JP3703097B2 - Optical disc apparatus, optical disc recording method, optical disc, and optical disc manufacturing method - Google Patents

Description

【００５１】
なおここでＨｒ１（ｐ，ｂ）は、補正値データＤＦにより選択される遅延回路２２のタップであり、値０の場合がセンタータップである。またＨｒ０（ｐ，ｂ）は、初期値でなる補正値データＤＦにより選択される遅延回路２２のタップであり、この実施の形態において、Ｈｒ０（ｐ，ｂ）は、値０に設定されていることになる。またａは定数である。ここでこの実施の形態において、ａは１以下の値（例えば０．７など）に設定され、ノイズなどの影響があっても、確実に補正値データを収束させることができるように、乗せられる。
【００５２】
コンピュータ４４は、このようにしてＲＯＭライター４５に補正値データＤＦを格納すると、ステップＳＰ１２に移ってこの処理手順を終了する。続いてコンピュータ４４は、同様の処理手順をディジタル２値化信号の立ち下がりエッジについて実行し、これにより補正値テーブル２０を完成する。
【００５３】
以上の構成において、光ディスク装置１においては（図１）、立ち上がりエッジ補正回路１７Ａ及び立ち下がりエッジ補正回路１７Ｂにおける補正値テーブル２０を初期値に設定することにより、従来のコンパクトディスクの作成条件と同一の条件により評価用のディスク原盤２が作成され（図４）、このディスク原盤２より評価用のコンパクトディスク４１が作成される。
【００５４】
この評価用のコンパクトディスク４１は、基本周期Ｔの整数倍の周期で信号レベルが変化するＥＦＭ信号によりレーザービームＬをオンオフ制御してディスク原盤２が順次露光されてピットが形成され、これにより再生信号が隣接するピット、ランドからの符号間干渉を受ける。従ってこのコンパクトディスク４１より得られる再生信号は、スライスレベルを横切るタイミングが前後のピット及びランドの形状に応じて、すなわちＥＦＭ信号の変化パターンに応じて変化し、ジッタが発生することになる。
【００５５】
このコンパクトディスク４１は、コンパクトディスクプレイヤー４２により再生され、再生信号ＲＦがディジタルオシロスコープ４３によりディジタル信号に変換された後、コンピュータ４４により２値化信号、ＥＦＭ復号信号、再生クロックが生成される。さらにコンパクトディスク４１は、２値化信号の各エッジ毎に、ＥＦＭ復号信号より前後のピット及びランドが検出されてＥＦＭ信号の変化パターンが検出され、各変化パターン毎に、再生クロックに対する各エッジのジッタ量が時間計測される。
【００５６】
さらにこれら時間計測結果が各変化パターン毎に平均値化され、符号間干渉により発生するジッタ量が各変化パターン毎に検出される。コンパクトディスク４１は、このようにして検出したジッタ量により、ジッタ補正単位でなる、遅延回路２２（図３）のタップ間遅延時間差τを基準にした（１）式の演算処理を実行することにより、遅延回路２２のセンタータップを基準にして、この検出したジッタ量を打ち消すことができる遅延回路２２のタップ位置が検出され、このタップ位置を特定するデータが補正値データＤＦとしてリードオンリメモリに格納され、これにより補正値テーブル２０が形成される。
【００５７】
このようにして補正値テーブル２０を形成すると、ディジタルオーディオテープレコーダ３（図１）より入力されるオーディオデータＤ１及びサブコードデータは、変調回路１３により規定のデータ処理を受け、基本周期Ｔを単位にして信号レベルが変化するＥＦＭ信号Ｓ２に変換される。このＥＦＭ信号Ｓ２は、レベル変換回路１５において信号レベルがＴＴＬレベルに変換された後、ＰＬＬ回路１６によりクロックＣＫが再生され、また立ち上がりエッジ補正回路１７Ａ及び立ち下がりエッジ補正回路１７Ｂにおいて（図３）、１３段のラッチ回路１９Ａ〜１９Ｍで順次ラッチされて、変化パターンが検出される。
【００５８】
さらにＥＦＭ信号Ｓ２は、このラッチ回路１９Ａ〜１９Ｍの中間のラッチ回路よりモノステーブルマルチバイブレータ２１に入力され、立ち上がりエッジ補正回路１７Ａにおいては、立ち上がりエッジのタイミングで、立ち下がりエッジ補正回路１７Ｂにおいては、立ち下がりエッジのタイミングで、モノステーブルマルチバイブレータ２１をトリガし、それぞれ立ち上がりエッジ及び立ち下がりエッジのタイミングで信号レベルが立ち上がる立ち上がりパルス信号及び立ち下がりパルス信号を生成する。
【００５９】
これら立ち上がりパルス信号及び立ち下がりパルス信号は、それぞれ立ち上がりエッジ補正回路１７Ａ及び立ち下がりエッジ補正回路１７Ｂの遅延回路２２において、補正値データＤＦの算出に利用された遅延時間τを単位にして順次遅延され、この遅延回路２２のタップ出力がセレクタ２３に出力される。これに対してラッチ回路１９Ａ〜１９Ｍで検出されたＥＦＭ信号Ｓ２の変化パターンは、ラッチ回路１９Ａ〜１９Ｍのラッチ出力をアドレスにした補正値テーブル２０のアクセスにより、対応する補正値データＤＦが検出され、この補正値データＤＦによりセレクタ２３の接点が切り換えられる。
【００６０】
これによりそれぞれ立ち上がりエッジ補正回路１７Ａ及び立ち下がりエッジ補正回路１７Ｂのセレクタ２３より、評価用のコンパクトディスク４１で検出されたジッタを補正するように、ＥＦＭ信号Ｓ２の立ち上がりエッジ及び立ち下がりエッジのタイミングをそれぞれ補正してなる立ち上がりエッジ信号ＳＳ及び立ち下がりエッジ信号ＳＲが出力され、これら立ち上がりエッジ信号ＳＳ及び立ち下がりエッジ信号ＳＲ（図１）が、フリップフロップ２５により合成される。さらにこのフリップフロップ２５の出力信号Ｓ５がレベル逆変換回路２６により信号レベルの補正を受け、これにより評価用のコンパクトディスク４１で検出したジッタを補正するように、すなわち符号間干渉を低減するように、ＥＦＭ信号Ｓ２のエッジのタイミングをそれぞれ補正してなる変調信号Ｓ１が生成され、この変調信号Ｓ１によりディスク原盤２が露光される。
【００６１】
これによりディスク原盤２においては、符号間干渉を打ち消すように、エッジの位置が補正されて順次ピットが形成され、このディスク原盤２より従来に比して格段的にジッタを低減したコンパクトディスクが作成される。
【００６２】
以上の構成によれば、ＥＦＭ信号Ｓ２の変化パターンに応じて、ＥＦＭ信号Ｓ２のタイミングを補正して変調信号Ｓ１を生成し、この変調信号Ｓ１によりディスク原盤２を露光したことにより、変化パターンに応じて変化する符号間干渉によるジッタを、従来に比して格段的に低減することができる。
【００６３】
またこのとき評価用のコンパクトディスクを作成して補正値データＤＦを生成したことにより、コンパクトディスクの作成条件が変化した場合においても、再度補正値データＤＦを求め直すことで、常に正しい補正値データＤＦによりコンパクトディスクを作成することができる。
【００６４】
（２）第２の実施の形態
図６は、本発明の第２の実施の形態に係る光ディスク装置を示すブロック図である。この光ディスク装置５０では、所定のタイミングでレーザービームＬの光量を立ち上げてディスク原盤２を露光し、これにより局所的に幅広のピットを形成し、コンパクトディスクの反射率を局所的に変化させる。これによりこの光ディスク装置５０では、この局所的な反射率の変化により、文字、画像等を目視確認することができるように、これら文字、画像等をコンパクトディスクの情報記録面に記録する。なおこの図６に示す構成のうち、第１の実施の形態について上述した光ディスク装置１と同一の構成は、対応する符号を付して示し、重複した説明は省略する。
【００６５】
すなわちこの光ディスク装置５０において、文字信号発生回路５１は、光量切換信号ＳＣ１を出力して、レーザービームＬの光路中に介挿した光変調器５２を駆動し、これによりレーザービームＬの光量を切り換え制御する。
【００６６】
ここで図７に示すように、文字信号発生回路５１において、Ｎ進カウンタ５３は、リングカウンタでなり、ＦＧ信号ＦＧをカウントしてカウント値ＣＴ１を出力する。またスピンドルモータ４の回転周期でカウント値が０に切り換わり、このときトラック信号Ｃ１を出力する。
【００６７】
Ｍ進カウンタ５４は、トラック信号Ｃ１をカウントするＭ進のカウンタで構成され、カウント値ＣＴ２を出力する。これにより文字信号発生回路５１は、Ｎ進カウンタ５３及びＭ進カウンタ５４により、ディスク原盤２の円周方向及び半径方向の位置をそれぞれ表してなるカウント値ＣＴ１及びＣＴ２を出力する。
【００６８】
文字信号生成テーブル５５は、各種文字情報のピクセル値を保持するリードオンリメモリ回路で構成され、カウント値ＣＴ１及びＣＴ２をアドレスにして各ピクセル値のデータを出力する。かくするにつきこのピクセル値のデータは、ディスク原盤２に記録する文字、画像をビットマップ形式により表現した各ビットのデータにより構成される。
【００６９】
