JP4337223B2 - Information recording apparatus, information recording medium, and information reproducing apparatus - Google Patents

Description

【００３７】
副搬送波生成回路１６Ａ及び１６Ｂは、例えばデータ転送クロックＣＫ１を基準にして動作するＰＬＬ（Phase Locked Loop ）回路と低域通過フィルタとで構成され、データ転送クロックＣＫ１がローレベルからハイレベルに変化するタイミングをｔ＝０とおいて、それぞれ次式により表されるデータ転送クロックＣＫ１の周波数ｆ０の３倍の周波数ｆ２の正弦波信号ＳＣ３及び余弦波信号ＳＣ４を生成して出力する。
【００３８】
【数２】

【００３９】
乗算回路１７Ａは、レベル変換回路１４Ａの出力信号と正弦波信号ＳＣ１とを乗算することにより、ディジタル信号ＤＤ０〜ＤＤ３の最下位ビットＤＤ０の振幅変調信号Ｍ１を生成して出力する。乗算回路１７Ｂは、レベル変換回路１４Ｂの出力信号と余弦波信号ＳＣ２とを乗算することにより、乗算回路１７Ａによる振幅変調信号に対して、狭義の直交した関係となるディジタル信号ＤＤ０〜ＤＤ３の最下位から１ビット目のビットＤＤ１の振幅変調信号Ｍ２を生成して出力する。
【００４０】
乗算回路１８Ａは、レベル変換回路１４Ｃの出力信号と正弦波信号ＳＣ３とを乗算することにより、ディジタル信号ＤＤ０〜ＤＤ３の下位側２ビット目のビットＤＤ２の振幅変調信号Ｍ３を生成して出力する。乗算回路１８Ｂは、レベル変換回路１４Ｄの出力信号と余弦波信号ＳＣ４とを乗算することにより、乗算回路１８Ａによる振幅変調信号に対して、狭義の直交した関係となるディジタル信号ＤＤ０〜ＤＤ３の最上位ビットＤＤ３の振幅変調信号Ｍ４を生成して出力する。
【００４１】
これらにより乗算回路１７Ａ〜１８Ｂより出力される振幅変調信号Ｍ１〜Ｍ４は、それぞれ次式により示されることになる。なおここでＡ１〜Ａ４は、それぞれビットＤＤ０〜ＤＤ３の論理値に対応する値１又は値−１の定数である。
【００４２】
【数３】

【００４３】
加算回路１９は、キャリア周波数ｆ１による直交する関係である乗算回路１７Ａ及び１７Ｂの変調信号Ｍ１及びＭ２を加算し、これにより直交変調による変調信号ＭＡを出力する。また加算回路２０は、キャリア周波数ｆ２による直交する関係である乗算回路１８Ａ及び１８Ｂの変調信号Ｍ３及びＭ４を加算し、これにより直交変調による変調信号ＭＢを出力する。
【００４４】
これらにより変調信号ＭＡ及びＭＢは、それぞれディジタル信号ＤＤ０〜ＤＤ３のビットＤＤ０、ＤＤ１及びＤＤ２、ＤＤ３の論理値に応じて、元の正弦波信号ＳＣ１、ＳＣ３に対して、位相が４５度、１３５度、２２５度、３１５度にキーイングされて出力されることになり、また振幅も元の正弦波信号ＳＣ１、ＳＣ３の２^1/2 となって出力されることになる。
【００４５】
同期信号生成回路２３は、例えば低域通過フィルタで構成され、発振器１３から出力されるデータ転送クロックＣＫ１の高調波成分を除去することにより、周波数ｆ０の正弦波である同期信号ＳＹＮＣを生成する。さらにこのとき同期信号生成回路２３は、変調信号ＭＡ及びＭＢの振幅に比して同期信号ＳＹＮＣの振幅が大きくなるように、この同期信号を生成し、これによりデータ転送クロックＣＫ１がローレベルからハイレベルに変化するタイミングをｔ＝０とおいて、次式で示す同期信号ＳＹＮＣを続く加算回路２２に出力する。なおここでは、同期信号ＳＹＮＣの振幅を（３）式との対比により値１０と置く。
【００４６】
【数４】

