a recording track of an information signal, and at least address information etc. at a predetermined wobbling cycle interval are landed. In a recording and / or reproducing method for recording and / or reproducing the information signal on a disk-shaped recording medium in which lands prerecorded as prepits are alternately formed spirally or concentrically,
  First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam Receive light atA light receiving step to
  in front1st and 2nd light receiving areaOutput fromOf each received light outputSet as the land pre-pit detection sideFor one received light outputA predetermined initial value is set when the information signal recording and / or reproducing operation is started, and a value changed by variable control is set after the operation is started.Multiply coefficientCalculationA coefficient multiplication step to be output,
  Of the light receiving outputs of the first and second light receiving regions, the other light receiving output is multiplied by the coefficient multiplication step.CalculationA push-pull signal generation step for outputting a difference obtained by subtracting the output of the result as a radial push-pull signal;
  A land pre-pit signal amplitude detecting step for extracting a land pre-pit signal corresponding to a land pre-pit of the land from the radial push-pull signal and detecting and outputting the amplitude of the land pre-pit signal;
  A wobbling signal amplitude detection step of extracting a wobbling signal of the wobbling groove from the radial push-pull signal and detecting and outputting an amplitude of the wobbling signal;
  A sum signal generation step of taking the sum of the light receiving outputs of the first and second light receiving regions and outputting a sum signal;
  A normalized land pre-pit signal amplitude generating step for outputting the amplitude of the normalized land pre-pit signal by dividing the amplitude of the land pre-pit signal by the sum signal;
  A normalized wobbling signal amplitude generating step for outputting the normalized amplitude of the wobbling signal by dividing the amplitude of the wobbling signal by the sum signal;
  At the time of starting the recording and / or reproducing operation of the information signal, the initial value is set as the coefficient in the coefficient multiplication step, and after the operation starts,Based on the amplitude of the normalized land pre-pit signal, or the amplitude of the normalized land pre-pit signal and the amplitude of the normalized wobbling signal1. Greater than 0 and within the range where the land pre-pit signal can be detectedThe value that is variably controlled is fed back to the coefficient multiplication step as the coefficient.A coefficient setting step for setting.
[0019]
  According to a seventh aspect of the present invention, there is provided a recording and / or reproducing method according to the present invention, wherein a wobbling groove wobbled at a predetermined frequency and used as a recording track for an information signal, and at least address information at a predetermined wobbling cycle interval are landed. In a recording and / or reproducing method for recording and / or reproducing the information signal on a disk-shaped recording medium in which lands prerecorded as prepits are alternately formed in a spiral shape or a concentric shape,
  First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam Receive light atA light receiving step to
  in front1st and 2nd light receiving areaOutput fromOf each received light outputSet as the land pre-pit detection sideFor one received light outputA predetermined initial value is set when the information signal recording and / or reproducing operation is started, and a value changed by variable control is set after the operation is started.Multiply coefficientCalculationA coefficient multiplication step to be output,
  Of the light receiving outputs of the first and second light receiving regions, the other light receiving output is multiplied by the coefficient multiplication step.CalculationA push-pull signal generation step for outputting a difference obtained by subtracting the output of the result as a radial push-pull signal;
  An error rate calculating step of calculating and outputting an error rate at the time of detection of a land pre-pit signal included in the radial push-pull signal;
  At the time of starting the recording and / or reproducing operation of the information signal, the initial value is set as the coefficient in the coefficient multiplication step, and after the operation starts,Based on the error rate1. Greater than 0 and within the range where the land pre-pit signal can be detectedThe value that is variably controlled is fed back to the coefficient multiplication step as the coefficient.A coefficient setting step for setting.
[0020]
  Furthermore, the recording and / or reproducing method according to the present invention described in claim 8 is a method of recording wobbling grooves wobbled at a predetermined frequency and serving as a recording track for information signals, and at least address information at a predetermined wobbling cycle interval. In a recording and / or reproducing method for recording and / or reproducing the information signal on a disk-shaped recording medium in which lands prerecorded as prepits are alternately formed in a spiral shape or a concentric shape,
  First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam Receive light atA light receiving step to
  in front1st and 2nd light receiving areaOutput fromOf each received light outputSet as the land pre-pit detection sideFor one received light outputA predetermined initial value is set when the information signal recording and / or reproducing operation is started, and a value changed by variable control is set after the operation is started.Multiply coefficientCalculationA coefficient multiplication step to be output,
  Of the light receiving outputs of the first and second light receiving regions, the other light receiving output is multiplied by the coefficient multiplication step.CalculationA push-pull signal generation step for outputting a difference obtained by subtracting the output of the result as a radial push-pull signal;
  A lens shift amount detection step of detecting a lens shift amount in the radial direction from the center of the optical axis of the objective lens of the optical pickup that irradiates the light beam onto the disk-shaped recording medium, and outputting the lens shift amount;
  At the time of starting the recording and / or reproducing operation of the information signal, the initial value is set as the coefficient in the coefficient multiplication step, and after the operation starts,Based on the lens shift amount1. Greater than 0 and within the range where the land pre-pit signal can be detectedThe value that is variably controlled is fed back to the coefficient multiplication step as the coefficient.A coefficient setting step for setting.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The recording and / or reproducing apparatus and method according to the present invention can be applied to a disk recording / reproducing apparatus for recording / reproducing data on a DVD-R or DVD-RW (hereinafter collectively referred to as a DVD).
[0022]
First, as shown in FIG. 1, the DVD 31 used in the disk recording / reproducing apparatus of this embodiment has a spiral wobbling groove 32 and a convex land 33 spirally formed on one surface of a disk-shaped transparent substrate K. Alternatively, they are formed by injection molding or the like alternately in concentric circles. Also, a dye film 35 as a data recording layer is formed on the wobbling groove 32 and the land 33, and the recording light modulated according to data to be recorded on the dye film 35 (hereinafter referred to as recording data). By irradiating the beam B from the other surface side of the transparent substrate K, a pit row corresponding to recording data is formed irreversibly.
[0023]
The DVD 31 has a wobbling groove 32 wobbled in response to a wobbling signal having a predetermined frequency component, and the wobbling groove 32 is a data recording track for recording the recording data.
[0024]
Further, on this DVD 31, land pre-pits 34 in which, for example, address information (absolute position information) on the surface of the optical disc is recorded at predetermined wobbling cycle intervals are formed on lands 33 between adjacent wobbling grooves 32. ing.
[0025]
A gold vapor deposition film 36 is formed on the dye film 35. In the DVD 31, when reproducing the recording data recorded on the data recording track, the reproducing light beam B irradiated on the data recording track is reflected by the gold vapor deposition film 36 with a high reflectance. ing. Further, a protective film 37 is formed on the gold vapor deposition film 36.
[0026]
When recording or reproducing recorded data on such a DVD 31, the wobbling frequency of the wobbling groove 32 provided as a data recording track is detected, and the DVD 31 is driven to rotate based on this wobbling frequency. It has become. Further, address information and the like are detected from the land pre-pit 34, and a recording position is detected based on this address information, and recording data is recorded in the wobbling groove 32 and reproduced.
[0027]
Here, when recording the recording data, the recording light beam B modulated according to the recording data is irradiated so that the center of the light spot coincides with the center of the wobbling groove 32. As a result, a pit row corresponding to the recording data is formed on the data recording track on the wobbling groove 32 and recording of the recording data is performed. At this time, as shown in FIG. 1, the size of the light spot SP of the recording light beam B is partially irradiated not only to the wobbling groove 32 but also to the land 33 between the adjacent wobbling grooves 32. Is set as follows.
[0028]
Then, a part of the reflected light of the light spot SP irradiated on the land 33 is received by a photodetector divided by a dividing line optically parallel to the tangential direction of the wobbling groove 32, that is, the rotating direction of the DVD 31, Based on the output from the photo detector, for example, a push-pull signal is formed and tracking servo is applied, and the wobbling signal of the wobbling groove 32 is extracted from the photo detector, and the wobbling signal is binarized and generated based on the wobbling pulse generated. Thus, a recording clock synchronized with the rotation of the DVD 31 is formed.
[0029]
Next, a recording format of address information recorded in advance on the DVD 31 will be described with reference to FIG.
[0030]
In FIG. 2, the upper row shows the recording format of the recording data, and the lower waveform shows the wobbling state of the wobbling groove 32 for recording the recording data (meandering state confirmed when the wobbling groove 32 is viewed in plan). Yes. An upward arrow between the upper stage showing the recording format in the recording data and the lower stage showing the wobbling state of the wobbling groove 32 schematically shows the position where the land pre-pits 34 are formed.
[0031]
The wobbling state of the wobbling groove 32 in FIG. 2 is shown with an amplitude larger than the actual amplitude in order to facilitate understanding. Actually, the recording data is recorded on the center line of the wobbling groove 32 as described above.
[0032]
As shown in FIG. 2, the recording data recorded on the DVD 31 is divided in advance for each sync frame as an information unit. One recording sector is composed of 26 sync frames. One recording (ECC) block is composed of 16 recording sectors.
[0033]
One sync frame has a length of 1488 times (1488T) the unit length T corresponding to the pit interval defined by the recording format when recording the recording data. In the portion corresponding to the length of 14T at the head of one sync frame, synchronization information SY for synchronizing each sync frame is recorded.
[0034]
On the other hand, the address information (land pre-pit 34) recorded on the DVD 31 is recorded in advance for each sync frame of the recording data when the optical disc is manufactured. Here, when the address information is recorded on the DVD 31 by the land pre-pit 34, the sync signal in the address information is indicated on the land 33 adjacent to the area where the sync information SY in each sync frame of the recorded data is recorded. As shown in FIG. 2, a land pre-pit 34 (land pre-pit B0) indicated by an arrow B0 is formed, and an address to be recorded on the land 33 adjacent to the first half portion in the sync frame other than the synchronization information SY. As the contents of information, both or one of the land prepits 34 (land prepit B1 and land prepit B2) indicated by arrows B1 and B2 in FIG. 2 are formed.