レベル変換回路５６は、順次入力されるピクセル値のデータを順次ラッチし、光変調器５２（図６）の駆動に適した信号レベルにより出力する。この実施の形態においては、このようにして光変調器５２を駆動して、レーザービームＬの光量を１００〔％〕の光量から８５〔％〕の光量の切り換え、これにより図８に示すように、文字、画像等をディスク表面に記録する。
【００７０】
ところでこのようにしてレーザービームＬの光量を１００〔％〕の光量から８５〔％〕の光量に切り換え制御すると、再生信号も変化するようになる。具体的には、図９及び図１０にそれぞれ１００〔％〕の光量及び８５〔％〕の光量による再生信号のアイパターンを示すように、再生信号の振幅Ｗ１及びＷ２が変化する。これを連続した波形として観察すると、図１１に示すように、正しく再生信号を２値化するためのスライスレベルＳＬ１及びＳＬ２が、１００〔％〕の光量による場合と、８５〔％〕の光量による場合とで相違するようになる。すなわち１００〔％〕の光量による部分と、８５〔％〕の光量による部分とで、アシンメトリーが大きく変化するようになる。
【００７１】
一般のコンパクトディスクプレイヤーにおいては、このようなアシンメトリーの変化に対応してスライスレベルを補正するスライスレベル自動調整回路を備えてはいるものの、このようにして記録する文字、画像等をハッキリと目視確認できるように、レーザービームＬの光量を急激に変化させて輪郭を強調すると、結局、スライスレベル自動調整回路ではこの種の急激な変化には追従することが困難になり、これにより文字、画像等の境目部分で、非常に長いバースト・エラーを発生する。
【００７２】
このためこの実施の形態では、２系統のエッジ補正回路５７Ａ及び５７Ｂより、それぞれ１００〔％〕及び８５〔％〕の光量に対応する変調信号Ｓ１Ａ及びＳ１Ｂを出力する。さらにデータセレクタ５８により、レーザービームＬの光量の切り換えに連動して変調信号Ｓ１Ａ及びＳ１Ｂを選択出力する。
【００７３】
これにより光ディスク装置５０では、レーザービームＬの光量を切り換えて変化するピット幅に応じて、変調信号Ｓ１Ａ及びＳ１Ｂを選択しレーザービームを照射するタイミングを可変し、これによりピット幅の変化に対応して各ピットにおけるエッジの位置を可変する。これによりこのディスク原盤２により作成されるコンパクトディスクにおいては、ピット幅の相違による戻り光の変化を補正するように、同一のデータが割当られたピット間で、ピット長が異なるように形成される。
【００７４】
またこのときピット幅の変化により各光量における符号間干渉の程度も変化することから、それぞれエッジ位置補正回路５７Ａ及び５７ＢによりＥＦＭ信号Ｓ２の変化パターンに対応して変調信号Ｓ１Ａ及びＳ１Ｂのタイミングを可変し、これによりジッタを低減する。かくするにつきエッジ位置補正回路５７Ａ及び５７Ｂは、補正値テーブルに、それぞれ１００〔％〕及び８５〔％〕の光量により作成した補正値データＤＦを保持するようになされている。
【００７５】
かくして実験により観察した結果を図１２に示すように、このようにして変調信号のタイミングを切り換えて、アシンメトリーの変化を有効に回避することができ、これによりスライスレベルＳＬにより１００〔％〕の光量による部分の再生信号と、８５〔％〕の光量による部分の再生信号とを正しく２値化することができた。
【００７６】
図６に示す構成によれば、レーザービームの光量の切り換えに連動して、データセレクタ５８により変調信号Ｓ１Ａ、Ｓ１Ｂを切り換えて変調信号のタイミングを切り換えたことにより、単一のスライスレベルで再生信号を正しく２値化することができ、これによりエラーを有効に回避して正しくデータ再生することができる。
【００７７】
（３）他の実施の形態
なお上述の実施の形態においては、評価用のコンパクトディスクにより作成した補正値テーブルを直接使用してコンパクトディスクを作成する場合について述べたが、本発明はこれに限らず、評価用のコンパクトディスクにより作成した補正値テーブルを用いて改めて評価用のコンパクトディスクを作成し、この改めて作成した評価用のコンパクトディスクにより補正値テーブルを修正してもよい。このように繰り返し補正値テーブルを修正すれば、その分確実にジッタを低減することができる。
【００７８】
また上述の実施の形態においては、ＥＦＭ信号を１３サンプリングして変化パターンを検出する場合について述べたが、本発明はこれに限らず、必要に応じてサンプリング数を増大してもよく、これにより長い記録情報パターンに対応することができる。
【００７９】
さらに上述の実施の形態においては、基本のクロックを基準にした２値化信号の時間計測によりジッタ量を計測し、この計測結果より補正値データを生成する場合について述べたが、本発明はこれに限らず、実用上十分な精度を確保できる場合は、この時間計測によるジッタ量の計測に代えて、基本のクロックを基準にした再生信号の信号レベル検出により補正値データを生成してもよい。なおこの場合、検出した再生信号の信号レベルよりスライスレベルまでの誤差電圧を計算し、この誤差電圧と再生信号の過渡応答特性により補正値データを算出することになる。
【００８０】
また上述の実施の形態においては、テーブル化した補正値データに従って変調信号のタイミングを補正する場合について述べたが、本発明はこれに限らず、実用上十分な精度を確保できる場合は、予め検出した補正値データに代えて、演算処理により補正値データを算出し、これにより変調信号のタイミングを補正してもよい。
【００８１】
さらに上述の実施の形態においては、評価用のコンパクトディスクにより補正値データを算出する場合について述べたが、本発明はこれに限らず、例えばライトワンス型の光ディスク装置に適用する場合は、いわゆる試し書き領域における試し書き結果に基づいて補正値データを算出してもよい。
【００８２】
また上述の実施の形態においては、本発明をコンパクトディスクに適用した場合について述べたが、本発明はこれに限らず、ピットにより種々のデータを記録する光ディスク装置に広く適用することができる。因みに、再生信号の過渡応答特性の相違により種々のデータを多値記録するようになされた光ディスク装置にも広く適用することができる。
【００８３】
【発明の効果】
上述のように本発明によれば、変調信号の変化パターンに応じて変調信号のタイミングを補正することにより、符号間干渉によるジッタを低減することができ、その分読み取りマージンを向上し、記録されたデータを確実に再生することができる。
【００８４】
しかしてこの変調信号のタイミングの補正を、レーザービームの光量の切り換えに連動して実行することにより、アシンメトリーを補正して、単一のスライスレベルにより正しくデータ再生することができる。またレーザービームの光量切り換えに伴うジッタの劣化を有効に回避することができ、これらのことから画像、文字等を記録して、記録されたデータを確実に再生することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係る光ディスク装置を示すブロック図である。
【図２】図１の光ディスク装置のエッジ位置補正回路の動作の説明に供する信号波形図である。
【図３】図１の光ディスク装置の立ち上がりエッジ補正回路を示すブロック図である。
【図４】図１の光ディスク装置における補正値テーブルの作成工程を示す工程図である。
【図５】図４の工程におけるコンピュータの処理手順を示すフローチャートである。
【図６】本発明の第２の実施の形態に係る光ディスク装置を示すブロック図である。
【図７】図６の光ディスク装置の文字信号発生回路を示すブロック図である。
【図８】図６の光ディスク装置により作成されるコンパクトディスクを示す平面図である。
【図９】コンパクトディスクの１００〔％〕の光量による部分の再生信号を示す信号波形図である。
【図１０】コンパクトディスクの８５〔％〕の光量による部分の再生信号を示す信号波形図である。
【図１１】光量の相違によるスライスレベルの変化を示す信号波形図である。
【図１２】図１１との対比により図８のコンパクトディスクによる再生信号を示す信号波形図である。
【符号の説明】
１、５０……光ディスク装置、２……ディスク原盤、１３……変調回路、１４５７Ａ、５７Ｂ……エッジ位置補正回路、１７Ａ……立ち上がりエッジ補正回路、１７Ｂ……立ち下がりエッジ補正回路、２０……補正値テーブル、２２……遅延回路、２３……セレクタ、５１……文字信号発生回路[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc, an optical disc apparatus, and an optical disc recording method. For example, the present invention is applied to a compact disc and reproduces by correcting the timing at which a laser beam rises to the write light amount in conjunction with switching of the write light amount. The jitter at the time is reduced, and the recorded data can be surely reproduced.
