JP2004079089A - Optical disk device and adjustment method thereof - Google Patents

Abstract

An object of the present invention is to use a stabilizing member which suppresses surface deviation of an optical disk by utilizing aerodynamic force according to Bernoulli's law when recording / reproducing using a sheet-shaped optical disk having flexibility. The relative positional relationship between the optical disk and the optical disk is accurately adjusted, the focal position of the optical pickup and the stabilization position of the optical disk are precisely matched, and the recording and / or reproducing operation is stabilized.
A defocus component remaining even after a focus servo of an optical pickup is turned on, that is, a focus residual error signal is monitored so that a maximum amplitude of the focus residual error signal is equal to or less than an arbitrarily set reference value. The Z-axis direction position and tilt angle of the stabilizing member 8 are set in the Z-axis direction / stabilizing member / pickup unit position control section 40, the X-axis direction / stabilizing member / pickup unit tilt angle control section 42, and the Y-axis direction. The adjustment is performed by operating the stabilizing member / pickup unit tilt angle control unit 43.
[Selection] Fig. 8

Description

【００４１】
（表１）にて分かるように、本構成では面ぶれの最大幅が略１１μｍであって、面ぶれのばらつきの３σが２μｍ程度となる好結果を得られた。
【００４２】
本安定化部材８は、装置本体ケースに設置しても、カートリッジ内に内設しても、いずれの場合にも前記のような良好な面ぶれ安定化が得られた。
【００４３】
そして、前記構成の光ディスク装置を波長４０５ｎｍ、かつＮＡ０．９の光ピックアップを用いて記録再生を行った。例えば光ディスクにおける記録位置は半径４５ｍｍとし、最短記録ビット長を０．１２μｍ、かつランダムなデジタルデータを１−７ＲＬＬで変調して記録した。
【００４４】
記録線速度は１０ｍ／ｓ，記録ピークパワーは５ｍＷ，消去パワーは２．６ｍＷ，記録ボトムパワーは０．１ｍＷの３値変調，再生は０．２５ｍＷで行ったとき、基本クロックと記録信号との間のジッターは８％未満であった。さらに記録信号のエンベロープの乱れもなく、安定したフォーカスおよびトラッキングが行われていた。
【００４５】
本発明者らは、上述した光ディスクの面ぶれをさらに安定化させるために、このコントロール方法について鋭意検討した結果、光ピックアップのフォーカスサーボのオン後にもなお残留するデフォーカス成分、すなわちフォーカス残留エラー信号に含まれるディスク面ぶれ情報を解析し、この解析値が任意基準を満たすように光ディスクと安定化部材との三次元空間における相対位置関係を調整することにより、結果的にディスク面ぶれを低減・調整できることを見出した。
【００４６】
一般的に、光ディスク装置においては、ディスク面／対物レンズ間の距離に応じて図６に示すようなＳ字特性に従って検出波形を返すフォーカスエラー検出系を具備しており、検出されたフォーカスエラー信号が一定値（一般的には零目標）となるように、ドライブアンプによって光ピックアップの合焦位置を制御（フォーカスサーボ）し、光ピックアップがディスク面上で焦点を結ぶようにコントロールしている。このフォーカスサーボがディスク面ぶれに追従しきれなかった成分、すなわちフォーカスサーボオン時に光ピックアップから見た実効的な面ぶれ成分がフォーカス残留エラーとして検出される。このように、フォーカス残留エラー信号は直接的なディスク面ぶれ情報を含んでおり、この解析値を指標とすることにより前記調整・制御が可能となるわけである。
【００４７】
図７は光ディスクと安定化部材とにおける三次元空間の相対位置調整用の制御系の一例を示すブロック図であり、光ピックアップ６におけるディテクタなどからなるフォーカスエラー信号検出系３０から検出されたフォーカスエラー信号を受けて、位相補償ドライブアンプ３１では位相補償を行い適正フォーカスにするためのサーボ駆動信号が光ピックアップ６へ出力する。またフォーカスエラー信号検出系３０におけるフォーカス残留エラー信号を安定化部材駆動装置３２で監視して光ディスク１の面ぶれ信号を得て、光ピックアップ６の焦点位置でのディスク面振れが小さくなるように、安定化部材８の位置を調整する。このことによって、面ぶれの小さい位置での安定した記録／再生動作が実現できるようになる。
【００４８】
なお、図７に示す例は、光ディスク１と安定化部材８との三次元空間における相対位置関係の調整を安定化部材８側、すなわち安定化部材駆動装置３２に持たせた場合の一例であるが、この構成に限られるものではない。
【００４９】
また、フォーカスエラー検出系３０の具体例としては、シリンドリカルレンズおよび４分割フォトディテクタを用いた非点収差法、プリズムを用いたフーコー法などの数種の検出系が考えられ、また、光ピックアップ６のフォーカス位置の制御系も対物レンズを機械的に動かす方法、電歪素子などを用いた方法などの数種の方法があるが、本発明において特に限定されるものではない。
【００５０】
また、本実施形態においては、光ピックアップ６のフォーカスサーボをオンした状態、さらにはトラッキングサーボをオンした状態において、ディスク面ぶれ検出，制御が可能であることが１つの特徴となっている。これにより、光ディスク１における記録／再生が行われる半径位置を移動させながら連続した記録／再生動作が行われる場合においても、追従して常に光ピックアップ６の焦点位置におけるディスク面ぶれを調整することが可能となる。この点が、本件出願人先願の特願２００２−１２７１７号に記載の発明と大きく異なる点である（先願においては、フォーカスサーボオフでのディスク面ぶれ検出，制御に限られる）。
【００５１】
図８は本発明の実施形態１を説明するための光ディスク装置の概略構成図である。なお、以下の説明において、既述した部材に対応する部材には同一符号を付して詳しい説明は省略する。
【００５２】
図８において、４０はＺ軸方向・安定化部材／ピックアップユニット位置制御部、４１はＸ軸方向・安定化部材／ピックアップユニット位置制御部、４２はＸ軸方向・安定化部材／ピックアップユニットチルト角制御部、４３はＹ軸方向・安定化部材／ピックアップユニットチルト角制御部、４４は安定化部材８と光ピックアップ６とを保持してなる安定化部材／ピックアップユニット共通筐体、４５は安定化部材８と光ピックアップ６間の対向間隔を調整する安定化部材／ピックアップ間隔調整部である。Ｘ軸方向・安定化部材／ピックアップユニットチルト角制御部４２とＹ軸方向・安定化部材／ピックアップユニットチルト角制御部４３は安定化部材８の表面中心位置Ｏを回転中心としてチルト角を調節することができる機構である。また、光ピックアップ６は、レーザ光が常に安定化部材８の表面中心位置Ｏに垂直入射するように安定化部材／ピックアップユニット共通筐体４４に固定してある。なお、シート状の光ディスク１および安定化部材８は既述したものと同様の仕様のものである。
【００５３】
実施形態１における面ぶれ安定化のための調整制御について、図９のフローチャートを参照して説明する。
【００５４】
すなわち、ＣＰＵにスタート信号が入力することによって、スピンドルモータ４が始動して光ディスク１を回転させ（Ｓ１−１）、所定の回転数に達したときに（Ｓ１−２のＹＥＳ）、安定化部材８を光ディスク１の半径方向へ移動させ、安定化部材８の表面中心位置Ｏを光ディスク１の半径方向における所定の位置に合わせ、光ディスク１に対して安定化部材８を近接させる（Ｓ１−３）。その後、安定化部材８によりディスク設置基準面（光ディスクが平坦であると仮定した場合の安定化部材８の表面）よりも、約０．５ｍｍだけ光ディスク１を押し込み、光ディスク１の面ぶれが略安定化した時点で（Ｓ１−４）、安定化部材／ピックアップ間隔調整部４５により、光ピックアップ６の仮フォーカス位置と安定化部材８の表面中心位置Ｏとが一致するように調整する（Ｓ１−５）。このステップより、光ピックアップ６の仮フォーカス位置と安定化部材８の表面中心位置Ｏとが一致するように調整することにより、光ピックアップの焦点位置を、光ディスクの「回転軸方向の変動範囲」の略中心位置に設定することができる。この後、フォーカスサーボ，トラッキングサーボの順にサーボをオンにする（Ｓ１−６，Ｓ１−７）。