【００４７】
加算回路２２は、これら加算回路１９及び２０による加算信号ＭＡ及びＭＢ、同期信号ＳＹＮＣを加算して出力する。
【００４８】
信号レベル補正回路２４は、光変調器７より出力されるレーザービームＬ１の光量がこのようにして得られる加算回路２２の出力信号レベルに比例するように、加算回路２２の出力信号レベルを補正して記録信号ＲＳを生成する。具体的に、信号レベル補正回路２４は、光変調器７の非線型性を補うように、また加算回路２２の出力信号におけるボトム値でレーザービームＬ１がほぼ完全に遮光されるように、所定利得ＡＡにより加算回路２２の出力信号を増幅してオフセット電圧ＢＢを与える。これにより信号レベル補正回路２４は、次式により表される記録信号ＲＳを出力する。
【００４９】
【数５】

【００５０】
図３は、このようにして露光したディスク原盤２より作成される光ディスクを示す斜視図である。ディスク原盤２においては、正弦波信号、余弦波信号を搬送波信号にしてなる記録信号ＲＳによりレーザービームＬ１の光量が変調されて露光されることにより、レーザービームＬ１の光量に応じた幅による連続した露光軌跡が情報記録面の変化としてディジタル情報ＤＩＮＦＯの記録により形成される。これにより光ディスク３０は、この露光軌跡に対応するグルーブがらせん状に形成され、このグルーブの幅が記録信号ＲＳに応じて変化するように形成される。これにより光ディスク３０は、レーザービームＬ１の照射による情報記録面の連続的な変化がグルーブにより形成されてディジタル情報ＤＩＮＦＯが記録されることになる。
【００５１】
図４は、この光ディスク３０を再生する光ディスク装置を示すブロック図である。光ディスク装置３１において、スピンドルモーター３２は、光ディスク３０を回転駆動し、底部に保持したＦＧ信号発生回路より、所定の回転角毎に信号レベルが立ち上がるＦＧ信号ＦＧ２を出力する。スピンドルサーボ回路３３は、光ディスク３０に対する光ピックアップ３４によるレーザービーム照射位置に応じてこのＦＧ信号ＦＧ２の周波数が所定の周波数になるようにスピンドルモーター３２を駆動し、これにより光ディスク３０を所定の回転数により回転駆動する。
【００５２】
光ピックアップ３４は、コンパクトディスクプレーヤー等に適用されるいわゆる３ビーム方式の光ピックアップであり、半導体レーザーのレーザービームから回折格子により−１次、０次、＋１次の回折光を生成し、対物レンズによりこれらの回折光を光ディスク３０に集光する。光ピックアップ３４は、これらの回折光の戻り光を所定の受光素子により受光し、その受光結果を電流電圧変換処理してマトリックス演算することにより、グルーブの中心であるトラックセンターに対するトラッキングエラー量に応じて信号レベルが変化するトラッキングエラー信号ＴＥ、フォーカスエラー量に応じて信号レベルが変化するフォーカスエラー信号ＦＥ、グルーブの幅に応じて信号レベルが変化する再生信号ＳＵを出力する。
【００５３】
２軸サーボ回路３５は、光ピックアップ３４から出力されるトラッキングエラー信号ＴＥ、フォーカスエラー信号ＦＥにより光ピックアップ３４の対物レンズを可動し、これによりトラッキング制御、フォーカス制御の処理を実行する。
【００５４】
再生信号補正回路３６は、光ピックアップ３４から出力される再生信号ＳＵから直流成分を除去することにより、信号レベル補正回路２４で付加したバイアス電圧に対応する成分を除去した後、所定の利得により増幅し、これにより（３）〜（５）式との対比により次式で表される再生信号ＧＲＦを出力する。なおここでＡＳは、振幅を表す定数である。
【００５５】
【数６】

【００５６】
同期信号再生回路３７は、このようにして得られる再生信号ＧＲＦからデータ転送クロックＣＫ１を再生して出力し、データ再生回路３８は、このデータ転送クロックＣＫ１を基準にした再生信号ＧＲＦの信号処理によりディジタル情報ＤＩＮＦＯを再生して出力する。
【００５７】
図５は、同期信号再生回路３７を示すブロック図である。同期信号再生回路３７は、ＰＬＬ（Phase Locked Loop ）回路により構成される。すなわち同期信号再生回路３７において、電圧制御型発振回路（ＶＣＯ：Voltage Controlled Oscillator ）４０は、制御電圧ＶＣに応じて周波数を可変してデータ転送クロックＣＫ１を生成して出力し、位相検出回路４１は、再生信号ＧＲＦ中に含まれる同期信号と、データ転送クロックＣＫ１との位相差を検出し、検出結果を位相差信号ＰＥとして出力する。ループフィルタ４２は、位相差信号ＰＥを帯域制限すると共に所定利得により増幅して制御電圧ＶＣを生成し、この制御電圧ＶＣを電圧制御型発振回路４０に出力する。これにより同期信号再生回路３７は、再生信号ＧＲＦ中に含まれる同期信号にデータ転送クロックＣＫ１が同期するようにフィードバックループを構成してデータ転送クロックＣＫ１を再生する。
【００５８】
このため位相検出回路４１において、正弦波信号生成回路４５は、データ転送クロックＣＫ１を帯域制限することにより、データ転送クロックＣＫ１が再生信号ＧＲＦの同期信号に同期していることを前提として、データ転送クロックＣＫ１の信号レベルが立ち上がるタイミングを時点ｔ＝０とおいて、次式による表される正弦波信号ＣＣ１を生成する。
【００５９】
【数７】