[0002]
[Prior art]
Conventionally, in a compact disc, after data to be recorded is processed, EFM (Eight-to-Fourteen Modulation) modulation is performed to form a pit train having a period of 3T to 11T with respect to a predetermined basic period T. Thus, audio data or the like is recorded.
[0003]
Correspondingly, the compact disc player receives a return light by irradiating the compact disc with a laser beam, thereby obtaining a playback signal whose signal level changes according to the amount of the return light, and this playback signal is predetermined. A binarized signal is generated by binarizing according to the slice level. Further, a PLL circuit is driven from the binarized signal to generate a reproduction clock, and the binarized signal is sequentially latched by the reproduction clock, whereby a period 3T to 11T corresponding to a pit string formed on the compact disc. Generate playback data.
[0004]
The compact disc player processes the reproduction data generated in this way in accordance with the data processing at the time of recording, and reproduces audio data and the like recorded on the compact disc.
[0005]
[Problems to be solved by the invention]
By the way, in the conventional compact disc player, the reproduction signal includes jitter. This jitter is considered to be caused by various causes such as laser beam noise used for reading, electrical thermal noise, disk noise, etc., which reduces the phase margin of the playback signal and makes it difficult to correctly reproduce data if it is severe. To do.
[0006]
However, this jitter is essentially due to intersymbol interference from the front and rear pits (Shigeo Kubota, “Aplanatic condition required to reproduce jitter-free signals in an optical digital disk system”, App. Optics 1987, Vol26. , No.18, pp3961-3970), and changes depending on the lands and pits before and after the laser beam irradiation position.
[0007]
The present invention has been made in view of the above points, and intends to propose an optical disc, an optical disc apparatus, and an optical disc recording method capable of reducing jitter during reproduction and reliably reproducing recorded data. It is.
[0008]
[Means for Solving the Problems]
  In order to solve such a problem, in the invention of claim 1, a light amount switching means for switching the light amount of writing and a light amount switching means applied to the optical disc apparatus.The amount of light to write inAnd a timing control means for correcting the timing at which the light amount of the laser beam rises to the light amount for writing is varied.However, the timing correction means corrects the timing of the modulation signal so that the asymmetry of the playback signal does not change even when the writing light quantity is switched.To do.
[0009]
  Further, in the invention of claim 4, when applied to an optical disk recording method, the light quantity of writing is increased in a predetermined area of the disk-shaped recording medium,In order not to change the asymmetry of the playback signal,Correct the timing at which the light quantity of the laser beam rises to the light quantity for writing.
[0010]
  According to a fifth aspect of the present invention, when applied to an optical disk, a high reflectance region and a low reflectance region are formed on the information recording surface, so that a desired image is recorded on the information recording surface and high reflection is achieved. The rate region and the low reflectivity region areThe asymmetry of the reproduction signal is not changed by the switching of the light amount, which is formed by switching the light amount of the laser beam used for forming the pit and the correction of the rise and fall timing linked with the switching of the light amount. likeTo be formed.
