JP2004030813A - Optical disk apparatus and method of controlling the optical disk apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk apparatus that employs a stabilizing member for stabilizing the surface vibration of an optical disk by utilizing air pressure by the Bernouilli's principle in the case of recording / reproducing information by using an optical disk being a flexible sheet, properly adjusts a relative positional relation between the stabilizing member and the optical disk, and surely makes the focal position of an optical pickup coincide with the surface vibration stabilizing position of the optical disk so as to stabilize the recording and / or reproducing operations. <P>SOLUTION: A servo drive signal of a servo drive system applying tracking control to the focal position of the optical pickup 6 to track the face of the optical disk 1 is monitored, and the position in a Z axial direction and the tilt angle of the stabilizing member 8 are adjusted by operating a Z axis direction stabilizing member / pickup unit position control section 40, an X axis direction stabilizing member / pickup unit tilt angle control section 42, and a Y axis direction stabilizing member / pickup unit tilt angle control section 43 so that the maximum amplitude of the servo drive signal is a reference value that is optionally set or below. <P>COPYRIGHT: (C)2004,JPO

Description

【００３９】
（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。
【００４０】
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。
【００４１】
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。
【００４２】
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。記録再生ともフォーカスの残留エラーを測定したが、デフォーカス量は±０．１２μｍ以下になっていた。０．８以上の高いＮＡでは、デフォーカスマージンがきわめて狭く、ＤＶＤなどに比べて数分の１しかなく、デフォーカス量を±０．２μｍ以下にすることが必須である。その意味においては十分なフォーカス安定化が行われていたといえる。
【００４３】
また、線速度を２０ｍ／ｓに上げて再生を行ってデフォーカスを評価したが、その量は前記と同様に±０．１２μｍ以下であった。従来の高剛性ディスクでは、線速度を上げると、共振などの作用のために面ぶれが増え、デフォーカス量が増えるのに比べると良い結果が得られた。これは、本発明においては、空気力安定化を用いているために高線速になるほど安定化させる力が大きくなるからである。
【００４４】
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コントロールする方法について鋭意検討した結果、フォーカスサーボ機構により光ピックアップの焦点位置を光ディスク面に追従制御させた場合においては、この追従制御時のサーボ駆動信号がディスク面の面ぶれと相関関係があり、このサーボ駆動信号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かつ調整することができることを見出した。
【００４５】
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７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（一般的にはゼロ目標）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。このコントロールに用いられるサーボ駆動信号には光ディスクの面ぶれに関する情報が含まれており、その波形解析により光ディスクの面ぶれ量を見積ることができ、前記調整／制御が可能となる。
【００４６】
図６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。また前記サーボ駆動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ぶ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。
【００４７】
なお、図６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。
【００４８】
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。
【００４９】
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）。
【００５０】
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。
【００５１】
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。
【００５２】
実施形態１における面ぶれ安定化のための図示しないＣＰＵ（中央演算処理ユニット）による調整制御について、図９のフローチャートを参照して説明する。
【００５３】
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１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６の焦点位置を、光ディスク１の回転軸方向における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）。
【００５４】
その後、ＣＰＵでは既述したようにフォーカスサーボのサーボ駆動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、サーボ駆動信号の最大振幅が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。
【００５５】
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とを常に実施させるようにすれば、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光ディスク１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、面ぶれの安定化した位置で記録／再生動作を連続して常に実行することが可能となる。
【００５６】
また光ディスク１の面ぶれの監視と調整とを常に実施させなくても、記録／再生が行われる任意のディスク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の焦点位置における光ディスク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、本発明では本実施形態のものに限定されるものではない。
【００５７】
なお、前記サーボ駆動信号の最大振幅の基準値０．５Ｖという値は、あらかじめサーボ信号振幅と光ディスク１の面ぶれ量との相関関係から決定した値であり、面ぶれ量としては５μｍに相当する。ここではサーボ駆動信号を電圧として捉えたが、電流あるいは電力としてみることも可能である。また前記基準値はあくまで一例であって、各種サーボ駆動系ごとに固有の値を設定すればよい。なお、面ぶれ基準値が５μｍという値は、前記光ディスク１を３１００ｒｐｍで回転させ、安定化部材８により半径４０ｍｍの位置で光ディスクの面ぶれを安定化させた場合に得られた最適安定化点における面ぶれ振幅２．５μｍを基にして、上限２０μｍまでの範囲で任意に設定したものである。
【００５８】
このような調整制御を行うことにより、安定化部材８による光ディスク１における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。
【００５９】
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、評価対象の光ディスクにおける半径位置，回転数，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。
【００６０】
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。
【００６１】
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。
【００６２】
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１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における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）。
【００６３】
その後、ＣＰＵでは既述したようにフォーカスサーボのサーボ駆動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、サーボ駆動信号の最大振幅が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。
【００６４】