【００６０】
同様に余弦波信号生成回路４６は、データ転送クロックＣＫ１に対して１／４位相だけ位相ずれしてなる矩形波信号を帯域制限することにより、データ転送クロックＣＫ１が再生信号ＧＲＦの同期信号に同期していることを前提として、データ転送クロックＣＫ１の信号レベルが立ち上がるタイミングを時点ｔ＝０とおいて、次式による表される余弦波信号ＣＣ２を生成する。
【００６１】
【数８】

【００６２】
乗算回路４７及び４８は、それぞれ正弦波信号ＣＣ１及び余弦波信号ＣＣ２を再生信号ＧＲＦと乗算し、積分回路４９及び５０は、乗算回路４７及び４８の乗算結果を積分して出力する。これにより乗算回路４７及び積分回路４９、乗算回路４８及び積分回路５９は、それぞれ同期検波回路を構成し、それぞれ再生信号ＧＲＦに含まれてなる正弦波信号ＣＣ１、余弦波信号ＣＣ２と同相成分を検出して出力する。なお積分回路４９及び５０は、データ転送クロックＣＫ１の周期でリセットされ、これにより積分値が所定値以上に増大しないようになされている。
【００６３】
すなわち正弦波信号ＣＣ１と再生信号ＧＲＦ中に含まれる同期信号成分との位相差をΔθとおくと、位相差Δθに対応する時間誤差Δｔは、次式で表される。
【００６４】
【数９】

【００６５】
ここで、データ転送クロックＣＫ１の信号レベルが立ち上がるタイミングを時点ｔ＝０とおくと、積分回路４９による積分結果ＰＳは、次式により表される。
【００６６】
【数１０】

【００６７】
ここで周波数ｆ１、ｆ２は、データ転送クロックＣＫ１が再生信号ＧＲＦの同期信号に同期している場合には、データ転送クロックＣＫ１の周波数ｆ０の整数倍であることにより、積分区間中において定数Ａ１〜Ａ４が一定であり、かつ積分区間がデータ転送クロックＣＫ１の整数倍周期の場合、（１０）式における右辺第１項〜第４項の積分結果は値０となる。またノイズ等により積分区間中で定数Ａ１〜Ａ４が変化した場合でも、（１０）式の右辺第１項〜第４項の積分結果は、右辺、第５項の積分結果に比較して実用上十分に小さな値として観察される。これにより（１０）式は、次式のように近似することができる。但し、Ｔ０は、積分による一定の定数である。
【００６８】
【数１１】

【００６９】
これにより積分回路４９の積分結果ＰＳにおいては、再生信号ＧＲＦに含まれる正弦波信号ＣＣ１と同相の信号レベルを検出することになる。これに対して積分回路５０の積分結果ＰＣは、同様に、次式により表される。
【００７０】
【数１２】

【００７１】
これにより正弦波信号ＣＣ１の場合と同様に、（１２）式は、次式に示すように近似でき、これにより積分回路５０の積分結果ＰＣにおいては、再生信号ＧＲＦに含まれる余弦波信号ＣＣ２と同相の信号レベルを検出することになる。
【００７２】
【数１３】

【００７３】
位相比較回路５１は、積分結果ＰＳ、ＰＣから逆正接を求め、位相差信号ＰＥとして出力する。すなわち位相差信号ＰＥは、次式により表される。
【００７４】
【数１４】