[0011]
  And claims7In the invention ofApplied to optical disc manufacturing method for manufacturing optical disc from disc master,Depending on the data used for recording, the amount of laser beam is intermittently increased to the amount of light to be written and the data is recorded on the disk master, so that the amount of light to be written is increased in a predetermined area of the disk master. Corrects the timing to increase the amount of laser beam to the amount of writing so that the asymmetry of the playback signal does not change with the increase in the amount of lightTo do.
[0012]
  The light quantity switching means for switching the light quantity for writing and the light quantity switching means according to the structure of claim 1The amount of light to write inAnd a timing control means for correcting the timing at which the light amount of the laser beam rises to the writing light amount, by varying the timing of the modulation signal in conjunction withCorrects the timing of the modulation signal so that the asymmetry of the playback signal does not change even when the writing light intensity is switched.Then, when the amount of light is switched in order to record characters or the like on the information recording surface so as to be visible, the asymmetry that changes due to the switching of the amount of light can be corrected.
[0013]
Thereby, according to the structure of Claim 4, the recording method of the optical disk which can correct | amend the asymmetry which switches and changes light quantity for recording of a character etc. can be provided.
[0014]
  According to the fifth aspect of the present invention, a high reflectance region and a low reflectance region are formed on the information recording surface, whereby a desired image is recorded on the information recording surface, and a high reflectance region and a low reflectance are recorded. The area ofThe asymmetry of the reproduction signal is not changed by the switching of the light amount, which is formed by switching the light amount of the laser beam used for forming the pit and the correction of the rise and fall timing linked with the switching of the light amount. likeIf formed, characters and the like can be recorded on the information recording surface with the high reflectance region and the low reflectance region.do it,Different asymmetry can be corrected in the high reflectance region and the low reflectance region.
[0015]
  And claims7Depending on the configuration ofApplied to optical disc manufacturing method for manufacturing optical disc from disc master,Depending on the data used for recording, the amount of laser beam is intermittently increased to the amount of light to be written and the data is recorded on the disk master, so that the amount of light to be written is increased in a predetermined area of the disk master. Corrects the timing to increase the amount of laser beam to the amount of writing so that the asymmetry of the playback signal does not change with the increase in the amount of lightIf so, characters and the like can be recorded on the information recording surface in a highly reflective area and a low reflectance area.Different asymmetry can be corrected in the high reflectance region and the low reflectance region.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
[0017]
(1) First embodiment
FIG. 1 is a block diagram showing an optical disc apparatus according to an embodiment of the present invention.
The optical disk apparatus 1 records the audio data D1 output from the digital audio tape recorder 3 by exposing the disk master 2. In the manufacturing process of the optical disc, the master disc 2 is developed and then electroformed to produce a mother disc, and a stamper is produced from the mother disc. Further, in the manufacturing process of the optical disk, a disk-shaped substrate is prepared from the stamper thus prepared, and a reflective film and a protective film are formed on the disk-shaped substrate to form a compact disk.
[0018]
That is, in the optical disc apparatus 1, the spindle motor 4 rotates the disc master 2 and outputs an FG signal FG whose signal level rises at every predetermined rotation angle from the FG signal generator held at the bottom. The spindle servo circuit 5 drives the spindle motor 4 so that the frequency of the FG signal becomes a predetermined frequency in accordance with the exposure position of the disc master 2, thereby rotating the disc master 2 under the condition that the linear velocity is constant. .
[0019]
The recording laser 7 is composed of a gas laser or the like, and emits a laser beam L for exposing a disc master. The light modulator 8 is composed of an electroacoustic optical element, and emits the laser beam L under on / off control by a modulation signal S1. The mirror 10 bends the optical path of the laser beam L and emits it toward the disc master 2, and the objective lens 11 condenses the reflected light of the mirror 10 on the disc master 2. The mirror 10 and the objective lens 11 are sequentially moved in the radial direction of the disk master 2 in synchronization with the rotation of the disk master 2 by a thread mechanism (not shown), whereby the exposure position by the laser beam L is sequentially changed to the outer periphery of the disk master 2. Displace in the direction.
[0020]
As a result, in this optical disc apparatus 1, a spiral track is formed by the movement of the mirror 10 and the objective lens 11 while the disc master 2 is rotationally driven, and pits are sequentially formed on this track corresponding to the modulation signal S1. .
[0021]
The modulation circuit 13 inputs the audio data D1 from the digital audio tape recorder 3 and inputs the subcode data corresponding to the audio data D1, and the audio data D1 and the subcode data are processed by the data processing defined for the compact disc. Data is processed according to the method. That is, the modulation circuit 13 adds an error correction code to the audio data D1 and the subcode data, then performs an interleaving process, subsequently performs EFM modulation, and outputs an EFM signal S2.
[0022]
The edge position correction circuit 14 detects a change pattern of the EFM signal S2, and corrects the timing of the EFM signal S2 so as to effectively avoid intersymbol interference during reproduction according to the change pattern.
[0023]
That is, in the edge position correction circuit 14, the level conversion circuit 15 corrects the signal level of the EFM signal S2 having an output amplitude of 1 [V] to a TTL level having an output amplitude of 5 [V] and outputs the corrected signal. As shown in FIG. 2, the PLL circuit 16 generates and outputs a clock CK (FIG. 2B) from the EFM signal S2 (FIG. 2A). Accordingly, in the FFM signal S2, the signal level changes in the period of 3T to 11T with respect to the basic period T, so that the PLL circuit 16 changes the signal level in accordance with the basic period T synchronized with the EFM signal S2. The clock CK to be generated is generated.
[0024]
As shown in FIG. 3, the rising edge correction circuit 17 </ b> A connects 13 latch circuits 19 </ b> A to 19 </ b> M that operate with the clock CK in series, and inputs the output signal S <b> 3 of the level conversion circuit 15 to this series circuit. As a result, the rising edge correction circuit 17A samples the output signal S3 of the level conversion circuit 15 at the timing of the clock CK, and detects the change pattern of the EFM signal S2 from the sampling results of 13 consecutive points. That is, for example, when a latch output of “0001111000001” is obtained, in this case, it can be determined as a change pattern in which a pit having a length of 4T follows a space having a length of 5T. Similarly, when a latch output of “0011111000001” is obtained, it can be determined as a change pattern in which a pit having a length of 5T continues after a space having a length of 5T.
[0025]
The correction value table 20 is formed of a read only memory storing a plurality of correction data, and outputs the correction value data DF corresponding to the change pattern of the EFM signal S2 with the latch outputs of the latch circuits 19A to 19M as addresses. The monostable multivibrator (MM) 21 receives latch output inputs from thirteen central latch circuits 19G connected in series. The monostable multivibrator (MM) 21 receives a latch output input timing for a predetermined period (period 3T). A rising pulse signal in which the signal level rises is output for a sufficiently short period).
[0026]
The delay circuit 22 has twelve stages of tap outputs, and the delay time difference between the taps is set to the resolution of the timing correction of the modulation signal in the edge position correction circuit 14. The delay circuit 22 sequentially delays the rising pulse signal output from the monostable multivibrator 21 and outputs it from each tap. The selector 23 selectively outputs the tap output of the delay circuit 22 according to the correction value data DF, and thereby selects and outputs the rising pulse signal SS (FIG. 2D) having a delay time changed according to the correction value data DF. To do.