【００５５】
その後、ＣＰＵでは既述したようにフォーカスサーボのフォーカス残留エラー信号をモニタして特性解析し、この特性解析値に基づいて光ディスク１に対する安定化部材８の相対的位置調整制御を行う（Ｓ１−８，Ｓ１−９）。すなわち、フォーカス残留エラー信号の最大振幅が０．５Ｖ以下となるように、安定化部材８のＺ軸方向位置およびチルト角を、Ｚ軸方向・安定化部材／ピックアップユニット位置制御部４０，Ｘ軸方向・安定化部材／ピックアップユニットチルト角制御部４２，Ｙ軸方向・安定化部材／ピックアップユニットチルト角制御部４３を動作させて調整する。
【００５６】
前記調整後に、例えば、ステップ（Ｓ１−８），（Ｓ１−９）の動作を繰り返して、ディスク面ぶれの監視と調整を常に実施させておくようにすれば、光ディスク１における記録が行われる半径位置、あるいはディスク回転数といったディスク上の面ぶれ安定化位置に影響するパラメータを変更した場合にも、常に光ピックアップ６の焦点位置における面ぶれを安定化させるように制御することができ、例えば、記録／再生を行う光ディスク１における半径位置を移動させながら、連続した記録／再生動作を面振れの安定化した位置で常に実行することが可能となる。
【００５７】
あるいは、ディスク面振れの監視と調整を常に実施させなくても、記録／再生が行われる任意の半径位置における記録／再生動作ごとに、ステップ（Ｓ１−８），（Ｓ１−９）の動作により、随時、光ピックアップ６の焦点位置のディスク面ぶれを安定化させることも可能である。このような記録／再生におけるパターンは多岐に渡り、本発明では本実施形態のものに限定されるものではない。
【００５８】
なお、前記したフォーカス残留エラー信号最大振幅の基準値０．５Ｖという値は、あらかじめフォーカス残留エラー信号振幅とディスク面ぶれ量の相関関係から決定した値であり、面ぶれ量としては０．２μｍに相当する。また、前記基準値はあくまで本実施形態における一例であり、各種構成の光ピックアップごとに固有の値を設定する。なお、面ぶれ基準値０．２μｍという値は、ＮＡ０．８の光ピックアップにおいて要求されるデフォーカス量に基づいて任意に設定したものである。
【００５９】
このような調整制御を行うことにより、安定化部材８によるディスク面ぶれ安定化領域の位置を簡便かつ的確に設定することができ、ベルヌーイの法則を利用した可撓性を有する光ディスク１の面ぶれ安定性の利点を最大限に生かした安定した記録／再生を行うことができる。
【００６０】
なお、前記実施形態１における面ぶれ調整効果を確認するため、既述した光ディスク１を３１００ｒｐｍにて回転させ、半径４０ｍｍの位置でのピックアップ面におけるディスク面ぶれをレーザ変位計にて評価したところ、実効的な面ぶれは４μｍ以下に抑制されていることが確認され、本発明の有効性が実証された。さらに、実施形態１において、評価対象のディスク半径位置，ディスク回転数，ディスクの仕様などのパラメータを実用範囲内で変化させて前記評価テストを行ったところ、光ディスクにおける各ピックアップ面において一定の面ぶれ安定性を確保することが確認され、各面において面ぶれが４μｍ以下であった。
【００６１】
図１０は本発明の実施形態２を説明するための光ディスク装置の概略構成図であり、５０はＺ軸方向・安定化部材位置制御部、５１はＺ軸方向・ピックアップ位置制御部、５２はＸ軸方向・スピンドルチルト角制御部、５４はＸ軸方向・スピンドル位置制御部、５５はＹ軸方向・安定化部材チルト角制御部、５６はＹ軸方向・ピックアップチルト角制御部である。Ｙ軸方向・安定化部材チルト角制御部５５のチルト角は安定化部材８の表面中心位置Ｏを回転中心としてチルト角を調整することができるものである。Ｙ軸方向ピックアップチルト角制御部５６のチルト角は光ピックアップ６の焦点位置を回転中心としてチルト角を調整することができるものであって、また両チルト角制御部５５，５６は、光ピックアップ６の入出射光の光軸と安定化部材８の中心軸とが一致するように、常に連動するようにしてある。またスピンドル２のチルト角は、図示している傾きの方向へ略２度傾けて固定した。
【００６２】
実施形態２における面ぶれ安定化のための調整制御動作についても、実施形態１と同様に図９のフローチャートを参照して説明する。
【００６３】
すなわち、ＣＰＵにスタート信号が入力することによって、スピンドルモータ４が始動して光ディスク１を回転させ（Ｓ１−１）、所定の回転数に達したときに（Ｓ１−２のＹＥＳ）、安定化部材８を光ディスク１の半径方向へ移動させ、安定化部材８の表面中心位置Ｏを光ディスク１の半径方向における所定の位置に合わせ、光ディスク１に対して安定化部材８を近接させる（Ｓ１−３）。その後、安定化部材８によりディスク設置基準面（光ディスクが平坦であると仮定した場合の安定化部材８の表面）よりも、約０．５ｍｍだけ光ディスク１を押し込んで光ディスク１の面ぶれを略安定化（Ｓ１−４）させ、光ピックアップ６のＺ軸方向位置をＺ軸方向ピックアップ位置制御部５１により、光ピックアップ６の仮想フォーカス位置と安定化部材８の表面中心位置Ｏとが一致するように調整する（Ｓ１−５）。このステップより、光ピックアップ６の仮フォーカス位置と安定化部材８の表面中心位置Ｏとが一致するように調整することにより、光ピックアップの焦点位置を、光ディスクの「回転軸方向の変動範囲」の略中心位置に設定することができる。この後、フォーカスサーボ，トラッキングサーボの順にサーボをオンにする（Ｓ１−６，Ｓ１−７）。
【００６４】
その後、ＣＰＵでは既述したようにフォーカス残留エラー信号をモニタして特性解析し、この特性解析値に基づいて光ディスク１に対する安定化部材８の相対的位置調整制御を行う（Ｓ１−８，Ｓ１−９）。すなわち、フォーカス残留エラー信号の最大振幅が０．５Ｖ以下となるように、安定化部材８のチルト角をＹ軸方向・安定化部材チルト角制御部５５により調整する。
【００６５】
前記調整後に、例えば、ステップ（Ｓ１−８），（Ｓ１−９）の動作を繰り返して、ディスク面ぶれの監視と調整を常に実施させておくようにすれば、光ディスク１における記録／再生が行われる半径位置、あるいはディスク回転数といったディスク上の面振れ安定化位置に影響するパラメータを変更した場合にも、常に光ピックアップ焦点位置の面ぶれを安定化させるように制御することができ、例えば、光ディスク１における記録／再生が行われる半径位置を移動させながらの連続した記録／再生動作を常に面ぶれの安定化した位置で実行することが可能となる。
【００６６】
あるいは、光ディスク１における面ぶれの監視と調整を常に実施させなくても、光ディスク１に対して記録／再生が行われる半径位置での記録／再生動作ごとに、ステップ（Ｓ１−８），（Ｓ１−９）の動作により、随時、光ピックアップ６の焦点位置の光ディスク１の面ぶれを安定化させることも可能である。このような記録／再生に関わるパターンは多岐に渡り、本発明は本実施形態のものに限定されるものではない。
【００６７】
なお、前記したフォーカス残留エラー信号における最大振幅の基準値０．５Ｖという値は、あらかじめフォーカス残留エラー信号振幅とディスク面ぶれ量の相関関係から決定した値であり、面ぶれ量としては０．２μｍに相当する。また、前記基準値はあくまで一例であり、各種構成の光ピックアップごとに固有の値を設定する。なお、面ぶれ基準値０．２μｍという値は、ＮＡ０．８のピックアップにおいて要求されるデフォーカス量に基づいて任意に設定したものである。
【００６８】
このような調整制御を行うことにより、実施形態１と同様に、安定化部材８によるディスク面ぶれ安定化領域の位置を簡便かつ的確に設定することができ、ベルヌーイの法則を利用した可撓性を有する光ディスク１の面ぶれ安定性の利点を最大限に生かした安定した記録／再生を行うことができる。
【００６９】
なお、実施形態２における面ぶれ調整効果を確認するため、既述した光ディスク１を３１００ｒｐｍで回転させ、半径４０ｍｍの位置でのピックアップ面におけるディスク面ぶれをレーザ変位計にて評価テストを行ったところ、面ぶれを４μｍ以下に抑制することができることが確認され、実施形態２においても本発明に係る有効性が実証された。さらに、実施形態２において、評価対象のディスク半径位置，ディスク回転数，ディスクの仕様などのパラメータを実用範囲内で変化させて前記評価テストを行ったところ、光ディスクにおける各ピックアップ面において一定の面ぶれ安定性を確保することが確認され、各面において面ぶれが５μｍ以下であった。
【００７０】
次に本発明の実施形態３について説明する。実施形態３の光ディスク装置は図８に示す実施形態１と同様な装置構成であって図示は省略するが、記録／再生を行うディスク半径方向の位置，ディスク回転数，ディスクの各種仕様にそれぞれに対応して、面ぶれ安定状態になる安定化部材８における三次元上の位置を、既述したようなフォーカスエラー信号の検出信号に基づいて、あらかじめ見積もっておき、この見積値を安定化部材８の予備動作位置のデータとして、光ディスク装置に搭載されているＣＰＵのメモリに見積値Ａとして記憶させておく点で異なっている。
【００７１】
実施形態３における面ぶれ安定化のための調整制御について、図１１のフローチャートを参照して説明する。