【００７５】
これにより位相差信号ＰＥは、再生信号ＧＲＦ中に含まれる同期信号と、データ転送クロックＣＫ１との位相差を示すことになる。これにより同期信号再生回路３７は、この位相差信号ＰＥが０レベルになるようにフィードバックループを形成して、再生信号ＧＲＦ中に含まれる同期信号にデータ転送クロックＣＫ１を同期させるようになされている。
【００７６】
図６は、データ再生回路３８を示すブロック図である。副搬送波生成回路６０Ａ及び６０Ｂは、例えばＰＬＬ（Phase Locked Loop ）回路で構成され、データ転送クロックＣＫ１を基準にして、データ転送クロックＣＫ１の信号レベルが立ち上がるタイミングを時点ｔ＝０とおいて、次式により表される周波数ｆ１の正弦波信号ＳＷ１及び余弦波信号ＳＷ２をそれぞれ生成して出力する。
【００７７】
【数１５】

【００７８】
乗算回路６１Ａ及び６１Ｂは、それぞれ正弦波信号ＳＷ１及び余弦波信号ＳＷ２と再生信号ＧＲＦと乗算する。積分回路６２Ａ及び６２Ｂは、データ転送クロックＣＫ１によりリセットされて、乗算回路６１Ａ及び６１Ｂの乗算結果を積分して出力する。これにより乗算回路６１Ａ及び積分回路６２Ａ、乗算回路６１Ｂ及び積分回路６２Ｂは、それぞれ同期検波回路を構成し、それぞれ再生信号ＧＲＦに含まれてなる正弦波信号ＳＷ１、余弦波信号ＳＷ２と同相成分を検出して出力する。これにより積分回路６２Ａ及び６２Ｂは、それぞれ次式により表される積分結果ｄｅｍ１及びｄｅｍ２を出力する。
【００７９】
【数１６】

【００８０】
【数１７】

【００８１】
かくするにつきＡ１及びＡ２は、それぞれディジタル信号ＤＤ０〜ＤＤ４のビットＤＤ０、ＤＤ１の論理値に対応する値１又は値−１の定数であることから、積分結果ｄｅｍ１及びｄｅｍ２においては、これら下位側２ビットの論理値を示すことが判る。
【００８２】
レベル変換回路（ＬＴ）６４Ａ及び６４Ｂは、それぞれ積分結果ｄｅｍ１及びｄｅｍ２の信号レベルをＴＴＬレベルに変換して出力する。
【００８３】
副搬送波生成回路６５Ａ及び６５Ｂは、例えばＰＬＬ回路で構成され、データ転送クロックＣＫ１を基準にして、データ転送クロックＣＫ１の信号レベルが立ち上がるタイミングを時点ｔ＝０とおいて、次式により表される周波数ｆ１の正弦波信号ＳＷ３及び余弦波信号ＳＷ４をそれぞれ生成して出力する。
【００８４】
【数１８】

【００８５】
乗算回路６６Ａ及び６６Ｂは、それぞれ正弦波信号ＳＷ３及び余弦波信号ＳＷ４と再生信号ＧＲＦと乗算する。積分回路６７Ａ及び６７Ｂは、データ転送クロックＣＫ１によりリセットされて、乗算回路６６Ａ及び６６Ｂの乗算結果を積分して出力する。これにより乗算回路６６Ａ及び積分回路６７Ａ、乗算回路６６Ｂ及び積分回路６７Ｂは、それぞれ同期検波回路を構成し、それぞれ再生信号ＧＲＦに含まれてなる正弦波信号ＳＷ３、余弦波信号ＳＷ４と同相成分を検出して出力する。これにより積分回路６７Ａ及び６７Ｂは、それぞれ次式により表される積分結果ｄｅｍ３及びｄｅｍ４を出力する。
【００８６】
【数１９】