[0035]
However, the land pre-pit B1 and the land pre-pit B2 may not be formed in the first half of the sync frame other than the synchronization information SY depending on the content of the address information to be recorded.
[0036]
At this time, in one recording sector, a land pre-pit 34 is formed for every other sync frame, and address information and the like are recorded. In one recording sector, an EVEN frame and an ODD frame are alternately continued. As shown by an upward arrow in FIG. 2, when a land pre-pit 34 is formed in an EVEN frame, The land pre-pit 34 is not formed.
[0037]
  on the other hand, OWhen the land pre-pit 34 is formed in the DD frame, the land pre-pit 34 is not formed in the EVEN frame.
[0038]
When the land pre-pit 34 is formed in the EVEN frame, all the land pre-pits of the land pre-pit B0, the land pre-pit B1, and the land pre-pit B2 are formed in the first sync frame of the recording sector. In the sync frame other than the head of the recording sector, when the address information to be recorded in the sync frame is “1”, only the land prepit B0 and the land prepit B2 are formed, and the address information to be recorded is “ When “0”, only the land pre-pits B0 and B1 are formed.
[0039]
When the land pre-pit 34 is formed in the ODD frame, only the land pre-pit B0 and the land pre-pit B1 are formed in the head sync frame of the recording sector, and the sync frame other than the head of the recording sector is formed. Is the same as in the case of the EVEN frame.
[0040]
Note that whether the land pre-pit 34 is formed in the sync frame of the EVEN frame or the ODD frame is determined depending on the position of the land pre-pit 34 formed in advance on the adjacent land 33.
[0041]
That is, the land pre-pit 34 is normally formed in the EVEN frame. However, when the land pre-pit 34 is formed in the EVEN frame, the land pre-pit 34 is formed on the adjacent land 33 formed in advance. When the land pre-pit 34 overlaps in the radial direction of the DVD 31, the land pre-pit 34 is formed in the ODD frame.
[0042]
In other words, the land pre-pits 34 are formed so as not to overlap in the radial direction of the DVD 31 between adjacent lands 33 as shown in FIG. By forming the land pre-pits 34 in this way, the land pre-pits 34 are not formed at positions overlapping with each other in the radial direction of the DVD 31 between adjacent lands 33. The influence of land pre-pit crosstalk on adjacent lands can be reduced.
[0043]
In FIG. 3, the sync frame indicated by the black band at the top on the land 33 is a sync frame in which the land pre-pits 34 are formed, and the sync frame indicated by the white band at the top is This is a sync frame in which no land pre-pits 34 are formed.
[0044]
On the other hand, the wobbling groove 32 is wobbled at a constant wobbling frequency f0 of about 140 KHz (frequency at which wobbling signals corresponding to eight wobble cycles are included in one sync frame) over all sync frames. At this time, by extracting the wobbling frequency f0 of the wobbling signal, a signal for controlling the rotation operation of the DVD 31 is detected and a recording clock signal is generated.
[0045]
Further, in order to make the phase relationship between the land prepit 34 and the wobbling signal constant, the land prepits B0 to B2 are formed in advance at the time of manufacturing the optical disc, and are each 186T (1488T / 8) from the land prepits B0. A land pre-pit B1 and a land pre-pit B2 are separately formed in advance.
[0046]
Further, as described above, the land pre-pits 34 are formed on the lands 33 for every other sync frame, and are formed so as not to overlap in the radial direction of the DVD 31 between the adjacent lands 33. Accordingly, in two lands 33 adjacent to one wobbling groove 32, land prepits 34 appear every wobble 16 period of the wobbling groove 32, and the land prepits 34 are alternately arranged on both sides of the wobbling groove 32. It will appear.
[0047]
Next, FIG. 4 is a block diagram of the disk recording / reproducing apparatus of the embodiment. As can be seen from FIG. 4, the disk recording / reproducing apparatus of the embodiment irradiates the DVD 31 with a light beam from a semiconductor laser (not shown) through an objective lens (not shown). It has an optical pickup 2 that performs recording and reproduction, and a preamplifier 3 that amplifies and outputs a reproduction output from the optical pickup 2 with a predetermined gain.
[0048]
In FIG. 5A, a light detector PD (Photo Detector) in the optical pickup 2 is positioned at the center of the wobbling groove 32, and the land pre-pit 34 on the land 33 on the right side of the figure is formed by the light receiver PD. It is the schematic diagram which showed the state currently detected typically.
[0049]
The light receiving element PD described above is formed in a substantially rectangular shape, and although the entire light receiving region is divided into four equal parts by a straight line along the radial direction of the DVD 31 and a straight line along the track direction, this light receiving element PD The light spot SP imaged on the top is 2 in the set of two light receiving areas A and B on the outer peripheral side of the DVD 31 (optical disc) and in the set of two light receiving areas C and D on the inner peripheral side of the DVD 31. Since one set is formed, the straight line along the recording track direction of the DVD 31 is divided into two.
[0050]
When the light receiving output is outputted from the light receiving element PD, as shown in FIG. 5B, the light receiving signals of the two light receiving areas A and B on the outer peripheral side of the DVD 31 are added (A + B) signal. And a (C + D) signal obtained by adding the respective light receiving signals of the two light receiving areas C and D on the inner peripheral side of the DVD 31 are output to the land pre-pit 34 on the light receiving element PD at this time. Since the brightness is unbalanced on the outer peripheral side and the inner peripheral side of the DVD 31 due to the influence of the diffraction phenomenon of the light beam B, both the (A + B) signal and the (C + D) signal are mutually above the 0 level. The output is reversed.
[0051]
At this time, it is a necessary condition that the output amplitude of the (A + B) signal and the output amplitude of the (C + D) signal are substantially the same level, and both are not substantially the same due to the adjustment state of the optical pickup 2 or the like. As will be described later, before the differential signal is generated by the RPP generation circuit 8, the (A + B) addition circuit 4 and the (C + D) addition circuit 5 adjust the output amplitudes of both by an appropriate adjustment circuit so that they are substantially the same level. Just keep it.
[0052]
Thereafter, when generating a radial push-pull signal from the (A + B) signal and the (C + D) signal output from the light receiving element PD, in order to invert the polarities of the (C + D) signal and the (A + B) signal. Since a {−k (A + B)} signal obtained by multiplying a predetermined coefficient k by a − (minus) sign is obtained as shown in FIG. 5C above and below the 0 level, A difference signal {(C + D) -k (A + B))} obtained from the difference is generated as a radial push-pull signal. At this time, in FIG. 5B, the land pre-pit signal (LPP signal) is directed to the signal (A + B) side directed toward the 0 level side (directed downward) with the wobbling signal (WBL signal) as the center. On the other hand, it is only necessary to multiply a predetermined coefficient k by a minus sign (minus). Unlike the figure, if the land pre-pit signal (LPP signal) is directed downward on the (C + D) side, this is multiplied. However, this determination is not performed in the apparatus, and which side is to be multiplied can be set in advance. Therefore, the coefficient multiplication circuit 6 is connected to the (A + B) addition circuit 4 side as in the embodiment. It's a good thing.
[0053]
For this reason, the disc recording / reproducing apparatus detects an (A + B) signal obtained by adding the respective received light signals of the two light receiving areas A and B on the outer peripheral side of the DVD 31 (A + B), and the DVD 31 It has a (C + D) addition circuit 5 that detects a (C + D) signal obtained by adding the respective light reception signals of the two peripheral light receiving regions C and D.
[0054]
The disc recording / reproducing apparatus also inverts the polarity of the (A + B) signal from the (A + B) addition circuit 4 and multiplies a predetermined coefficient k {-k (A + B)} and outputs the coefficient multiplication circuit. 6.
[0055]
In the disc recording / reproducing apparatus, the predetermined coefficient k is varied according to the detection output of the radial push-pull signal, the error rate at the time of detecting the land pre-pit signal, and the shift amount of the objective lens of the optical pickup 2. Thus, the detection accuracy of land pre-pits (LPP) on the optical disk is improved.
[0056]
The disc recording / reproducing apparatus also generates an RPP generation circuit 8 that generates a radial push-pull signal {(C + D) -k (A + B)} based on the (C + D) signal and the {−k (A + B)} signal, and this RPP. A binary pre-pit signal (LPP signal) included in the radial push-pull signal from the generation circuit 8 is binarized, and a binary pre-pit signal (LPP) binarized by the binarizing circuit 9 Signal) address information and the like, and a CPU 11 that calculates an error rate of the land pre-pit signal decoded by the LPP decode circuit 10 and outputs the error rate.
[0057]
The disc recording / reproducing apparatus adds the (A + B) signal from the (A + B) adder circuit 4 and the (C + D) signal from the (C + D) adder circuit 5 to add the sum signal {RF signal: (A + B + C + D)}. A land pre-pit signal (LPP signal) is extracted from the radial push-pull signal from the RF circuit 7 for generating the RPP and the RPP generation circuit 8, and the amplitude of the land pre-pit signal is detected to set the LPPb generation circuit 14 and the coefficient setting. A wobbling signal (WBL signal) of a recording track is extracted from the radial push-pull signal from the LPP amplitude detection circuit (land pre-pit signal amplitude detection circuit) 12 output to the circuit 16 and the RPP generation circuit 8, and the wobbling signal WBL amplitude detection circuit (wobbling) that detects the amplitude and outputs it to the WBLb generation circuit 15 and the coefficient setting circuit 16 No. and a amplitude detection circuit) 13.
