JP3543816B2 - Disk-shaped recording medium and recording / reproducing device - Google Patents

Description

これにより、ｉ番目の記録再生クロック切り換え位置における最短ピット長ｌ_iは、次のようになる。
【００５６】

この最短ピット長が、記録再生クロック周波数を切り換える位置において、内周よりも外周の方が大きくなる条件は、次式のようになる。
【００５７】
Ｎ・ｄ・ｎ−Ｒ＞０
例えば、トラックピッチｄ＝1.5μmで、フォーマットされた光ディスク媒体１において、Ｎ＝１０２４、ｎ＝５１、Ｒ＝７０mmとすると、クロック切り換え位置における同一記録情報を持つピット長は、外周へ行くに従って単調増加することが可能となる。
【００５８】
このとき、トラックピッチｄ、最内周トラック半径Ｒ、最内周トラック内に含まれるセクタ４２の数ｎを一定とすると、記録クロックを切り換えるトラック本数Ｎを変化させるだけで、記録ピット長の増加傾向を制御することができる。記録再生クロック３２を切り換える位置４１における最短ピット長の推移のようすを第６図に示す。
【００５９】
これに反して、仮に、特開昭61-131236号公報記載のように、最短ピット長が内外周いずれの記録領域においても一定であるとすると、外周部での読み出しマージンが内周部よりも厳しくなる。この現象は、本発明の起点となるものであり、以下これを説明する。
【００６０】
光ディスク媒体１は、一定角速度で回転しているため、記録領域の内外周で線速度が異なる。このため、記録レーザ光を照射した時のピット形成に作用する膜面の到達温度カーブが、第７図に示すように、線速の大小によって異なる。また、記録レーザ光を照射する際、記録膜の不均一や線速度のゆらぎ等の原因によって、膜面の到達温度カーブが、第７図の点線のように変動することがある。上記変動の結果、ピットの形成位置がゆらぐことになり、到達温度カーブがゆるやかな勾配を持つ、線速度が大きい方、すなわち、外周部の方がピット形成位置の変動量ΔΦが大きいことになる。同様のことが、形成ピットの後縁にもいえる。
【００６１】
ここで、本実施例と比較するため、前述した従来技術によるピット形成方法により形成されるピットのピット長について検討する。
【００６２】
従来技術は、第８図に示すように、記録位置の線速度に比例して記録再生クロック３２の周波数を変えて、全記録領域に渡り線密度が一定になるように記録ピット２６を形成する。なお、第８図では、クロック周波数ｆ₀の内周部と、内周部の２倍の線速を持つ外周部（クロック周波数２ｆ₀）とにおける波形を示している。
【００６３】
第８図に示すように、この従来技術では、内周部より外周部の方が記録ピット長に対するそのピット長の変動量ΔΦが大きいため、結局、弁別クロック３６の弁別窓幅Ｗに占める検出信号位置の変動量の割合ΔΦ／Ｗが大きくなる。光ディスク媒体１の内周部から外周部にかけて同一のピット長で記録した時の弁別窓幅に占める検出信号位置の変動量の割合ΔΦ／Ｗの推移を、第９図に示す。 第９図に示されるように、記録位置が外周部へ行く程ΔΦ／Ｗが大きくなり、外周部での再生誤りが増える可能性がある。
【００６４】
本実施例によれば、この問題が解決される。そこで、この作用も含めて、次に、第１図により、情報データの記録再生動作について説明する。
【００６５】
まず、データの記録について説明する。
【００６６】
主制御回路６は、ホストコンピュータ５から書き込みデータと書き込み開始位置情報を受け取る。主制御回路６は、書き込み開始位置情報を、内蔵するメモリ（図示せず）に記憶されている変換テーブルに従って、アクセスするトラック番号４６、セクタ番号４７に変換する。位置付け制御回路１８は、主制御回路６から伝えられたトラック番号４６に、光ヘッド４の光スポットが位置付くように位置付け機構１９を制御する。
【００６７】
光ヘッド４を目的のトラックに位置付ける方法としては、例えば、セクタ４２内に予め作成されているＩＤ部の情報を用いるか、外部スケールを設けておき、スケール検出器２０で位置付け位置を読み取る方法を用いる。
【００６８】
また、主制御回路６では、変換されたトラック番号４６から、第１０図に示される変換テーブルによって、クロック情報３４を得て、これをシンセサイザ８に送る。
【００６９】
シンセサイザ８では、クロック情報３４から、それに対応する記録再生クロック３２を発生する。 第１０図において、記録再生クロック３２の切り換え位置４１を１０２４トラック毎にしたのは、クロック切り換え位置４１において、同一情報を持ったピット長が外周へ行く程長くなり、弁別窓幅に占める検出信号位置の変動量の割合（ΔΦ／Ｗ）も、ピット長を一定としたときよりも小さくなるためである。もちろん、これに限定されず、この条件を満すならば、他のトラック本数でもよい。
【００７０】
シンセサイザ８は、基本クロック発振器７で発生した基本クロック６１を固定分周器６２で分周し、リファレンスクロック６４を発生する。さらに、上記クロック情報３４で可変分周器６３の分周数をセットする。この出力である可変分周クロック６５の周波数とリファレンスクロック６４の周波数とが同値となるように、位相比較器６６は、出力信号６７の周波数を制御する。出力信号６７は、ローパスフィルタ６８を通り、ＶＣＯ回路６９で記録再生クロック３２となる。
【００７１】
また、記録再生クロック３２を可変分周器６３に入力することで、記録再生クロック３２の周波数を一定に保つようにする。この結果、記録再生クロック３２は、該当記録位置に応じたものになる。
【００７２】
変調回路９は、主制御回路６から受け取った書き込みデータ２１を２−７コードなどのコードデータ２２に変調する。ＮＲＺ符号器１０は、シンセサイザ８で発生した記録再生クロック３２に載せて、コード２２をＮＲＺコード２３に変換する。
【００７３】
前述したように該ＮＲＺコード２３でレーザ光を照射し、記録したとすると、光ディスク媒体の熱拡散特性により、ＮＲＺコード２３よりも長いあるいは短かい記録ピット長が形成されてしまう。この特性は、線速度により変化するので、最適値に補正することが必要である。また、ＮＲＺコード２３のコード長に記録ピット長を合致させるために、併せてレーザの記録パワーを制御するレーザ電流も最適化する必要がある。
【００７４】
そのため、ＮＲＺコード２３について、パルス幅設定器１２において、パルス幅を補正を含めて設定し、記録コード２４が生成される。これについて、さらに詳細に説明する。
【００７５】
変換されたＮＲＺコード２３は、パルス幅設定器１２の遅延素子７１に入力される。この遅延素子７１では、一定の遅延時間を伴った信号が複数の出力タップに出力される。なお、遅延素子として、ゲート遅延を用いる方法もある。
【００７６】
遅延素子７１からの出力は、セレクタ７２に入力され、いずれかの出力が記録補正器１１によって選択され、ＡＮＤゲート７３に入力される。ＡＮＤゲート７３の他方には、遅延されていない信号が入力されているため、遅延量だけ短かくなったパルスが生成されることになる。このパルスは、第１図、第４図の記録コード２４に対応し、レーザドライバ１４へ入力される。
【００７７】
上記方法では、短かく補正する場合であるが、逆に、長く補正する場合は、ＡＮＤゲート７３をＯＲゲートを変えるだけでよい。また、両者を併用することもできる。
【００７８】
一方、記録光パワーの制御は、レーザドライバ１４内の電流源の値を変えることで行う。該レーザドライバ１４は、カレントスイッチの構成を採っており、電流値を決定するトランジスタ７５のベース電位をＤ／Ａ変換器７４により変化させることにより、半導体レーザ７７がオン状態になったときの発光パワーを変えることができる。例えば、Ｄ／Ａ変換器７４によってトランジスタ７５のベース電位を高くすれば、エミッタ電位が上昇し、抵抗７６を流れる電流が増加する。従って、半導体レーザ７７の駆動電流も増加し、発光パワーが大きくなる。
【００７９】
記録補正器１１は、制御情報３３によって、パルス幅およびパワーの設定を行う。すなわち、クロック情報３４（またはトラック番号）等の制御情報３３を、内蔵するＲＯＭのアドレスとして入力とすると、出力として、対応する補正データが出力される。このデータを用いて、セレクタ７２によるパルス幅補正量の選択およびＤ／Ａ変換器７４への入力ビットを指定することができる。