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、光ディスク１の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光ディスク１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、記録再生半径位置を移動させながら行う連続した記録／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。
【００６５】
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）を実行することにより、随時、光ピックアップ６の焦点位置における光ディスク１の面ぶれを安定化させることも可能である。こうした記録／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。
【００６６】
なお、前記サーボ駆動信号における最大振幅の基準値０．５Ｖという値は、あらかじめサーボ信号振幅とディスク面ぶれ量との相関関係から決定した値であり、面ぶれ量としては５μｍに相当する。ここでは、サーボ駆動信号を電圧として捉えたが、電流あるいは電力として見ることも可能である。また前記基準値はあくまで一例であって、各種サーボ駆動系毎に固有の値を設定すればよい。
【００６７】
なお、面ぶれ基準値を５μｍという値は、光ディスク１を３１００ｒｐｍの範囲で回転させ、安定化部材８により半径４０ｍｍ位置における光ディスク１の面ぶれを安定化させた場合に、得られた最適安定化点における面ぶれ振幅２．５μｍを基に、上限２０μｍまでの範囲で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による光ディスク１の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の光ディスク装置の構成は図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、あらかじめ見積り、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サーボのサーボ駆動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、サーボ駆動信号の最大振幅が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、本実施形態において、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を採用しても、前記本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、サーボ駆動信号によって、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ぶ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，狭小ワークディスク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】本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７】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／ピックアップ間隔調整部
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 a relative position between a stabilization guide and an optical disk based on a detection result of a tracking error signal, and has proposed a focus position of an optical pickup and stable surface shake. In order to solve the above-mentioned important problem of matching the positions of the components.
[0014]
This method is unique in that it can reliably match the focal position of the optical pickup with the surface stabilization position, but in this control operation, the focus servo is turned off and the push-pull signal is applied. It is limited to a case where a typical tracking error signal can be detected, and 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 suppress surface deviation of an optical disc by using aerodynamic force according to Bernoulli's law when performing recording / reproduction using a flexible sheet-shaped optical disc. The relative positional relationship between the stabilizing member and the optical disk is accurately adjusted by using the stabilizing member, and the focal position of the optical pickup and the stabilization position of the optical disk are accurately matched to each other. By setting the disc surface deviation at the reproduction position to an extremely small value, it is possible to easily cope with a narrow defocus margin and a narrow work discance in an optical pickup with a high NA, and to stabilize the recording and / or reproducing operation. An object of the present invention is to provide an optical disk device and a method for adjusting the same.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 includes a rotation driving unit for rotating a flexible sheet-shaped optical disk, and writing or reading of information by emitting light to a recording surface of the optical disk. An optical pickup device comprising: an optical pickup that performs the following, and stabilizing means for stabilizing at least a portion of the optical disc on which writing or reading is performed in a rotational axis direction by a pressure difference of an airflow,
A control adjustment 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 servo drive signal of a servo drive system for controlling the focal position of the optical pickup to follow the optical disc surface. With this configuration, the stabilization state of the surface deviation of the optical disk at the position facing the optical pickup can be accurately determined based on the servo drive signal waveform, and the relative positional relationship between the optical disk and the stabilizing unit can be determined. By the adjustment, the focal position of the optical pickup with respect to the optical disk and the surface stabilization position on the optical disk can be accurately matched, and stable recording and / or reproduction can be realized at the position where the surface deviation is reduced. In addition, 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 discance 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 control and adjustment unit controls the optical disk and the stabilizing unit so that the maximum amplitude of the servo drive signal is equal to or less than a preset reference value. It is characterized in that the relative positional relationship in the three-dimensional space is adjusted, and with this configuration, the deviation of the optical pickup surface is adjusted to an arbitrary quantitative value or less.
