JP3693659B2 - Information recording method by information recording / reproducing apparatus using optical recording medium, signal collector and distributor for information recording, and information recording / reproducing apparatus using optical recording medium - Google Patents

Description

【００３６】
これらの幾何学的な模様によって、トラック２２の読み出す符号ビットが「１」の時、この符号ビットの位置に対して直角な方向に隣接するトラック２１及び２３の符号ビットを「０」にできることが視覚的に分かる。
【００３７】
さて、これら３０種類の２次元の符号ビット行列のうち例えば１６種類を選択する。すると、１次元の情報ビット４ビットを、これらの１６種類の２次元の符号ビット行列に変換することも可能となる。残りの２次元の符号ビット行列はビットの再同期パターンとして使用することも可能である。
【００３８】
また、この例ではどのトラックにおいても少なくとも１つの「１」及び「０」を含ませており、いわゆるＲＬＬ符号としている。つまり、ＰＬＬ回路におけるビット同期が容易な符号化方法が実現できる。
【００３９】
なお、３×３行列以上の２次元の符号ビット行列については、符号ビット行列数が多くなるため、紙面の都合上説明は省略する。
【００４０】
第５の実施例について以下に説明する。
【００４１】
図９は本発明の第５の実施例における符号化方法を示す図である。これは、図１２に示した従来のＲＬＬ符号変換表に基づいて符号化した後、符号ビットをトラックに沿う方向ではなく、トラックに直角な方向に並べていく方法である。たとえば、情報ビットを符号変換表の上から順番に並べて「０１１０１１００００１・・・」とすると、符号ビットは「１０００１０１０１０００００１・・・」となる。つまり、図１２の（１、７）ＲＬＬ符号では、符号ビットが「１」と次の「１」の間に少なくとも一つの「０」が入るため、符号ビット「１」に対して隣接トラックの符号ビットを必ず「０」にすることが可能となる。したがって、読み出し信号のクロストークが発生しない符号化方法を提供できる。また、図９のトラック数は６であり、ちょうど符号ビットの変換単位（３ビットあるいは６ビット）の整数倍（１または２）となっている。つまり、トラック数はＲＬＬ符号の種類によって整数倍となるように決定すれば、区切りのよい符号化ができる。
【００４２】
なお、上記では（１、７）ＲＬＬ符号を例に挙げたが、その他のＲＬＬ符号の場合も同様である。
【００４３】
また、光記録再生装置及び光記録媒体においては、隣接トラック同士の符号ビットの間隔が極めて短く（１〜２μｍ程度）、これによってクロストークも発生しやすいが、短い故に符号ビットどうしを同期させて隣に配列することが容易である。つまり、本発明は特に光記録再生装置及び光記録媒体において有効な符号化方法となる。
【００４４】
また、上記第１〜第５の実施例において隣接トラックの符号ビット同士を、トラックに沿う方向に対してすべて同期させている。これは、複数の光ビームをもつマルチビーム記録再生装置において、特に容易に記録再生が可能となる。つまり、マルチビーム記録再生装置では複数の光ビームの照射位置を固定可能であるため、常に同期した符号ビットを記録再生することが可能となる。
【００４５】
また、説明を簡単にするためにＮＲＺ記録に限定して説明したが、これに限定する必要はなく、いわゆるＮＲＺＩ記録などにおいても、トラックに記録する符号ビットを「記録マーク」と「非マーク」により表現すれば同様に符号化を行うことが可能である。
【００４６】
本発明に係るマルチビーム記録再生装置について、光記録再生装置を例として以下に説明する。
【００４７】
図２５は本発明の光記録再生装置を示す図である。情報記録時は情報ビット（記録データ）が符号器２１３に入力され、例えば３トラックにまたがる符号化が行われ、変調ビット（符号語）は分配器２１４に送られる。分配器２１４からは、第１トラックに記録する変調ビット、第２トラックに記録する変調ビット及び第３トラックに記録する変調ビットがそれぞれ出力される。これらの変調ビットはそれぞれ３つのレーザ駆動回路２１５０、２１６０、２１７０に送られる。レーザ駆動回路２１５０、２１６０、２１７０から駆動電流が半導体レーザ２１５、２１６、２１７に送られ、３つの光ビームがビームスプリッタ２５０、対物レンズ２５１を介して光ディスク２５２に照射され、分配された３つの変調ビットが同時に記録される。
【００４８】
情報再生時は光ディスク２５２に記録された記録ビットからの３つの反射光を対物レンズ２５１を介してビームスプリッタ２５０により光路を曲げ、３つのフォトディテクタ２１８、２１９、２２０に導く。電気信号に変換された再生信号はそれぞれアンプ２５３、２５４、２５５で増幅され、波形整形器２５６、２５７、２５８で「１」または「０」のデジタル信号に変換される。第１トラックからの再生ビット、第２トラックからの再生ビットおよび第３トラックからの再生ビットを収集器２２１に入力し、一つにまとめられた再生ビットは復号器２２２によって情報ビットへ復調される。なお、上記説明では光ビームが３本の場合のを示したが、光ビームが１本の場合は第１トラック、第２トラック及び第３トラックを一度に記録再生できないため、分配器２１４の代わりに図２２Ａに示した２つのバッファメモリが必要となる。
【００４９】
図２６は図２５における情報記録時のフローチャートを示す図である。情報ビット（記録データ）が符号器に入力され、例えば第３トラックにまたがる符号化が行われる（ステップｓ２１）。各トラック毎に変調ビットが分配される（ステップｓ２２）。つぎに第１トラックに記録する変調ビット、第２トラックに記録する変調ビットおよび第３トラックに記録する変調ビットがそれぞれ３つの光ビームによって光ディスクに記録される（ステップｓ２３）。
【００５０】