【００７２】
すなわち、ＣＰＵにスタート信号が入力することによって、スピンドルモータ４が始動して光ディスク１を回転させ（Ｓ２−１）、所定の回転数に達したときに（Ｓ２−２のＹＥＳ）、安定化部材８を光ディスク１の半径方向へ移動させ、かつ前記見積値Ａを読み出して、安定化部材８を光ディスク１に対する三次元空間上に設定し（Ｓ２−３）、安定化部材／ピックアップ間隔調整部４５により、光ピックアップ６の仮想フォーカス位置と安定化部材８の表面中心位置Ｏとが一致するように調整する（Ｓ２−４）。この後、フォーカスサーボ，トラッキングサーボの順にサーボをオンにする（Ｓ２−５，Ｓ２−６）。
【００７３】
その後、ＣＰＵでは既述したようにフォーカス残留エラー信号をモニタして特性解析し、この特性解析値に基づいて光ディスク１に対する安定化部材８の相対的位置の微調整制御を行う（Ｓ２−７，Ｓ２−８）。すなわち、フォーカス残留エラー信号の最大振幅が０．５Ｖ以下となるように、安定化部材８のＺ軸方向位置およびチルト角を、Ｚ軸方向・安定化部材／ピックアップユニット位置制御部４０，Ｘ軸方向・安定化部材／ピックアップユニットチルト角制御部４２，Ｙ軸方向・安定化部材／ピックアップユニットチルト角制御部４３を動作させて微調整する。
【００７４】
このような調整制御を行うことにより、実施形態１と同様に面ぶれの安定化を図ることができ、しかも安定化部材８の初期設定動作の簡略化を図ることができた。
【００７５】
また、本実施形態では、光ディスク１ごとに安定化部材８を大まかに位置設定する予備動作を見積る動作を含んでいるが、見積りのためのパラメータとしてはディスク材料，厚さ，機能構成層の種類といった代表的なパラメータをベースとして、代表的な安定化部材６の予備動作位置を何種類か用意しておけばよく、全てのパラメータに対応する見積りを設定する必要はない。
【００７６】
なお、シート状の光ディスク１の材料としてポリエチレンテレフタレートを使用した光ディスクであっても、前記実施形態の調整制御方法を実施することにより、安定化部材８によるディスク面ぶれの安定化における前記のような効果が得られることを確認した。
【００７７】
【発明の効果】
以上説明したように、本発明によれば、フォーカス残留エラー信号によって、光ピックアップと対向する位置の光ディスクにおける面ぶれ安定化状態を的確に判断し、光ディスクと安定化部材との相対位置関係の調整により、光ピックアップの光ディスクに対する焦点位置と光ディスクにおける面ぶれ安定化位置とを一致させ、光ディスク上の信号記録／再生位置におけるディスク面振れを極めて小さい値とすることにより、高ＮＡの光ピックアップの狭小デフォーカスマージン，狭小ワークディスタンスにも容易に対応できるようになり、安定した記録および／または再生動作が実現可能となる。
【図面の簡単な説明】
【図１】本発明の実施形態の基本構成を説明するための光ディスク装置の概略構成図
【図２】本発明の実施形態における光ピックアップを構成する記録手段と再生手段との説明図
【図３】本発明の実施形態に使用される可撓性を有するシート状の光ディスクの一部断面図
【図４】本発明の実施形態における可撓性を有するシート状の光ディスクにおける面ぶれ安定化についての説明図
【図５】本発明の実施形態の構成における光ディスクの面ぶれの測定結果の実測図（２回転分）
【図６】光ピックアップにおける信号検出系のフォトディテクタの一般的なＳ字特性の説明図
【図７】本発明の実施形態に係る光ディスクと安定化部材とにおける三次元空間の相対位置調整用の制御系の一例を示すブロック図
【図８】本発明の実施形態１，３を説明するための光ディスク装置の概略構成図
【図９】本発明の実施形態１，２における面ぶれ安定化のための調整制御動作に係るフローチャート
【図１０】本発明の実施形態２を説明するための光ディスク装置の概略構成図
【図１１】本発明の実施形態３における面ぶれ安定化のための調整制御動作に係るフローチャート
【符号の説明】
１　可撓性を有するシート状の光ディスク
２　スピンドルシャフト
４　スピンドルモータ
６　光ピックアップ
８　安定化部材
３０　フォーカスエラー信号検出系
３１　位相補償ドライブアンプ
３２　安定化部材駆動装置
４０　Ｚ軸方向・安定化部材／ピックアップユニット位置制御部
４１　Ｘ軸方向・安定化部材／ピックアップユニット位置制御部
４２　Ｘ軸方向・安定化部材／ピックアップユニットチルト角制御部
４３　Ｙ軸方向・安定化部材／ピックアップユニットチルト角制御部
４４　安定化部材／ピックアップユニット共通筐体
４５　安定化部材／ピックアップ間隙調整部
５０　Ｚ軸方向・安定化部材位置制御部
５１　Ｚ軸方向・ピックアップ位置制御部
５２　Ｘ軸方向・スピンドルチルト角制御部
５４　Ｘ軸方向・スピンドル位置制御部
５５　Ｙ軸方向・安定化部材チルト角制御部
５６　Ｙ軸方向・ピックアップチルト角制御部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention uses an optical disc, which is a flexible sheet-shaped optical information recording medium, and stabilizes the swing in the direction of the rotation axis at a portion where writing or reading is performed on the optical disc by a pressure difference of an air flow. The present invention relates to an optical disk device provided with stabilizing means and an adjusting method of the optical disk device, and more particularly to a technique for adjusting a relative positional relationship between an optical disk and a stabilizing member.
[0002]
[Prior art]
2. Description of the Related Art In recent years, digitalization of television broadcasts has begun, and optical discs are required to record a large amount of digital data. Among the techniques for increasing the density of an optical disk, a basic method is to reduce the spot diameter of light for recording / reproduction.
[0003]
For this reason, it is effective to shorten the wavelength of light used for recording / reproduction and increase the numerical aperture NA of the objective lens. As for the wavelength of light, a wavelength of near infrared light of 780 nm is used for CD (compact disk), and a wavelength of about 650 nm for red light is used for DVD (digital versatile disk). Recently, blue-violet semiconductor lasers have been developed, and it is expected that laser light near 400 nm will be used in the future.
[0004]
In addition, the objective lens for a CD has an NA of less than 0.5, but the objective lens for a DVD has an NA of about 0.6. In the future, it is required to further increase the numerical aperture (NA) to be 0.7 or more. However, increasing the NA of the objective lens and shortening the wavelength of the light also means that the influence of aberrations when the light is stopped is increased. Therefore, the margin for the tilt of the optical disk is reduced. Also, since the depth of focus is reduced by increasing the NA, the focus servo accuracy must be increased.