[0018]
According to a third aspect of the present invention, in the optical disk device according to the first or second aspect, the reference value is set to a value of a servo drive signal amplitude when a focus servo drive is performed on an arbitrary surface of a wobble optical disk. An arbitrary surface shake range is set based on the relative relationship with the surface shake amount, and the arbitrary surface shake range is determined by the rotation speed of the optical disc and the radial position on the optical disc on which arbitrary recording / reproduction is performed. The optical disc is characterized in that it is set to be larger than the optimal amount of surface shake at the stabilization point of the optical disk stabilized by the optimizing means and is set to 20 μm or less. By using this reference value, reliable and accurate judgment can be made. Becomes possible. In other words, by setting the limit value of the amount of surface deviation to 20 μm or less, even when using a high NA optical pickup (for example, NA 0.85 for DVR) having a work distance as narrow as about 0.05 mm to 0.3 mm, light The collision between the objective lens of the pickup and the optical disk can be reliably avoided, and the operation of the control adjustment system can be diverged by setting the lower limit of the amount of runout to an effective value for the optical disk. Can be prevented.
[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, wherein the optical disk and / or the stabilizing member are controlled based on an optical disk, a stabilizing member, and a relative position adjustment signal from the control adjusting means. Characterized in that it is provided with a moving mechanism for moving the position.
[0020]
According to a fifth aspect of the present invention, there is provided a rotation driving unit 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 A stabilizing means for stabilizing the deflection in the rotation axis direction at a portion where writing or reading is performed on the optical disc by a pressure difference of an airflow, an adjustment method used in an optical disc apparatus,
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 servo drive signal of a servo drive system for controlling a focal position of the optical pickup to follow the optical disc surface. According to this method, a servo drive signal is used to accurately judge the stabilization state of the optical disk at a position facing the optical pickup, and by adjusting the relative positional relationship between the optical disk and the stabilizing member, the optical drive of the optical pickup is And the stabilization position on the optical disc can be accurately matched with each other, and stable recording and / or reproduction can be realized at a 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 discance of an optical pickup having a high NA.
[0021]
According to a sixth aspect of the present invention, there is provided 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. A stabilizing means for stabilizing the deflection in the direction of the rotation axis in a portion where writing or reading is performed by a pressure difference of an air flow, an adjustment method used for an optical disc device,
The adjustment method according to claim 5 is executed for each optical disk having different specifications, and an adjustment reference condition of a relative positional relationship between the optical disk and the stabilizing member in a three-dimensional space is set in advance, and the optical disk to be used is set. A method according to claim 5, wherein the relative positional relationship between the optical disk and the stabilizing means in a three-dimensional space is adjusted. Since the conditions can be 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, compared with the method according to claim 5, The adjustment control operation and the arithmetic processing can be simplified, and a simpler and less expensive optical disk device is realized.
[0022]
According to a seventh aspect of the present invention, in the adjustment method of the optical disk device according to the fifth aspect, the adjustment according to the sixth aspect is performed as a 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.
[0023]
According to an eighth aspect of the present invention, in the adjustment method of the optical disk device according to any one of the fifth to seventh aspects, the optical disk and the optical disk drive are adjusted so that the maximum amplitude of the servo drive signal is equal to or less than a preset reference value. The method is characterized in that the relative positional relationship with the stabilizing means in a three-dimensional space is adjusted. By this method, the deviation of the optical pickup surface is adjusted to an arbitrary quantitative value or less.