【００８０】
また、クロック情報３４、トラック番号の代りに、外部のスケール検出器２０からの値を用いる方法、あるいは、ディスクの基準半径（例えば最内周）から現在までに横切ったトラック本数を用いて、位置を認識し、同様の制御を行うこともできる。
【００８１】
上記方法によって、第４図に示すように、記録光パルス２５は、記録位置における最適値に補正され、ＮＲＺコード２３と同じ長さの記録ピット２６をディスク媒体１上に形成することができる。 次に、データの再生について説明する。
【００８２】
主制御回路２６は、ホストコンピュータ５より読み出し開始位置の情報を受け取り、記録時と同様な動作を行い、光ヘッド４を目的トラックへ位置付ける。半導体レーザ７７の発光パワーを再生レベルにして、光ディスク媒体１にレーザ光を照射する。これによって、媒体上のデータは、光信号として得られ、光ヘッド４内の光検出器によって再生信号２７に変換される。該再生信号２７は、２値化回路１５によって再生コード２９として出力され、再生データ合成回路１６に入力される。
【００８３】
一方、主制御回路６は、読み出し開始位置情報からトラック番号４６とクロック情報３４を得て、クロック情報３４をシンセサイザ８に送る。シンセサイザ８では、上記クロック情報３４に対応して、記録時と同様に記録再生クロック３２を発生する。
【００８４】
本発明では、データの記録方式としてピットエッジ記録方式を採用している。そして、実際にエッジ記録を採用するに当って、記録ピットは、目的の長さに対して変化するため、前縁・後縁に対応したデータを個別なデータとして取り扱い、再合成する方式を用いている。
【００８５】
ここでいう前縁パルスと後縁パルスは、２値化回路１５から出力される再生コード２９の立ち上がりエッジ、立ち下がりエッジに対応する。
【００８６】
ＰＬＬ回路３５では、再生コード２９に同期した弁別クロック３７と同期化コード３６とを生成する。第１図では、それぞれ１系列で示してあるが実際は、前縁・後縁に対応した２系列のクロックおよびデータである。この際、記録再生クロック３２は、ＶＦＯ（バリアブル・フレクエンシー・オシレータ）の引き込み時の基準クロックとして用いている。
【００８７】
該ＰＬＬ回路３５からの出力は、再生データ合成回路１６に入力される。再生データ合成回路１６は、前縁・後縁の同期化コード３６について、既知のデータ（例えばＳＹＮＣパターンなど）の検出回路によって合成のタイミングを計り、２系列のデータ列を合成する。
【００８８】
上記再生データ合成回路１６の出力としてコード３０を得た後、復調回路１７によって変調時とは逆の動作を行い、データ３１を得る。この復調回路１７は、公知のものでよい。
【００８９】
以上の方法で再生されたデータは、主制御回路６よりホストコンピュータ５へ転送される。
【００９０】
第１０図はトラック番号４６、クロック情報３４、記録再生クロック周波数３２の変換テーブルを示したものである。この場合、記録再生クロック周波数３２を切り換えるトラック本数を１０２４本毎とし、外周に行くに従って、クロック切り換え位置４１ごとにトラックを構成するセクタ４２の数を１セクタづつ増加させている。
【００９１】
ここで、記録再生クロック周波数を求めてみる。光ディスク媒体１の回転数をＡrpm、最内トラックのセクタ数をｎ、１セクタの総ビット数をＺとすると、最内周トラック（０トラック）での記録再生クロック周波数ｆ₀は、以下のようになる。
【００９２】
ｆ₀＝２×Ａ／６０×ｎ×Ｚ （Ｈｚ）
また、クロック情報ｉでの記録再生クロック周波数ｆ_iは、以下のようになる。
【００９３】
ｆ_i＝２×Ａ／６０×(ｎ＋ｉ)×Ｚ （Ｈｚ）
第１１図は第１０図の変換テーブルを用いて、トラックピッチｄを1.5μm、最内周トラックのセクタ数ｎを５１、最内周トラック半径を７０mmとして設定した光ディスク媒体１のフォーマットの一例を示したものである。
【００９４】
第１４図は第１１図に示すフォーマットを持つ光ディスク媒体１の最短ピット長の推移を示す。
【００９５】
第１４図に示す最短ピット長の推移は、各ゾーンにおいて同一順位にあるトラックについて、データの記録に用いられるピットまたは記録ドメインの周方向長さが、外周ゾーンにいくに従って徐々に長くなることを示していいる。ここで、各ゾーンにおいて同一順位にあるトラックとは、例えば、各トラックにおいて、再内周側から同一の順番に配置されているトラックを意味する。具体的には、各ゾーンのｉ番目のトラック、例えば、１番目の再内周トラックである。
【００９６】
次に、本発明の記録／再生方式の他の実施例について説明する。
【００９７】
本実施例は、記録再生クロック周波数切り換え位置４１における記録ピット長の増加傾向と、上記第１１図のフォーマットのものより緩やかあるいは急激なものにする例である。そのため、本実施例は、記録クロック周波数を切り換えるトラックの本数を１０２４本固定ではなく、異なるトラック本数の２種を用意し、それらの組み合せにより、制御する。１０２４本固定のときより、記録ピットの増加傾向を抑えることができれば、光ディスク媒体の記憶容量を上げることができる。
【００９８】
すなわち、本実施例は、光ディスク媒体１上に、データの記録に用いられるピットまたは記録ドメインの周方向長さが、内周側で隣接するゾーンにおいて同一順位にあるトラックにおけるピットまたは記録ドメインの周方向長さより、短くなるゾーンを混在させるようにしたものである。
【００９９】
例えば、1.5μmのトラックピッチを持つ光ディスク媒体１において、１０２４本のトラックで記録再生クロックを切り換える領域を３つ連続させ、その後に、５１２本のトラックでクロックを切り換える領域を設けるものとする。すなわち、ｄ＝1.5μm、ｎ＝５１、Ｒ＝７０mmの条件において、Ｎ＝１０２４本のときは、ピット長を内周側よりも増大することになり、Ｎ＝５１２本のときは、ピット長を減少させることが可能になる。よって、内周部から外周部にかけてのピット長の増大傾向を抑えることができる。
【０１００】
本実施例の実現する記録／再生装置は、上記した第１図に示す光ディスク装置と同様の構成とすることができる。従って、ここでは、説明を繰り返さない。なお、本実施例では、クロック制御系のクロック情報生成手段を構成する主制御回路６において、第１５図に示すような変換テーブルを記憶保持している。この点は、上記実施例と相違する。
【０１０１】
第１５図は、上記実施例を実現するためのトラック番号４６、クロック情報３４および記録再生クロック周波数３２の変換テーブルである。
【０１０２】
第１６図は上記条件における媒体上のフォーマットを示したものである。第１６図に示すフォーマットについての記録再生クロック切り換え位置における最短ピット長の推移は、第１４図に示すように、折線グラフの形状を示す。
【０１０３】
上記実施例のように、異なるトラック本数で記録再生クロック３２を切り換えることにより、安定に再生することが可能な記録再生クロック周波数を選ぶことができ、記録容量を増大することができる。
【０１０４】
例として、１０２４本と５１２本で切り換える場合を述べたが、これは２のベキ乗本で切り換えれば、ソフトウェア処理などが容易となり、処理速度が高速にすることができるからである。本発明は、これに限定されるものではない。
【０１０５】
本実施例において、さらに、記録再生クロック３２を切り換える位置を任意に設定する構成としてもよい。このようにすれば、記録ピット長の増加分も任意に設定でき、弁別窓幅Ｗに占めるピット長の変動量ΔΦの割合（ΔΦ／Ｗ）を内外周どの記録位置でも、ほぼ一定にすることが可能となる。従って、全記録位置において、読み出しマージン一定で、安定に読み出し可能な最高密度の記録方法が実現できる。
【０１０６】
第１７図は弁別窓幅に占める検出信号位置の変動量の割合（ΔΦ／Ｗ）を示したものである。この図から明らかなように、本発明の上記各実施例のように、ピット長が記録位置が内周から外周になるほど大きくなるように、記録再生用のクロックの周波数を各ゾーンごとまたはトラックごとに設定すれば、（ΔΦ／Ｗ）をほぼ一定の範囲に抑えることができる。逆に、あらゆる記録位置で、（ΔΦ／Ｗ）が内周部と同じになるように設定するには、最短ピット長がどれくらいで、記録再生クロックをどれ程に設定すれば良いかがわかる。
【０１０７】