[0005]
Further, since the distance between the objective lens and the recording surface of the optical disk is reduced by using the objective lens with a high NA, it is necessary to reduce the fluctuation of the surface of the optical disk. In some cases, the objective lens may collide with the optical disk, which may cause a failure of the pickup.
[0006]
As shown in page 183 of O PLUS E (vol. 20 No. 2), as a large-capacity optical disk having a short wavelength and a high NA, for example, a recording film is formed on a substrate which is as thick and rigid as a CD. There has been proposed a system in which recording / reproducing light is recorded / reproduced to / from a recording film through a thin cover layer without passing through the substrate.
[0007]
Further, as described in, for example, JP-A-7-105657 and JP-A-10-308059, a flexible optical disk is rotated on a flat stabilizing plate to reduce surface deviation on the optical disk. Stabilization methods are known.
[0008]
[Problems to be solved by the invention]
However, in the above-mentioned conventional technique, when the substrate of the optical disk is formed of a rigid body, extremely accurate molding is performed and recording is performed at a low temperature so that thermal deformation does not occur in order to reduce surface runout and tilt of the rotating optical disk. A film must be formed. This results in a longer tact time for manufacturing an optical disc, which leads to an increase in cost.
[0009]
Further, in the method of rotating a flexible optical disk on a stabilizing plate, as described in JP-A-10-308059, when rotating on a simple flat plate, the optical disk comes into contact with the stabilizing plate. As a result, the optical disk vibrates, causing a high-frequency runout. This surface deviation often occurs in a frequency region in which a mechanical focus servo cannot respond, and it is not possible to sufficiently suppress the residual servo error.
[0010]
Furthermore, when the optical disk and the objective lens slide due to surface deviation, dust is generated, and the dust or the like causes an error. In particular, as described in JP-A-7-105657, if the recording film is present on the stabilizing plate side, the recording film of the optical disk is damaged by sliding, and a direct error is caused. .
[0011]
As one means for solving these problems, the present applicant has disclosed in Japanese Patent Application No. 2001-228943 that the opposing surface of the optical disk is not provided with the stabilizing guide member facing the entire recording layer of the optical disk. An area in which an arc-shaped cylindrical stabilizing guide member is used, and where air pressure does not act on the upstream side and the downstream side in the disk rotation direction in a portion of the optical disc where the surface run-out due to the action of air pressure by the stabilizing guide member is stable ( A space where there is no stabilizing guide member) is provided, so that there is a part that “runs away” on the optical disc before and after the part where the runout was stabilized, and the rebound of the optical disc at the part where the runout was stabilized An invention was proposed in which the effect of the stabilizing force by the aerodynamic force was increased by reducing the force.
[0012]
According to the present invention, it is possible to reliably suppress surface deflection of a flexible optical disk, enable high-density recording, and prevent occurrence of problems such as sliding contact with an objective lens. Since the stabilization position on the optical disk surface by the stabilization guide is affected by the disk rotation speed, the radial position, and the like, it is important to accurately match the focal position of the optical pickup with the stabilization position.
[0013]
In addition, the applicant of the present application has proposed, in Japanese Patent Application No. 2002-12717, an invention for controlling and adjusting the relative position of the stabilizing guide and the optical disk based on the detection result of the tracking error signal. Stabilization positions should be matched ".
[0014]
This method is unique, and can reliably match the focal position of the optical pickup with the stabilization position. However, this control operation is represented by a push-pull signal when the focus servo is off. Only when such a tracking error signal can be detected, it cannot be applied when the focus servo is turned on.
[0015]
SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems, and to stabilize a surface of an optical disc by using aerodynamic force when recording / reproducing using a flexible sheet-shaped optical disc. By precisely adjusting the relative positional relationship between the stabilizing means and the optical disc, the focus position of the optical pickup and the stabilization position of the optical disc are precisely matched, and the disc surface at the signal recording / reproducing position on the optical disc is adjusted. By setting the blur to a very small value, an optical disc apparatus that can easily cope with a narrow defocus margin and a narrow work distance in an optical pickup with a high NA and can stabilize a recording and / or reproducing operation and an adjustment thereof. It is to provide a method.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 includes a rotation driving unit that rotates a flexible sheet-shaped optical disk, and a device that writes or reads information by emitting light to a recording surface of the optical disk. 1. An optical disc apparatus comprising: an optical pickup for performing an optical pickup; and a stabilizing means for stabilizing at least a portion of the optical disc on which writing or reading is performed in a rotation axis direction by a pressure difference of an air flow, wherein a focus servo of the optical pickup is provided. A control adjustment unit that adjusts a relative positional relationship between the optical disc and the stabilization unit in a three-dimensional space based on an analysis value of a focus residual error signal that is a defocus component remaining after turning on. With this configuration, the surface deviation from the optical pickup side, that is, The effective position of the recording / reproducing operation is prevented from being determined accurately from the waveform of the focus residual error signal, and by adjusting the relative positional relationship between the optical disk and the stabilizing means, the focus position of the optical pickup with respect to the optical disk and the optical disk are adjusted. Can be accurately matched with the surface shake stabilizing position, and stable recording and / or reproduction can be realized at the position where the surface shake is reduced. Also, by setting the disc surface deviation at the signal recording / reproducing position on the optical disc to an extremely small value, it becomes possible to easily cope with a narrow defocus margin and a narrow work distance of an optical pickup having a high NA.
[0017]
According to a second aspect of the present invention, in the optical disk device according to the first aspect, the value obtained by converting the maximum amplitude of the focus residual error signal obtained by rotating the optical disk once into the amplitude of the optical disk surface by the control adjustment means is: The relative positional relationship between the optical disk and the stabilizing means in the three-dimensional space is adjusted so as to be equal to or less than the set reference value. With this configuration, the deviation of the optical disk surface is adjusted to an arbitrary quantitative value or less. Will be done.
[0018]
According to a third aspect of the present invention, in the optical disk device according to the second aspect, a defocus margin required to satisfy an arbitrary standard of recording / reproducing characteristics is determined in advance for each combination of an optical pickup and an optical disk. It is characterized in that the reference value is used as a reference value, and by using this reference value, it is possible to make a reliable and accurate determination.
[0019]
According to a fourth aspect of the present invention, there is provided the optical disk device according to any one of the first to third aspects, further comprising a moving unit that moves the position of the optical disk based on a relative position adjustment signal from the control adjusting unit. It is characterized by.
[0020]
According to a fifth aspect of the present invention, in the optical disk device according to any one of the first to third aspects, there is provided a moving means for moving the position of the stabilizing means based on a relative position adjustment signal from the control adjusting means. It is characterized by the following.
[0021]
According to a sixth aspect of the present invention, in the optical disk device according to any one of the first to third aspects, the moving means for moving the positions of the optical disk and the stabilizing means based on a relative position adjustment signal from the control adjusting means. It is characterized by having.
[0022]
According to a seventh aspect of the present invention, there is provided a rotation driving means for rotating a flexible sheet-shaped optical disk, an optical pickup for emitting light to a recording surface of the optical disk to write or read information, and at least an optical disk. A stabilizing means for stabilizing a deflection in a rotation axis direction at a portion where writing or reading is performed by a pressure difference of an air flow, wherein the focus servo of the optical pickup is turned on. The relative position of the optical disc and the stabilizing means in a three-dimensional space is adjusted based on an analysis value of a focus residual error signal, which is a defocus component remaining later. Side deviation from the side, that is, hindering stable recording / reproducing operation By accurately judging the effective surface shake state from the focus residual error signal waveform, the focus position of the optical pickup with respect to the optical disk and the surface shake stabilization position of the optical disk are adjusted by adjusting the relative positional relationship between the optical disk and the stabilizing means. Accurate matching can be achieved, and stable recording and / or reproduction can be realized at a position where the surface shake is reduced. Also, by setting the disc surface deflection at the signal recording / reproducing position on the optical disc to an extremely small value, it is possible to easily cope with a narrow defocus margin and a narrow work distance of a high NA pickup.