[0027]
Thus, the rising edge correction circuit 17A rises in response to the rising of the signal level of the EFM signal S2, and the delay times Δr (3, 3) and Δr (4, 3) of the rising edges with respect to the EFM signal S2. , Δr (3, 4), Δr (5, 3),... Are rising edges of the corresponding EFM signal S2, and rising edges that change according to the change pattern of the EFM signal S2 detected by a total of 13 samplings before and after. Generate SS.
[0028]
In FIG. 3, the change pattern of the modulation signal S2 is represented by a pit length p in units of one cycle of a clock (that is, a channel clock) CK and a pit interval b, and a delay time with respect to a rising edge is represented by Δr. This is indicated by (p, b). Therefore, in FIG. 2D, the delay time Δr (4, 3) described second is the delay time when there is a blank of 3 clocks before a pit of 4 clocks in length. As a result, the correction value table 20 stores correction value data DF corresponding to all combinations of p and b.
[0029]
Thus, in a compact disk, generally, the rising edge correction circuit 17A is configured to have a range of 12T before and after the basic period T by irradiating the laser beam L according to the EFM signal S2 to form pits. A pattern of pits formed on the compact disc is detected, and a rising edge signal SS is generated according to this pattern.
[0030]
The falling edge correction circuit 17B is the same as the rising edge correction circuit 17A except that the monostable multivibrator 21 operates based on the falling edge of the latch output and the content of the correction value table 20 is different. Composed.
[0031]
As a result, the falling edge correction circuit 17B rises in response to the fall of the signal level of the EFM signal S2, and the delay times Δf (3, 3), Δf (4, 4) of the rising edges with respect to the EFM signal S2. 4), Δf (3, 3), Δf (5, 4),... Change in accordance with the change pattern of the EFM signal S2 detected by a total of 13 samplings before and after the falling edge of the corresponding EFM signal S2. A falling edge signal SR (FIG. 2C) is generated. In FIG. 3, similarly to the delay time with respect to the rising edge, the delay time with respect to the falling edge is represented by Δf (p, b) by the pit length p and the pit interval b.
[0032]
Accordingly, the falling edge correction circuit 17B detects the pattern of pits formed on the compact disk in the range of 12T before and after the basic period T as a unit, and the timing of ending the irradiation of the laser beam according to this pattern The falling edge signal SR is generated by correcting the timing of the falling edge of the EFM signal S2.
[0033]
The flip-flop (F / F) 25 (FIG. 1) combines and outputs the rising edge signal SS and the falling edge signal SR. That is, the flip-flop 25 inputs the rising edge signal SS and the falling edge signal SR to the set terminal S and the reset terminal R, respectively, so that the signal level rises at the rising edge of the rising edge signal SS and then falls. A modulation signal S5 whose signal level falls at the rise of the signal level of the edge signal SR is generated.
The level inverse conversion circuit 26 corrects the signal level of the modulation signal S5 whose output amplitude is the TTL level, and outputs the signal with the original output amplitude of 1V.
[0034]
Thereby, in the modulation signal S1, the timing of the rising edge and the falling edge is corrected in accordance with the lengths of the front and rear pits and lands, and the laser beam L is applied to the disk master 2 correspondingly. The timing of the correction is also corrected in accordance with the lengths of the front and rear pits and lands. Therefore, in the compact disc produced by this disc master 2, the edge position is changed from the basic position in accordance with the front and rear pit lengths and land lengths, so that the same data is allocated between the pits. Thus, the pit length is changed and formed. As a result, the optical disc apparatus 1 corrects the positions of the front edge and the rear edge of each pit so as to reduce jitter generated by intersymbol interference during reproduction.
[0035]
FIG. 4 is a process diagram for explaining the generation of the correction value table 20 used for edge timing correction in this manner. In the optical disc apparatus 1, by appropriately setting the correction value table 20, the positions of the front edge and the rear edge of the pit can be set to optimum positions, and the reproduction signal can be changed at the correct timing synchronized with the clock CK. it can. That is, even when the pit size and the preceding and following blank lengths change, the reproduced signal passes through a predetermined slice level at the correct timing synchronized with the clock CK, and as a result, a reproduced signal with less jitter can be obtained. Become. Although the correction value table 20 exists in both the rising edge correction circuit 17A and the falling edge correction circuit 17B, since the setting method is the same for both, the description is limited to the rising edge correction circuit 17A here. .
[0036]
In this step, a correction value table is set on the evaluation master disc by the optical disc apparatus 1 based on the reproduction result of the compact disc created from the master disc.
[0037]
Here, at the time of creating the disc master for evaluation, a correction value table 20 for evaluation criteria is set in the optical disc apparatus 1. Here, the evaluation standard correction value table 20 is formed by setting the correction value data DF so that the selector 23 always selects and outputs the center tap output of the delay circuit 22. Thus, in this step, the master disc 2 is exposed under the same conditions as when the optical modulator 8 is directly driven by the EFM signal S3, that is, under the same conditions as in the conventional compact disc producing step.
[0038]
In this step, the exposed master disk 2 is developed and electroformed to create a mother disk, and a stamper 40 is formed from the mother disk. Further, a compact disc 41 is produced from this stamper 40 in the same manner as in a normal compact disc producing process.
[0039]
The compact disc player (CD player) 42 reproduces the evaluation compact disc 41 created in this way. At this time, the compact disc player 42 switches its operation under the control of the computer 44 and outputs the reproduction signal RF to the digital oscilloscope 43 from the built-in signal processing circuit. The reproduction signal RF changes in signal level in accordance with the amount of return light obtained from the compact disc, and is output from the output of the optical pickup via a predetermined buffer circuit. Accordingly, since the compact disk 41 is created under the same conditions as a normal compact disk, jitter is observed when the reproduction signal RF is observed with the digital oscilloscope 43 using the reproduction clock as a trigger. Become.
[0040]
The digital oscilloscope 43 switches the operation under the control of the computer 44, performs an analog-digital conversion process on the reproduction signal RF at a sampling frequency 20 times the channel clock, and outputs the resulting digital signal to the computer 44.
[0041]
The computer 44 controls the operation of the digital oscilloscope 43 and also processes the digital signal output from the digital oscilloscope 43, thereby sequentially calculating the correction value data DF. Further, the computer 44 drives the ROM writer 45 to sequentially store the calculated correction value data DF in the read-only memory, thereby forming the correction value table 20. In this step, the compact disc is finally manufactured by using the correction value table 20.
[0042]
FIG. 5 is a flowchart showing a processing procedure in the computer 44. In this processing procedure, the computer 44 proceeds from step SP1 to step SP2, and sets the jitter detection result Δr (p, b) and the jitter measurement count n (p, b) to the value 0. Here, the computer 44 calculates the jitter detection result Δr (p, b) for each combination of the pit length p and the pit interval b before and after the edge to be detected by jitter, and the jitter measurement count n (p, b). ). Therefore, in step SP2, the computer 44 sets all these jitter detection results Δr (p, b) and the number of jitter measurements n (p, b) to initial values.