なお、前記各実施例では、記録媒体としてディスク状媒体に楕円状のピットを形成する追記形光ディスクを用いたが、本発明は、これに限らず、他の光ディスク媒体（光磁気・相変化）、磁気ディスク媒体、フレキシブルディスク媒体などを用いた場合も、同様に実施できる。
【０１０８】
また、上記実施例の光ディスク装置は、記録機能と再生機能の両者を備えているが、いずれか一方の機能のみを備える装置としてもよい。
【０１０９】
【発明の効果】
本発明は、以上説明したように構成されているので以下に記載されるような効果を奏する。
【０１１０】
ディスク状記録媒体を一定角速度で回転できるので、光ヘッドの位置付けにディスク状記録媒体の回転数安定時間を必要としない。また、内外周の全ての記録位置において安定な信号品質が保障され、記録再生クロック切り換え位置において、弁別窓幅Ｗに占めるその変動量ΔΦとの割合をほぼ一定にでき、全記録位置において安定に読み出し可能な高密度記録が行える。
【図面の簡単な説明】
【図１】本発明を適用した光ディスク装置の一実施例の基本構成を示すブロック図。
【図２】光ディスク媒体の概要フォーマットの説明図。
【図３】１セクタの構成を示す説明図。
【図４】データ記録方法を示す波形図。
【図５】データ再生方法を示す波形図。
【図６】記録再生クロック切り換え位置における最短記録ピット長の推移を示すグラフ。
【図７】記録膜面の到達温度曲線を示すグラフ。
【図８】記録ピットの変動を示したモデル波形図。
【図９】弁別窓幅に占める検出信号位置の変動量の割合の推移を示すグラフ。
【図１０】クロック情報の変換テーブルを示す説明図。
【図１１】第１０図の変換テーブルに対応する光ディスク媒体のフォーマットを示す説明図。
【図１２】シンセサイザの構成の一例を示すブロック図。
【図１３】記録時の補正を行う回路の構成を示すブロック図。
【図１４】記録再生クロック切り換え位置における最短記録ピット長の推移を示すグラフ。
【図１５】クロック情報の変換テーブルを示す説明図。
【図１６】第１５図に示す変換テーブルに対応する光ディスク媒体のフォーマットを示す説明図。
【図１７】弁別窓幅に占める検出信号位置の変動量の割合の推移を示すグラフである。
【符号の説明】
１…光ディスク媒体、２…スピンドルモータ、４…光ヘッド、５…ホストコンピュータ、６…主制御回路、７…基本クロック発振器、８…シンセサイザ、９…変調回路、１０…ＮＲＺ符号器、１１…記録補正器、１２…パルス幅設定器、１３…パワー設定器、１４…レーザドライバ、１５…値化回路、１６…再生データ合成回路、１７…復調回路、１８…位置付け制御回路、１９…位置付け機構、２０…スケール検出器、４２…セクタ。[0001]
[Industrial applications]
The present invention relates to a recording / reproducing device having a disk-shaped recording medium, and more particularly to a large-capacity disk file device.
[0002]
[Prior art]
For recording and reproducing information on an optical disk or the like, a CAV (Constant Angular Velocity) method in which the disk is rotated at a constant angular velocity to perform recording and reproduction, and a CLV (Constant Linear Velocity) in which the disk is rotated at a constant linear velocity to perform recording and reproduction. ) Method.
[0003]
The former has the problems that recording and reproduction can be performed stably, but the recording density is low, and the quality of signals on the inner and outer circumferences is different. On the other hand, the latter can raise the recording density, but has a problem that the access speed is slow because the rotation speed of the disk is changed at the time of access.
[0004]
Conventionally, for solving such a problem, for example, one disclosed in Japanese Patent Application Laid-Open No. 61-131236 has been proposed. According to the method described in the publication, the recording clock frequency is switched according to the linear velocity of a track on a recording medium rotating at a constant angular velocity, and the recording pit length or the recording domain length on the inner and outer circumferences is made constant in the entire recording area. Is supposed to.
[0005]
Other devices that switch the recording clock frequency between the inner and outer circumferences include, for example, JP-A-60-177404 and JP-A-60-117448. The methods described in these two publications increase the recording / reproducing clock frequency for each of a plurality of tracks as the recording position moves toward the outer periphery, thereby increasing the recording capacity.
[0006]
As described above, in the recording / reproducing apparatus using the disk-shaped recording medium rotating at a constant angular velocity, the recording / reproducing frequency in the outer peripheral track is changed according to the linear velocity of the recording position with respect to the inner peripheral recording / reproducing clock frequency. By increasing the height, the recording pit length or the recording domain length can be made equal at the inner and outer circumferences of the recording area. Thus, it can be expected that the recording capacity recorded on the disc can be increased.