【００８７】
【数２０】

【００８８】
レベル変換回路（ＬＴ）６８Ａ及び６８Ｂは、それぞれ積分結果ｄｅｍ３及びｄｅｍ４の信号レベルをＴＴＬレベルに変換して出力する。
【００８９】
ビット数変換回路６９は、レベル変換回路６４Ａ〜６８Ｂの出力信号をデータ転送クロックＣＫ１を基準にして順次ラッチして４ビットパラレルのデータを再生する。さらにビット数変換回路６９は、光ディスク装置１におけるビット数変換回路６９とは逆に、この４ビットパラレルのデータを元の配列に戻し、これによりディジタル情報ＤＩＮＦＯを再生して出力する。
【００９０】
（２）実施の形態の動作
以上の構成において、情報源３より出力されるディジタル情報ＤＩＮＦＯは（図２）、ビット数変換回路４において４ビットパラレルのディジタル信号ＤＤ０〜ＤＤ３に変換される。このディジタル信号ＤＤ０〜ＤＤ３は（図１）、データ転送クロックＣＫ１に同期したタイミングにより順次続く記録信号生成回路５に入力され、ここでレベル変換回路１４Ａ〜１４Ｄによりそれぞれ０レベルを基準にして信号レベルが変化するように信号レベルが補正される。
【００９１】
記録信号生成回路５においては、データ転送クロックＣＫ１を基準にして、このデータ転送クロックＣＫ１の周波数ｆ０の２倍及び３倍の周波数ｆ１及びｆ２であって、データ転送クロックＣＫ１に対して所定の位相関係に保持された正弦波信号ＳＣ１及びＳＣ３、余弦波信号ＳＣ２及びＳＣ４が生成され、乗算回路１７Ａ〜１７Ｄにおいて、これらの正弦波信号及び余弦波信号ＳＣ１〜ＳＣ４にそれぞれレベル変換回路１４Ａ〜１４Ｄの出力信号が乗算される。
【００９２】
これにより記録信号生成回路５においては、周波数ｆ１、ｆ２の正弦波信号及び余弦波信号ＳＣ１〜ＳＣ４による４つの搬送波をそれぞれ搬送波として使用して、ディジタル信号ＤＤ０〜ＤＤ３の各ビット列により各搬送波をキーイングし、ディジタル信号ＤＤ０〜ＤＤ３の各ビット列による振幅変調信号Ｍ１〜Ｍ４が生成される。
【００９３】
記録信号生成回路５においては、それぞれ加算回路１９及び２０において、同一キャリア周波数に係る変調信号Ｍ１及びＭ２、Ｍ３及びＭ４が加算され、これによりベクトル合成に係る直交振幅変調信号ＭＡ及びＭＢが生成される。さらにこれら変調信号ＭＡ及びＭＢが加算回路２２で加算されて多重化に係る変調信号が生成され、ボトム値が０レベルとなって信号レベルが変化するように、また光変調器７の非線型性を補うように、この変調信号の信号レベルが信号レベル補正回路２４により補正されて記録信号ＲＳが生成される。
【００９４】
このとき記録信号生成回路５は、データ転送クロックＣＫ１と一定の位相関係に保持され（すなわちデータ転送クロックＣＫ１を介して正弦波信号及び余弦波信号ＳＣ１〜ＳＣ４と一定の位相関係に保持され）、かつデータ転送クロックＣＫ１と同一周波数ｆ０による正弦波信号が同期信号生成回路２３で生成され、この正弦波信号が同期信号ＳＹＮＣとして加算回路２２により変調信号に重畳される。これにより光ディスク装置１では、連続した信号レベルの変化による記録信号ＲＳに、正弦波信号による同期信号ＳＹＮＣが多重化される。
【００９５】
さらにこのとき同期信号ＳＹＮＣは、他の変調信号Ｍ１〜Ｍ４に比して大きな振幅により変調信号に加算される。これにより記録信号ＲＳにおいては、他の変調信号Ｍ１〜Ｍ４による信号波形の変化に対して、この同期信号ＳＹＮＣによる信号波形の変化が大きく観察されるように生成される。
【００９６】
光ディスク装置１では、このようにして生成された記録信号ＲＳを基準にした光変調器７の動作により、レーザー光源６から出射されるレーザービームＬ０が強度変調され、その結果得られるレーザービームＬ１が回転するディスク原盤２に集光される。これにより光ディスク装置１では、露光軌跡の連続する幅の変化として同期信号ＳＹＮＣを重畳してなるディジタル情報ＤＩＮＦＯがディスク原盤２に記録される。
【００９７】
このようにして生成されたディスク原盤２においては、現像処理の後、電鋳処理等を経てマザーディスクが作成され、このマザーディスクを用いた一連の処理によりディスク基板が量産される。このようにして生成されるディスク基板においては、ディスク原盤２における露光軌跡に溝が形成され、この溝の形成されてなる側に反射膜、保護膜等を作成して光ディスク３０（図３）が量産される。かくするにつき光ディスク３０においては、この溝によりレーザービームのガイド溝であるグルーブが形成され、このグルーブの幅が記録信号ＲＳに応じて変化するように形成される。
【００９８】
これにより光ディスク３０においては、データの記録を中断して同期信号を記録する場合のような記録容量の低下を防止して確実に同期捕捉することが可能となる。
【００９９】
すなわち光ディスク３０は、光ディスク装置３１（図４）において、レーザービームを照射して得られる戻り光の受光結果よりグルーブの幅に応じて信号レベルが変化する再生信号ＳＵが検出され、この再生信号ＳＵの再生信号補正回路３６における信号レベルの補正により記録時における加算回路２２の出力信号（図１）と同等の再生信号ＧＲＦが検出される。
【０１００】
光ディスク装置３１では、この再生信号ＧＲＦが同期信号再生回路３７に入力され、ここで電圧制御型発振回路４０（図５）より出力されるデータ転送クロックＣＫ１を基準にして正弦波信号ＣＣ１、余弦波信号ＣＣ２が生成され、再生信号ＧＲＦと正弦波信号ＣＣ１、余弦波信号ＣＣ２がそれぞれ乗算されて乗算結果が積分回路４９、５０により積分され、これにより再生信号ＧＲＦに含まれる正弦波信号ＣＣ１、余弦波信号ＣＣ２と同相分の信号レベルが検出される。光ディスク装置３１では、このようにして検出される信号レベルより位相比較回路５１で再生信号ＧＲＦに含まれる同期信号ＳＹＮＣに対するデータ転送クロックＣＫ１の位相差が検出され、ループフィルタ４２を介してこの位相差が０となるように、すなわち再生信号ＧＲＦに含まれる同期信号ＳＹＮＣにデータ転送クロックＣＫ１が同期するように、電圧制御型発振回路４０におけるデータ転送クロックＣＫ１の周波数が補正される。これにより光ディスク装置３１では、ＰＬＬ回路構成の同期信号再生回路３７により、光ディスク３０に連続して記録された同期信号ＳＹＮＣにより同期捕捉することができ、簡易な構成により確実に同期捕捉することができる。
【０１０１】
さらにこのときこの同期信号ＳＹＮＣの周波数ｆ０を基本の周波数に設定して、データ転送用の正弦波信号及び余弦波信号の周波数ｆ１、ｆ２を基本周波数ｆ０の整数倍である２倍及び３倍に設定したことにより、同期信号ＳＹＮＣにデータ転送クロックＣＫ１が同期した場合に、これらデータ転送による変調信号によっては、積分回路４９、５０における積分結果には何ら影響を与えないようにすることができる。これによりこの実施の形態では、変調信号に同期信号を多重化して記録しても、確実に同期捕捉することができる。