[0043]
Subsequently, the computer 44 proceeds to step SP3, and compares the digital signal output from the digital oscilloscope 43 with a predetermined slice level to generate a digital binarized signal obtained by binarizing the reproduction signal RF. In this process, the computer 44 binarizes the digital signal so that the value above the slice level is 1 and the value 0 is below the slice level.
[0044]
Subsequently, the computer 44 proceeds to step SP4, and generates a reproduction clock from the binarized signal composed of this digital signal. Here, the computer 44 simulates the operation of the PLL circuit by a calculation process based on the binarized signal, thereby generating a reproduction clock.
[0045]
Further, in the following step SP5, the computer 44 samples the binarized signal at the timing of each falling edge of the reproduction clock thus generated, and thereby decodes the EFM signal (hereinafter, the decoded EFM signal is referred to as the EFM signal). Called EFM decoded signal).
[0046]
Subsequently, the computer 44 proceeds to step SP6 to detect a time difference e from the time point of the rising edge of the binarized signal to the time point of falling edge of the reproduction clock closest to this edge, and thereby jitter at this edge. Time measurement. Subsequently, in step SP7, the computer 44 detects the pit length p and the pit interval b before and after the edge measured in step SP6 from the EFM decoded signal.
[0047]
Subsequently, in step SP8, the computer 44 adds the time difference e detected in step SP6 to the jitter detection result Δr (p, b) corresponding to the pit length p and the pit interval b before and after, and the corresponding jitter. The measurement number n (p, b) is incremented by a value 1. Subsequently, the computer 44 proceeds to step SP9, determines whether or not the time measurement has been completed for all the rising edges, and returns a step SP5 when a negative result is obtained.
[0048]
As a result, the computer 44 repeats the processing procedure of steps SP5-SP6-SP7-SP8-SP9-SP5, cumulatively adds the time-measured jitter detection results for each change pattern appearing in the reproduction signal RF, and counts the number of additions. To do.
[0049]
When the jitter time measurement is completed for all the edges in this way, the computer 44 moves to step SP10 when an affirmative result is obtained in step SP9, and here, for each change pattern appearing in the reproduction signal RF, the time is increased. Average the measured jitter detection results. That is, since the jitter detected in step SP6 is affected by noise, the computer 44 averages the jitter detection result in this way, thereby improving the jitter measurement accuracy.
[0050]
After averaging the jitter detection results in this way, the computer 44 proceeds to step SP11. Based on the detection results, the computer 44 generates correction value data DF for each change pattern, and stores each correction value data DF in the ROM. Output to writer 45. Here, the correction value data DF is calculated by executing a calculation process of the following equation, where τ is a delay time difference between taps in the delay circuit 22.
[Expression 1]

[0051]
Here, Hr1 (p, b) is a tap of the delay circuit 22 selected by the correction value data DF, and a value of 0 is a center tap. Hr0 (p, b) is a tap of the delay circuit 22 selected by the correction value data DF which is an initial value. In this embodiment, Hr0 (p, b) is set to a value of 0. It will be. A is a constant. Here, in this embodiment, a is set to a value of 1 or less (for example, 0.7), and is placed so that the correction value data can be reliably converged even if there is an influence of noise or the like. .
[0052]
When the computer 44 stores the correction value data DF in the ROM writer 45 in this way, the computer 44 proceeds to step SP12 and ends this processing procedure. Subsequently, the computer 44 executes the same processing procedure for the falling edge of the digital binarized signal, thereby completing the correction value table 20.
[0053]
In the above configuration, in the optical disk apparatus 1 (FIG. 1), the correction value table 20 in the rising edge correction circuit 17A and the falling edge correction circuit 17B is set to the initial value, thereby being the same as the conventional compact disk creation conditions. The evaluation disc master 2 is created under the conditions (FIG. 4), and the evaluation compact disc 41 is created from this disc master 2.
[0054]
The compact disc 41 for evaluation is subjected to on / off control of the laser beam L by an EFM signal whose signal level changes at an integer multiple of the basic cycle T, and the master disc 2 is sequentially exposed to form pits, thereby reproducing the disc. The signal receives intersymbol interference from adjacent pits and lands. Therefore, the reproduction signal obtained from the compact disc 41 changes the timing of crossing the slice level according to the shape of the front and rear pits and lands, that is, according to the change pattern of the EFM signal, and jitter occurs.
[0055]
The compact disc 41 is reproduced by the compact disc player 42, and the reproduction signal RF is converted into a digital signal by the digital oscilloscope 43, and then a binary signal, an EFM decoded signal, and a reproduction clock are generated by the computer 44. Further, the compact disk 41 detects pits and lands before and after the EFM decoded signal for each edge of the binarized signal to detect a change pattern of the EFM signal. For each change pattern, the edge of each edge with respect to the reproduction clock is detected. The amount of jitter is timed.
[0056]
Further, these time measurement results are averaged for each change pattern, and the amount of jitter generated by intersymbol interference is detected for each change pattern. The compact disk 41 executes the arithmetic processing of the expression (1) based on the delay time difference τ between taps of the delay circuit 22 (FIG. 3), which is a jitter correction unit, based on the jitter amount thus detected. The tap position of the delay circuit 22 capable of canceling the detected jitter amount is detected with reference to the center tap of the delay circuit 22, and data specifying the tap position is stored in the read-only memory as correction value data DF. Thus, the correction value table 20 is formed.
[0057]
When the correction value table 20 is formed in this way, the audio data D1 and subcode data input from the digital audio tape recorder 3 (FIG. 1) are subjected to prescribed data processing by the modulation circuit 13, and the basic period T is a unit. Thus, it is converted into an EFM signal S2 whose signal level changes. The signal level of the EFM signal S2 is converted to the TTL level by the level conversion circuit 15, and then the clock CK is reproduced by the PLL circuit 16, and the rising edge correction circuit 17A and the falling edge correction circuit 17B (FIG. 3). Are sequentially latched by the 13-stage latch circuits 19A to 19M, and the change pattern is detected.
[0058]
Further, the EFM signal S2 is input to the monostable multivibrator 21 from an intermediate latch circuit of the latch circuits 19A to 19M. The rising edge correction circuit 17A has a rising edge timing, and the falling edge correction circuit 17B The monostable multivibrator 21 is triggered at the timing of the falling edge, and a rising pulse signal and a falling pulse signal whose signal level rises at the timing of the rising edge and the falling edge, respectively, are generated.
[0059]
The rising pulse signal and the falling pulse signal are sequentially delayed in units of the delay time τ used for calculating the correction value data DF in the delay circuit 22 of the rising edge correction circuit 17A and the falling edge correction circuit 17B, respectively. The tap output of the delay circuit 22 is output to the selector 23. On the other hand, in the change pattern of the EFM signal S2 detected by the latch circuits 19A to 19M, the corresponding correction value data DF is detected by accessing the correction value table 20 using the latch outputs of the latch circuits 19A to 19M as addresses. The contact of the selector 23 is switched by the correction value data DF.