[0007]
[Problems to be solved by the invention]
Incidentally, the above-mentioned conventional technique does not mention at all the relationship between the pit length or the recording domain length recorded on the disk-shaped medium and the recording method. Similarly, it does not mention how the pit length or the domain length changes from the inner circumference to the outer circumference of the disk.
[0008]
However, it has been clarified by the present inventors that these are important points to be noted in performing stable reproduction of information. In particular, in a so-called pit edge recording method in which information is provided at the leading edge and trailing edge of a pit or a recording domain generated at the time of recording, that is, in a pit edge recording method, the edge detection position is determined by a change in pit length or domain length. It has been clarified that the fluctuation amount increases and the detection information deteriorates. Hereinafter, this point will be described.
[0009]
First, consider the clock. The clock has a circuit fluctuation. Therefore, assuming that the fluctuation amount is substantially constant irrespective of the frequency, the fluctuation amount in the clock width increases as the frequency increases.
[0010]
Next, the relationship between pit formation and linear velocity will be discussed. According to experiments performed by the present inventors, as a characteristic of a recording medium, the temperature rise and fall gradients during pit formation differ depending on the linear velocity. As the linear velocity increases, the edge of the recording pit occupying the read discrimination window width increases. The result that the fluctuation amount of the detection position increased was obtained. That is, as shown in FIG. 9, when the recording clock frequency is changed so as to have the same recording pit length on the inner and outer circumferences of the recording area, the ratio of the fluctuation amount ΔΦ to the discrimination window width W is It tends to increase from the circumference to the outer circumference.
[0011]
As described above, when recording is performed with the same pit length, there is a problem that the read margin is stricter at the time of reproduction of the outer periphery than at the inner periphery, and stable reproduction cannot be performed.
[0012]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable and large-capacity information recording / reproducing method which solves the above-mentioned problems and ensures stable signal quality at all recording positions on the inner and outer peripheries to perform stable reproduction. It is in.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a recording pit length or a recording domain length having the same recording information at a recording signal switching position is set from an inner circumference according to a recording position of a disk-shaped medium rotating at a constant angular velocity. The recording clock frequency is changed so as to become longer toward the outer circumference. In addition, the clock frequency of the reproduction discrimination window is changed in order to maintain high reliability of the reproduction signal in the outer peripheral portion. Further, in order to further simplify the circuit configuration, the recording / reproducing clock is switched for each zone composed of a plurality of tracks.
[0014]
That is, according to the present invention, the recording area of the disk-shaped recording medium is divided into a plurality of zones that are sequentially adjacent in the radial direction, and a clock for recording and reproduction is assigned to each zone, and assigned to each zone. A recording / reproducing method for recording / reproducing data by a clock is provided.
[0015]
Further, according to the present invention, as the recording position with respect to the recording area of the disc-shaped recording medium changes from the inner circumference to the outer circumference, the recording capacity of one track increases, and the pits or recording domains of the pits or recording domains used for recording data are increased. A recording / reproducing method for recording / reproducing data by changing a recording / reproducing clock frequency so that the circumferential length gradually increases is provided.
[0016]
Further, according to the present invention, there is provided a recording / reproducing apparatus for recording and / or reproducing data in a recording area by rotating a disk-shaped recording medium at a constant angular velocity, wherein the recording / reproducing apparatus is arranged in accordance with a radial position of the recording medium. Information recording for setting a recording area to a plurality of zones, providing a clock control system for controlling a clock for recording and reproduction to be set for each zone, and recording data with a clock assigned to each zone A recording / reproducing apparatus provided with a system and / or an information reproducing system for reproducing data by a clock assigned to each zone.
[0017]
Further, according to the present invention, the recording area is divided into a plurality of zones which are sequentially adjacent in the radial direction, and the circumferential length of a pit or a recording domain used for data recording for tracks having the same rank in each zone. However, there is provided a disk-shaped recording medium on which the data is recorded so as to become longer as it goes to the outer peripheral zone.
[Action]
The present invention provides a recording / reproducing apparatus for rotating a disk-shaped recording medium at a constant angular velocity so that the recording capacity of one track increases as the recording position with respect to the recording area of the disk-shaped recording medium changes from the inner circumference to the outer circumference. Data recording / reproduction is performed by changing the clock frequency. As a result, even at a constant angular velocity, the recording capacity to be recorded on the disc can be increased.
[0018]
At this time, the clock frequency for recording / reproducing is set so that the circumferential length of a pit or a recording domain used for data recording gradually increases. That is, when a discrimination window is set to detect a signal generated by the edge of a pit or a domain recorded on a disc-shaped recording medium and data is reproduced, a change in the appearance position of the detection signal in the discrimination window width W is obtained. The clock frequency for recording and reproduction is changed so that the ratio of the amount ΔΦ (ΔΦ / W) is kept within a substantially constant range on the inner and outer circumferences of the recording medium. As a result, the discrimination window width W becomes larger at the outer periphery, the read margin is sufficient at the outer periphery, and read errors are reduced. Therefore, stable signal quality is guaranteed at all recording positions on the inner and outer circumferences, and stable and highly reliable reproduction can be performed.
[0019]
Further, the present invention divides a recording area of a disk-shaped recording medium into a plurality of zones which are sequentially adjacent in the radial direction, allocates a recording / reproducing clock to each zone, and uses a clock allocated to each zone. Record / reproduce data. Therefore, clock control can be easily performed with a simple circuit configuration.
[0020]
In this case, the recording / reproducing clock for each zone may be assigned with a different frequency so that the recording capacity of one track increases toward the outer peripheral zone. Further, for the tracks having the same rank in each zone, the frequency may be changed and set so that the circumferential length of a pit or a recording domain used for data recording gradually increases toward the outer circumferential zone. .
[0021]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
FIG. 1 is a schematic diagram showing an embodiment of an optical disk apparatus to which the present invention is applied.
[0023]
The optical disk apparatus shown in FIG. 1 includes an optical disk medium 1 having a recording area 2, a spindle motor 3 for rotating the optical disk medium 1, an optical head 4 for reading and writing information from and on the optical disk medium 1, and an entire system. A main control circuit 6 to be controlled and a positioning control system, an information recording system, an information reproduction system, and a clock control system for the optical head 4 functioning under the control of the main control circuit 6 are provided.
[0024]
The positioning control system for the optical head 4 functions as a positioning mechanism 19 for positioning the optical head 4 at a target position, a positioning control circuit 18 for performing positioning control on the positioning mechanism 19, and a unit for detecting an access position of the optical head 4. And a scale detector 20.
[0025]
The information recording system modulates the data 21 to be written into a code 22 of a run length limited code sequence such as a 2-7 modulation code, for example, and further modulates the modulated code 22 into an NRZ (Non Return to Zero). The NRZ encoder 10 converts the NRZ code 23 into a code 23, the pulse width setting device 12 sets the write pulse width of the NRZ code 23 including correction, and sets the recording code 24, and the laser element ( The laser driver 14 drives a laser beam to the optical head 4 by driving a laser beam (not shown in FIG. 1).