[0058]
In the disc recording / reproducing apparatus, the level of the land pre-pit signal (LPP signal) extracted by the LPP amplitude detection circuit 12 is normalized with respect to the level of the sum signal (A + B + C + D) generated by the RF circuit 7. An LPPb generation circuit (normalized land prepit signal amplitude detection circuit) 14 that outputs as a land prepit signal (hereinafter referred to as an LPPb signal) and the level of the wobbling signal extracted by the WBL amplitude detection circuit 13 7, a WBLb generation circuit (normalized wobbling signal amplitude detection circuit) 15 that outputs a normalized wobbling signal (hereinafter referred to as a WBLb signal) with respect to the level of the sum signal (A + B + C + D) generated in 7, and an optical pickup 2. This lens system detects the amount of lens shift in the radial direction from the center of the optical axis of the objective lens. And a lens shift amount detection circuit 17 for outputting a preparative amount.
[0059]
The disc recording / reproducing apparatus also detects an error rate when detecting the land pre-pit signal from the CPU 11, the amplitude of the land pre-pit signal from the LPP amplitude detection circuit 12, the amplitude of the wobbling signal from the WBL amplitude detection circuit 13, and LPPb. In accordance with the normalized LPPb signal from the generation circuit 14, the normalized WBLb signal from the WBLb generation circuit 15, and the lens shift amount detected by the lens shift amount detection circuit 17, a predetermined coefficient k of the coefficient multiplication circuit 6 is obtained. The coefficient setting circuit 16 is set. It should be noted that the combination of the amplitude of the land pre-pit signal from the LPP amplitude detection circuit 12 and the amplitude of the wobbling signal from the WBL amplitude detection circuit 13, or the normalized LPPb signal from the LPPb generation circuit 14, Only one of the normalized WBLb signal sets may be connected to the coefficient setting circuit 16.
[0060]
Next, a description will be given of a land pre-pit (LPP) detection operation, which is a main part of the present invention, in the disk recording / reproducing apparatus of the present embodiment having such a configuration.
[0061]
In FIG. 6, FIG. 7, FIG. 8 and the like described below, the wobbling signal and the LPP signal are approximated by straight lines and are different from those of FIG. 12, FIG. It's just something.
[0062]
The present invention includes reproducing an unrecorded portion and measuring related basic parameters for the disc. However, in an actual recording / reproducing apparatus, an unrecorded area on the disc can be recognized. Thus, the above parameters can be obtained. The lead-in area on the innermost circumference of the disc or the lead-out area on the outermost circumference of the disc is a portion that is recorded after all user data has been recorded on the disc. Do not record. The measurement of the relevant basic parameters for the disc in the present invention can also be performed on this lead-in area or lead-out area.
[0063]
First, FIG. 6 shows the sum signal output (A + B + C + D) from the RF circuit 7 when the unrecorded portion of the DVD 31 is reproduced and the radial push-pull signal {(C + D) −k (A + B)} from the RPP generation circuit 8. As shown in FIG. 6, the level of the RF signal obtained by adding the signals A to D is the difference signal obtained by subtracting the {−k (A + B)} signal from the (C + D) signal. It becomes larger than the level of the radial push-pull signal.
[0064]
The radial push-pull signal is superimposed with a land pre-pit signal (LPP signal) that appears at a timing of 90 ° phase of the wobbling signal on a wobbling signal (WBL signal) that swings up and down around the zero level. I understand that. At this time, the amplitude R1 of the sum signal (A + B + C + D), the amplitude W1 of the wobbling signal (WBL), and the amplitude L1 of the land prepit signal (LPP signal) are values between 0 level and each signal in the upper part of the figure. And The land pre-pit signal (LPP signal) described above is a diagram showing a signal on the normal side with respect to the track, and illustration of a land pre-pit signal (LPP signal) which is not normal on the opposite side is omitted. ing.
[0065]
Next, FIG. 7 shows the radial push-pull signal {(C + D) -k (A + B)} when the unrecorded portion described in FIG. 6 is reproduced, the (C + D) signal, and the polarity inverted {-k (A + B)} signal is shown separately, but as can be seen from FIG. 7, the (C + D) signal appears on the positive polarity side at the 0 level, and the {−k (A + B)} signal is 0. Appears on the negative polarity side of the level. The (C + D) signal and the {−k (A + B)} signal are each formed by superimposing a land pre-pit signal (LPP signal) appearing at a timing of 90 ° phase of the wobbling signal on the wobbling signal. You will understand.
[0066]
At this time, the amplitude R2 up to the center level of the (C + D) signal on the positive polarity side and the amplitude kR2 up to the center level of the {−k (A + B)} signal on the negative polarity side are displayed with reference to the 0 level as shown in the figure. . Further, the amplitude W2 of the wobbling signal (WBL signal) corresponding to the (C + D) signal and the amplitude L2 of the land prepit signal (LPP signal) are from the center level of the (C + D) signal to the top of each signal in the upper part of the figure. The value between. Further, the amplitude kW2 of the wobbling signal (WBL) corresponding to the {−k (A + B)} signal and the amplitude kL2 of the land pre-pit signal (LPP signal) are shown upward from the center level of the {−k (A + B)} signal. The value up to the apex of each signal.
[0067]
Next, FIG. 8 shows a state when an information signal is recorded in the wobbling groove 32 on the DVD 31. For example, when the information signal is recorded with the pulsed light beam B, the irradiation light amount of the light beam B is large. When a portion (a portion corresponding to “1 of the information signal”) is a high power irradiation unit and a portion where the irradiation light amount of the light beam B is small (a portion corresponding to “0 of the information signal”) is a low power irradiation unit, It is the figure which shows separately the envelope of a high power irradiation part, and the envelope of a low power irradiation part with respect to the (C + D) signal of a positive polarity side, and the {-k (A + B)} signal of a negative polarity side.
[0068]
As can be seen from FIG. 8, if both the (C + D) signal and the {−k (A + B)} signal are present, the (C + D) signal and the {−k (A + B)} signal You will see that each level is a different level. Since such a level difference occurs between the high power irradiating unit and the low power irradiating unit, an erroneous detection of the land pre-pit signal occurs later.
[0069]
In the following description, the recording will be described. At the time of reproduction, the portion where the recording pit is formed on the optical disc corresponds to the low power irradiation portion, and the unrecorded portion where the recording pit is not formed is high. Since it is sufficient to detect the land pre-pit signal as corresponding to the power irradiating unit, the description at the time of reproduction is omitted.
[0070]
  Therefore, the disk recording / reproducing apparatus of the present embodiment variably controls a predetermined coefficient k to be multiplied to obtain a {−k (A + B)} signal whose polarity is inverted, whereby the radial push-pull signal {(C + D) −k (A + B)}, the level on the {−k (A + B)} signal side is adjusted by a predetermined coefficient k to improve the detection accuracy of the land pre-pit signal in the subsequent stage. Note that the {(A + B) -k (C + D)} signal may be used as the radial push-pull signal. In this case, the level on the {-k (C + D)} signal side is adjusted.ArrangeIn the following description, the case of adjusting the level on the {−k (A + B)} signal side will be described.
[0071]
That is, first, at the time of recording (or reproduction), a light beam for recording (or reproduction) is emitted from the optical pickup 2, and the optical pickup 2 uses the reflected light of this light beam as shown in FIG. The received light is received by the described four-divided light receiving element PD, and the received light signals of the received light areas A and B are supplied to the adder circuit 4 via the preamplifier 3 and the received light signals of the received light areas C and D. Is supplied to the (C + D) addition circuit 5 via the preamplifier 3.
[0072]
The (A + B) adding circuit 4 adds the light receiving signals of the light receiving area A and the light receiving area B to generate an (A + B) signal, which is supplied to the coefficient multiplying circuit 6 and supplied to the RF circuit 7. The (C + D) addition circuit 5 adds the light reception signals of the light reception region C and the light reception region D to generate a (C + D) signal, which is supplied to the RPP generation circuit 8 and supplied to the RF circuit 7. To do.
[0073]
The RF circuit 7 adds the (A + B) signal and the (C + D) signal to generate a sum signal that is an (A + B + C + D) signal, and supplies the sum signal to the LPPb generation circuit 14 and the WBLb generation circuit 15, respectively.
[0074]
The predetermined coefficient k is set to “1” so that the initial value of the coefficient of the coefficient multiplication circuit 6 is output as it is without changing the level of the input (A + B) signal. Therefore, in this case, the (A + B) signal supplied to the coefficient multiplication circuit 6 is supplied to the RPP generation circuit 8 as it is in the initial state without changing the level only by inverting the polarity. As will be described later, since the predetermined coefficient k is varied by feedback from the coefficient setting circuit 16, the following description of the RPP generation circuit 8 will be described using the predetermined coefficient k.
[0075]
The RPP generation circuit 8 calculates a radial push-pull signal {(C + D) −k (A + B) signal} by calculating a differential signal obtained by subtracting the {−k (A + B) signal} whose polarity is inverted from the (C + D) signal. And the radial push-pull signal is supplied to the binarization circuit 9, the LPP amplitude detection circuit 12, and the WBL amplitude detection circuit 13, respectively.
[0076]
The binarization circuit 9 binarizes the land pre-pit signal (LPP signal) included in the radial push-pull signal.
[0077]
The LPP amplitude detection circuit 12 extracts the land pre-pit (LPP) component included in the radial push-pull signal, detects the amplitude of the land pre-pit signal (LPP signal), and outputs the detected output to the LPPb generation circuit 14 and the coefficient. This is supplied to the setting circuit 16.