【０１０２】
また他の変調信号に比して同期信号ＳＹＮＣの振幅を大きなものとしたことにより、このようにしてＰＬＬ回路構成により同期捕捉する際に、高いＳＮ比により位相差信号ＰＥを得ることができ、これによっても簡易かつ確実に同期捕捉することができる。
【０１０３】
光ディスク装置３１では、このようにして生成されたデータ転送クロックＣＫ１を基準にして、ディジタル情報ＤＩＮＦＯが再生される。すなわち光ディスク装置３１では（図６）、このデータ転送クロックＣＫ１より、記録時に生成した正弦波信号ＳＣ１、ＳＣ３、余弦波信号ＳＣ２、ＳＣ４と同等の正弦波信号ＳＷ１、ＳＷ３、余弦波信号ＳＷ２、ＳＷ４が副搬送波生成回路６０Ａ、６０Ｂ、６５Ａ、６５Ｂで生成され、これら正弦波信号ＳＷ１、ＳＷ３、余弦波信号ＳＷ２、ＳＷ４と再生信号ＧＲＦとの乗算結果が乗算回路６１Ａ、６１Ｂ、６６Ａ、６６Ｂで生成される。
【０１０４】
これら乗算回路６１Ａ、６１Ｂ、６６Ａ、６６Ｂの乗算結果は、それぞれ積分回路６２Ａ、６２Ｂ、６７Ａ、６７Ｂによりデータ転送クロックＣＫ１の周期で積分され、これによりディジタル信号ＤＤ０〜ＤＤ３の各ビットＤＤ０〜ＤＤ３の論理値に応じて信号レベルが変化する積分結果ｄｅｍ１〜ｄｅｍ４が検出される。さらにこの積分結果ｄｅｍ１〜ｄｅｍ４がレベル変換回路６４Ａ〜６８ＢによりＴＴＬレベルに変換された後、ビット数変換回路６９でラッチされて元のディジタル信号ＤＤ０〜ＤＤ３が再生され、このディジタル信号ＤＤ０〜ＤＤ３のビット配列が補正されて元のディジタル情報ＤＩＮＦＯが再生される。
【０１０５】
（３）実施の形態の効果
以上の構成によれば、直交する複数系統の搬送波信号を使用して複数系列の変調信号を生成し、この複数系統の変調信号を加算した記録信号によりグルーブの幅を連続的に変化させて所望のデータを記録する際に、データ転送クロックの再生基準である同期信号を記録信号に加算して記録することにより、簡易な構成により記録容量の低下を防止して確実に同期捕捉することができる。
【０１０６】
このとき同期信号を基準にして、この同期信号の周波数の整数倍の周波数による正弦波信号、余弦波信号により変調信号を生成したことにより、このような変調信号による影響を回避して確実に同期信号により同期捕捉することができる。
【０１０７】
また変調信号の振幅に比して同期信号の振幅を大きくしたことによっても、再生側において高いＳＮ比により同期捕捉することができ、これによっても簡易な構成で確実に同期捕捉することができる。
【０１０８】
（４）他の実施の形態
なお上述の実施の形態においては、２組の直交する正弦波信号、余弦波信号により変調信号を生成して加算することにより記録信号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、種々の数による複数組の基準信号により振幅変調信号を生成して記録する場合、さらには単に正弦波信号だけ、余弦波信号だけを振幅変調して記録する場合等に適用して、上述の実施の形態と同様の効果を得ることができる。
【０１０９】
また上述の実施の形態においては、直交する正弦波信号、余弦波信号により変調信号を生成して記録する場合について述べたが、本発明はこれに限らず、各系統におけるデータ再生に十分なＳＮ比を確保できる場合、このような直交する関係の適用を排除することもできる。
【０１１０】
また上述の実施の形態においては、直交する正弦波信号、余弦波信号を振幅変調して変調信号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、周波数変調により変調信号を生成して多重化する場合等にも広く適用することができる。
【０１１１】
また上述の実施の形態においては、グルーブの幅の変化により所望のデータを記録する場合について述べたが、本発明はこれに限らず、グルーブの蛇行、グルーブ壁面の蛇行、グルーブの深さの変化により記録する場合、さらにはグルーブとは逆の形状である細長い連続する突起（突条）を形成し、この突条の蛇行、壁面の蛇行、高さの変化により記録する場合等に広く適用することができる。
【０１１２】
また上述の実施の形態においては、情報記録面の連続した変化としてグルーブの幅の変化により所望のデータを記録する場合について述べたが、本発明はこれに限らず、例えば光磁気ディスクに適用して、情報記録面の連続した変化として所定の極性に磁化された領域の幅の変化、蛇行等により所望のデータを記録する場合にも広く適用することができる。
【０１１３】
また上述の実施の形態においては、情報記録面の連続した変化としてグルーブにより所望のデータを記録する場合にについて述べたが、本発明はこれに限らず、上述の記録信号をＰＷＭ（Pulse Width Modulation）等により変調して記録信号を２値信号に変換し、この記録信号によりレーザービームをオンオフ制御することによりピット列により所望のデータを記録する場合、さらにはマーク列により所望のデータを記録する場合にも広く適用することができる。
【０１１４】
また上述の実施の形態においては、レーザービームの照射により所望のデータを記録する場合について述べたが、本発明はこれに限らず、レーザービームに代えて電子線ビームにより所望のデータを記録する場合にも広く適用することができる。
【０１１５】
また上述の実施の形態においては、ディスク形状の情報記録媒体である光ディスクに所望のデータを記録する場合について述べたが、本発明はこれに限らず、カード形状の情報記録媒体に所望のデータを記録する場合等、種々の形状による情報記録媒体に所望のデータを記録する場合に広く適用することができる。
【０１１６】
【発明の効果】
上述のように本発明によれば、例えば直交する複数系統の搬送波信号を使用して複数系列の変調信号を生成し、この複数系統の変調信号を加算した記録信号によりグルーブ等を変化させて所望のデータを記録する場合に、データ転送クロックの再生基準の同期信号を記録信号に加算して記録することにより、簡易な構成により記録容量の低下を防止して確実に同期捕捉することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係る光ディスク装置に適用される記録信号生成回路を示すブロック図である。
【図２】本発明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３】図２の光ディスク装置による光ディスクを示す斜視図である。
【図４】図３の光ディスクを再生する光ディスク装置を示すブロック図である。