[0023]
The invention according to claim 8 is a rotation driving means for rotating a flexible sheet-shaped optical disc, an optical pickup for emitting light to a recording surface of the optical disc to write or read information, and at least an optical disc. And a stabilizing means for stabilizing the deflection in the rotation axis direction at the portion where writing or reading is performed by the pressure difference of the air flow. The reference condition for the relative positional relationship between the optical disc and the stabilizing means in the three-dimensional space is set in advance, and the relative positional relationship between the optical disc and the stabilizing means used in the three-dimensional space based on the set reference conditions is determined. Characterized by adjusting, by this method, a typical control on the optical disc used The condition is set in advance, and the focal position of the optical pickup with respect to the optical disk and the surface shake stabilization position of the optical disk can be accurately matched based on the control conditions. The adjustment control operation and the arithmetic processing can be simplified, and a simpler and less expensive optical disk device is realized.
[0024]
According to a ninth aspect of the present invention, in the adjustment method of the optical disk device according to the seventh aspect, the position adjustment according to the eighth aspect is performed as fine adjustment in a relative positional relationship between the optical disk and the stabilizing means in a three-dimensional space. With this method, the adjustment control operation can be simplified and speeded up.
[0025]
According to a tenth aspect of the present invention, in the adjustment method of the optical disk device according to any one of the seventh to ninth aspects, the optical disk device is stabilized with the optical disk such that the maximum amplitude of the focus residual error signal is equal to or less than a preset reference value. The method is characterized in that the relative positional relationship between the optical disk and the optical disk is adjusted in a three-dimensional space. With this method, the deviation of the optical disk surface is adjusted to an arbitrary quantitative value or less.
[0026]
According to an eleventh aspect of the present invention, in the adjustment method of the optical disk device according to the seventh to tenth aspects, it is necessary to satisfy the standard of the recording / reproducing characteristics for each different combination of the optical pickup and the optical disk used. The defocus margin is determined in advance, and is used as a reference value for adjustment. By this method, reliable and accurate adjustment can be performed.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0028]
FIG. 1 is a schematic configuration diagram of an optical disk device for explaining a basic configuration of an embodiment of the present invention. 1 is a flexible sheet-shaped optical disk, 2 is a spindle shaft that holds a hub 3 of the optical disk 1, Reference numeral 4 denotes a spindle motor for driving the spindle shaft 2 to rotate. Reference numeral 6 denotes an optical pickup as recording means for writing information on the optical disk 1 and reproduction means for reading the written information. Reference numeral 7 denotes an optical pickup 6. A pickup positioning mechanism 8 for moving the optical disk 1 in the radial direction is provided to face the optical pickup 6 with the optical disk 1 interposed therebetween, and a stabilizing member for preventing surface deviation of the optical disk 1, and 9 is a stabilizing member 8. The positioning mechanism for stabilizing guide, which moves in the radial direction of the optical disk 1 in conjunction with the optical pickup 6, An apparatus body for housing the formed member.
[0029]
FIG. 2 is an explanatory view of a recording means and a reproducing means constituting the optical pickup. As the recording means, as shown in FIG. A signal processing circuit 11 for performing processing, a laser driving control circuit 12 for generating a laser driving control signal based on an output from the signal processing circuit 11, and a semiconductor laser or the like receiving an output from the laser driving control circuit 12 The laser drive unit 13 drives the laser light source 14, and the like. The emitted light La of high emission energy emitted from the laser light source 14 is condensed by the objective lens 15 of the optical pickup 6 shown in FIG. The recording surface is irradiated as a light spot, and information recording by bit formation is performed.
[0030]
Further, as shown in FIG. 2B, the reproducing means includes a photoelectric conversion element 17 such as a photodiode and a reproduction signal processing circuit 18 for reproducing recorded bits formed on the recording surface of the optical disk 1. Then, a laser beam having low emission energy is emitted from the laser light source 14, the reflected light Lb is received by the photoelectric conversion element 17 through the objective lens 15, and the output from the photoelectric conversion element 17 is subjected to signal expansion by the reproduction signal processing circuit 18. Processing is performed to generate a reproduced signal.
[0031]
The optical disk 1 has a configuration as shown in the cross-sectional view of FIG. 3, and is mounted on the spindle shaft 2 such that the recording layer 20 faces the objective lens 15 of the optical pickup 6 and the substrate 21 faces the stabilizing member 8. It is set on the provided chucking section.
[0032]
A specific example of the optical disc 1 will be described. As a substrate, a thin sheet of about 0.1 mm was used in order to have flexibility. For example, a groove having a stamper pitch of 0.6 μm and a width of 0.3 μm is transferred by thermal transfer to a sheet made of polyethylene terephthalate having a thickness of 80 μm, and then the sheet / Ag reflective layer is formed by sputtering to a thickness of 120 nm / (ZrO ₂ −Y _2). O ₃₎ was formed in the order of _{-SiO 2, 7nm / AgInSbTeGe, 10nm} / ZnS-SiO 2, 25nm / Si 3 N 4. The sheet is spin-coated with a UV resin, cured by ultraviolet irradiation to form a transparent protective film having a thickness of 5 μm, and further, the recording layer is melt-crystallized with a large-diameter laser beam to obtain a reflectance. Was used.
[0033]
With reference to the explanatory diagram of FIG. 4, the stabilization of the surface deviation of a flexible sheet-shaped optical disk will be described. At the time of recording / reproduction, the flexible optical disk 1 having the above-described configuration is rotated between the optical pickup 6 and the stabilizing member 8. The rotating optical disk 1 itself has a small but rigidity, and also has a force that tends to be straightened by the action of centrifugal force when rotated. Therefore, by bringing the stabilizing member 8 closer to the optical disc 1 and generating a repulsive force due to the pressure difference of the airflow based on Bernoulli's law and applying the repulsive force to the optical disc 1, a force for the optical disc 1 to straighten, By balancing the repulsive force from the stabilizing member 8, large surface runout (runout in the disk rotation axis direction) can be reduced.
[0034]
In the present embodiment, the stabilizing member 8 is prevented from being opposed to the entire recording layer 20 of the optical disc 1. For example, in the configuration example of FIG. 4, a columnar stabilizing member 8 having an arc-shaped surface facing the optical disk 1 is used, and a portion of the optical disk 1 where the stabilization of the stabilizing member 8 by the air pressure is stabilized. Areas (spaces without stabilizing member 8) B and C in which the action of the air pressure does not occur are provided on the upstream side and the downstream side in the disk rotation direction in A, and the optical disk is located before and after the part A where the surface run-out is stabilized. The presence of a “runaway” portion in 1 makes it possible to reduce the repulsive force of the optical disc 1 in the portion A where the runout has been stabilized. By doing so, the effect of the stabilizing force by the aerodynamic force is increased.
[0035]
Further, the stabilizing member 8 exists on the side of the substrate 21 opposite to the recording layer 20 of the optical disc 1, and condenses recording / reproducing light La, Lb on the recording layer 20 of the optical disc 1 for recording. / Play. The stabilizing member 8 stabilizes the side of the substrate 21 opposite to the recording layer 20. Thus, even if a sliding state occurs between the stabilizing member 8 and the optical disk 1, the recording layer 20 will not be damaged and will not directly cause an error. Note that it is also possible to arrange the stabilizing member 8 on the recording layer 20 side so that a recording / reproducing laser is incident on the recording layer through the substrate 21. In this case, the overcoating on the recording layer 20 can be performed. Processing or the like is effective in preventing the recording layer 20 from being damaged.
[0036]
This will be described more specifically with reference to the explanatory diagram of FIG. In FIG. 4, when the optical disc 1 is used in a state in which the components other than the stabilizing member 8 or the apparatus main body case or the optical disc 1 are housed in a cartridge, the optical disc 1 is removed from the optical disc 1 so that the cartridge does not operate according to Bernoulli's law. Are separated by about 1 mm or more. However, exceptionally, when the objective lens 15 has a high NA, the working distance becomes short, so that the objective lens 15 approaches 0.05 mm to 0.3 mm.