[0078]
The WBL amplitude detection circuit 13 extracts the wobble (WBL) component contained in the radial push-pull signal, detects the amplitude of the wobbling signal (WBL signal), and outputs the detected output to the WBLb generation circuit 15 and the coefficient setting circuit. 16 is supplied.
[0079]
Further, the LPPb generation circuit 14 generates a land pre-pit signal for the sum signal based on the sum signal from the RF circuit 7 and the amplitude of the LPP component included in the radial push-pull signal detected by the LPP amplitude detection circuit 12. An LPPb signal indicating the amplitude ratio is calculated and supplied to the coefficient setting circuit 16.
[0080]
Specifically, the amplitude of the sum signal (A + B + C + D) shown in FIG. 6 is “R1”, the amplitude of the land pre-pit signal is “L1”, and the amplitude of the (C + D) signal shown in FIG. 7 is “R2”, (C + D). The amplitude of the land pre-pit signal in the signal is “L2”, the amplitude of the {−k (A + B)} signal shown in FIG. 7 is “kR2”, and the amplitude of the land pre-pit signal in the {−k (A + B)} signal is Assuming “kL2”, the LPPb generation circuit 15 generates an LPPb signal normalized by the following calculation (1), and supplies this to the coefficient setting circuit 16.
[0081]
LPPb signal = L1 / R1 = kL2 / kR2 = L2 / R2 (Expression 1)
Similarly, the WBLb generation circuit 15 calculates a WBLb signal indicating the ratio of the amplitude of the wobbling signal to the sum signal based on the sum signal from the RF circuit 7 and the wobbling signal detected by the WBL amplitude detection circuit 13. This is supplied to the coefficient setting circuit 16.
[0082]
Specifically, the amplitude of the sum signal (A + B + C + D) shown in FIG. 6 is “R1”, the amplitude of the wobbling signal is “W1”, the amplitude of the (C + D) signal shown in FIG. 7 is “R2”, and in the (C + D) signal 7 is assumed to be “W2”, the amplitude of the {−k (A + B)} signal shown in FIG. 7 is “kR2”, and the amplitude of the wobbling signal in the {−k (A + B)} signal is “kW2”. The WBLb generation circuit 15 generates a normalized WBLb signal by the following (Equation 2) calculation, and supplies this to the coefficient setting circuit 16.
[0083]
WBLb signal = W1 / R1 = kW2 / kR2 = W2 / R2 (Expression 2)
On the other hand, the binarization circuit 9 binarizes the land pre-pit signal (LPP signal) included in the radial push-pull signal from the RPP generation circuit 8 and converts the binarized land pre-pit signal (LPP signal) to the LPP. This is supplied to the decoding circuit 10. The LPP decoding circuit 10 decodes address information and the like included in the land pre-pit signal (LPP signal) based on the binarized land pre-pit signal (LPP signal).
[0084]
Then, an error rate at the time of detecting a land pre-pit signal (LPP signal) is supplied to the CPU 11 at the time of decoding. The CPU 11 supplies the error rate to the coefficient setting circuit 16, and the predetermined coefficient k is set in consideration of the error rate when setting the predetermined coefficient k, which will be described later, so that the error rate is reduced in the coefficient setting circuit 16. Is further corrected.
[0085]
The lens shift amount detection circuit 17 determines whether the optical axis center of the objective lens of the optical pickup 2 is shifted to the outer peripheral side in the radial direction of the DVD 31 or to the inner peripheral side of the DVD 31. The lens shift amount is detected by ± according to the outer peripheral side and the inner peripheral side, and a lens shift amount signal indicating the lens shift amount is supplied to the coefficient setting circuit 16 so that the DVD 31 has a predetermined coefficient k set later. The predetermined coefficient k is further corrected by an amount in consideration of the lens shift amount shifted to the outer peripheral side or the inner peripheral side.
[0086]
That is, in FIG. 5A described above, when a lens shift occurs, the position of the light spot SP imaged on the light receiving element PD shifts in the radial direction of the optical disc with respect to the center of the light receiving element PD (A + B). ), (C + D) output level changes. Therefore, this output level can be corrected by correcting the lens shift amount.
[0087]
Specifically, the lens shift amount detection circuit 17 is not illustrated here, but a slit plate provided on a bobbin for driving an objective lens, a light source for irradiating light to the slit plate, and a slit plate The light receiving element (light receiving area E, light receiving area F) that receives the light emitted from the light source through the slits of the light is equally received. The difference (E−F) between the received light amounts of the light received in the areas E and F is detected as the lens shift amount.
[0088]
In addition to such a method of detecting the mechanical lens shift amount, for example, an offset of the objective lens can be detected based on a radial push-pull signal, and this can be used as the lens shift amount.
[0089]
In a system that detects tracking errors by the so-called differential push-pull method (DPP method), the DPP method itself cancels the effect of lens shift, so the offset of the objective lens is based on the differential push-pull signal. Cannot be detected.
[0090]
For this reason, in this case, a radial push-pull signal detection system is provided separately from the tracking error detection system by the DPP method, and the radial push-pull signal detection system is detected while applying the tracking servo by the DPP method. The offset of the objective lens may be detected based on the push-pull signal.
[0091]
Next, the predetermined coefficient k set in the coefficient multiplication circuit 6 as described above is set to “k = 1” in the initial state of the apparatus, and thereafter, the coefficient setting circuit 16 performs the predetermined coefficient k. Based on the LPPb signal, WBLb signal, error rate, and lens shift amount signal fed back when k is set to “1”, the predetermined coefficient k of the coefficient multiplication circuit 6 is variably controlled optimally as described below. is doing.
[0092]
Specifically, conventionally, a mini-disc (MD) or a CD-R is known as a recording medium on which a recording track is wobbled. In this MD or CD-R recording / reproducing apparatus, FIG. Although the adjustment is made so that the recording noise is minimized at the crossing point (zero crossing point) between the wobbling signal and the 0 level shown, the applicant's long-term research has made it a little farther than this zero crossing point. It has been found that the detection accuracy of the land pre-pit signal is improved by adjusting so that the recording noise is minimized at the point.
[0093]
This will be described in detail below. First, FIG. 9 is a diagram in which the wobbling signal component in the radial push-pull signal is temporarily set to zero to remove the wobbling signal component, and attention is paid only to the land pre-pit signal in the radial push-pull signal. The positive polarity side shows the land pre-pit signal of the high power irradiation portion and the land pre-pit signal of the low power irradiation portion of the (C + D) signal, while the negative polarity side at the 0 level is the {−k (A + B)} signal. The land pre-pit signal of the high power irradiation part and the land pre-pit signal of the low power irradiation part are shown.
[0094]
Further, the {−k (A + B)} signal is a land pre-pit signal of the low power irradiation unit in a case where a predetermined coefficient k to be multiplied is appropriately varied, for example, from near 0.9 to near 1.6. And a land pre-pit signal of the high power irradiation unit.
[0095]
Further, the (C + D) signal indicates that the land pre-pit signal under level of the low power irradiation unit is “m1”, the land pre-pit signal under level of the high power irradiation unit is “m2”, and the land pre-pit of the low power irradiation unit. When the peak level for the under level of the signal is “a”, the peak level for the under level of the land pre-pit signal of the high power irradiation unit is “b”, and a / m1 = b / m2 = L, the high power irradiation unit The amplitude LB1 of the (C + D) signal, which is the amplitude from the top of the land pre-pit signal waveform to the top of the land pre-pit signal waveform of the low power irradiation unit, is calculated by the following (Equation 3).
[0096]
LB1 = m2-m1 + ba = m2-m1 + L * m2-L * m1 (3 formulas)
Similarly to the above, the {−k (A + B)} signal indicates that the under level of the land pre-pit signal of the low power irradiation unit is “−km1” and the under level of the land pre-pit signal of the high power irradiation unit is “−. km2 ”, the peak level with respect to the under level of the land pre-pit signal of the low power irradiation unit is“ ka ”, the peak level with respect to the under level of the land pre-pit signal of the high power irradiation unit is“ kb ”, and −ka / −km 1 = When −kb / −km2 = L, the amplitude of the {−k (A + B)} signal that is the amplitude from the top of the land pre-pit signal waveform of the low power irradiation unit to the top of the land pre-pit signal waveform of the high power irradiation unit The amplitude LB2 is calculated by the following formula (formula 4).
[0097]

The relationship between (Equation 3) and (Equation 4) will be described later.
[0098]
Next, FIGS. 10 and 11 show (C + D) in order to reliably binarize the land pre-pit signal in the radial push-pull signal {(C + D) −k (A + B)} in the binarization circuit 9. Focusing only on the signal and the land pre-pit signal in the {−k (A + B)} signal, the simulation shows how the allowable fluctuation width (slice window width) of the land pre-pit signal changes according to a predetermined coefficient k. Thus, the slice window width capable of reliably and simultaneously detecting both the land pre-pit signal of the high-power irradiation unit and the land pre-pit signal of the low-power irradiation unit is obtained according to a predetermined coefficient k. . At this time, the slice window width for the land pre-pit signal is set in the binarization circuit 9.
[0099]
First, the cases of FIGS. 10A to 10F are special cases in which a / m1 = b / m2 = L described in FIG. 9 is satisfied. Here, the value of L is set to 0, for example. .2 is set for simulation.
[0100]
FIG. 10B shows a case where the predetermined coefficient k is set to “1.0”. In this case, a conventional radial push-pull signal {(C + D) − (A + B)} is obtained. . In this example, the under level of the land pre-pit signal of the high power irradiation unit and the under level of the land pre-pit signal of the low power irradiation unit are both the same reference level (hereinafter referred to as 0 level). Although the wobbling signal in which is omitted can be detected satisfactorily, the detection of the land pre-pit signal cannot be improved.