[0026]
The information reproducing system synchronizes the reproduction code 29 with a binarization circuit 15 for binarizing a reproduction signal 27 detected by a photodetector (not shown) in the optical head 4 to obtain a reproduction code 29, and And a PLL circuit 35 for outputting a discrimination clock 37, a reproduction data synthesizing circuit 16 for synthesizing a code 30 of reproduction data from the synchronization code 36, and a demodulation circuit 17 for demodulating data 31 from the code 30. You.
[0027]
The clock control system includes a basic clock oscillator 7 for generating a basic clock, a synthesizer 8 for generating a target recording / reproducing clock from the basic clock based on the set clock information, Alternatively, it is provided with clock information generating means for outputting to the synthesizer 8 clock information 34 specifying a recording / reproducing clock assigned to each of two or more tracks. The clock information generating means is configured as one function of the main control circuit 6.
[0028]
As shown in FIG. 2, the optical disc medium 1 has a recording area 2 partitioned into a plurality of zones 2a to 2f that are sequentially adjacent in the radial direction. A plurality of tracks are provided in each of the zones 2a to 2f, and information recording and reproduction are performed here. Further, the optical disc medium 1 has a recording / reproducing clock frequency switching position 41 for every several tracks in the recording area 2 at the boundary between the zones 2a to 2f. The number of sectors 42 is increased by one from the number of sectors 42 included in the track on the peripheral side.
[0029]
In the optical disc medium 1 according to the present embodiment, as described later, the circumferential length of the pits or recording domains used for data recording for the tracks having the same rank in each of the zones 2a to 2f goes to the outer peripheral zone. It is recorded to be longer according to.
[0030]
In this embodiment, an example is shown in which a write-once optical disc is used.
[0031]
The main control circuit 6 includes, for example, although not shown, a central processing unit (CPU), a ROM for storing programs of the CPU, a RAM for storing various data, and the like. As described above, the main control circuit 6 has a function as clock information generation means of a clock control system. For this reason, the main control circuit 6 stores a conversion table as shown in FIGS. 10 and 15 described later in a ROM or a RAM, and, based on information from the host computer 5, causes the CPU to The information 34 is configured to be extracted.
[0032]
For example, as shown in FIG. 12, the synthesizer 8 has a fixed frequency divider 62 for dividing the basic clock 61 from the basic clock oscillator 7 and outputting a reference clock 64, and a recording / reproducing clock which is an output of the synthesizer 8. 32, a variable frequency divider 63 for dividing the frequency in accordance with the frequency division number set by the clock information 34 from the main control circuit 6, a frequency of the variable frequency divided clock 65 outputted from the variable frequency divider 63, and A phase comparator 66 for comparing the reference clock 64 to detect an error and controlling the output signal 67 so that the two coincide with each other, a low-pass filter 68, and a VCO oscillating at a frequency corresponding to the voltage of the output signal 67 (Voltage Controlled Oscillator) circuit 69.
[0033]
The output of the VCO circuit 69 is output as the recording / reproducing clock 32 and is also fed back to the variable frequency divider 63 as described above.
[0034]
The modulation circuit 9 and the NRZ encoder 10 may have a commonly used circuit configuration.
[0035]
The pulse width setting unit 12 selects a delay element 71 in which an input signal is output from a plurality of output taps with a certain delay time and an output from the output tap of the delay element 71 in accordance with a correction command of the recording corrector 11. And an AND circuit 73 that calculates the logical product of the output of the selector 72 and the NRZ code 23 input to the delay element 71.
[0036]
The laser driver 14 has a current switch configuration that switches according to the value of the recording code 24, thereby driving the semiconductor laser 77 on and off.
[0037]
The power setter 13 is connected in series to the semiconductor laser 77, sets a drive current for the transistor 75, a resistor 76 connected in series with the transistor 75, and digitally outputs a command value from the recording corrector 11. And a D / A converter 74 for performing analog conversion and setting the base potential of the transistor 75.
[0038]
The recording corrector 11 includes, for example, a ROM and the like. In this ROM, a command for selecting a pulse width correction amount by the selector 72 and a command value of an input bit to the D / A converter 74 are stored using the control information 33 as an address.
[0039]
The binarizing circuit 15, the PLL circuit 35, the reproduced data synthesizing circuit 16 and the like may each have a known circuit configuration. This type of circuit is described in, for example, JP-A-63-53722.
[0040]
Next, an embodiment of the information recording / reproducing method of the present invention will be described by taking as an example the case where the optical disk device shown in FIG. 1 is used.
[0041]
First, in describing the recording / reproducing operation, the principle of a pit edge recording method, which is a recording method adopted in the present invention, will be described.
[0042]
FIG. 4 is a waveform diagram showing a process of signal change when data is converted into a code by modulation and recorded on a disk, and pits formed on the disk. FIG. 5 is a waveform diagram showing a process of reproducing information from pits recorded on a disk and demodulating the information to original data.
[0043]
In FIG. 1, an optical disk medium 1 is rotated at a constant angular velocity by a spindle motor 3. In this state, data reading and writing are performed.
[0044]
In FIG. 1, data 21 to be recorded is modulated by a modulation circuit 9 into a code 22. This coding may be performed by any modulation method. In this embodiment, a case of 2-7 modulation is shown as shown in FIG. The code 22 is converted by the NRZ encoder 10 into an NRZ code 23.
[0045]
By the way, if the NRZ code 23 is recorded on the optical disc medium 1, pits longer than the irradiation recording width are generally formed. This is because the heat of the laser light emitted from the semiconductor laser 77 in the laser driver 14 propagates through the recording film, and even in a portion not irradiated with the recording pulse light, a state where the melting point of the recording film is exceeded may occur. is there. On the other hand, depending on the relative relationship between the melting point of the recording film and the irradiation light power, the NRZ code may be shorter than the NRZ code.
[0046]
Therefore, in order to make the length of the formed recording pit 26 correspond to the length of the NRZ code 23, the recording code 24 whose pulse width has been corrected (shortened in the illustrated case) is used. Further, the power of the recording light pulse 25 is corrected according to the linear velocity of the optical disk medium on which recording is performed. The setting of the recording light pulse width and the recording light power is performed under the control of the recording corrector 11 using the respective setting devices 12 and 13. In response, the laser driver 14 drives the semiconductor laser 77 to form the recording pit 26. That is, the leading edge and the trailing edge of the formed pit correspond to "1" of the 2-7 code, and data is recorded on the optical disk medium 1.
[0047]
Next, a case where the data 31 is demodulated from the recording pit 26 will be described with reference to FIG.
[0048]
The amount of light reflected from the optical disk medium 1 when the laser light is irradiated changes depending on the presence or absence of the recording pit 26, and a reproduction signal 27 which is an analog signal is obtained. The reproduction signal 27 can be binarized by the binarization circuit 15 using a certain slice level 28 to obtain a reproduction code 29.
[0049]
As another method, the reproduction signal 27 can be second-order differentiated, its zero-cross point can be detected, and a binarized reproduction code 29 can be obtained.