[0037]
Further, FIG. 5 shows an actual measurement diagram (for two rotations) of the measurement result of the surface deviation of the optical disk in the configuration of FIG. The stabilizing member 8 has a tip having a radius of 50 mm and a diameter of 20 mm, and the optical disc 1 has a tracking groove of 0.65 μm pitch formed on an 80 μm PET (polyethylene terephthalate) sheet, and a recording film is formed by sputtering. The diameter was 45 mm, the number of rotations was 2000 rpm, and the runout was measured using a laser displacement meter. The set interval between the stabilizing member 8 and the optical disc 1 is about 5 μm.
[0038]
Since there was no abnormal vibration in the stabilizing member 8 and no sliding scratches occurred on the optical disc 1, it can be determined that excessive air levitation was not performed and no sliding state occurred. Further, it can be seen that the disk runout is about 5 μm, which is extremely small in view of the fact that a normal rigid disk causes a runout of 50 μm or more.
[0039]
Further, (Table 1) is a table summarizing the results obtained by rotating the surface for 10 rotations in the same manner as the measuring method described with reference to FIG. 5, and as shown in this embodiment, a stabilizing member is provided on one side of the optical disk. The optical disk having the configuration described above was compared with a conventional optical disk having a guide member provided on the entire surface thereof.
[0040]
[Table 1]

[0041]
As can be seen from Table 1, good results were obtained in which the maximum width of the runout was approximately 11 μm and 3σ of the runout variation was about 2 μm.
[0042]
Regardless of whether the stabilizing member 8 is installed in the apparatus main body case or inside the cartridge, the above-described excellent stabilization of the run-out is obtained.
[0043]
Then, recording and reproduction were performed on the optical disk device having the above configuration using an optical pickup having a wavelength of 405 nm and an NA of 0.9. For example, the recording position on the optical disk was 45 mm in radius, the shortest recording bit length was 0.12 μm, and random digital data was modulated by 1-7 RLL and recorded.
[0044]
The recording linear velocity is 10 m / s, the recording peak power is 5 mW, the erasing power is 2.6 mW, the recording bottom power is 0.1 mW, ternary modulation, and the reproduction is performed at 0.25 mW. The jitter between them was less than 8%. Furthermore, stable focus and tracking were performed without disturbance of the envelope of the recording signal.
[0045]
The present inventors have conducted intensive studies on this control method in order to further stabilize the above-mentioned surface deviation of the optical disk. As a result, the defocus component which remains after turning on the focus servo of the optical pickup, that is, the focus residual error signal Is analyzed, and the relative positional relationship between the optical disk and the stabilizing member in the three-dimensional space is adjusted so that the analysis value satisfies an arbitrary standard. I found that I could adjust it.
[0046]
In general, an optical disk device includes a focus error detection system that returns a detection waveform according to an S-shaped characteristic as shown in FIG. 6 according to the distance between the disk surface and the objective lens. The drive amplifier controls the focus position of the optical pickup (focus servo) so that the optical pickup has a constant value (generally, a zero target), and controls the optical pickup to focus on the disk surface. A component that the focus servo cannot follow the disk surface shake, that is, an effective surface shake component viewed from the optical pickup when the focus servo is turned on is detected as a focus residual error. As described above, the focus residual error signal includes direct disk surface shake information, and the adjustment and control can be performed by using the analysis value as an index.
[0047]
FIG. 7 is a block diagram illustrating an example of a control system for adjusting the relative position of the three-dimensional space between the optical disc and the stabilizing member. The focus error detected by the focus error signal detection system 30 including a detector and the like in the optical pickup 6. Upon receiving the signal, the phase compensation drive amplifier 31 outputs a servo drive signal to the optical pickup 6 for performing phase compensation and achieving proper focus. Further, the stabilizing member drive unit 32 monitors the focus residual error signal in the focus error signal detection system 30 to obtain a surface shake signal of the optical disk 1 so that the disk surface shake at the focal position of the optical pickup 6 is reduced. Adjust the position of the stabilizing member 8. This makes it possible to realize a stable recording / reproducing operation at a position with a small surface deviation.
[0048]
The example shown in FIG. 7 is an example in which the adjustment of the relative positional relationship between the optical disc 1 and the stabilizing member 8 in the three-dimensional space is provided on the stabilizing member 8 side, that is, the stabilizing member driving device 32. However, the present invention is not limited to this configuration.
[0049]
Further, as specific examples of the focus error detection system 30, several types of detection systems such as an astigmatism method using a cylindrical lens and a four-segment photodetector and a Foucault method using a prism can be considered. There are several methods of controlling the focus position, such as a method of mechanically moving the objective lens and a method of using an electrostrictive element, but are not particularly limited in the present invention.
[0050]
One feature of the present embodiment is that disc surface shake detection and control can be performed in a state where the focus servo of the optical pickup 6 is turned on and further in a state where the tracking servo is turned on. Thus, even when a continuous recording / reproducing operation is performed while moving a radial position on the optical disc 1 where recording / reproduction is performed, it is possible to always adjust the disk surface shake at the focal position of the optical pickup 6 by following the operation. It becomes possible. This is a significant difference from the invention described in Japanese Patent Application No. 2002-12717 filed by the present applicant (the prior application is limited to detection and control of disk surface shake with focus servo off).
[0051]
FIG. 8 is a schematic configuration diagram of an optical disc device for describing Embodiment 1 of the present invention. In the following description, members corresponding to the members described above are denoted by the same reference numerals, and detailed description is omitted.
[0052]
8, reference numeral 40 denotes a Z-axis direction / stabilizing member / pickup unit position controller, 41 denotes an X-axis direction / stabilizing member / pickup unit position controller, and 42 denotes an X-axis direction / stabilizing member / pickup unit tilt angle. A control unit 43 is a Y-axis direction / stabilizing member / pickup unit tilt angle control unit, 44 is a stabilizing member / pickup unit common housing holding the stabilizing member 8 and the optical pickup 6, and 45 is a stabilizing unit. It is a stabilizing member / pickup interval adjusting unit that adjusts the opposing interval between the member 8 and the optical pickup 6. The X-axis direction / stabilizing member / pickup unit tilt angle control unit 42 and the Y-axis direction / stabilizing member / pickup unit tilt angle control unit 43 adjust the tilt angle using the surface center position O of the stabilizing member 8 as the center of rotation. It is a mechanism that can. The optical pickup 6 is fixed to the stabilizing member / pickup unit common case 44 so that the laser beam always enters the surface center position O of the stabilizing member 8 vertically. The sheet-shaped optical disk 1 and the stabilizing member 8 have the same specifications as those described above.
[0053]
The adjustment control for stabilizing the runout in the first embodiment will be described with reference to the flowchart in FIG.
[0054]
That is, when a start signal is input to the CPU, the spindle motor 4 is started to rotate the optical disk 1 (S1-1). When a predetermined number of rotations is reached (YES in S1-2), the stabilizing member is rotated. 8 is moved in the radial direction of the optical disc 1, the center position O of the surface of the stabilizing member 8 is adjusted to a predetermined position in the radial direction of the optical disc 1, and the stabilizing member 8 is brought close to the optical disc 1 (S1-3). . Thereafter, the stabilizing member 8 pushes the optical disc 1 by about 0.5 mm from the disc installation reference plane (the surface of the stabilizing member 8 when the optical disc is assumed to be flat), and the surface deviation of the optical disc 1 is substantially stabilized. At this point (S1-4), the stabilizing member / pickup interval adjusting unit 45 adjusts the temporary focus position of the optical pickup 6 so that the surface center position O of the stabilizing member 8 matches (S1-5). ). From this step, by adjusting the temporary focus position of the optical pickup 6 so that the center position O of the surface of the stabilizing member 8 coincides, the focal position of the optical pickup can be set within the “variation range in the rotation axis direction” of the optical disk. It can be set to approximately the center position. Thereafter, the servo is turned on in the order of focus servo and tracking servo (S1-6, S1-7).
[0055]
Thereafter, the CPU monitors the focus residual error signal of the focus servo and analyzes the characteristics as described above, and controls the relative position adjustment of the stabilizing member 8 with respect to the optical disc 1 based on the characteristic analysis value (S1-8). , S1-9). That is, the Z-axis direction position and the tilt angle of the stabilizing member 8 are adjusted so that the maximum amplitude of the focus residual error signal is 0.5 V or less, and the Z-axis direction / stabilizing member / pickup unit position control unit 40 and the X-axis The direction / stabilization member / pickup unit tilt angle control unit 42 and the Y-axis direction / stabilization member / pickup unit tilt angle control unit 43 are operated and adjusted.