[0101]
That is, the slice window width for detecting the land pre-pit signal of the high power irradiating unit and the land pre-pit signal of the low power irradiating unit is the peak level of the land pre-pit signal of the low power irradiating unit, the zero level, The level difference between the two lands is 4.0, and the value of the slice window width = 4.0 is slightly small, so that both land pre-pit signals cannot be reliably detected.
[0102]
In addition, as shown in FIG. 10A with respect to FIG. 10B described above, when the predetermined coefficient k is set to “0.96” slightly smaller than “1.0”, The slice for detecting both the land pre-pit signals when both the under level of the land pre-pit signal of the high power irradiation unit and the under level of the land pre-pit signal of the low power irradiation unit rise above 0 level. The window width has a level difference of 0.92 between the peak level of the land pre-pit signal of the low power irradiation unit and the under level of the land pre-pit signal of the high power irradiation unit, and the value of this slice window width = 0.92. 10 becomes extremely smaller than that in FIG. 10B, making it difficult to detect the land pre-pit signal, and the wobbling signal not shown is also shown in FIG. A little less than in the case.
[0103]
On the other hand, when the predetermined coefficient k is set slightly larger than “1.0” and set to “1.1” as shown in FIG. The slice for detecting both the land pre-pit signals when the land pre-pit signal under level of the high power irradiation unit and the land pre-pit signal under level of the low power irradiation unit both fall below the zero level. As for the window width, the level difference between the peak level of the land pre-pit signal of the low power irradiation unit and the under level of the land pre-pit signal of the low power irradiation unit is 4.1, and the value of this slice window width = 4.1 Is slightly larger than that in FIG. 10B, so that detection of the land pre-pit signal is slightly improved.
[0104]
At this time, although the wobbling signal (not shown) is slightly inferior to the case of FIG. 10B, it is more important that the land pre-pit signal can be reliably detected than the deterioration of the detection of the wobbling signal. Even in the cases of FIGS. 10D to 10F, the detection of the wobbling signal gradually deteriorates.
[0105]
Further, as shown in FIG. 10D, when the predetermined coefficient k is set to “1.2” larger than that in FIG. 10C, the same tendency as in FIG. The slice window width for detecting both land pre-pit signals has a level difference of 4.4 between the peak level of the land pre-pit signal of the low power irradiation unit and the under level of the land pre-pit signal of the low power irradiation unit. The slice window width value = 4.4 is a good value that can reliably and reliably detect both land pre-pit signals.
[0106]
Further, as shown in FIG. 10E, when the predetermined coefficient k is set to “1.5” which is larger than that in FIG. In the state where the level and the under level of the land pre-pit signal of the low power irradiation unit are both lower than the 0 level, the peak level of the land pre-pit signal of the high power irradiation unit and the land pre-pit of the low power irradiation unit Both the peak levels of the signals match at the zero level.
[0107]
The width of the slice window for detecting both land pre-pit signals is 0 level (= the peak level of the land pre-pit signal of the high power irradiation unit and the low power irradiation unit) and the land pre-pit of the low power irradiation unit. The level difference from the under level of the signal is 5.0, and the value of the slice window width = 5.0 is the maximum value at which both land pre-pit signals can be detected with certainty. Therefore, a / m1 = A predetermined coefficient k = 1.5 under the condition of b / m2 = L is a theoretical upper limit value. A method for obtaining the theoretical lower limit value of the predetermined coefficient k will be described later.
[0108]
Further, as shown in FIG. 10 (f), when the predetermined coefficient k is set to “1.6” which is larger than that in FIG. 10 (d), the peak of the land pre-pit signal of the high power irradiation portion is set. Both the level and the peak level of the land pre-pit signal of the low-power irradiation unit fall below the zero level, and the peak level of the land pre-pit signal of the high-power irradiation unit is lower than that of the low-power irradiation unit. The slice window width for detecting both land pre-pit signals is the peak level of the land pre-pit signal of the high power irradiation section and the land pre-pit of the low power irradiation section. The level difference from the under level of the signal is 2.0, and this slice window width value = 2.0 is a predetermined coefficient from the case of FIG. The cause decreased slightly 0.1 only increased despite extreme, the detection of both the land pre-pit signal is extremely deteriorated.
[0109]
Accordingly, as shown in FIG. 10E, the predetermined upper limit value is obtained when the predetermined coefficient k is “1.5”. When the predetermined upper limit value is set, the predetermined coefficient k is set. Since there is no allowance in the direction in which the value is larger than 1.5, as shown in FIG. 10D, the predetermined coefficient k is “1.2” to “1.4” from the viewpoint of reliability and safety. (Partially omitted) is a practical value under the condition of a / m1 = b / m2 = L.
[0110]
Here, as shown in FIG. 10 (e), the condition when the predetermined coefficient k takes the theoretical upper limit under the condition of a / m1 = b / m2 = L is as described above (Formula 3). ) When the amplitude LB1 of the land pre-pit signal in the (C + D) signal and the amplitude LB2 of the land pre-pit signal in the {−k (A + B)} signal according to (4) are the same value. The theoretical upper limit value of k is obtained, and from this, the predetermined coefficient k becomes a value calculated by the following five expressions from (Expression 3) = (Expression 4).
[0111]

Further, L in (Expression 5) is clearly equivalent to the case where the normalized LPPb signal = L1 / R1 = kL2 / kR2 = L2 / R2 calculated according to (Expression 1) is calculated from FIG. Therefore, the above L value can be replaced with the normalized LPPb signal value, that is, (Equation 5) can be replaced with the following (Equation 6), whereby the output result from the LPPb generation circuit 14 Is supplied to the coefficient setting circuit 16 to obtain a predetermined coefficient k of the theoretical upper limit value by (Equation 6).
[0112]
k = (1 + LPPb) / (1-LPPb) (6 formulas)
Next, in the case of FIGS. 11A to 11E, a / m1 = b / m2 = L does not hold as described in FIG. 9, that is, a / m1 ≠ b / m2 ≠. This is a general case of L. Here, the value of L is set to approximately 0.2, for example, and simulation is performed.
[0113]
11 (a) to 11 (e) are similar to the concept described with reference to FIG. 10, and both the land pre-pit signal of the high power irradiation unit and the land pre-pit signal of the low power irradiation unit are given to the predetermined coefficient K. The slice window width for reliable detection is obtained. Further, the absolute value of the slaus window width obtained here is different from the absolute value obtained in FIG. 10 because, of course, factors other than the predetermined coefficient k are different.
[0114]
That is, FIG. 11A shows the case where the predetermined coefficient k is set to “0.9”. In this case, the underlevel of the land pre-pit signal of the high power irradiator and the land pre-pit of the low power irradiator are shown. Both the under level of the pit signal rises above the 0 level, and the slice window width for detecting the land pre-pit signal of the high power irradiation unit and the land pre-pit signal of the low power irradiation unit is low power. The level difference between the peak level of the land pre-pit signal of the irradiation unit and the under level of the land pre-pit signal of the high-power irradiation unit is 3.5. This value of 3.5 is a small value that makes it difficult to detect the land pre-pit signal.
[0115]
FIG. 11B shows a case where the predetermined coefficient k is set to “1.0”. In this case, a radial push-pull signal {(C + D) − (A + B)} that is conventionally performed is obtained. It is.
[0116]
In this case, both the under level of the land pre-pit signal of the high power irradiation unit and the under level of the land pre-pit signal of the low power irradiation unit are the same 0 level (reference level), and the wobbling not shown here is shown. Although the signal can be detected well, the detection of the land pre-pit signal cannot be improved. That is, the slice window width for detecting both land pre-pit signals has a level difference of 8.0 between the peak level of the land pre-pit signal of the low power irradiation portion and the zero level, and the value of this slice window width. Since = 8.0 is slightly small, both land pre-pit signals cannot be detected reliably.
[0117]
FIG. 11C shows the case where the predetermined coefficient k is set to “1.1”. In this case, the underlevel of the land pre-pit signal of the high power irradiation section and the land pre-pit of the low power irradiation section. Both the under level of the pit signal falls below the 0 level, and the slice window width for detecting both land pre-pit signals is the peak level of the land pre-pit signal of the low power irradiation unit and the low power irradiation. The difference in level between the land pre-pit signal and the under-level is 8.4, and the value of the slice window width = 8.4 is a good value for reliably detecting both land pre-pit signals with high reliability.
[0118]
FIG. 11D shows the case where the predetermined coefficient k is set to “1.2”. In this case, the underlevel of the land pre-pit signal in the high power irradiation unit and the land pre-in the low power irradiation unit. The peak level of the land pre-pit signal of the high power irradiation part and the peak level of the land pre-pit signal of the low power irradiation part are both lower than the 0 level in a state where both the under level of the pit signal is lowered below the 0 level. It matches up.
[0119]
The slice window width for detecting both land pre-pit signals includes the peak level of the land pre-pit signal of the high power irradiation unit and the low power irradiation unit, and the under level of the land pre-pit signal of the low power irradiation unit. The level difference of 8.8 is 8.8, and the value of this slice window width = 8.8 is the maximum value that can reliably detect both land pre-pit signals, so that the condition under the condition of a / m1 ≠ b / m2 ≠ L The predetermined coefficient k = 1.2 is a theoretical upper limit value.
[0120]
FIG. 11E shows a case where the predetermined coefficient k is set to “1.3”. In this case, the peak level of the land pre-pit signal of the high power irradiation unit and the land pre-pit of the low power irradiation unit are shown. Both the peak level of the signal falls below the 0 level, and the peak level of the land pre-pit signal of the high power irradiation unit is lower than the peak level of the land pre-pit signal of the low power irradiation unit, The slice window width for detecting both land pre-pit signals has a level difference of 7.0 between the peak level of the land pre-pit signal of the high power irradiation unit and the under level of the land pre-pit signal of the low power irradiation unit. Thus, the value of the slice window width = 7.0 becomes smaller than those in FIGS. 11 (c) and 11 (d). Detection of a pit signal is deteriorated.