[0050]
Pulses corresponding to the rising and falling edges of the reproduced code 29 are generated, and a code 30 is obtained from both. The data 31 can be reproduced by inputting this to the demodulation circuit 17 which performs the reverse operation of the modulation circuit 9.
[0051]
In FIG. 5, the recording / reproducing clock 32 is described in order to correspond to FIG. 4. However, when the code 30 is reproduced from the reproducing code 29, the reproducing code A discrimination clock 37 synchronized with the clock 29 is generated (see FIG. 1).
[0052]
Here, the length of the pit formed on the optical disc medium 1 of the present embodiment will be discussed.
[0053]
When the 2-7 modulation method is used, there are six types of recording pit lengths. Here, the shortest pit length will be obtained.
[0054]
The total bit number of the sector 42 of the optical disk medium 1 is Z, the track pitch is d μm, the number of tracks for switching the recording clock is N, the innermost track radius is Rm, and the number of sectors included in the innermost track is n. Then, the shortest pit length l _o in the innermost track is expressed by the following equation.
[0055]

Thus, the shortest pit length l _i at the _ith recording / reproducing clock switching position is as follows.
[0056]

The condition that the shortest pit length is larger on the outer circumference than on the inner circumference at the position where the recording / reproducing clock frequency is switched is as follows.
[0057]
NdnR> 0
For example, if N = 1024, n = 51, and R = 70 mm in the optical disk medium 1 formatted with a track pitch d = 1.5 μm, the pit length having the same recording information at the clock switching position is monotonous toward the outer circumference. It is possible to increase.
[0058]
At this time, assuming that the track pitch d, the innermost track radius R, and the number n of the sectors 42 included in the innermost track are constant, the recording pit length increases only by changing the number N of tracks for switching the recording clock. Can control trends. FIG. 6 shows the transition of the shortest pit length at the position 41 where the recording / reproducing clock 32 is switched.
[0059]
On the other hand, assuming that the shortest pit length is constant in both the inner and outer recording areas as described in JP-A-61-131236, the read margin at the outer periphery is larger than that at the inner periphery. It becomes severe. This phenomenon is a starting point of the present invention, and will be described below.
[0060]
Since the optical disk medium 1 is rotating at a constant angular velocity, the linear velocities are different between the inner and outer circumferences of the recording area. For this reason, the temperature curve of the film surface which affects the formation of pits when the recording laser beam is irradiated is different depending on the magnitude of the linear velocity as shown in FIG. Further, when irradiating the recording laser beam, the ultimate temperature curve of the film surface may fluctuate as shown by the dotted line in FIG. 7 due to the non-uniformity of the recording film or fluctuation of the linear velocity. As a result of the above fluctuation, the pit formation position fluctuates, and the temperature curve has a gentle gradient and the linear velocity is larger, that is, the fluctuation amount ΔΦ of the pit formation position is larger in the outer peripheral portion. . The same can be said for the trailing edge of the formed pit.
[0061]
Here, for comparison with the present embodiment, the pit length of the pit formed by the above-described pit forming method according to the related art will be examined.
[0062]
In the prior art, as shown in FIG. 8, the recording pit 26 is formed by changing the frequency of the recording / reproducing clock 32 in proportion to the linear velocity at the recording position so that the linear density is constant over the entire recording area. . FIG. 8 shows waveforms at the inner peripheral portion of the clock frequency f ₀ and at the outer peripheral portion (clock frequency 2f ₀ ) having a linear velocity twice that of the inner peripheral portion.
[0063]
As shown in FIG. 8, in this prior art, since the fluctuation amount ΔΦ of the pit length with respect to the recording pit length is larger in the outer peripheral portion than in the inner peripheral portion, detection of the discrimination clock 36 in the discrimination window width W is eventually completed. The ratio ΔΦ / W of the fluctuation amount of the signal position increases. FIG. 9 shows the transition of the ratio ΔΦ / W of the fluctuation amount of the detection signal position in the discrimination window width when recording is performed with the same pit length from the inner circumference to the outer circumference of the optical disc medium 1. As shown in FIG. 9, ΔΦ / W increases as the recording position moves toward the outer peripheral portion, and there is a possibility that reproduction errors in the outer peripheral portion increase.
[0064]
According to the present embodiment, this problem is solved. The recording / reproducing operation of the information data will now be described with reference to FIG.
[0065]
First, data recording will be described.
[0066]
The main control circuit 6 receives write data and write start position information from the host computer 5. The main control circuit 6 converts the write start position information into a track number 46 and a sector number 47 to be accessed according to a conversion table stored in a built-in memory (not shown). The positioning control circuit 18 controls the positioning mechanism 19 so that the light spot of the optical head 4 is positioned at the track number 46 transmitted from the main control circuit 6.
[0067]
As a method of positioning the optical head 4 on a target track, for example, a method of using information of an ID part created in advance in the sector 42 or providing an external scale and reading the positioning position by the scale detector 20 is used. Used.
[0068]
Further, the main control circuit 6 obtains the clock information 34 from the converted track number 46 by using the conversion table shown in FIG. 10 and sends the clock information 34 to the synthesizer 8.
[0069]
The synthesizer 8 generates a recording / reproducing clock 32 corresponding to the clock information 34 from the clock information 34. In FIG. 10, the switching position 41 of the recording / reproducing clock 32 is set every 1024 tracks because the pit length having the same information becomes longer toward the outer periphery at the clock switching position 41, and the detection signal occupying the discrimination window width. This is because the ratio of the position variation (ΔΦ / W) is also smaller than when the pit length is fixed. Of course, the present invention is not limited to this, and if this condition is satisfied, another number of tracks may be used.
[0070]
The synthesizer 8 divides the frequency of the basic clock 61 generated by the basic clock oscillator 7 with a fixed frequency divider 62 to generate a reference clock 64. Further, the frequency division number of the variable frequency divider 63 is set by the clock information 34. The phase comparator 66 controls the frequency of the output signal 67 so that the output frequency of the variable frequency-divided clock 65 and the frequency of the reference clock 64 have the same value. The output signal 67 passes through a low-pass filter 68 and becomes a recording / reproducing clock 32 in a VCO circuit 69.
[0071]
The frequency of the recording / reproducing clock 32 is kept constant by inputting the recording / reproducing clock 32 to the variable frequency divider 63. As a result, the recording / reproducing clock 32 corresponds to the corresponding recording position.
[0072]
The modulation circuit 9 modulates the write data 21 received from the main control circuit 6 into code data 22 such as a 2-7 code. The NRZ encoder 10 converts the code 22 into an NRZ code 23 on the recording / reproducing clock 32 generated by the synthesizer 8.
[0073]
As described above, if laser light is irradiated and recorded using the NRZ code 23, a recording pit length longer or shorter than the NRZ code 23 is formed due to the thermal diffusion characteristics of the optical disk medium. Since this characteristic changes depending on the linear velocity, it is necessary to correct the characteristic to an optimum value. Further, in order to match the recording pit length with the code length of the NRZ code 23, it is also necessary to optimize the laser current for controlling the recording power of the laser.
[0074]
Therefore, the pulse width of the NRZ code 23 is set by the pulse width setting unit 12 including the correction, and the recording code 24 is generated. This will be described in more detail.