図２７は図２５における情報再生時のフローチャートを示す図である。第１トラックに記録された記録ビット、第２トラックに記録された記録ビットおよび第３トラックに記録された記録ビットが３つの光ビームによってそれぞれ再生される（ステップｓ３１）。再生した第１トラックの再生ビット、第２トラックの再生ビットおよび第３トラックの再生ビットを収集器で収集する（ステップｓ３２）。つぎに収集した再生ビットを復号器において情報ビットに復号する（ステップｓ３３）。なお、上記フローチャートでは光ビームが３本の場合を示したが、光ビームが１本の場合は第１トラック、第２トラック及び第３トラックを一度に記録再生できないため、光ビームのそれぞれのトラックへの移動およびバッファメモリへの蓄積動作が必要となる。
【００５１】
上記では、マルチビーム記録装置により、隣接トラックの符号ビット同士をトラックに沿う方向に対してすべて同期させる例を示したが、これに限らず、シングルビームにより同期させることも可能であり、例えば良く知られているサンプルサーボ装置により同期させることも可能である。この装置はディスクに予め穴形状により記録されたクロックピットを再生して、これに同期した記録クロックを発生し、この記録クロックを基に記録マークを記録していく装置である。この装置では、ディスクの隣接トラックのクロックピットも予め記録されているため、隣接トラック同士の記録クロックをトラックに沿う方向に同期させることが可能なため、符号ビット同士も同期させることが可能となる。
【００５２】
以下の第６及び第７の実施例は、図２５における符号器２１３、分配器２１４及び収集器２２１、復号器２２２に主に関連する。
【００５３】
第６の実施例について以下に説明する。
【００５４】
図１４は本発明の第６の実施例における情報記録方法である。この例では、３つの光ビーム例を示す。光ビーム２０１、２０２及び２０３はそれぞれトラック２０７、２０８及び２０９を矢印Ａの方向に移動しながら、符号ビットを記録再生する。
【００５５】
図１６には符号化方法の一例として、よく知られている（１、７）ＲＬＬコードの変換表を示す。この符号ビットを図１４のトラックに記録する。つまり、まず符号ビット「１００」をそれぞれ１ビットづつトラック２０７、２０８及び２０９に記録する。
【００５６】
すると、情報ビット２ビット「０１」を符号ビット１ビット分の時間で記録することができる。言い換えると、トラックに沿う方向へ１ビット分の記録長により記録できる。次に符号ビット「０１０」をそれぞれ１ビットづつトラック２０７、２０８及び２０９に記録すると、情報ビット２ビット「１０」を符号ビット１ビット分の時間で記録することができる。同様に符号ビット「１０１」、「０００００１」を記録していくことができる。再生も同様に短い時間で行うことができる。
【００５７】
したがって、１語あるいは１バイトを複数の記録トラックに分割して記録を行う事により、高速記録再生が可能となる。この場合は従来の３倍に高速化可能となる。
【００５８】
このように、記録を続けていけば、同様に１セクタ分の情報の記録時間も光ビームの数に反比例して短縮可能となる。言い換えると、トラックに沿う方向の１セクタ分の記録長が短縮できる。
【００５９】
また、上記実施例では可変長符号である（１、７）ＲＬＬコードを例に挙げたが、これに限らず例えば固定長符号である８／１０変調コードの場合は符号ビットが１０ビットであるから、光ビーム数が３本の場合は、最小公倍数である３０ビットを一つのブロックとして記録すれば、区切りのよい記録再生ができる。
【００６０】
あるいは、３０ビットの整数倍のビット数を１ブロックしてもよい。
【００６１】
図１７は、図２５の光記録再生装置の部分を示す図である。
【００６２】
図１７において、情報記録時は記録データを符号器２１３によって符号化し、符号ビット信号ｂを分配器２１４に送り、符号ビットｂを１ビットづつ記録ビット信号ｃ１、ｃ２、ｃ３に分配し、それぞれ半導体レーザ２１５、２１６、２１７に送り、３つの光ビームｄ１、ｄ２、ｄ３によって、記録媒体に情報を記録することができる。情報再生時は記録媒体からの透過光または反射光ｅ１、ｅ２、ｅ３をそれぞれフォトダイオード２１８、２１９、２２０に導き、再生信号ｆ１、ｆ２、ｆ３を収集器２２１に導いて、記録時とは逆の方法で再生ビットを収集し、再生ビット信号ｇを復号器に送って、再生データに復号する。
【００６３】
図１８を用いて図１７における分配器２１４をさらに詳細に説明する。符号器２１３からの符号ビット信号ｂを分配器２１４におけるシフトレジスタ２２３に入力する。クロックｃｋ１をシフトレジスタ２２３と三分周器２２４に入力する。シフトレジスタ２２３ではクロックｃｋ１の立ち上がりエッジ毎に符号ビット信号ｂをシフトさせる。
【００６４】
シフトレジスタ２２３の三つの出力端子からビット信号ｈ１、ｈ２、ｈ３をＤ−ＦＦ２２５、２２６、２２７のデータ入力端子Ｄに入力し、三分周器２２４の出力ｃｋ２をクロック入力端子ｃｋに入力する。
【００６５】
Ｄ−ＦＦ２２５、２２６、２２７の出力端子ｏｕｔからは記録ビット信号ｃ１、ｃ２、ｃ３をそれぞれ出力する。
【００６６】
図１９は図１８の波形を示す図である。シフトレジスタ２２３においてクロックｃｋ１によってシフトされたビット信号ｈ１、ｈ２、ｈ３をクロックｃｋ２の立ち上がりエッジでとらえられると、記録ビット信号ｃ１、ｃ２、ｃ３を得ることができる。記録ビット信号ｃ１、ｃ２、ｃ３はシリアルに並んだ符号ビット信号ｂを３ビットづつパラレルビットに変換したものとなる。
【００６７】
図２０を用いて図１７における収集器２２１を詳細に説明する。再生信号ｆ１、ｆ２、ｆ３をシフトレジスタ２２８、２２９、２３０に入力する。クロックｃｋ３をシフトレジスタ２３１と三分周器２３２に入力する。三分周器２３２の出力信号ｃｋ４をシフトレジスタ２２８、２２９、２３０と２３１に入力する。シフトレジスタ２２８、２２９、２３０ではクロックｃｋ４の立ち上がりエッジ毎に再生ビット信号ｉ１、ｉ２、ｉ３をそれぞれシフトさせる。シフトレジスタ２３１ではクロックｃｋ４の立ち上がりエッジ毎に３つの再生ビット信号ｉ１、ｉ２、ｉ３を一度に取り込み、クロックｃｋ３の立ち上がりエッジ毎に１ビットづつシフトさせる。シフトレジスタ３１の出力からは再生ビット信号ｇを復合器２２２へ送り出す。
【００６８】