[0121]
Therefore, as shown in FIG. 11 (d), when the predetermined coefficient k is “1.2”, the theoretical upper limit value is obtained. When this theoretical upper limit value is set, the predetermined coefficient k is set. Since there is no allowance in the direction in which the value is larger than 1.2, from the viewpoint of reliability and safety, as shown in FIG. This is a practical value under the condition of / m1 ≠ b / m2 ≠ L.
[0122]
Here, as shown in FIG. 11 (d), the condition when the predetermined coefficient k takes the theoretical upper limit under the condition that a / m1 ≠ b / m2 ≠ L is as described above (Formula 5) and It can be inferred from (Expression 6), and the following (Expression 7) and (Expression 8) hold.
[0123]
1.0 <k <α × {(1 + L) / (1-L)} (Expression 7)
1.0 <k <α × {(1 + LPPb) / (1−LPPb)} (Expression 8)
At this time, the coefficient α in (Expression 7) and (Expression 8) is a coefficient that depends on the performance of the optical pickup 2, the recording power based on the optical pickup 2, and the reproduction power in the reproduction mode. The value of the coefficient α may be stored in advance in the memory.
[0124]
Next, FIG. 12 is a diagram in which the land pre-pit signal component in the radial push-pull signal is set to zero to remove the land pre-pit signal component, and attention is paid only to the wobbling signal in the radial push-pull signal. The positive polarity side at the boundary indicates the wobbling signal of the high power irradiation portion and the low power irradiation portion of the (C + D) signal, while the negative polarity side at the 0 level indicates the {−k (A + B)} signal. The wobbling signal of a high power irradiation part and the wobbling signal of a low power irradiation part are shown.
[0125]
The {−k (A + B)} signal is simulated by varying the predetermined coefficient k to be multiplied in the same manner as described with reference to FIG. 9, but for the convenience of illustration, the predetermined coefficient k = 1.0, Only the case of k = 1.1 and k = 1.2 is shown.
[0126]
In addition, the (C + D) signal indicates that the center level of the wobbling signal of the low power irradiation unit is “m1”, the center level of the wobbling signal of the high power irradiation unit is “m2”, and is higher than the center level of the wobbling signal of the low power irradiation unit. When the amplitude on one side is “c”, the amplitude on the upper side from the center level of the wobbling signal of the high power irradiation unit is “d”, and c / m1 = d / m2 = W, the wobbling signal waveform of the high power irradiation unit The amplitude WB1 of the (C + D) signal, which is the amplitude from the top of the signal to the top of the wobbling signal waveform of the low power irradiation unit, is calculated by the following (Equation 9).
[0127]
WB1 = m2-m1 + dc = m2-m1 + W × m2-W × m1 (Expression 9)
In the same manner as described above, the {−k (A + B)} signal indicates that the center level of the wobbling signal of the low power irradiation unit is “−km1”, the center level of the wobbling signal of the high power irradiation unit is “−km2”, The amplitude on the upper side from the center level of the wobbling signal of the power irradiation unit is “kc”, the amplitude on the upper side from the center level of the wobbling signal of the high power irradiation unit is “kd”, and −kc / −km1 = −kd / − When km2 = W, the amplitude WB2 of the {−k (A + B)} signal, which is the amplitude from the apex of the wobbling signal waveform of the low power irradiation unit to the apex of the wobbling signal waveform of the high power irradiation unit, is expressed by the following formula ( (10 formulas).
[0128]

The relationship between the above (Equation 9) and (Equation 10) will also be described later.
[0129]
Next, FIG. 13 shows (C + D) and {C + D) signals in order to reliably binarize the land pre-pit signal in the radial push-pull signal {(C + D) −k (A + B)} in the binarization circuit 9. −k (A + B)} By paying attention only to the wobbling signal in the signal and simulating how this wobbling signal changes according to a predetermined coefficient k, the amplitude of the wobbling signal of the high power irradiation unit and the low The theoretical lower limit value of the predetermined coefficient k is determined from the relationship with the amplitude of the wobbling signal of the power irradiation unit. In the figure, the case where the predetermined coefficient k is “1.0”, “1.1”, “1.2” is shown in FIG.
[0130]
First, the cases of FIGS. 13A to 13C are special cases where c / m1 = d / m2 = W is satisfied as described in FIG. 12, and the value of W is expressed here. For example, the simulation is set to 0.05.
[0131]
First, FIG. 13A shows a case where a predetermined coefficient k is set to “1.0”. In this case, a radial push-pull signal {(C + D) − (A + B)} that has been conventionally used is obtained. It is. In this example, both the wobbling signal of the high power irradiation unit and the wobbling signal of the low power irradiation unit have the same period, and the amplitude of the wobbling signal of the high power irradiation unit is the wobbling signal of the low power irradiation unit. It is larger than the amplitude. This state corresponds to FIG. 10B described above, and although the wobbling signal can be detected satisfactorily, the detection of the land pre-pit signal cannot be improved.
[0132]
FIG. 13B shows a case where the predetermined coefficient k is set to “1.1”. In this example, the wobbling signal of the high power irradiation unit and the wobbling signal of the low power irradiation unit have different periods. However, the apex of the waveform of the wobbling signal of the low power irradiation unit and the apex of the waveform of the wobbling signal of the high power irradiation unit coincide with each other above the center level, and this state is c / m1 = d / m2 = The predetermined coefficient k = 1.1 under the condition of W is the theoretical lower limit value. This state corresponds to FIG. 10C described above, and although detection of the land pre-pit signal can be detected somehow although detection of the wobbling signal is slightly inferior to that of FIG. The coefficient k = 1.1 is the theoretical lower limit value.
[0133]
FIG. 13C shows a case where the predetermined coefficient k is set to “1.2”. In this example, the wobbling of the high power irradiation unit is located below the top of the waveform of the wobbling signal of the low power irradiation unit. It is located without the vertices of the signal waveform intersecting. This state corresponds to FIG. 10 (d) described above, and the detection of the wobbling signal is further deteriorated, while the detection of the land pre-pit signal is improved. This has already been described.
[0134]
Here, as shown in FIG. 13B, the condition when the predetermined coefficient k takes the theoretical lower limit under the condition that c / m1 = d / m2 = W is, as described above, (Equation 9 ) When the amplitude WB1 of the wobbling signal in the (C + D) signal is the same as the amplitude WB2 of the wobbling signal in the {−k (A + B)} signal according to (10). The lower limit value is obtained, whereby the predetermined coefficient k is a value calculated by the following equation (11 equation) from (9 equation) = (10 equation).
[0135]

Further, W in (Expression 11) is clearly equivalent to the case where the normalized WBLb signal = W1 / R1 = kW2 / kR2 = W2 / R2 calculated according to (Expression 2) described above is calculated from FIG. Therefore, the above-described W value can be replaced with the normalized WBLb signal value, that is, (Equation 11) can be replaced with the following (Equation 12), whereby the output result from the WBLb generation circuit 15 is obtained. Is supplied to the coefficient setting circuit 16, the predetermined coefficient k of the theoretical lower limit value is obtained from (Equation 12).
[0136]
k = (1 + WBLb) / (1-WBLb) (12 formulas)
Although not shown here, the predetermined coefficient k as described in FIG. 12 does not satisfy c / m1 = d / m2 = W, that is, c / m1 ≠ d / m2 ≠ W. Even in the general case, when the apex of the waveform of the wobbling signal of the low power irradiation unit and the apex of the waveform of the wobbling signal of the high power irradiation unit are substantially the same as shown in FIG. This is a theoretical lower limit value of the predetermined coefficient k under the condition that c / m1 ≠ d / m2 ≠ W.
[0137]
In this case, (Expression 13) and (Expression 14) that form a pair with (Expression 7) and (Expression 8) described above are established.
[0138]
1.0 <k <β × {(1 + W) / (1-W)} (13)
1.0 <k <β × {(1 + WBLb) / (1−WBLb)} (Expression 14)
At this time, the coefficient β in (Expression 13) and (Expression 14) is a coefficient that depends on the performance of the optical pickup 2, the recording power based on the optical pickup 2, and the reproduction power in the reproduction mode. The value of the coefficient β may be stored in advance in the memory.
[0139]
In summary of the above-described details, the predetermined coefficient k is established individually for each of the land pre-pit signals (Formula 5), (Formula 6), (Formula 7), and (Formula 8). In addition, (Equation 11), (Equation 12), (Equation 13), and (Equation 14) described above with respect to the wobbling signal are individually established, and these are defined as the land prepit signal side, the wobbling signal, Apply in combination.
[0140]
Therefore, if the predetermined coefficient k is within the range between the theoretical upper limit value and the theoretical lower limit value, the landed pre-pit signal can be detected accurately and reliably, whereby the following (Equation 15) to (Equation 18) is established.
[0141]
That is, under the conditions of a / m1 = b / m2 = L and c / m1 = d / m2 = W,

On the other hand, under the conditions of a / m1 ≠ b / m2 ≠ L and c / m1 ≠ d / m2 ≠ W,

More specifically, the predetermined coefficient k is conventionally set to “1.0”, but in the present invention, (1) the amplitude of the land prepit signal or the amplitude of the land prepit signal and Based on the amplitude of the wobbling signal, the predetermined coefficient value is set to a value larger than 1.0 and the land pre-pit signal can be detected by feedback, or (2) the normalized land pre- Based on the amplitude of the pit signal, or the normalized land prepit signal and the normalized wobbling signal, the value of the predetermined coefficient is larger than 1.0 and the land prepit signal can be detected. By feeding back and setting to the range value, the landed pre-pit signal can be detected accurately and reliably. Land de prepit signal corresponding to the preformed land de prepit 3 can be accurately detected.