[0024]
According to a ninth aspect of the present invention, in the method for adjusting an optical disk device according to any one of the fifth to eighth aspects, the reference value is set to an arbitrary surface of the optical disk whose surface is out of focus by focus servo drive. Is set within an arbitrary surface wobble range based on the relative relationship between the servo drive signal amplitude and the surface wobble amount, and the arbitrary surface wobble range is set to the rotation speed of the optical disk and to an arbitrary optical disk on which recording / reproduction is performed. The method is characterized by using a value larger than the optimum amount of surface shake at the optimum optical disk surface shake stabilization point stabilized by the stabilizing means and equal to or less than 20 μm on the condition of the radius position. Makes a good decision. In other words, by setting the limit value of the amount of surface deviation to 20 μm or less, even when an optical pickup with a high NA having a work distance as narrow as about 0.05 mm to 0.3 mm (for example, NA 0.85 for DVR) is used. Collision between the objective lens of the pickup and the optical disk can be reliably avoided, and the operation of the control adjustment system can be diverged by setting the lower limit of the amount of runout to an effective value for the optical disk. Can be prevented.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0026]
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 10 for the stabilizing member, which is moved in the radial direction of the optical disk 1 in conjunction with the optical pickup 6, comprises An apparatus body for housing the member.
[0027]
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.
[0028]
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.
[0029]
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.
[0030]
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 to a sheet made of polyethylene terephthalate having a thickness of 80 μm by thermal transfer, and then the sheet / Ag reflective layer is formed by sputtering to a thickness of 120 nm / (ZrO). ₂ -Y ₂ O ₃ ) -SiO ₂ , 7 nm / AgInSbTeGe, 10 nm / ZnS-SiO ₂ , 25nm / Si ₃ N ₄ In this order. 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.
[0031]
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.
[0032]
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.
[0033]
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 beam is incident on the recording layer through the substrate 21. Forming a protective film such as overcoating is effective in preventing the recording layer 20 from being damaged.
[0034]
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.
[0035]
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.
[0036]
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.
[0037]
(Table 1) is a table summarizing the results obtained by measuring the run-out state by rotating 10 times in the same manner as the measurement method described with reference to FIG. 5, and as shown in the present embodiment, a stabilizing member was installed on one side of the optical disk. The configuration and the conventional optical disk in which a guide member is provided on the entire surface were compared.
[0038]
[Table 1]

[0039]
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.
[0040]
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.
[0041]
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.
[0042]
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. The residual error of focus was measured for both recording and reproduction, and the defocus amount was less than ± 0.12 μm. At a high NA of 0.8 or more, the defocus margin is extremely narrow, which is only a fraction of that of a DVD or the like, and it is essential that the defocus amount be ± 0.2 μm or less. In that sense, it can be said that sufficient focus stabilization has been performed.
[0043]
The defocus was evaluated by performing reproduction at a linear velocity of 20 m / s, and the amount was ± 0.12 μm or less as described above. In the conventional high-rigidity disk, when the linear velocity was increased, the runout increased due to the action such as resonance, and a better result was obtained as compared with the case where the defocus amount increased. This is because, in the present invention, since the aerodynamic stabilization is used, the stabilizing force increases as the linear velocity increases.
[0044]
The present inventors have conducted intensive studies on a method for controlling the above-described surface runout of the optical disc to further stabilize the result. As a result, when the focus position of the optical pickup is controlled to follow the optical disc surface by the focus servo mechanism, The servo drive signal at the time of this follow-up control has a correlation with the runout of the disk surface, and by adjusting the relative positional relationship between the optical disk and the stabilizing member in the three-dimensional space so that the servo drive signal satisfies an arbitrary standard. As a result, it has been found that disk surface runout can be reduced and adjusted.
[0045]
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. 7 according to the distance between the disk surface and the objective lens. The drive amplifier controls the focus position of the optical pickup so that the optical pickup has a constant value (generally, a zero target), and controls the optical pickup so as to focus on the disk surface. The servo drive signal used for this control contains information on the runout of the optical disk, and the waveform analysis can estimate the runout amount of the optical disk, and the adjustment / control can be performed.
[0046]
FIG. 6 is a block diagram showing 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 the detector in the optical pickup 6 is shown. 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. The servo drive signal is monitored by the stabilizing member driving device 32 to obtain a surface shake signal of the optical disk 1, and the position of the stabilizing member 8 is adjusted so that the disk surface shake at the focal position of the optical pickup 6 is reduced. adjust. This makes it possible to realize a stable recording / reproducing operation at a position with a small surface deviation.
[0047]
Note that the example shown in FIG. 6 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.