図２１は図２０の波形を示す図である。シフトレジスタ２３１ではクロックｃｋ４の立ち上がりエッジ毎に３つの再生ビット信号ｉ１、ｉ２、ｉ３を一度に取り込み、クロックｃｋ３の立ち上がりエッジ毎に１ビットづつシフトさせる。再生ビット信号ｇはパラレルに並んだ再生ビット信号ｉ１、ｉ２、ｉ３を３ビットづつシリアルに並べた信号となる。
【００６９】
第７の実施例について以下に説明する。
【００７０】
図１５は本発明の第７の実施例における情報記録方法である。図１４に比べて、光ビーム２０４、２０５及び２０６の配列方向がトラック２１０、２１１及び２１２と直角ではないが、その他は同様であるため詳細な説明は省略する。もし、光ビームの位置ずれによる時間ずれが発生する場合は、遅延素子等により、時間ずれの分だけそれぞれの記録再生時間を調整すればよい。その他は同様である。
【００７１】
【発明の効果】
また、本発明によれば、１バイトあるいは１語のデータを記録あるいは再生する時間が、従来に比べてビーム数分の１となり、１バイトあるいは１語分の記録あるいは再生時間が大幅に短絡可能となる。つまり、ビーム数が増える分だけ記録再生時間を高速化することが可能となる。
【００７２】
特に、トラックピッチが約１μｍ〜２μｍとなり、大容量化が可能な光記録再生装置では、大量のデータを転送する必要があり、本発明によって、より高速転送が実現できる。
【００７３】
また、１バイトあるいは１語のビット数が光ビームの数で割り切れない場合、あるいは逆に光ビーム数が１バイトあるいは１語のビット数で割り切れない場合は、ｎ本の光ビームと、情報語を変換したｍビットの符号語の最小公倍数を１つのブロック単位として、複数の記録トラックに分割し、区切りよく記録を行う事も可能となる。
【００７４】
同様に、１セクタのデータを記録あるいは再生する時間も、従来に比べてビーム数分の１となり、１セクタ分の記録あるいは再生時間が大幅に短縮可能となる。つまり、ビーム数が増える分だけ記録再生時間を高速化することが可能となる。
【００７５】尚、本発明は光磁気ディスク記録再生装置を初めとする光記録再生装置や、それ以外のカード、テープ等の記録再生装置や、追記型、相変化型の光記録再生装置においても、同様の効果が得られる。
【図面の簡単な説明】
【図１】 本発明の第１の実施例による符号変換表を示す図である。
【図２】 図１の符号変換表によって記録した符号ビットを示す図である。
【図３】 本発明の第２の実施例による符号変換表を示す図である。
【図４】 図１及び図２の符号変換表の付加ビットを示す図である。
【図５】 本発明の第３の実施例による符号変換表を示す図である。
【図６】 本発明の第４の実施例による２次元の符号ビット行列を示す図である。
【図７】 図６の符号変換表によって記録した符号ビットを示す図である。
【図８】 本発明の第４の実施例による２次元の符号ビット行列の幾何学的な模様を示す図である。
【図９】 本発明の第５の実施例による符号ビット配置を示す図である。
【図１０】 従来のマルチビーム記録再生装置の読み出しの説明図である。
【図１１】 従来のマルチビーム記録再生装置の読み出しの説明図である。
【図１２】 従来の符号変換表を示す図である。
【図１３】 図１２の符号変換表によって記録した符号ビットを示す図である。
【図１４】 本発明の第６の実施例による情報記録方法の説明図である。
【図１５】 本発明の第７の実施例による情報記録方法の説明図である。
【図１６】 符号コードの一例である（１、７）ＲＬＬコードの変換表を示す図である。
【図１７】 本発明の第６の実施例による情報記録方法を実現するための構成図である。
【図１８】 図１７における分配器の詳細説明図である。
【図１９】 図１８における分配器の各部の波形を示す図である。
【図２０】 図１７における収集器の詳細説明図である。
【図２１】 図２０における収集器の各部の波形を示す図である。
【図２２Ａ】 本発明の第１の実施例に係る情報記録再生装置の構成図である。
【図２２Ｂ】 情報記録再生装置の符号器の構成を示す図である。
【図２３】 本発明の第１の実施例に係る情報記録方法を示すフローチャートである。
【図２４】 本発明の第１の実施例に係る情報再生方法を示すフローチャートである。
【図２５】 本発明の第６の実施例に係るマルチビーム記録再生装置の構成図である。
【図２６】 本発明の第６の実施例に係る情報記録方法を示すフローチャートである。
【図２７】 本発明の第１の実施例に係る情報再生方法を示すフローチャートである。
【符号の説明】
１０ 偶数番目のトラック
１１、１２ 奇数番目のトラック
１３ 付加ビット[0001]
[Industrial application fields]
  The present invention relates to a method for recording information on a recording medium at a high density,Information recording / reproducing apparatus,And a signal collector and distributor for an information recording / reproducing apparatus.
[0002]
[Prior art]
As a first conventional example, there is an optical memory device disclosed in JP-B-2-31330. In this example, information bits are converted into code bits by a so-called RLL code and recorded along a track. FIG. 12 shows a well-known (1, 7) RLL code conversion table. For example, as shown in FIG. 13, code bits converted by so-called NRZ recording are serially recorded along the track 101 in accordance with this conversion rule. The tracks 102 and 103 were similarly recorded.