【図５】図４の光ディスク装置の同期信号再生回路を示すブロック図である。
【図６】図４の光ディスク装置のデータ再生回路を示すブロック図である。
【符号の説明】
１、３１……光ディスク装置、２……ディスク原盤、３……情報源、５……記録信号生成回路、７……光変調器、３０……光ディスク、３７……同期信号再生回路、３８……データ再生回路[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an information recording device, an information recording medium, and an information reproducing device, and can be applied to, for example, an optical disc device and an optical disc. In the present invention, for example, a plurality of series of modulated signals are generated by using orthogonal orthogonal carrier signals, and desired data is recorded by changing a groove or the like by a recording signal obtained by adding the plurality of modulation signals. In addition, by adding a synchronization signal as a reproduction reference of the data transfer clock to the recording signal and recording, it is possible to prevent the recording capacity from being lowered and to reliably acquire the synchronization with a simple configuration.
[0002]
[Prior art]
Conventionally, in an optical disc such as a compact disc, desired data is recorded by sequentially forming pits or marks based on a predetermined reference period.
[0003]
That is, in the process of creating a compact disc, an error correcting code (ECC) is added to audio data obtained by sampling an audio signal, and then a modulated signal is generated by EFM (Eight to Fourteen Modulation) modulation. In addition, the compact disc creation process uses the modulated signal to turn on and off the laser beam to expose the master disc, then develop this master disc to create a mother disc, and then use this mother disc to create a compact disc. To do.
[0004]
As a result, the 8-bit string data is converted into 17-bit string data by EFM modulation, and then converted into a serial data string. The compact disk has a length of 0.3 [μm] corresponding to the logic level of the serial data string. Pits or spaces are sequentially formed in units of length.
[0005]
When playing back data recorded in this way, the compact disc player receives the return light obtained by irradiating the compact disc with a laser beam and generates a playback signal whose signal level changes according to the pit sequence. The reproduction signal is binary-identified to generate reproduction data corresponding to the serial data at the time of recording.
[0006]
Therefore, in a compact disc player, reproduction data is generated by identifying the lengths of pits and spaces formed on a compact disc with a length of 0.3 [μm] as a unit. ], The serial signal is reproduced by binary-identifying the signal level of the reproduction signal at a short time interval corresponding to the length of []. As a result, in a compact disc player, the logical level in the reproduction data may be reproduced erroneously due to instantaneous noise mixing.
[0007]