[0056]
After the adjustment, for example, by repeating the operations of steps (S1-8) and (S1-9) to constantly monitor and adjust the disc surface deviation, the radius at which recording is performed on the optical disc 1 is performed. Even when a parameter that influences the stabilization position on the disk, such as the position or the number of revolutions of the disk, is changed, control can be performed so that the stabilization at the focal position of the optical pickup 6 is always stabilized. While moving the radial position on the optical disc 1 for recording / reproducing, continuous recording / reproducing operation can always be executed at a position where the surface runout is stabilized.
[0057]
Alternatively, the operations of steps (S1-8) and (S1-9) can be performed for each recording / reproduction operation at an arbitrary radial position where recording / reproduction is performed, without always monitoring and adjusting the disk surface deflection. At any time, it is also possible to stabilize the disc surface deviation at the focal position of the optical pickup 6. The patterns in such recording / reproduction are various, and the present invention is not limited to the present embodiment.
[0058]
The above-mentioned reference value of 0.5 V of the maximum focus residual error signal amplitude is a value determined in advance from the correlation between the focus residual error signal amplitude and the disk surface shake amount, and the surface shake amount is 0.2 μm. Equivalent to. Further, the reference value is merely an example in the present embodiment, and a unique value is set for each optical pickup having various configurations. The reference value of 0.2 μm is set arbitrarily based on the defocus amount required for an optical pickup having an NA of 0.8.
[0059]
By performing such adjustment control, the position of the disk surface stabilization region by the stabilizing member 8 can be easily and accurately set, and the surface deviation of the flexible optical disk 1 using Bernoulli's law. It is possible to perform stable recording / reproducing while maximizing the advantage of stability.
[0060]
In addition, in order to confirm the surface shake adjusting effect in the first embodiment, the above-described optical disk 1 was rotated at 3100 rpm, and the disk surface shake on the pickup surface at a position of a radius of 40 mm was evaluated by a laser displacement meter. It was confirmed that the effective surface deviation was suppressed to 4 μm or less, and the effectiveness of the present invention was proved. Further, in the first embodiment, the above evaluation test was performed by changing parameters such as a disk radial position to be evaluated, a disk rotation speed, and disk specifications within a practical range. It was confirmed that the stability was ensured, and the run-out on each surface was 4 μm or less.
[0061]
FIG. 10 is a schematic configuration diagram of an optical disk device for explaining Embodiment 2 of the present invention. 50 is a Z-axis direction / stabilizing member position control unit, 51 is a Z-axis direction / pickup position control unit, and 52 is An axial direction / spindle tilt angle control unit, 54 is an X axis direction / spindle position control unit, 55 is a Y axis direction / stabilizing member tilt angle control unit, and 56 is a Y axis direction / pickup tilt angle control unit. The tilt angle of the Y-axis direction / stabilizing member tilt angle control unit 55 can be adjusted with the center O of the surface of the stabilizing member 8 as the center of rotation. The tilt angle of the Y-axis direction pickup tilt angle control unit 56 can adjust the tilt angle with the focus position of the optical pickup 6 as a center of rotation, and both tilt angle control units 55 and 56 And the center axis of the stabilizing member 8 always coincides with each other. Further, the tilt angle of the spindle 2 was fixed by inclining at about 2 degrees in the illustrated inclination direction.
[0062]
The adjustment control operation for stabilizing the runout in the second embodiment will be described with reference to the flowchart of FIG. 9 similarly to the first embodiment.
[0063]
That is, when a start signal is input to the CPU, the spindle motor 4 is started to rotate the optical disk 1 (S1-1). When a predetermined number of rotations is reached (YES in S1-2), the stabilizing member is rotated. 8 is moved in the radial direction of the optical disc 1, the center position O of the surface of the stabilizing member 8 is adjusted to a predetermined position in the radial direction of the optical disc 1, and the stabilizing member 8 is brought close to the optical disc 1 (S1-3). . Thereafter, the stabilizing member 8 pushes the optical disc 1 by about 0.5 mm from the disc installation reference plane (the surface of the stabilizing member 8 when the optical disc is assumed to be flat) to substantially stabilize the runout of the optical disc 1. (S1-4), and the Z-axis direction position of the optical pickup 6 is set by the Z-axis direction pickup position control unit 51 so that the virtual focus position of the optical pickup 6 and the surface center position O of the stabilizing member 8 match. It is adjusted (S1-5). From this step, by adjusting the temporary focus position of the optical pickup 6 so that the center position O of the surface of the stabilizing member 8 coincides, the focal position of the optical pickup can be set within the “variation range in the rotation axis direction” of the optical disk. It can be set to approximately the center position. Thereafter, the servo is turned on in the order of focus servo and tracking servo (S1-6, S1-7).
[0064]
Thereafter, the CPU monitors and analyzes the characteristics of the residual focus error signal as described above, and performs the relative position adjustment control of the stabilizing member 8 with respect to the optical disc 1 based on the characteristic analysis value (S1-8, S1- 9). That is, the tilt angle of the stabilizing member 8 is adjusted by the Y-axis direction / stabilizing member tilt angle control unit 55 so that the maximum amplitude of the focus residual error signal is 0.5 V or less.
[0065]
After the adjustment, for example, if the operations of steps (S1-8) and (S1-9) are repeated to constantly monitor and adjust the disc surface deviation, the recording / reproduction on the optical disc 1 can be performed. Even when a parameter that affects the surface run-out stabilization position on the disk, such as the radial position or the disk rotation speed, can be controlled so as to always stabilize the surface run-out of the optical pickup focal position. A continuous recording / reproducing operation while moving the radial position on the optical disc 1 where recording / reproducing is performed can always be executed at a position where the runout is stabilized.
[0066]
Alternatively, steps (S1-8) and (S1) may be performed for each recording / reproducing operation at a radial position where recording / reproducing is performed on the optical disc 1 without always monitoring and adjusting the surface shake on the optical disc 1. Through the operation of -9), it is also possible to stabilize the surface deviation of the optical disc 1 at the focal position of the optical pickup 6 at any time. Such patterns related to recording / reproduction are diversified, and the present invention is not limited to the present embodiment.
[0067]
Note that the reference value of 0.5 V of the maximum amplitude in the focus residual error signal is a value previously determined from the correlation between the focus residual error signal amplitude and the disk surface shake amount, and the surface shake amount is 0.2 μm. Is equivalent to The reference value is merely an example, and a unique value is set for each optical pickup having various configurations. The reference value of 0.2 μm is set arbitrarily based on the defocus amount required for a pickup having an NA of 0.8.
[0068]
By performing such adjustment control, similarly to the first embodiment, the position of the stabilizing region of the disk surface by the stabilizing member 8 can be set easily and accurately, and the flexibility using the Bernoulli's law can be improved. The recording / reproduction can be performed stably while making the most of the advantage of the surface runout stability of the optical disc 1 having the above.
[0069]
In order to confirm the effect of adjusting the surface deviation in the second embodiment, the optical disk 1 described above was rotated at 3100 rpm, and an evaluation test was performed on the disk surface deviation on the pickup surface at a position with a radius of 40 mm using a laser displacement meter. It was confirmed that surface runout could be suppressed to 4 μm or less, and the effectiveness according to the present invention was also demonstrated in the second embodiment. Further, in the second embodiment, when the evaluation test was performed by changing parameters such as the radius position of the disk to be evaluated, the number of rotations of the disk, and the specification of the disk within a practical range, the surface deviation was constant at each pickup surface of the optical disk. It was confirmed that the stability was ensured, and the run-out on each surface was 5 μm or less.
[0070]
Next, a third embodiment of the present invention will be described. The optical disk device according to the third embodiment has the same device configuration as that of the first embodiment shown in FIG. 8 and is not shown. However, the position in the disk radial direction for performing recording / reproduction, the disk rotation speed, and various specifications of the disk are different. Correspondingly, a three-dimensional position of the stabilizing member 8 which is in the stable state of surface shake is estimated in advance based on the detection signal of the focus error signal as described above, and this estimated value is calculated. Is stored in the memory of the CPU mounted on the optical disk device as the estimated value A as the data of the preliminary operation position.