[0003]
As a second conventional example, there has been a multi-beam recording / reproducing apparatus disclosed in JP-A-2-247837. In this example, in order to reduce crosstalk from the adjacent track, the first read signal is reproduced from the code bit by the first light beam, and the second read from the code bit of the adjacent track is performed by the second light beam. The signal was reproduced and the second readout signal was subtracted from the first readout signal to reduce crosstalk.
[0004]
As a third conventional example, there is an information signal recording and reproducing apparatus disclosed in Japanese Patent Laid-Open No. 4-341974. In this example, the video format signal is divided into video signals of three channels, and recording is performed with three multi-beams.
[0005]
[Problems to be solved by the invention]
However, when recording is performed according to the code rule of the first conventional example, a reproduction error occurs due to crosstalk from adjacent tracks 102 and 103 as shown in FIG. For example, at the position of the light spot A, “1” or “record mark” is read, and the adjacent tracks 102 and 103 are “0” or “non-mark”, so the crosstalk is zero. In this example, so-called NRZ recording is performed, and “1” is recorded as “record mark” and “0” is recorded as “non-mark”. However, since the sign of the adjacent track 103 is “1” in the light spot B and the sign bit of both the adjacent tracks 102 and 103 is “1” in the light spot C, crosstalk occurs and a reproduction error occurs. I was letting.
[0006]
In order to solve this problem, the second conventional example reduces crosstalk by the above method. However, the second light beam inevitably reads the sign bit of the adjacent track. Therefore, since the second read signal also has crosstalk from the adjacent track, there is a problem that even if this is subtracted from the first read signal, the crosstalk cannot be sufficiently reduced.
[0007]
In recent years, as shown in FIGS. 10 and 11, a multi-beam recording / reproducing apparatus that performs recording / reproduction with a plurality of light beams and enables high-speed recording / reproduction has been proposed. For example, a single beam recording / reproducing apparatus can only record / reproduce one sector at a time, but a multi-beam recording / reproducing apparatus records / reproduces a plurality of sectors at a time.
[0008]
However, recording is conventionally performed by the recording method of the first conventional example, and even if it is a multi-beam recording / reproducing apparatus, recording or reproducing time for one sector is required to record or reproduce data of one sector. It was necessary. That is, it is impossible to increase the speed when recording / reproducing the same number of sectors as the number of beams or less. Of course, in order to record or reproduce 1-byte data, it is necessary to record or reproduce at least 1 byte. That is, the same applies to the case where the number of bytes equal to or less than the number of beams is recorded and reproduced.
[0009]
In the third conventional example, the video signal is divided into three channels and recorded and reproduced by three light beams. However, the division method is not disclosed, and the digital data for the computer is not used at all. It was not disclosed. Further, since the identification signal is recorded on different time axes of adjacent tracks, it is difficult to speed up the recording / reproducing time of one video information after all.
[0010]
[Means for Solving the Problems]
  In order to solve the above-mentioned problem, the present invention provides a recording method for encoding and recording recording data based on a predetermined rule when recording on an optical recording medium by a multi-beam recording / reproducing apparatus as described in claim 1 When the first code bit obtained by encoding the record data of the first track is “1” or “record mark”, the first track of the second track adjacent to the first track Encode a second code bit that encodes recorded data adjacent to the code bit in a direction perpendicular to the track as “0” or “non-mark” based on the encoding rule;n light beams and the least common multiple of m-bit code bits encoded by the encoding of the recording data or the integer multiples thereof are divided into a plurality of recording tracks as one block unit,The plurality of encoded code bits across a plurality of recording tracksLine up in a direction perpendicular to the trackAn information recording method by a multi-beam recording / reproducing apparatus using an optical recording medium characterized by performing recording.
[0012]
  Further, as described in claim 3,A signal distributor for distributing a code bit signal to a plurality of recording tracks in a multi-beam recording / reproducing apparatus using an optical recording medium, the shift register for inputting the code bit, a frequency divider and a track 4. A signal distributor according to claim 3, comprising a number of D flip-flops.
[0013]
  Moreover, according to the present invention,A signal collector for collecting reproduction signals from a plurality of recording tracks in a multi-beam recording / reproducing apparatus for reproducing recording bits of an optical recording medium, comprising: a shift register for the number of tracks for inputting reproduction signals; 5. The signal collector according to claim 4, further comprising a frequency divider and a shift register for storing data obtained by collecting a plurality of signals.Is provided.
[0014]
  According to the invention,6. The multi-beam recording / reproducing apparatus according to claim 5, wherein a recording bit of the optical recording medium recorded by the information recording method according to claim 1 is reproduced.Is provided.
[0015]
[Action]
The signal distributor according to the present invention uses the number of track frequency dividers and D flip-flops to distribute the code bits input to the shift register to a plurality of recording tracks.
[0016]
The signal collector of the present invention inputs reproduction signals from a plurality of recording tracks to a shift register for the number of tracks, and stores it in the shift register using a frequency divider for the number of tracks.
[0017]
【Example】
An information recording / reproducing apparatus according to the present invention will be described below using an optical recording / reproducing apparatus as an example.
[0018]
FIG. 22A is a diagram showing an optical recording / reproducing apparatus of the present invention. At the time of information recording, information bits (recording data) are input to the encoder 151, for example, encoding is performed over three tracks, and modulation bits (codewords) are temporarily stored in the buffer memory 152. When the light beam is tracked to the first track, the modulation bit to be recorded on the first track is first output from the buffer memory, and then when the light beam is tracked to the second track, the modulation bit to be recorded on the second track is recorded When tracking is performed, modulation bits to be recorded on the third track are sequentially output. These modulation bits are sent to the laser drive circuit 153. A drive current is sent from the laser drive circuit 153 to the semiconductor laser 154, a light beam is irradiated onto the optical disk 157 via the beam splitter 155 and the objective lens 156, and the modulation bits are sequentially applied to the first track, the second track, and the third track. To be recorded.