[0060]
Accordingly, the timing of the rising edge and the falling edge of the EFM signal S2 is adjusted so that the jitter detected by the compact disc 41 for evaluation is corrected by the selector 23 of the rising edge correction circuit 17A and the falling edge correction circuit 17B. A rising edge signal SS and a falling edge signal SR that are respectively corrected are output, and the rising edge signal SS and the falling edge signal SR (FIG. 1) are combined by the flip-flop 25. Further, the output signal S5 of the flip-flop 25 is subjected to signal level correction by the level inverse conversion circuit 26, thereby correcting the jitter detected by the evaluation compact disk 41, that is, reducing the intersymbol interference. The modulation signal S1 is generated by correcting the edge timing of the EFM signal S2, and the master disk 2 is exposed by the modulation signal S1.
[0061]
As a result, in the master disc 2, the edge positions are corrected so that the intersymbol interference is corrected, and pits are formed in sequence, and a compact disc with much lower jitter than the conventional master disc 2 is created. Is done.
[0062]
According to the above configuration, the modulation signal S1 is generated by correcting the timing of the EFM signal S2 in accordance with the change pattern of the EFM signal S2, and the disk master 2 is exposed to the modulation signal S1, so that the change pattern is obtained. Jitter due to intersymbol interference that changes accordingly can be significantly reduced as compared with the prior art.
[0063]
At this time, by creating a compact disk for evaluation and generating correction value data DF, even if the compact disk creation conditions change, the correction value data DF is obtained again, so that the correct correction value data is always obtained. Compact discs can be created using DF.
[0064]
(2) Second embodiment
FIG. 6 is a block diagram showing an optical disc apparatus according to the second embodiment of the present invention. In this optical disk device 50, the amount of the laser beam L is raised at a predetermined timing to expose the disk master 2, thereby forming a wide pit locally and locally changing the reflectance of the compact disk. Thereby, in this optical disc device 50, these characters, images, etc. are recorded on the information recording surface of the compact disc so that the characters, images, etc. can be visually confirmed by this local change in reflectance. Of the configuration shown in FIG. 6, the same configuration as that of the optical disc apparatus 1 described above with respect to the first embodiment is indicated by the corresponding reference numeral, and redundant description is omitted.
[0065]
That is, in this optical disc apparatus 50, the character signal generation circuit 51 outputs the light quantity switching signal SC1 to drive the optical modulator 52 inserted in the optical path of the laser beam L, thereby switching the light quantity of the laser beam L. Control.
[0066]
Here, as shown in FIG. 7, in the character signal generating circuit 51, the N-ary counter 53 is a ring counter, counts the FG signal FG, and outputs a count value CT1. Further, the count value is switched to 0 at the rotation cycle of the spindle motor 4, and at this time, the track signal C1 is output.
[0067]
The M-ary counter 54 is composed of an M-ary counter that counts the track signal C1, and outputs a count value CT2. As a result, the character signal generation circuit 51 outputs count values CT1 and CT2 representing the positions of the disc master 2 in the circumferential direction and the radial direction by the N-ary counter 53 and the M-ary counter 54, respectively.
[0068]
The character signal generation table 55 is composed of a read-only memory circuit that holds pixel values of various character information, and outputs data of each pixel value with the count values CT1 and CT2 as addresses. Thus, the pixel value data is composed of data of each bit in which characters and images to be recorded on the disc master 2 are expressed in a bitmap format.
[0069]
The level conversion circuit 56 sequentially latches data of pixel values that are sequentially input, and outputs the data at a signal level suitable for driving the optical modulator 52 (FIG. 6). In this embodiment, the light modulator 52 is driven in this way, and the light amount of the laser beam L is switched from the light amount of 100 [%] to the light amount of 85 [%], and as shown in FIG. Record characters, images, etc. on the disk surface.
[0070]
By the way, when the light amount of the laser beam L is switched from the light amount of 100 [%] to the light amount of 85 [%] in this way, the reproduction signal also changes. Specifically, the amplitudes W1 and W2 of the reproduction signal change so that the eye pattern of the reproduction signal with the light amount of 100 [%] and the light amount of 85 [%] is shown in FIGS. When this is observed as a continuous waveform, as shown in FIG. 11, the slice levels SL1 and SL2 for correctly binarizing the reproduction signal are based on the light amount of 100 [%] and the light amount of 85 [%]. It becomes different from the case. That is, the asymmetry changes greatly between the portion with the light amount of 100 [%] and the portion with the light amount of 85 [%].
[0071]
A general compact disc player has a slice level automatic adjustment circuit that corrects the slice level in response to such a change in asymmetry, but clearly confirms the characters and images to be recorded in this way. If the contour is enhanced by abruptly changing the light amount of the laser beam L so that it can be done, it becomes difficult for the slice level automatic adjustment circuit to follow such a sudden change. A very long burst error occurs at the boundary of
[0072]
Therefore, in this embodiment, the modulation signals S1A and S1B corresponding to the light amounts of 100 [%] and 85 [%] are output from the two systems of edge correction circuits 57A and 57B, respectively. Further, the data selector 58 selectively outputs the modulation signals S1A and S1B in conjunction with the switching of the light amount of the laser beam L.
[0073]
Thereby, in the optical disc apparatus 50, the modulation signals S1A and S1B are selected and the timing of irradiating the laser beam is varied in accordance with the pit width that changes by switching the light amount of the laser beam L, thereby responding to the change in the pit width. To change the position of the edge in each pit. As a result, the compact disc produced by the master disc 2 is formed so that the pit lengths are different between pits to which the same data is assigned so as to correct the change in the return light due to the difference in the pit width. .
[0074]
At this time, since the degree of intersymbol interference in each light quantity also changes due to the change in the pit width, the timings of the modulation signals S1A and S1B are made variable by the edge position correction circuits 57A and 57B in accordance with the change pattern of the EFM signal S2. This reduces jitter. Accordingly, the edge position correction circuits 57A and 57B hold the correction value data DF created with the light amounts of 100 [%] and 85 [%] in the correction value table, respectively.
[0075]
Thus, as shown in FIG. 12, the result of the experiment observation is such that the timing of the modulation signal can be switched in this way to effectively avoid the change in asymmetry. It was possible to correctly binarize the reproduction signal of the portion due to and the reproduction signal of the portion due to the light amount of 85 [%].
[0076]
According to the configuration shown in FIG. 6, in conjunction with switching of the light amount of the laser beam, the modulation signal S1A and S1B are switched by the data selector 58 to switch the timing of the modulation signal, thereby reproducing the reproduction signal at a single slice level. Can be correctly binarized, and thus data can be reproduced correctly while effectively avoiding errors.
[0077]
(3) Other embodiments
In the above-described embodiment, the case of creating a compact disk by directly using the correction value table created by the evaluation compact disk has been described. However, the present invention is not limited to this, and the evaluation compact disk is used. A compact disk for evaluation may be newly created using the created correction value table, and the correction value table may be corrected using the newly created compact disk for evaluation. If the correction value table is corrected repeatedly in this way, the jitter can be reliably reduced accordingly.