[0071]
The adjustment control for stabilizing the runout in the third embodiment will be described with reference to the flowchart in FIG.
[0072]
That is, when a start signal is input to the CPU, the spindle motor 4 starts to rotate the optical disk 1 (S2-1), and when a predetermined number of rotations is reached (YES in S2-2), the stabilizing member is rotated. 8 is moved in the radial direction of the optical disc 1 and the estimated value A is read out, and the stabilizing member 8 is set in a three-dimensional space with respect to the optical disc 1 (S2-3). Thus, adjustment is performed so that the virtual focus position of the optical pickup 6 and the surface center position O of the stabilizing member 8 match (S2-4). Thereafter, the servo is turned on in the order of focus servo and tracking servo (S2-5, S2-6).
[0073]
Thereafter, the CPU monitors and analyzes the characteristic of the focus residual error signal as described above, and performs fine adjustment control of the relative position of the stabilizing member 8 with respect to the optical disc 1 based on the characteristic analysis value (S2-7, S2-8). That is, the Z-axis direction position and the tilt angle of the stabilizing member 8 are adjusted so that the maximum amplitude of the focus residual error signal is 0.5 V or less, and the Z-axis direction / stabilizing member / pickup unit position control unit 40 and the X-axis The direction / stabilization member / pickup unit tilt angle control unit 42 and the Y-axis direction / stabilization member / pickup unit tilt angle control unit 43 are operated to perform fine adjustment.
[0074]
By performing such adjustment control, stabilization of run-out can be achieved as in the first embodiment, and the initial setting operation of the stabilizing member 8 can be simplified.
[0075]
Further, in the present embodiment, the operation for estimating the preliminary operation for roughly setting the position of the stabilizing member 8 for each optical disk 1 is included, but the parameters for the estimation include the disk material, the thickness, and the type of the functional constituent layer. It is sufficient to prepare several types of preliminary operation positions of the representative stabilizing member 6 based on the typical parameters such as above, and it is not necessary to set the estimates corresponding to all the parameters.
[0076]
Incidentally, even in the case of an optical disk using polyethylene terephthalate as the material of the sheet-shaped optical disk 1, the above-described stabilization of the disk surface deviation by the stabilizing member 8 can be performed by performing the adjustment control method of the above embodiment. It was confirmed that the effect was obtained.
[0077]
【The invention's effect】
As described above, according to the present invention, it is possible to accurately judge the stabilization state of the optical disk at a position facing the optical pickup based on the focus residual error signal and adjust the relative positional relationship between the optical disk and the stabilizing member. In this way, the focus position of the optical pickup with respect to the optical disk and the stabilization position of the optical disk are made to coincide with each other, and the disk surface deflection at the signal recording / reproducing position on the optical disk is set to an extremely small value. A defocus margin and a narrow work distance can be easily coped with, and a stable recording and / or reproducing operation can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an optical disk device for explaining a basic configuration of an embodiment of the present invention. FIG. 2 is an explanatory diagram of a recording unit and a reproducing unit that constitute an optical pickup according to an embodiment of the present invention. FIG. 4 is a partial cross-sectional view of a flexible sheet-shaped optical disk used in the embodiment of the present invention. FIG. 5 is an actual measurement diagram (for two rotations) of a measurement result of a surface shake of an optical disc in the configuration of the embodiment of the present invention.
FIG. 6 is an explanatory diagram of a general S-shaped characteristic of a photodetector of a signal detection system in an optical pickup. FIG. FIG. 8 is a block diagram showing an example of a system. FIG. 8 is a schematic configuration diagram of an optical disk device for explaining Embodiments 1 and 3 of the present invention. FIG. Flowchart relating to adjustment control operation FIG. 10 is a schematic configuration diagram of an optical disk device for explaining Embodiment 2 of the present invention FIG. Flow chart [Explanation of reference numerals]
DESCRIPTION OF SYMBOLS 1 Sheet-shaped optical disk having flexibility 2 Spindle shaft 4 Spindle motor 6 Optical pickup 8 Stabilizing member 30 Focus error signal detection system 31 Phase compensation drive amplifier 32 Stabilizing member driving device 40 Z-axis direction / stabilizing member / pickup Unit position controller 41 X-axis direction / stabilizing member / pickup unit position controller 42 X-axis direction / stabilizing member / pickup unit tilt angle controller 43 Y-axis direction / stabilizing member / pickup unit tilt angle controller 44 Stable Stabilizing member / pickup gap controller 50 Z-axis direction / stabilizing member position controller 51 Z-axis direction / pickup position controller 52 X-axis / spindle tilt angle controller 54 X-axis Direction / spindle position controller 55 Y axis direction / stable Member tilt angle controller 56 Y-axis direction / pickup tilt angle controller

Claims (11)

Rotation driving means for rotating a flexible sheet-shaped optical disk, an optical pickup for emitting light to the recording surface of the optical disk to write or read information, and at least a portion on the optical disk where writing or reading is performed An optical disk device comprising:
Control adjusting means for adjusting a relative positional relationship between the optical disc and the stabilizing means in a three-dimensional space based on an analysis value of a focus residual error signal which is a defocus component remaining after the focus servo of the optical pickup is turned on. An optical disk device comprising: The optical disk and the stabilizing device are controlled so that a value obtained by converting the maximum amplitude of a focus residual error signal obtained by rotating the optical disk one time into an amplitude of the optical disk surface by the control adjustment means is equal to or less than a set reference value. 2. The optical disk device according to claim 1, wherein a relative positional relationship with the means in a three-dimensional space is adjusted. 3. The optical disk apparatus according to claim 2, wherein a defocus margin required to satisfy an arbitrary standard of recording / reproducing characteristics is determined in advance for each combination of the optical pickup and the optical disk and set as the reference value. . The optical disk device according to claim 1, further comprising a moving unit configured to move a position of the optical disk based on a relative position adjustment signal from the control adjusting unit. 4. The optical disk device according to claim 1, further comprising a moving unit configured to move a position of the stabilizing unit based on a relative position adjustment signal from the control adjusting unit. 4. The optical disk device according to claim 1, further comprising a moving unit configured to move the positions of the optical disk and the stabilizing unit based on a relative position adjustment signal from the control adjusting unit. Rotation driving means for rotating a flexible sheet-shaped optical disk, an optical pickup for emitting light to the recording surface of the optical disk to write or read information, and at least a portion on the optical disk where writing or reading is performed A stabilizing means for stabilizing deflection in a rotation axis direction by a pressure difference of an air flow, wherein the stabilizing means is used for an optical disc apparatus, wherein a focus which is a defocus component remaining after a focus servo of the optical pickup is turned on. An adjustment method for an optical disc device, comprising: adjusting a relative positional relationship between the optical disc and the stabilizing means in a three-dimensional space based on an analysis value of a residual error signal. Rotation driving means for rotating a flexible sheet-shaped optical disk, an optical pickup for emitting light to the recording surface of the optical disk to write or read information, and at least a portion on the optical disk where writing or reading is performed A stabilizing means for stabilizing the deflection in the rotation axis direction by a pressure difference of an air flow, the adjusting method being used for an optical disc device, wherein for each optical disc having different specifications, A reference condition for a relative positional relationship in the original space is set in advance, and a relative positional relationship between the optical disc used and the stabilizing means in the three-dimensional space is adjusted based on the set reference condition. Adjustment method for optical disk device. 9. The method according to claim 7, wherein the position adjustment according to claim 8 is performed as a fine adjustment in a relative positional relationship between the optical disk and the stabilizing unit in a three-dimensional space. 10. A relative positional relationship between the optical disc and the stabilizing means in a three-dimensional space such that the maximum amplitude of the focus residual error signal is equal to or less than a preset reference value. The method for adjusting an optical disk device according to claim 1. A defocus margin necessary for satisfying a standard of recording / reproducing characteristics is obtained in advance for each different combination of an optical pickup and an optical disk to be used, and is used as a reference value for the adjustment. 7. The method for adjusting an optical disk device according to any one of 7 to 10.

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