[0019]
At the time of information reproduction, the reflected light from the recording bit recorded on the optical disk 157 is guided to the photodetector 158 by bending the optical path by the beam splitter 155 via the objective lens 156. The reproduction signal converted into the electric signal is amplified by the amplifier 159 and converted into a digital signal of “1” or “0” by the waveform shaper. In the first track, the reproduction bits from the first track are first stored in the buffer memory 161, then in the second track, the reproduction bits from the second track, and in the third track in the order of the reproduction bits from the third track. The The stored reproduction bits of the three tracks are demodulated into one information bit by the decoder 162. In the above description, the case where there is one light beam is shown. However, when there are three light beams, the first track, the second track, and the third track can be recorded and reproduced at a time. 152 and 161 are not necessary.
[0020]
FIG. 23 is a diagram showing a flowchart at the time of recording information in FIG. 22A. Information bits (recording data) are input to the encoder, for example, encoding is performed across the third track, and modulation bits (codewords) are temporarily stored in the buffer memory (step s1). Next, the light beam is moved to the first track (step s2). A modulation bit to be recorded on the first track is output from the buffer memory and recorded on the optical disc (step s3). Next, the light beam is moved to the second track (step s4). A modulation bit to be recorded on the second track is output from the buffer memory and recorded on the optical disc (step s5). Next, the light beam is moved to the third track (step s6). A modulation bit to be recorded on the third track is output from the buffer memory and recorded on the optical disc (step s7).
[0021]
FIG. 24 is a diagram showing a flowchart at the time of information reproduction in FIG. 22A. First, the light beam is moved to the first track (step s11). The recording bits recorded on the first track are reproduced and stored in the buffer memory (step s12). The light beam is moved to the second track (step s13). The recording bits recorded on the second track are reproduced and stored in the buffer memory (step s14). The light beam is moved to the third track (step s15). The recording bits recorded on the third track are reproduced and stored in the buffer memory (step s16). The stored reproduction bits of the first track, reproduction bit of the second track, and reproduction bit of the third track are input to the decoder, and the information bits are decoded (step s17). In the above flowchart, the case where there is one light beam is shown. However, when there are three light beams, the first track, the second track, and the third track can be recorded and reproduced at a time. Movement to the track and accumulation operation in the buffer memory are unnecessary.
[0022]
The first to fifth embodiments described below relate to the encoding method of the encoder 151 in FIG. 22A, that is, step s1 of the flowchart of FIG. The configuration of the encoder 151 will be described based on FIG. 22B. The encoder 151 includes a code bit converter 171 and an encoding table 172. The sign bit converter 171 converts information bits into sign bits according to the contents of the coding table.
[0023]
In addition to configuring the encoder using the encoding table in this way, the encoder can also be configured by converting input information bits into directly encoded bits by a logic operation circuit. .
[0024]
The first embodiment will be described below.
[0025]
FIG. 1 is a code conversion table in the first embodiment of the present invention. This is an example in which 1 bit of information bits is converted to 3 bits of code bits, which are divided into coding rules of even-numbered tracks and odd-numbered tracks. That is, on the other hand, the information bit “0” of the even-numbered track is converted to “000” and “1” is converted to “010”. On the other hand, the information bit “0” of the odd-numbered track is converted to “001” and “1” is converted to “100”.
[0026]
FIG. 2 shows an example in which code bits are recorded on a track based on this code conversion table. For the sake of simplicity, the following description will be limited to so-called NRZ recording, and “record marks” and “non-marks” will be substituted using “1” and “0”.
[0027]
The information bit “01” is converted and recorded in the even-numbered track 10. On the odd-numbered tracks 11 and 12, “01” and “10” are converted and recorded respectively. Then, as shown in the figure, when the code bit read out from the even-numbered track 10 is “1”, the code bits of the odd-numbered tracks 11 and 12 adjacent in the direction perpendicular to the position of this code bit are set to “0”. Can be. The same applies to the odd-numbered tracks 11 and 12 code bits. Therefore, it is possible to provide an encoding method that does not cause crosstalk of read signals.
[0028]
The second embodiment will be described below.
[0029]
FIG. 3 is a code conversion table in the second embodiment of the present invention. This is also divided into encoding rules for even-numbered tracks and odd-numbered tracks, but this time is an example in which 2 bits of information bits are converted to 4 bits of code bits. Since the rest is the same as in the first embodiment, detailed description is omitted, but when the code bit read out from the even-numbered track 10 is “1”, it is adjacent in the direction perpendicular to the position of this code bit. The sign bits of the even-numbered tracks 11 and 12 can be set to “0”. In the first and second embodiments, since the sign bit “0” may be continuous, it is difficult to achieve bit synchronization by the PLL. In this case, if the additional bit shown in FIG. 4 is added for each byte, for example, it is possible to avoid the continuous “0”.
[0030]
A third embodiment will be described below.
[0031]
FIG. 5 is a code conversion table in the third embodiment of the present invention. This is also an example in which the coding rules for even-numbered tracks and odd-numbered tracks are divided, and 3 bits of information bits are converted to 8 bits of code bits. The last 2 bits of the 8 sign bits are additional bits for avoiding the continuation of “0”. Note that conversion of information bits of 4 bits or more other than those in the first to third embodiments can be sequentially performed in the same manner as in the first, second, and third embodiments. Is omitted.
[0032]
A fourth embodiment will be described below.
[0033]
FIG. 6 shows an example of an encoding method in the fourth embodiment of the present invention. This is a two-dimensional code bit matrix {Ci, Rj, which represents a one-dimensional information bit before encoding, which is a 3 × 3 matrix composed of 3 bits along the trunk and 3 bits perpendicular to the track. } (I = 1, 2, 3, j = 1, 2, 3). Further, when the matrix element {Ci, Rj} is “1”, at least one of {Ci, Rj−1} and {Ci, Rj + 1} is set to “0”. For example, the code bit matrix 20 is “100” for the track 21, “010” for the track 22, and “100” for the track 23. Then, as shown in FIG. 7, when the code bit read from the track 22 is “1”, the code bits of the tracks 21 and 23 adjacent in the direction perpendicular to the position of the code bit can be set to “0”. The same applies to the sign bits of tracks 21 and 23. Therefore, it is possible to provide an encoding method that does not cause crosstalk of read signals.