[0075]
The converted NRZ code 23 is input to the delay element 71 of the pulse width setting device 12. In the delay element 71, a signal with a fixed delay time is output to a plurality of output taps. Note that there is a method using a gate delay as the delay element.
[0076]
The output from the delay element 71 is input to the selector 72, and one of the outputs is selected by the recording corrector 11 and input to the AND gate 73. Since a signal that has not been delayed is input to the other of the AND gate 73, a pulse that is shorter by the delay amount is generated. This pulse corresponds to the recording code 24 in FIGS. 1 and 4 and is input to the laser driver 14.
[0077]
In the above method, correction is made short, but when correction is made long, conversely, it is only necessary to change the AND gate 73 with the OR gate. Moreover, both can be used together.
[0078]
On the other hand, the control of the recording light power is performed by changing the value of the current source in the laser driver 14. The laser driver 14 has a current switch configuration, and emits light when the semiconductor laser 77 is turned on by changing the base potential of a transistor 75 for determining a current value by a D / A converter 74. Power can be changed. For example, if the base potential of the transistor 75 is increased by the D / A converter 74, the emitter potential increases, and the current flowing through the resistor 76 increases. Therefore, the driving current of the semiconductor laser 77 also increases, and the light emission power increases.
[0079]
The recording corrector 11 sets the pulse width and the power based on the control information 33. That is, when control information 33 such as clock information 34 (or a track number) is input as an address of a built-in ROM, corresponding correction data is output as an output. Using this data, the selection of the pulse width correction amount by the selector 72 and the input bit to the D / A converter 74 can be designated.
[0080]
In addition, the clock information 34, a method using an external scale detector 20 in place of the track number, or the number of tracks that have traversed from the reference radius (for example, the innermost circumference) of the disk to the present time are used. And the same control can be performed.
[0081]
By the above method, as shown in FIG. 4, the recording light pulse 25 is corrected to the optimum value at the recording position, and the recording pit 26 having the same length as the NRZ code 23 can be formed on the disk medium 1. Next, data reproduction will be described.
[0082]
The main control circuit 26 receives information on the read start position from the host computer 5, performs the same operation as during recording, and positions the optical head 4 on the target track. The optical disc medium 1 is irradiated with laser light by setting the emission power of the semiconductor laser 77 to the reproduction level. As a result, the data on the medium is obtained as an optical signal, and is converted into a reproduction signal 27 by a photodetector in the optical head 4. The reproduction signal 27 is output as a reproduction code 29 by the binarization circuit 15 and is input to the reproduction data synthesis circuit 16.
[0083]
On the other hand, the main control circuit 6 obtains the track number 46 and the clock information 34 from the read start position information, and sends the clock information 34 to the synthesizer 8. The synthesizer 8 generates a recording / reproducing clock 32 corresponding to the clock information 34 in the same manner as during recording.
[0084]
In the present invention, a pit edge recording method is adopted as a data recording method. When actually using edge recording, the recording pits change with respect to the target length, so the data corresponding to the leading edge and trailing edge is treated as individual data, and a method of re-synthesizing is used. ing.
[0085]
The leading edge pulse and the trailing edge pulse here correspond to the rising edge and the falling edge of the reproduction code 29 output from the binarization circuit 15.
[0086]
The PLL circuit 35 generates a discrimination clock 37 synchronized with the reproduction code 29 and a synchronization code 36. In FIG. 1, each is shown in one series, but actually, it is two series of clocks and data corresponding to the leading edge and the trailing edge. At this time, the recording / reproducing clock 32 is used as a reference clock at the time of pulling in a VFO (Variable Frequency Oscillator).
[0087]
The output from the PLL circuit 35 is input to the reproduction data synthesis circuit 16. The reproduction data synthesizing circuit 16 measures the synchronizing code 36 of the leading edge and the trailing edge by a known data (for example, a SYNC pattern) detection circuit, and synthesizes two series of data strings.
[0088]
After the code 30 is obtained as an output of the reproduction data synthesizing circuit 16, the demodulation circuit 17 performs the reverse operation of the modulation to obtain data 31. The demodulation circuit 17 may be a known one.
[0089]
The data reproduced by the above method is transferred from the main control circuit 6 to the host computer 5.
[0090]
FIG. 10 shows a conversion table of the track number 46, the clock information 34, and the recording / reproducing clock frequency 32. In this case, the number of tracks at which the recording / reproducing clock frequency 32 is switched is set to every 1024, and the number of the sectors 42 constituting the track at each clock switching position 41 is increased one by one toward the outer periphery.
[0091]
Here, the recording / reproducing clock frequency will be obtained. Assuming that the rotation speed of the optical disc medium 1 is A rpm, the number of sectors in the innermost track is n, and the total number of bits in one sector is Z, the recording / reproducing clock frequency f _{0 on} the innermost track (track 0) is as follows. become.
[0092]
f ₀ = 2 × A / 60 × n × Z (Hz)
Further, the recording and reproducing clock frequency f _i at the clock information i is as follows.
[0093]
f _i = 2 × A / 60 × (n + i) × Z (Hz)
FIG. 11 shows an example of the format of the optical disc medium 1 in which the track pitch d is set to 1.5 μm, the number of sectors n of the innermost track is set to 51, and the innermost track radius is set to 70 mm using the conversion table of FIG. It is shown.
[0094]
FIG. 14 shows the transition of the shortest pit length of the optical disc medium 1 having the format shown in FIG.
[0095]
The transition of the shortest pit length shown in FIG. 14 indicates that, for tracks having the same rank in each zone, the circumferential length of pits or recording domains used for data recording gradually increases toward the outer circumferential zone. Is showing. Here, the track having the same rank in each zone means, for example, a track arranged in the same order from the innermost side in each track. Specifically, it is the i-th track in each zone, for example, the first re-inner track.
[0096]
Next, another embodiment of the recording / reproducing method of the present invention will be described.
[0097]
This embodiment is an example in which the recording pit length at the recording / reproducing clock frequency switching position 41 tends to increase, and the recording pit length is made gentler or steeper than that of the format shown in FIG. For this reason, in the present embodiment, the number of tracks for switching the recording clock frequency is not fixed to 1024, but two types of different numbers of tracks are prepared and controlled by a combination thereof. If the tendency to increase the number of recording pits can be suppressed as compared with the case where the number of recording pits is fixed to 1024, the storage capacity of the optical disk medium can be increased.
[0098]
That is, in the present embodiment, the circumferential length of a pit or a recording domain used for recording data on the optical disc medium 1 is the same as that of a pit or a recording domain in a track having the same rank in an adjacent zone on the inner circumferential side. Zones shorter than the length in the direction are mixed.
[0099]
For example, in the optical disc medium 1 having a track pitch of 1.5 μm, three areas for switching the recording / reproducing clock are consecutively arranged on 1024 tracks, and thereafter, an area for switching the clocks on 512 tracks is provided. That is, under the conditions of d = 1.5 μm, n = 51 and R = 70 mm, when N = 1024, the pit length is longer than that on the inner peripheral side, and when N = 512, the pit length is longer. Can be reduced. Therefore, the tendency of the pit length to increase from the inner peripheral portion to the outer peripheral portion can be suppressed.