[0142]
Further, in the disk recording / reproducing apparatus of the present embodiment, the coefficient setting circuit 16 shifts the error rate when detecting the LPP signal, WBL signal, LPPb signal, WBLb signal, and land pre-pit signal, and the objective lens shift of the optical pickup 2. Based on the quantity, the value of the predetermined coefficient k set in the coefficient multiplication circuit 6 is set to a value between the theoretical upper limit value and the theoretical lower limit value. More specifically, the value of the predetermined coefficient k is set to a value larger than 1.0 and within a range where the land pre-pit signal can be detected.
[0143]
As a result, the land pre-pit signal can be accurately and reliably detected during recording regardless of the high-power irradiating part and the low-power irradiating part on the DVD 31. Regardless of the part, the land pre-pit signal can be detected accurately and reliably.
[0144]
【The invention's effect】
  Claim 1~According to the recording and / or reproducing apparatus and method of the present invention as set forth in claim 8, there is a groove wobbled at a predetermined frequency and serving as a recording track for an information signal, and at least address information at a predetermined wobbling cycle interval. When recording and / or reproducing an information signal on a disk-shaped recording medium in which lands prerecorded as land prepits are alternately formed in a spiral or concentric shape, a light beam is applied to the disk-shaped recording medium. The first and second light receiving areas obtained by dividing the returned reflected light into at least two equal parts along the recording track of the disk-shaped recording mediumLight receiving element havingAnd receive the first and second light receiving areas.Output fromOf each received light outputSet as the land pre-pit detection sideFor one received light outputClerkMultiply by numberCalculateBefore the other received light output.ReporterMultiply by numberCalculationThe difference obtained by subtracting the output of the result is taken out as a radial push-pull signal, and the land pre-pit signal corresponding to the land pre-pit is detected from the radial push-pull signal.ReporterThe number is conventionally set to “1.0”, but in the present invention,
  (1) The amplitude of the land pre-pit signal or the amplitude of the land pre-pit signal and the wobbling signal,
  (2) The amplitude of the normalized land pre-pit signal, the amplitude of the normalized land pre-pit signal and the amplitude of the normalized wobbling signal,
  (3) error rate obtained from radial push-pull signal,
  (4) The amount of lens shift in the radial direction from the optical axis center of the objective lens of the optical pickup.
On the basis of the1. Range larger than 0 and the land pre-pit signal can be detectedA coefficient setting means (coefficient setting step) for feeding back and setting the value variably controlled as a coefficient to a coefficient multiplication means (coefficient multiplication step) is provided.Therefore, the land pre-pit signal can be accurately and reliably detected regardless of the high power irradiation unit and the low power irradiation unit using the light beam on the disk-shaped recording medium during recording. In addition, the land pre-pit signal can be accurately and reliably detected regardless of the recorded pit formation site and unrecorded site on the disc-shaped recording medium during reproduction.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the structure of a DVD on which recording / reproduction is performed by a disk recording / reproducing apparatus according to an embodiment to which the recording / reproducing apparatus and method according to the present invention are applied.
FIG. 2 is a diagram for explaining the format of the DVD;
FIG. 3 is a diagram for explaining a land pre-pit recording position recorded on a land of the DVD.
FIG. 4 is a block diagram of the disk recording / reproducing apparatus according to the embodiment.
FIG. 5 is a diagram for explaining a divided light receiving region of a light receiving element provided in the optical pickup of the disk recording / reproducing apparatus of the embodiment.
FIG. 6 is a waveform diagram of a wobbling signal and a land pre-pit signal that form a radial push-pull signal.
FIG. 7 is a waveform diagram of a wobbling signal and a land prepit signal that form a (C + D) signal and a {−k (A + B)} signal for detecting a radial push-pull signal, respectively.
FIG. 8 is a waveform diagram of a high power irradiation unit and a low power irradiation unit of a (C + D) signal and a {−k (A + B)} signal.
FIG. 9 is a diagram in which each waveform of a high power irradiation unit and a low power irradiation unit of a {−k (A + B)} signal that changes in accordance with a value of a predetermined coefficient k to be multiplied is viewed by paying attention to a land pre-pit signal. It is.
10 is a high-power irradiation unit of a {−k (A + B)} signal that changes in accordance with the value of a predetermined coefficient k to be multiplied when a / m1 = b / m2 = L shown in FIG. FIG. 5 is a view of each waveform of the low power irradiation unit, paying attention to a land pre-pit signal.
FIG. 11 shows each of a high power irradiation unit and a low power irradiation unit of a {−k (A + B)} signal that changes in accordance with a value of a predetermined coefficient k to be multiplied when a / m1 ≠ b / m2 ≠ L. It is the figure which looked at the waveform paying attention to the land prepit signal.
FIG. 12 is a diagram of the waveforms of a high power irradiation unit and a low power irradiation unit of a {−k (A + B)} signal that changes according to a value of a predetermined coefficient k to be multiplied, focusing on the wobbling signal. .
13 is a high-power irradiation unit of a {−k (A + B)} signal that changes according to the value of a predetermined coefficient k to be multiplied when c / m1 = d / m2 = W shown in FIG. FIG. 5 is a view of each waveform of the low power irradiation unit, paying attention to the wobbling signal.
[Explanation of symbols]
2 ... optical pickup, 3 ... preamplifier, 4 ... (A + B) addition circuit, 5 ... (C + D) addition circuit, 6 ... coefficient multiplication circuit, 7 ... RF circuit, 8 ... RPP generation circuit, 9 ... binarization circuit, 10 DESCRIPTION OF SYMBOLS ... LPP decoding circuit, 11 ... CPU, 12 ... LPP amplitude detection circuit, 13 ... WBL amplitude detection circuit, 14 ... LPPb generation circuit, 15 ... WBLb generation circuit, 16 ... Coefficient setting circuit, 17 ... Lens shift amount detection circuit, 31 ... DVD, 32 ... Wobbling groove, 33 ... Land, 34 ... Land pre-pit

Claims (8)

A wobbling groove wobbling at a predetermined frequency and serving as an information signal recording track and a land in which at least address information is recorded in advance as land prepits at predetermined wobbling cycle intervals are alternately formed in a spiral or concentric shape. In a recording and / or reproducing apparatus for recording and / or reproducing the information signal with respect to a disc-shaped recording medium,
First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam A light receiving element that receives light at
Before SL first, the second of the lands the set one received output as a side for detecting the pre-pits of the light receiving output which is outputted from the light receiving regions, recording and / or reproducing operation start of the information signal when the initially set value is predetermined is, after the start of the operation and the coefficient multiplying means for outputting the calculated multiplication coefficients values changed by the variable control is set,
A push-pull signal generating means for outputting the first, the difference obtained by subtracting the output of the result of the calculated multiplication by said coefficient multiplying means from the other light receiving output of the light receiving output of the second light-receiving region as the radial push-pull signal ,
A land pre-pit signal amplitude detecting means for extracting a land pre-pit signal corresponding to the land pre-pit of the land from the radial push-pull signal, detecting the amplitude of the land pre-pit signal, and outputting it;
A wobbling signal amplitude detecting means for extracting the wobbling signal of the wobbling groove from the radial push-pull signal and detecting and outputting the amplitude of the wobbling signal;
When the recording and / or reproducing operation of the information signal is started, the initial value is set as the coefficient in the coefficient multiplying unit, and after the operation is started, the amplitude of the land prepit signal or the land prepit signal is set. based on the amplitude of the amplitude and the wobbling signal, 1. And / or coefficient setting means for feeding back and setting as a coefficient a value that is variably controlled within a range in which the land pre-pit signal can be detected. Playback device. A wobbling groove wobbling at a predetermined frequency and serving as an information signal recording track and a land in which at least address information is recorded in advance as land prepits at predetermined wobbling cycle intervals are alternately formed in a spiral or concentric shape. In a recording and / or reproducing apparatus for recording and / or reproducing the information signal with respect to a disc-shaped recording medium,
First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam A light receiving element that receives light at
Before SL first, the second of the lands the set one received output as a side for detecting the pre-pits of the light receiving output which is outputted from the light receiving regions, recording and / or reproducing operation start of the information signal when the initially set value is predetermined is, after the start of the operation and the coefficient multiplying means for outputting the calculated multiplication coefficients values changed by the variable control is set,
A push-pull signal generating means for outputting the first, the difference obtained by subtracting the output of the result of the calculated multiplication by said coefficient multiplying means from the other light receiving output of the light receiving output of the second light-receiving region as the radial push-pull signal ,
A land pre-pit signal amplitude detecting means for extracting a land pre-pit signal corresponding to the land pre-pit of the land from the radial push-pull signal, detecting the amplitude of the land pre-pit signal, and outputting it;
A wobbling signal amplitude detecting means for extracting the wobbling signal of the wobbling groove from the radial push-pull signal and detecting and outputting the amplitude of the wobbling signal;
Sum signal generating means for taking the sum of the light receiving outputs of the first and second light receiving regions and outputting a sum signal;
Normalizing land pre-pit signal amplitude generating means for outputting the amplitude of the normalized land pre-pit signal by dividing the amplitude of the land pre-pit signal by the sum signal;
A normalized wobbling signal amplitude generating means for outputting the amplitude of the normalized wobbling signal by dividing the amplitude of the wobbling signal by the sum signal;
At the start of the recording and / or reproducing operation of the information signal, the initial value is set as the coefficient in the coefficient multiplying unit, and after the operation starts, the amplitude of the normalized land pre-pit signal, or the based on the amplitude of the amplitude and the normalized wobble signal normalized land pre-pit signal, 1. And / or coefficient setting means for feeding back and setting as a coefficient a value that is variably controlled within a range in which the land pre-pit signal can be detected. Playback device. A wobbling groove wobbling at a predetermined frequency and serving as an information signal recording track and a land in which at least address information is recorded in advance as land prepits at predetermined wobbling cycle intervals are alternately formed in a spiral or concentric shape. In a recording and / or reproducing apparatus for recording and / or reproducing the information signal with respect to a disc-shaped recording medium,
First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam A light receiving element that receives light at