[0034]
FIG. 6 shows one two-dimensional code bit matrix, but in order to explain the other matrices in an easy-to-understand manner, “1” and “1” are connected by straight lines 24 and 25, respectively. Considering that a two-dimensional code bit matrix is represented by a geometric pattern, this is shown in FIG. The two-dimensional code bit matrix in FIG. 6 is shown at 26 in FIG. These 30 types of two-dimensional code bit matrix patterns can be easily understood by classifying them according to point symmetry or line symmetry as follows.
[0035]
[Table 1]

[0036]
With these geometric patterns, when the code bit read out of the track 22 is “1”, the code bits of the tracks 21 and 23 adjacent in the direction perpendicular to the position of the code bit can be set to “0”. Visually understandable.
[0037]
For example, 16 types are selected from these 30 types of two-dimensional code bit matrices. Then, 4 one-dimensional information bits can be converted into these 16 kinds of two-dimensional code bit matrices. The remaining two-dimensional code bit matrix can also be used as a bit resynchronization pattern.
[0038]
In this example, every track includes at least one “1” and “0”, which is a so-called RLL code. That is, an encoding method with easy bit synchronization in the PLL circuit can be realized.
[0039]
Since the number of code bit matrices increases for a two-dimensional code bit matrix of 3 × 3 matrix or more, the description is omitted for the sake of space.
[0040]
The fifth embodiment will be described below.
[0041]
FIG. 9 is a diagram showing an encoding method in the fifth embodiment of the present invention. In this method, after encoding based on the conventional RLL code conversion table shown in FIG. 12, the code bits are arranged in a direction perpendicular to the track, not in the direction along the track. For example, if the information bits are arranged in order from the top of the code conversion table to be “01101100001...”, The code bits are “100010101000001. That is, in the (1, 7) RLL code of FIG. 12, since at least one “0” is included between the code bit “1” and the next “1”, The sign bit can always be set to “0”. Therefore, it is possible to provide an encoding method that does not cause crosstalk of read signals. Further, the number of tracks in FIG. 9 is 6, which is exactly an integral multiple (1 or 2) of the conversion unit of code bits (3 bits or 6 bits). That is, if the number of tracks is determined to be an integral multiple according to the type of RLL code, encoding with good separation can be performed.
[0042]
In the above, the (1, 7) RLL code is taken as an example, but the same applies to other RLL codes.
[0043]
Also, in the optical recording / reproducing apparatus and the optical recording medium, the interval between the code bits between adjacent tracks is extremely short (about 1 to 2 μm), and this tends to cause crosstalk. It is easy to arrange next to each other. That is, the present invention is an effective encoding method particularly in an optical recording / reproducing apparatus and an optical recording medium.
[0044]
In the first to fifth embodiments, the sign bits of adjacent tracks are all synchronized with respect to the direction along the track. This is particularly easy in a multi-beam recording / reproducing apparatus having a plurality of light beams. That is, since the irradiation positions of a plurality of light beams can be fixed in the multi-beam recording / reproducing apparatus, it is possible to always record / reproduce synchronized code bits.
[0045]
Further, for the sake of simplicity, the description is limited to NRZ recording. However, the present invention is not limited to this, and in so-called NRZI recording, the code bits to be recorded on a track are “record mark” and “non-mark”. Can be encoded in the same manner.
[0046]
A multi-beam recording / reproducing apparatus according to the present invention will be described below using an optical recording / reproducing apparatus as an example.
[0047]
FIG. 25 is a diagram showing an optical recording / reproducing apparatus of the present invention. At the time of information recording, information bits (recording data) are input to the encoder 213, for example, encoding is performed over three tracks, and modulation bits (codewords) are sent to the distributor 214. The distributor 214 outputs a modulation bit to be recorded on the first track, a modulation bit to be recorded on the second track, and a modulation bit to be recorded on the third track. These modulation bits are sent to three laser drive circuits 2150, 2160, 2170, respectively. Drive currents are sent from the laser drive circuits 2150, 2160, and 2170 to the semiconductor lasers 215, 216, and 217, and three optical beams are irradiated onto the optical disk 252 via the beam splitter 250 and the objective lens 251, and the three modulations distributed. Bits are recorded simultaneously.
[0048]
At the time of information reproduction, the three reflected lights from the recording bits recorded on the optical disk 252 are bent by the beam splitter 250 through the objective lens 251 and guided to the three photodetectors 218, 219, and 220. The reproduction signals converted into electrical signals are amplified by amplifiers 253, 254, and 255, respectively, and converted into digital signals of “1” or “0” by waveform shapers 256, 257, and 258, respectively. The reproduced bits from the first track, the reproduced bits from the second track, and the reproduced bits from the third track are input to the collector 221, and the combined reproduced bits are demodulated into information bits by the decoder 222. . In the above description, the case where there are three light beams is shown. However, when one light beam is used, the first track, the second track, and the third track cannot be recorded / reproduced at a time. In addition, the two buffer memories shown in FIG. 22A are required.
[0049]
FIG. 26 is a diagram showing a flowchart for recording information in FIG. Information bits (recording data) are input to the encoder, and for example, encoding over the third track is performed (step s21). Modulation bits are distributed for each track (step s22). Next, the modulation bit to be recorded on the first track, the modulation bit to be recorded on the second track, and the modulation bit to be recorded on the third track are each recorded on the optical disk by three light beams (step s23).