[0078]
In the above-described embodiment, the case where the change pattern is detected by sampling 13 EFM signals has been described. However, the present invention is not limited to this, and the number of samplings may be increased as necessary. A long recording information pattern can be handled.
[0079]
Further, in the above-described embodiment, the case where the jitter amount is measured by the time measurement of the binarized signal based on the basic clock and the correction value data is generated from the measurement result has been described. However, if sufficient accuracy can be ensured in practice, the correction value data may be generated by detecting the signal level of the reproduction signal based on the basic clock instead of measuring the jitter amount by this time measurement. . In this case, an error voltage from the signal level of the detected reproduction signal to the slice level is calculated, and correction value data is calculated from the error voltage and the transient response characteristic of the reproduction signal.
[0080]
In the above-described embodiment, the case where the timing of the modulation signal is corrected according to the correction value data tabulated has been described. However, the present invention is not limited to this, and in the case where sufficient accuracy can be secured in practice, detection is performed in advance. Instead of the correction value data, the correction value data may be calculated by arithmetic processing, thereby correcting the timing of the modulation signal.
[0081]
Further, in the above-described embodiment, the case where correction value data is calculated using a compact disc for evaluation has been described. However, the present invention is not limited to this, and for example, when applied to a write-once type optical disc apparatus, a so-called trial is performed. The correction value data may be calculated based on the test writing result in the writing area.
[0082]
In the above-described embodiment, the case where the present invention is applied to a compact disc has been described. However, the present invention is not limited to this, and can be widely applied to optical disc apparatuses that record various data using pits. Incidentally, the present invention can be widely applied to an optical disk apparatus adapted to record various data in a multi-valued manner due to a difference in transient response characteristics of a reproduction signal.
[0083]
【The invention's effect】
As described above, according to the present invention, jitter due to intersymbol interference can be reduced by correcting the timing of the modulation signal in accordance with the change pattern of the modulation signal, thereby improving the read margin and recording. Data can be reproduced reliably.
[0084]
Therefore, by correcting the timing of the modulation signal in conjunction with the switching of the light amount of the laser beam, it is possible to correct the asymmetry and to correctly reproduce the data with a single slice level. Further, it is possible to effectively avoid the deterioration of jitter associated with the switching of the light amount of the laser beam, and from these facts, it is possible to record images, characters, etc., and reliably reproduce the recorded data.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an optical disc apparatus according to a first embodiment of the present invention.
2 is a signal waveform diagram for explaining the operation of the edge position correction circuit of the optical disc apparatus of FIG. 1; FIG.
3 is a block diagram showing a rising edge correction circuit of the optical disc apparatus of FIG. 1. FIG.
4 is a process diagram showing a correction value table creation process in the optical disc apparatus of FIG. 1; FIG.
5 is a flowchart showing a processing procedure of a computer in the step of FIG.
FIG. 6 is a block diagram showing an optical disc apparatus according to a second embodiment of the present invention.
7 is a block diagram showing a character signal generation circuit of the optical disc apparatus of FIG. 6. FIG.
8 is a plan view showing a compact disc created by the optical disc apparatus of FIG. 6. FIG.
FIG. 9 is a signal waveform diagram showing a reproduction signal of a portion with a light quantity of 100 [%] of a compact disc.
FIG. 10 is a signal waveform diagram showing a reproduction signal of a portion of a compact disc with a light amount of 85 [%].
FIG. 11 is a signal waveform diagram showing a change in slice level due to a difference in light amount.
12 is a signal waveform diagram showing a reproduction signal by the compact disc of FIG. 8 in comparison with FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,50 ... Optical disk apparatus, 2 ... Disc master, 13 ... Modulation circuit, 1457A, 57B ... Edge position correction circuit, 17A ... Rising edge correction circuit, 17B ... Falling edge correction circuit, 20 ... Correction value table, 22 ... delay circuit, 23 ... selector, 51 ... character signal generation circuit

Claims (7)

An optical disc apparatus that generates a modulation signal according to data to be recorded, drives a laser light source according to the modulation signal, intermittently raises the light amount of a laser beam to a write light amount, and records the data on a disc-shaped recording medium In
A light amount switching means for switching the light amount of the writing;
E Bei and said interlocked with switching of the light quantity of the writing in the light intensity switching means varying the timing of the modulation signal, timing control means for correcting the timing of launching the light amount of the laser beam to the light intensity of the writing,
The timing correction means includes
An optical disc apparatus , wherein the modulation signal timing is corrected so that the asymmetry of the reproduction signal does not change even when the write light quantity is switched . The timing control means includes
Change pattern detection means for detecting a change pattern of the modulation signal by sequentially sampling the modulation signal at a clock timing synchronized with the data;
When the reproduction signal obtained from the disc-shaped recording medium is binarized at a predetermined slice level in accordance with the change pattern to generate a binarized signal, the binarized signal in units of the basic period of pits The timing correction means for correcting the timing of the modulation signal so as to change, a plurality of systems corresponding to the switching of the write light amount ,
2. The optical disk apparatus according to claim 1, wherein the timing of the modulation signal is varied in conjunction with the light quantity switching means by switching of the timing correction means in conjunction with the light quantity switching means . The timing correction means includes
According to the correction data stored in the correction data storage means, correct the timing of the modulation signal,
The correction data is
The optical disc apparatus according to claim 2, wherein the optical disc apparatus is set in advance based on a reproduction result of a disc-shaped recording medium for evaluation. In the recording method of the optical disc in which the data is recorded on the disc-shaped recording medium by raising the light amount of the laser beam intermittently to the light amount of writing according to the data provided for recording,
In a predetermined area of the disc-shaped recording medium, the amount of light for writing is increased, and the amount of light of the laser beam is set to the amount of light for writing so that the asymmetry of the reproduction signal does not change as the amount of light for writing increases. A method of recording an optical disc, wherein the timing for raising is corrected. In an optical disc on which desired data is recorded by pits formed on the information recording surface,
By forming a high reflectance region and a low reflectance region on the information recording surface, a desired image is recorded on the information recording surface,
The high reflectivity region and the low reflectivity region are:
It is formed by switching the amount of laser beam used for pit formation,
The optical disk is formed so that the asymmetry of the reproduction signal is not changed by the switching of the light amount by switching the correction of the rise and fall timing of the light amount in conjunction with the switching of the light amount . When the reproduction signal is binarized at a predetermined slice level and the binarized signal is generated by correcting the rise and fall timings of the light amount, the binarized signal in units of the basic period of pit formation The optical disc according to claim 5, wherein the optical disc is set to change . In an optical disk manufacturing method for manufacturing an optical disk from a disk master,
According to the data to be used for recording, the light amount of the laser beam is intermittently raised to the light amount of writing, and the data is recorded on the disc master,
The timing at which the light amount of the laser beam is raised to the write light amount so that the write light amount is increased and the asymmetry of the reproduction signal does not change with respect to the increase of the write light amount in a predetermined area of the disc master. A method of manufacturing an optical disc, wherein

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