[0048]
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.
[0049]
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).
[0050]
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.
[0051]
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.
[0052]
An adjustment control by a CPU (Central Processing Unit) (not shown) for stabilizing the runout in the first embodiment will be described with reference to a flowchart of FIG.
[0053]
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 optical disc 1 is pushed by about 0.5 mm by the stabilizing member 8 from the disc installation reference plane (the surface of the stabilizing member 8 when the optical disc 1 is assumed to be flat), and the surface deviation of the optical disc 1 is substantially reduced. At the time of stabilization (S1-4), the stabilizing member / pickup interval adjusting unit 45 adjusts the tentative focus position of the optical pickup 6 and the surface center position O of the stabilizing member 8 to match (S1-). 5). From this step, the focus position of the optical pickup 6 is adjusted so that the temporary focus position of the optical pickup 6 coincides with the surface center position O of the stabilizing member 8 so that the focal position of the optical pickup 6 is within the range of variation in the rotation axis direction of the optical disc 1. 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).
[0054]
Thereafter, the CPU monitors the servo drive signal of the focus servo and analyzes the characteristics 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 Z-axis direction position and the tilt angle of the stabilizing member 8 are set to the Z-axis direction / stabilizing member / pickup unit position control unit 40 and the X-axis direction so that the maximum amplitude of the servo drive signal is 0.5 V or less. The adjustment is performed by operating the stabilizing member / pickup unit tilt angle controller 42 and the Y-axis direction.
[0055]
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 radial position where recording is performed on the optical disc 1 is performed. In addition, even when a parameter that affects the stabilization position of the optical disk 1 such as the number of rotations of the optical disk 1 is changed, it is possible to always control the stabilization of the surface deviation at the focal position of the optical pickup 6. The recording / reproducing operation can always be continuously performed at a position where the runout is stabilized while moving the radial position on the optical disc 1 for performing / reproducing.
[0056]
Further, even if the monitoring and adjustment of the runout of the optical disk 1 are not always performed, the steps (S1-8) and (S1-9) are performed for each recording / reproducing operation at an arbitrary disk radial position where recording / reproduction is performed. By the operation described above, it is 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 relating to recording / reproduction are various, and the present invention is not limited to the present embodiment.
[0057]
The reference value of 0.5 V, which is the reference value of the maximum amplitude of the servo drive signal, is a value determined in advance from the correlation between the servo signal amplitude and the amount of surface deviation of the optical disc 1, and corresponds to 5 μm as the amount of surface deviation. . Here, the servo drive signal is regarded as a voltage, but may be regarded as a current or an electric power. Further, the reference value is merely an example, and a unique value may be set for each servo drive system. The reference value of 5 μm for the runout reference value is the optimum stabilization point obtained when the optical disc 1 is rotated at 3100 rpm and the stabilization member 8 stabilizes the runout of the optical disc at a position of a radius of 40 mm. It is arbitrarily set within a range of up to 20 μm based on the surface shake amplitude of 2.5 μm.
[0058]
By performing such adjustment control, the position of the surface stabilization region on the optical disk 1 by the stabilizing member 8 can be easily and accurately set, and the flexible optical disk 1 using Bernoulli's law can be set. It is possible to perform stable recording / reproduction by making the most of the advantage of the runout stability.
[0059]
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-described evaluation test was performed by changing parameters such as the radial position, the number of revolutions, and the specifications of the optical disk to be evaluated within a practical range. Was confirmed, and the run-out on each surface was 4 μm or less.
[0060]
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.
[0061]
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.
[0062]
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 1 is assumed to be flat) to substantially reduce the surface deviation of the optical disc 1. The optical pickup 6 is stabilized (S1-4), and the Z-axis position of the optical pickup 6 is set by the Z-axis 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. (S1-5). From this step, the focus position of the optical pickup 6 is adjusted so that the temporary center position of the optical pickup 6 coincides with the surface center position O of the stabilizing member 8 so that the focal position of the optical pickup is substantially at the center of the fluctuation range in the rotation axis direction of the optical disk. Position can be set. Thereafter, the servo is turned on in the order of focus servo and tracking servo (S1-6, S1-7).