Before SL first, the second of the lands the set one received output as a side for detecting the pre-pits of the light receiving output which is outputted from the light receiving regions, recording and / or reproducing operation start of the information signal when the initially set value is predetermined is, after the start of the operation and the coefficient multiplying means for outputting the calculated multiplication coefficients values changed by the variable control is set,
A push-pull signal generating means for outputting the first, the difference obtained by subtracting the output of the result of the calculated multiplication by said coefficient multiplying means from the other light receiving output of the light receiving output of the second light-receiving region as the radial push-pull signal ,
An error rate calculating means for calculating and outputting an error rate at the time of detection of a land pre-pit signal included in the radial push-pull signal;
When the information signal recording and / or reproducing operation is started, the initial value is set as the coefficient in the coefficient multiplying unit, and after the operation is started , 1 . And / or coefficient setting means for feeding back and setting as a coefficient a value that is variably controlled within a range in which the land pre-pit signal can be detected. Playback device. A wobbling groove wobbling at a predetermined frequency and serving as an information signal recording track and a land in which at least address information is recorded in advance as land prepits at predetermined wobbling cycle intervals are alternately formed in a spiral or concentric shape. In a recording and / or reproducing apparatus for recording and / or reproducing the information signal with respect to a disc-shaped recording medium,
First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam A light receiving element that receives light at
Before SL first, the second of the lands the set one received output as a side for detecting the pre-pits of the light receiving output which is outputted from the light receiving regions, recording and / or reproducing operation start of the information signal when the initially set value is predetermined is, after the start of the operation and the coefficient multiplying means for outputting the calculated multiplication coefficients values changed by the variable control is set,
A push-pull signal generating means for outputting the first, the difference obtained by subtracting the output of the result of the calculated multiplication by said coefficient multiplying means from the other light receiving output of the light receiving output of the second light-receiving region as the radial push-pull signal ,
A lens shift amount detecting means for detecting a lens shift amount in the radial direction from the optical axis center of the objective lens of the optical pickup that irradiates the light beam onto the disc-shaped recording medium, and outputting the lens shift amount;
When the information signal recording and / or reproducing operation is started, the initial value is set as the coefficient in the coefficient multiplying unit, and after the operation is started , 1 . And / or coefficient setting means for feeding back and setting as a coefficient a value that is variably controlled within a range in which the land pre-pit signal can be detected. Playback device. A wobbling groove wobbling at a predetermined frequency and serving as an information signal recording track and a land in which at least address information is recorded in advance as land prepits at predetermined wobbling cycle intervals are alternately formed in a spiral or concentric shape. In a recording and / or reproducing method for recording and / or reproducing the information signal with respect to a disc-shaped recording medium,
First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam A light receiving step for receiving light at
Before SL first, the second of the lands the set one received output as a side for detecting the pre-pits of the light receiving output which is outputted from the light receiving regions, recording and / or reproducing operation start of the information signal when the initially set value is predetermined is, after the start of the operation and coefficient multiplying step and outputting the calculated multiplication coefficients values changed by the variable control is set,
A push-pull signal generation step of outputting the first, the difference obtained by subtracting the output of the result of the calculated multiplication by the coefficient multiplying step from the other light receiving output of the light receiving output of the second light-receiving region as the radial push-pull signal ,
A land pre-pit signal amplitude detecting step for extracting a land pre-pit signal corresponding to a land pre-pit of the land from the radial push-pull signal and detecting and outputting the amplitude of the land pre-pit signal;
A wobbling signal amplitude detection step of extracting a wobbling signal of the wobbling groove from the radial push-pull signal and detecting and outputting an amplitude of the wobbling signal;
When the information signal recording and / or reproducing operation starts, the initial value is set as the coefficient in the coefficient multiplication step, and after the operation starts, the amplitude of the land prepit signal or the land prepit signal based on the amplitude of the amplitude and the wobbling signal, 1. And a coefficient setting step for feeding back and setting a value, which is larger than 0 and variably controlled within a range in which the land pre-pit signal can be detected, to the coefficient multiplying step as the coefficient. Method. A wobbling groove wobbling at a predetermined frequency and serving as an information signal recording track and a land in which at least address information is recorded in advance as land prepits at predetermined wobbling cycle intervals are alternately formed in a spiral or concentric shape. In a recording and / or reproducing method for recording and / or reproducing the information signal with respect to a disc-shaped recording medium,
First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam A light receiving step for receiving light at
Before SL first, the second of the lands the set one received output as a side for detecting the pre-pits of the light receiving output which is outputted from the light receiving regions, recording and / or reproducing operation start of the information signal when the initially set value is predetermined is, after the start of the operation and coefficient multiplying step and outputting the calculated multiplication coefficients values changed by the variable control is set,
A push-pull signal generation step of outputting the first, the difference obtained by subtracting the output of the result of the calculated multiplication by the coefficient multiplying step from the other light receiving output of the light receiving output of the second light-receiving region as the radial push-pull signal ,
A land pre-pit signal amplitude detecting step for extracting a land pre-pit signal corresponding to a land pre-pit of the land from the radial push-pull signal and detecting and outputting the amplitude of the land pre-pit signal;
A wobbling signal amplitude detection step of extracting a wobbling signal of the wobbling groove from the radial push-pull signal and detecting and outputting an amplitude of the wobbling signal;
A sum signal generation step of taking the sum of the light receiving outputs of the first and second light receiving regions and outputting a sum signal;
A normalized land pre-pit signal amplitude generating step for outputting the amplitude of the normalized land pre-pit signal by dividing the amplitude of the land pre-pit signal by the sum signal;
A normalized wobbling signal amplitude generating step for outputting the normalized amplitude of the wobbling signal by dividing the amplitude of the wobbling signal by the sum signal;
At the start of recording and / or reproducing operation of the information signal, the initial value is set as the coefficient in the coefficient multiplication step, and after the operation is started, the amplitude of the normalized land pre-pit signal, or based on the amplitude of the amplitude and the normalized wobble signal normalized land pre-pit signal, 1. And a coefficient setting step for feeding back and setting a value, which is larger than 0 and variably controlled within a range in which the land pre-pit signal can be detected, to the coefficient multiplying step as the coefficient. Method. A wobbling groove wobbling at a predetermined frequency and serving as an information signal recording track and a land in which at least address information is recorded in advance as land prepits at predetermined wobbling cycle intervals are alternately formed in a spiral or concentric shape. In a recording and / or reproducing method for recording and / or reproducing the information signal with respect to a disc-shaped recording medium,
First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam A light receiving step for receiving light at
Before SL first, the second of the lands the set one received output as a side for detecting the pre-pits of the light receiving output which is outputted from the light receiving regions, recording and / or reproducing operation start of the information signal when the initially set value is predetermined is, after the start of the operation and coefficient multiplying step and outputting the calculated multiplication coefficients values changed by the variable control is set,
A push-pull signal generation step of outputting the first, the difference obtained by subtracting the output of the result of the calculated multiplication by the coefficient multiplying step from the other light receiving output of the light receiving output of the second light-receiving region as the radial push-pull signal ,
An error rate calculation step of calculating and outputting an error rate at the time of detection of a land pre-pit signal included in the radial push-pull signal;
When the information signal recording and / or reproducing operation is started, the initial value is set as the coefficient in the coefficient multiplying step, and after the operation is started , 1 . And a coefficient setting step for feeding back and setting a value, which is larger than 0 and variably controlled within a range in which the land pre-pit signal can be detected, to the coefficient multiplying step as the coefficient. Method. A wobbling groove wobbling at a predetermined frequency and serving as an information signal recording track and a land in which at least address information is recorded in advance as land prepits at predetermined wobbling cycle intervals are alternately formed in a spiral or concentric shape. In a recording and / or reproducing method for recording and / or reproducing the information signal with respect to a disc-shaped recording medium,
First and second light receiving areas in which reflected light from the disk-shaped recording medium is divided into at least two equal parts along the recording track of the disk-shaped recording medium when the disk-shaped recording medium is irradiated with a light beam A light receiving step for receiving light at
Before SL first, the second of the lands the set one received output as a side for detecting the pre-pits of the light receiving output which is outputted from the light receiving regions, recording and / or reproducing operation start of the information signal when the initially set value is predetermined is, after the start of the operation and coefficient multiplying step and outputting the calculated multiplication coefficients values changed by the variable control is set,
A push-pull signal generation step of outputting the first, the difference obtained by subtracting the output of the result of the calculated multiplication by the coefficient multiplying step from the other light receiving output of the light receiving output of the second light-receiving region as the radial push-pull signal ,
A lens shift amount detection step of detecting a lens shift amount in the radial direction from the center of the optical axis of the objective lens of the optical pickup that irradiates the light beam onto the disc-shaped recording medium, and outputting the lens shift amount;
When the information signal recording and / or reproducing operation is started, the initial value is set as the coefficient in the coefficient multiplication step, and after the operation is started , 1 . And a coefficient setting step for feeding back and setting a value, which is larger than 0 and variably controlled within a range in which the land pre-pit signal can be detected, to the coefficient multiplying step as the coefficient. Method.

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