[0100]
The recording / reproducing apparatus realized by this embodiment can have the same configuration as the optical disk apparatus shown in FIG. Therefore, the description will not be repeated here. In this embodiment, the conversion table as shown in FIG. 15 is stored and held in the main control circuit 6 constituting the clock information generating means of the clock control system. This point is different from the above embodiment.
[0101]
FIG. 15 is a conversion table of the track number 46, the clock information 34, and the recording / reproducing clock frequency 32 for realizing the above embodiment.
[0102]
FIG. 16 shows a format on a medium under the above conditions. The transition of the shortest pit length at the recording / reproducing clock switching position for the format shown in FIG. 16 shows a shape of a line graph as shown in FIG.
[0103]
As in the above embodiment, by switching the recording / reproducing clock 32 with different numbers of tracks, a recording / reproducing clock frequency capable of performing stable reproduction can be selected, and the recording capacity can be increased.
[0104]
As an example, the case of switching between 1024 lines and 512 lines has been described. This is because if the switching is performed by a power of 2, software processing or the like becomes easy and the processing speed can be increased. The present invention is not limited to this.
[0105]
In the present embodiment, the position at which the recording / reproducing clock 32 is switched may be further set arbitrarily. In this way, the increment of the recording pit length can be set arbitrarily, and the ratio (ΔΦ / W) of the fluctuation amount ΔΦ of the pit length to the discrimination window width W is made substantially constant at any of the inner and outer recording positions. Becomes possible. Accordingly, it is possible to realize a recording method of the highest density that can read stably with a constant read margin at all recording positions.
[0106]
FIG. 17 shows the ratio (ΔΦ / W) of the variation of the detection signal position to the discrimination window width. As is clear from this figure, as in the above embodiments of the present invention, the frequency of the recording / reproducing clock is changed for each zone or track so that the pit length increases from the inner circumference to the outer circumference. , It is possible to keep (ΔΦ / W) within a substantially constant range. Conversely, in order to set (ΔΦ / W) to be the same as the inner peripheral portion at all recording positions, it is possible to know how long the shortest pit length is and how much the recording / reproducing clock should be set.
[0107]
In each of the above embodiments, a write-once optical disk in which elliptical pits are formed on a disk-shaped medium is used as a recording medium. However, the present invention is not limited to this, and other optical disk media (magneto-optical / phase change) In the case where a magnetic disk medium, a flexible disk medium, or the like is used, the present invention can be similarly implemented.
[0108]
Further, the optical disk device of the above embodiment has both the recording function and the reproducing function, but may have only one of the functions.
[0109]
【The invention's effect】
Since the present invention is configured as described above, it has the following effects.
[0110]
Since the disk-shaped recording medium can be rotated at a constant angular velocity, the rotation speed stabilization time of the disk-shaped recording medium is not required for positioning the optical head. In addition, stable signal quality is guaranteed at all recording positions on the inner and outer circumferences, and the ratio of the fluctuation amount ΔΦ to the discrimination window width W can be made almost constant at the recording / reproducing clock switching position, and stable at all recording positions. Readable high-density recording can be performed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a basic configuration of one embodiment of an optical disk device to which the present invention is applied.
FIG. 2 is an explanatory diagram of a general format of an optical disk medium.
FIG. 3 is an explanatory diagram showing a configuration of one sector.
FIG. 4 is a waveform chart showing a data recording method.
FIG. 5 is a waveform chart showing a data reproducing method.
FIG. 6 is a graph showing a transition of the shortest recording pit length at a recording / reproducing clock switching position.
FIG. 7 is a graph showing an attained temperature curve of a recording film surface.
FIG. 8 is a model waveform diagram showing a change in a recording pit.
FIG. 9 is a graph showing a change in the ratio of the variation of the detection signal position to the discrimination window width.
FIG. 10 is an explanatory diagram showing a conversion table of clock information.
FIG. 11 is an explanatory diagram showing a format of an optical disk medium corresponding to the conversion table in FIG. 10;
FIG. 12 is a block diagram illustrating an example of a configuration of a synthesizer.
FIG. 13 is a block diagram illustrating a configuration of a circuit that performs correction at the time of recording.
FIG. 14 is a graph showing the transition of the shortest recording pit length at the recording / reproducing clock switching position.
FIG. 15 is an explanatory diagram showing a conversion table of clock information.
FIG. 16 is an explanatory diagram showing a format of an optical disk medium corresponding to the conversion table shown in FIG. 15;
FIG. 17 is a graph showing a change in the ratio of the fluctuation amount of the detection signal position to the discrimination window width.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical disk medium, 2 ... Spindle motor, 4 ... Optical head, 5 ... Host computer, 6 ... Main control circuit, 7 ... Basic clock oscillator, 8 ... Synthesizer, 9 ... Modulation circuit, 10 ... NRZ encoder, 11 ... Recording Corrector, 12: pulse width setting device, 13: power setting device, 14: laser driver, 15: digitizing circuit, 16: reproduction data synthesizing circuit, 17: demodulation circuit, 18: positioning control circuit, 19: positioning mechanism, 20: scale detector, 42: sector.

Claims (3)

A recording area having a plurality of tracks is divided into a plurality of zones adjacent in the radial direction, and in each zone, for a track at the same rank and the innermost circumference, a shortest pit or a shortest recording domain used for data recording is used. The length in the circumferential direction becomes longer as going to the outer peripheral zone, and is recorded so as to increase the number of sectors of each track as going to the outer peripheral zone,
A disk, wherein the number of tracks belonging to a first zone of the plurality of zones is the same as the number of tracks belonging to a second zone which is separated from the first zone by a plurality of zones in an outer peripheral direction. Recording medium. In a recording medium having a plurality of tracks having a plurality of sectors, a recording area is divided into a plurality of zones radially adjacent to each other, and each of the sectors has a header portion in which a sector number is recorded.
In each of the plurality of zones, the header portion of the sector of the track having the same rank and the innermost circumference has a length in the circumferential direction of the shortest pit or the shortest recording domain for recording the sector number. It is recorded so as to become longer as it goes, and as the number of sectors in each track increases as it goes to the outer peripheral zone,
A disk, wherein the number of tracks belonging to a first zone of the plurality of zones is the same as the number of tracks belonging to a second zone which is separated from the first zone by a plurality of zones in an outer peripheral direction. Recording medium. In a recording / reproducing apparatus for a recording medium having a plurality of tracks having a plurality of sectors, a recording area is divided into a plurality of zones radially adjacent to each other, and each of the sectors has a header portion in which a sector number is recorded.
In the recording medium, the shortest pit or shortest recording domain in the circumferential direction of the shortest pit or the shortest recording domain for recording the sector number in the header portion of the sector of the track at the same rank and the innermost circumference in each of the plurality of zones. Are recorded so as to become longer as going to the outer peripheral zone, and to increase the number of sectors of each track as going to the outer peripheral zone,
The number of tracks belonging to a first zone of the plurality of zones is the same as the number of tracks belonging to a second zone which is separated from the first zone by a plurality of zones in an outer peripheral direction,
The recording and reproducing apparatus reproduces the sector number from a header of a track belonging to the plurality of zones.
that's all

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