[0063]
Thereafter, the CPU monitors the servo drive signal of the focus servo and analyzes the characteristics 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 servo drive signal is 0.5 V or less.
[0064]
After the adjustment, for example, if the operations of steps (S1-8) and (S1-9) are repeated to constantly monitor and adjust the surface runout of the optical disk 1, the recording / reproduction on the optical disk 1 can be performed. Even if parameters that affect the stabilization position on the optical disc 1, such as the radial position at which the optical pickup 6 is performed or the number of revolutions of the disc, are changed, control is performed so that the stabilization at the focal position of the optical pickup 6 is always stabilized. For example, a continuous recording / reproducing operation performed while moving the recording / reproducing radius position can be always executed at a position where the runout is stabilized.
[0065]
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. By performing -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 various, and the present invention is not limited to the present embodiment.
[0066]
The reference value of the maximum amplitude of 0.5 V in the servo drive signal is a value determined in advance from the correlation between the servo signal amplitude and the disk surface shake amount, and corresponds to 5 μm as the surface shake amount. Here, the servo drive signal is considered as a voltage, but can be viewed as a current or power. The reference value is merely an example, and a unique value may be set for each servo drive system.
[0067]
Note that the value of 5 μm as the reference value of the surface deviation is the optimum stabilization obtained when the optical disk 1 is rotated in the range of 3100 rpm and the surface deviation of the optical disk 1 at the position of 40 mm radius is stabilized by the stabilizing member 8. It is set arbitrarily within the range of up to 20 μm based on the surface shake amplitude of 2.5 μm at the point.
[0068]
By performing such adjustment control, similarly to the first embodiment, the position of the stabilization region of the optical disc 1 by the stabilizing member 8 can be set easily and accurately, and the position using the Bernoulli's law can be utilized. It is possible to perform stable recording / reproducing while making the most of the advantage of the surface shake stability of the flexible optical disc 1.
[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 configuration of the optical disc device of the third embodiment is the same as that of the first embodiment shown in FIG. 8 and is not shown in the drawings. The three-dimensional position of the stabilizing member 8 which is in the stabilization state is estimated in advance based on the detection signal of the focus error signal as described above, and the 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 the servo drive signal of the focus servo and analyzes the characteristics 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 set to the Z-axis direction / stabilizing member / pickup unit position control unit 40 and the X-axis direction so that the maximum amplitude of the servo drive signal is 0.5 V or less. Fine adjustment is performed by operating the stabilizing member / pickup unit tilt angle controller 42 and the Y axis direction.
[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]
In the present embodiment, even if an optical disk using polyethylene terephthalate as the material of the sheet-shaped optical disk 1 is employed, by performing the adjustment control method of the present embodiment, the deviation of the disk surface caused by the stabilizing member 8 can be achieved. It was confirmed that the above-described effect in stabilization 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 disc at a position facing the optical pickup by using the servo drive signal, and adjust the relative positional relationship between the optical disc and the stabilizing member. By making the focal position of the optical pickup relative to the optical disk coincide with the surface wobbling stabilization position of the optical disk, and making the disk surface wobble at the signal recording / reproducing position on the optical disk an extremely small value, the narrow defocus of the high NA optical pickup is achieved. It is possible to easily cope with a margin and a narrow work discance, 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 describing 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 the optical pickup according to the embodiment;
FIG. 3 is a partial cross-sectional view of a flexible sheet-shaped optical disk used in the present embodiment.
FIG. 4 is an explanatory diagram of stabilization of surface deviation in a flexible sheet-shaped optical disk according to the embodiment.
FIG. 5 is an actual measurement diagram (for two rotations) of a measurement result of a runout of an optical disc in the configuration of the present embodiment;
FIG. 6 is a block diagram showing an example of a control system for adjusting a relative position in a three-dimensional space between the optical disc and the stabilizing member according to the embodiment;
FIG. 7 is an explanatory diagram of a general S-shaped characteristic of a photodetector of a signal detection system in an optical pickup.
FIG. 8 is a schematic configuration diagram of an optical disc device for describing Embodiments 1 and 3 of the present invention.
FIG. 9 is a flowchart relating to an adjustment control operation for stabilization of run-out in Embodiments 1 and 2 of the present invention.