[0050]
FIG. 27 is a diagram showing a flowchart at the time of information reproduction in FIG. The recording bit recorded on the first track, the recording bit recorded on the second track, and the recording bit recorded on the third track are respectively reproduced by three light beams (step s31). The reproduced bit of the reproduced first track, the reproduced bit of the second track, and the reproduced bit of the third track are collected by the collector (step s32). Next, the collected reproduced bits are decoded into information bits by the decoder (step s33). In the above flow chart, the case where there are three light beams is shown. However, when the number of light beams is one, the first track, the second track, and the third track cannot be recorded / reproduced at a time. And storage operation in the buffer memory is required.
[0051]
In the above, an example in which all the sign bits of adjacent tracks are synchronized with each other in the direction along the track by the multi-beam recording apparatus is shown. However, the present invention is not limited to this, and can be synchronized by a single beam. It is also possible to synchronize with a known sample servo device. This apparatus reproduces clock pits recorded in advance in the shape of holes on a disk, generates a recording clock synchronized with the clock pits, and records a recording mark based on the recording clock. In this apparatus, since the clock pits of the adjacent tracks of the disk are also recorded in advance, the recording clocks of the adjacent tracks can be synchronized in the direction along the tracks, so that the code bits can also be synchronized. .
[0052]
The following sixth and seventh embodiments mainly relate to the encoder 213, the distributor 214, the collector 221 and the decoder 222 in FIG.
[0053]
The sixth embodiment will be described below.
[0054]
FIG. 14 shows an information recording method according to the sixth embodiment of the present invention. In this example, three examples of light beams are shown. The light beams 201, 202, and 203 record and reproduce code bits while moving the tracks 207, 208, and 209 in the direction of arrow A, respectively.
[0055]
FIG. 16 shows a well-known (1, 7) RLL code conversion table as an example of an encoding method. This code bit is recorded on the track of FIG. That is, first, the code bit “100” is recorded on the tracks 207, 208 and 209 one bit at a time.
[0056]
  Then, 2 information bits “01” can be recorded in a time corresponding to 1 sign bit. In other words, recording can be performed with a recording length of 1 bit in the direction along the track. Next, the sign bit “010” is tracked by 1 bit each.207,208as well as209In this case, 2 information bits “10” can be recorded in a time corresponding to 1 sign bit. Similarly, code bits “101” and “000001” can be recorded. Reproduction can be performed in a short time as well.
[0057]
Therefore, high-speed recording / reproduction is possible by dividing one word or one byte into a plurality of recording tracks for recording. In this case, the speed can be increased to three times that of the prior art.
[0058]
Thus, if recording is continued, the recording time of information for one sector can be shortened in inverse proportion to the number of light beams. In other words, the recording length for one sector in the direction along the track can be shortened.
[0059]
In the above embodiment, the (1, 7) RLL code which is a variable length code is taken as an example. However, the present invention is not limited to this. For example, in the case of an 8/10 modulation code which is a fixed length code, the sign bit is 10 bits. Therefore, when the number of light beams is 3, recording and reproduction with good separation can be performed by recording the least common multiple of 30 bits as one block.
[0060]
Alternatively, the number of bits that is an integer multiple of 30 bits may be blocked.
[0061]
FIG. 17 is a diagram showing a portion of the optical recording / reproducing apparatus of FIG.
[0062]
In FIG. 17, at the time of recording information, the recording data is encoded by the encoder 213, the code bit signal b is sent to the distributor 214, and the code bit b is distributed to the recording bit signals c1, c2, and c3 one by one. Information can be recorded on the recording medium by the three light beams d1, d2, and d3 that are sent to the lasers 215, 216, and 217. At the time of information reproduction, transmitted light or reflected light e1, e2, e3 from the recording medium is guided to the photodiodes 218, 219, 220, respectively, and the reproduced signals f1, f2, f3 are guided to the collector 221, which is opposite to the recording time. The reproduction bits are collected by the above method, and the reproduction bit signal g is sent to the decoder to be decoded into reproduction data.
[0063]
The distributor 214 in FIG. 17 will be described in more detail with reference to FIG. The code bit signal b from the encoder 213 is input to the shift register 223 in the distributor 214. The clock ck1 is input to the shift register 223 and the three-frequency divider 224. The shift register 223 shifts the sign bit signal b every rising edge of the clock ck1.
[0064]
Bit signals h1, h2, and h3 are input to the data input terminals D of the D-FFs 225, 226, and 227 from the three output terminals of the shift register 223, and the output ck2 of the three-frequency divider 224 is input to the clock input terminal ck.
[0065]
Recording bit signals c1, c2, and c3 are output from output terminals out of the D-FFs 225, 226, and 227, respectively.
[0066]
FIG. 19 shows the waveform of FIG. When the bit signals h1, h2, and h3 shifted by the clock ck1 in the shift register 223 are captured at the rising edge of the clock ck2, the recording bit signals c1, c2, and c3 can be obtained. The recording bit signals c1, c2, and c3 are obtained by converting the serially arranged code bit signal b into parallel bits by 3 bits.
[0067]
The collector 221 in FIG. 17 will be described in detail with reference to FIG. The reproduction signals f1, f2, and f3 are input to the shift registers 228, 229, and 230. The clock ck3 is input to the shift register 231 and the third frequency divider 232. The output signal ck4 of the three-frequency divider 232 is input to the shift registers 228, 229, 230 and 231. The shift registers 228, 229, and 230 shift the reproduction bit signals i1, i2, and i3 at every rising edge of the clock ck4, respectively. The shift register 231 takes in three reproduction bit signals i1, i2, and i3 at every rising edge of the clock ck4 and shifts them by one bit at every rising edge of the clock ck3. From the output of the shift register 31, the reproduction bit signal g is sent to the decoder 222.
[0068]
FIG. 21 shows the waveform of FIG. The shift register 231 takes in three reproduction bit signals i1, i2, and i3 at every rising edge of the clock ck4 and shifts them by one bit at every rising edge of the clock ck3. The reproduction bit signal g is a signal in which the reproduction bit signals i1, i2, and i3 arranged in parallel are serially arranged in units of 3 bits.