FIG. 10 is a schematic configuration diagram of an optical disk device for describing Embodiment 2 of the present invention;
FIG. 11 is a flowchart according to an adjustment control operation for stabilization of run-out in a third embodiment of the present invention.
[Explanation of symbols]
1. Flexible sheet optical disk
2 spindle shaft
4 spindle motor
6 Optical pickup
8 Stabilizing members
30 Focus error signal detection system
31 Phase Compensation Drive Amplifier
32 Stabilizing member drive
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 Stabilizer / Pickup unit common housing
45 Stabilizer / Pickup interval adjuster
50 Z-axis direction / stabilizing member position controller
51 Z-axis direction / Pickup position control unit
52 X axis direction / spindle tilt angle control unit
54 X axis direction / spindle position controller
55 Y-axis direction / Stabilizing member tilt angle controller
56 Y-axis direction / Pickup tilt angle control unit

Claims (9)

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 writing or reading to or from the optical disk An optical disc device comprising:
A control adjustment 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 servo drive signal of a servo drive system for controlling the focal position of the optical pickup to follow the optical disc surface. An optical disk device comprising means. The control adjustment unit adjusts a relative positional relationship between the optical disc and the stabilization unit in a three-dimensional space such that a maximum amplitude of the servo drive signal is equal to or less than a preset reference value. The optical disk device according to claim 1, wherein The reference value is set within an arbitrary surface shake range based on a relative relationship between a servo drive signal amplitude and a surface shake amount when a focus servo drive is performed on an arbitrary surface of the optical disk having a surface shake. The arbitrary surface fluctuation range stabilized at the optimum optical disk surface fluctuation stabilization point by the stabilization means, on the condition that the arbitrary surface fluctuation range is the rotation speed of the optical disk and the radial position on the optical disk where arbitrary recording / reproduction is performed. 3. The optical disk device according to claim 1, wherein the amount is set to be larger than the amount and equal to or less than 20 [mu] m. 2. A moving means for moving a position of the optical disc and / or the stabilizing means based on a relative position adjustment signal between the optical disc and the stabilizing means from the control adjusting means. The optical disk device according to any one of claims 1 to 3, 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 writing or reading to or from the optical disk A stabilizing means for stabilizing the deflection in the direction of the rotation axis in the portion by the pressure difference of the airflow, an adjustment method used for an optical disc device,
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 servo drive signal of a servo drive system for controlling a focal position of the optical pickup to follow the optical disc surface. A method for adjusting an optical disk device. 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 writing or reading to or from the optical disk A stabilizing means for stabilizing the deflection in the direction of the rotation axis in the portion by the pressure difference of the airflow, an adjustment method used for an optical disc device,
The adjustment method according to claim 5 is executed for each optical disk having different specifications, and an adjustment reference condition of a relative positional relationship between the optical disk and the stabilizing member in a three-dimensional space is set in advance, and the optical disk to be used is set. 6. An adjustment method for an optical disk device, wherein the adjustment method according to claim 5 is executed to adjust a relative positional relationship between the optical disk and the stabilizing means in a three-dimensional space. 7. The adjustment method for an optical disk device according to claim 5, wherein the adjustment according to claim 6 is performed as a fine adjustment in a relative positional relationship between the optical disk and the stabilizing unit in a three-dimensional space. The relative positional relationship between the optical disc and the stabilizing means in a three-dimensional space is adjusted so that the maximum amplitude of the servo drive signal is equal to or less than a preset reference value. The method for adjusting an optical disk device according to claim 1. The reference value is set within an arbitrary surface shake range based on a relative relationship between a servo drive signal amplitude and a surface shake amount when a focus servo drive is performed on an arbitrary surface of the optical disk having a surface shake. The arbitrary surface fluctuation range stabilized at the optimum optical disk surface fluctuation stabilization point by the stabilization means, on the condition that the arbitrary surface fluctuation range is the rotation speed of the optical disk and the radial position on the optical disk where arbitrary recording / reproduction is performed. 9. The method for adjusting an optical disk device according to claim 5, wherein a value larger than the amount and not more than 20 [mu] m is used.

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