[0069]
The seventh embodiment will be described below.
[0070]
FIG. 15 shows an information recording method according to the seventh embodiment of the present invention. Compared to FIG. 14, the arrangement direction of the light beams 204, 205, and 206 is not perpendicular to the tracks 210, 211, and 212. If a time shift occurs due to the position shift of the light beam, each recording / reproduction time may be adjusted by a delay element or the like by the time shift. Others are the same.
[0071]
【The invention's effect】
In addition, according to the present invention, the time for recording or reproducing data of 1 byte or 1 word becomes 1 / number of beams as compared with the conventional case, and the recording or reproducing time for 1 byte or 1 word can be greatly short-circuited. It becomes. That is, the recording / reproducing time can be increased by the amount of increase in the number of beams.
[0072]
In particular, in an optical recording / reproducing apparatus having a track pitch of about 1 μm to 2 μm and capable of increasing the capacity, it is necessary to transfer a large amount of data, and higher speed transfer can be realized by the present invention.
[0073]
When the number of bits of one byte or one word cannot be divided by the number of light beams, or conversely, when the number of light beams cannot be divided by the number of bits of one byte or one word, n light beams and information words The least common multiple of the m-bit codeword obtained by converting can be divided into a plurality of recording tracks as one block unit, and recording can be performed with good separation.
[0074]
Similarly, the time for recording or reproducing data of one sector is one-tenth the number of beams compared to the conventional case, and the recording or reproducing time for one sector can be greatly shortened. That is, the recording / reproducing time can be increased by the amount of increase in the number of beams.
The present invention also applies to an optical recording / reproducing apparatus such as a magneto-optical disk recording / reproducing apparatus, a recording / reproducing apparatus such as a card or a tape, or a write-once type or phase change type optical recording / reproducing apparatus. A similar effect can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing a code conversion table according to a first embodiment of the present invention.
FIG. 2 is a diagram showing code bits recorded by the code conversion table of FIG. 1;
FIG. 3 is a diagram showing a code conversion table according to a second embodiment of the present invention.
4 is a diagram showing additional bits in the code conversion tables of FIGS. 1 and 2. FIG.
FIG. 5 is a diagram showing a code conversion table according to a third embodiment of the present invention.
FIG. 6 is a diagram illustrating a two-dimensional code bit matrix according to a fourth embodiment of the present invention.
7 is a diagram showing code bits recorded by the code conversion table of FIG. 6; FIG.
FIG. 8 is a diagram illustrating a geometric pattern of a two-dimensional code bit matrix according to a fourth embodiment of the present invention.
FIG. 9 is a diagram illustrating a code bit arrangement according to a fifth embodiment of the present invention.
FIG. 10 is an explanatory diagram of reading by a conventional multi-beam recording / reproducing apparatus.
FIG. 11 is an explanatory diagram of reading by a conventional multi-beam recording / reproducing apparatus.
FIG. 12 is a diagram illustrating a conventional code conversion table.
13 is a diagram showing code bits recorded by the code conversion table of FIG.
FIG. 14 is an explanatory diagram of an information recording method according to a sixth embodiment of the present invention.
FIG. 15 is an explanatory diagram of an information recording method according to a seventh embodiment of the present invention.
FIG. 16 is a diagram showing a conversion table of (1, 7) RLL code, which is an example of a code code.
FIG. 17 is a block diagram for realizing an information recording method according to a sixth embodiment of the present invention.
FIG. 1817FIG.
FIG. 1918It is a figure which shows the waveform of each part of the divider | distributor in.
FIG. 2017It is a detailed explanatory view of the collector.
FIG. 2120It is a figure which shows the waveform of each part of the collector in FIG.
FIG. 22A is a block diagram of the information recording / reproducing apparatus in the first example of the present invention.
FIG. 22B is a diagram showing a configuration of an encoder of the information recording / reproducing apparatus.
FIG. 23 is a flowchart showing an information recording method according to the first embodiment of the present invention.
FIG. 24 is a flowchart showing an information reproducing method according to the first embodiment of the present invention.
FIG. 25 is a block diagram of a multi-beam recording / reproducing apparatus in a sixth example of the present invention.
FIG. 26 is a flowchart showing an information recording method according to a sixth example of the present invention.
FIG. 27 is a flowchart showing an information reproducing method according to the first embodiment of the present invention.
[Explanation of symbols]
  10 Even numbered track
  11, 12 Odd track
  13 Additional bits

Claims (4)

A recording method for encoding and recording recording data based on a predetermined rule when recording on an optical recording medium by a multi-beam recording / reproducing apparatus,
When the first code bit obtained by encoding the recording data of the first track is “1” or “record mark”, the first code bit of the second track adjacent to the first track is tracked. A second code bit encoded in the recording data adjacent to the direction perpendicular to the direction is encoded as “0” or “non-mark” based on the encoding rule,
n light beams and the least common multiple of m-bit code bits encoded by the encoding of the recording data or the integer multiples thereof are divided into a plurality of recording tracks as one block unit, An information recording method using a multi-beam recording / reproducing apparatus using an optical recording medium, wherein recording is performed by arranging a plurality of encoded code bits across a plurality of recording tracks in a direction perpendicular to the tracks . A signal distributor for distributing a code bit signal to a plurality of recording tracks in a multi-beam recording / reproducing apparatus using an optical recording medium according to the information recording method according to claim 1, wherein the shift is for inputting the code bit. A signal distributor comprising a register, a track number divider, and a track number D flip-flop. A signal collector for collecting reproduced signals from a plurality of recording tracks in a multi-beam recording / reproducing apparatus for reproducing recorded bits of an optical recording medium recorded by the information recording method according to claim 1. A signal collector comprising a shift register for the number of tracks for inputting a signal, a frequency divider for the number of tracks, and a shift register for storing data obtained by collecting a plurality of signals. A multi-beam recording / reproducing apparatus for reproducing recorded bits of an optical recording medium recorded by the information recording method according to claim 1.

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