In a compact disc player, such a bit error in reproduced data is subjected to error correction processing to a practically sufficient level by an error correction code added at the time of recording. Incidentally, the DVD (Digital Video Disk) is the same as the compact disc player in that the reproduction signal is generated by binary identification of the reproduction signal at such a short time interval.
[0008]
If bit errors in the reproduced data due to such noise can be reduced, it is considered that the recording density in this type of optical disk can be improved accordingly.
[0009]
For this reason, in Japanese Patent Application Laid-Open No. 11-316951, a modulation signal is generated by modulating a carrier wave signal by a sine wave signal with data used for recording, and desired data is recorded by changing the groove using the modulation signal. There have been proposed methods for reducing bit errors in reproduced data due to noise.
[0010]
That is, this type of noise is considered to be mainly caused by dust, dust, etc. on the disk surface, and appears concentrated on a relatively low frequency band of the reproduction signal. Thus, in the method disclosed in Japanese Patent Application Laid-Open No. 11-316951, a carrier wave signal by a sine wave signal is modulated by data used for recording to generate a modulated signal, and the groove is changed by this modulated signal to obtain desired data. Record. During reproduction, a change in the groove is detected to generate a reproduction signal, and the synchronous detection result of the reproduction signal is integrated for each period corresponding to one bit at the time of recording to reproduce the original data. The desired data is reproduced by reducing the influence of noise.
[0011]
At this time, a plurality of carrier wave signals orthogonal to each other are used to change the groove with a plurality of modulation signals, thereby ensuring recording density. According to this method, it is possible to efficiently record and reproduce desired data using the frequency characteristic of the signal-to-noise ratio in the optical disc, and as a result, it is possible to improve the information recording density of the optical disc.
[0012]
[Problems to be solved by the invention]
However, in this method, it is necessary to reset the integration result every period corresponding to 1 bit at the time of recording by integrating the synchronous detection result on the reproducing apparatus side. In order to detect this timing, It is necessary to transmit a synchronization signal. That is, it is necessary to record a synchronization signal on an optical disc together with a plurality of modulation signals using a plurality of orthogonal carrier signals.
[0013]
In general, in an optical disc, recording is performed by intermittently inserting a synchronization signal between data. In the synchronization signal recorded in this way, the higher the frequency of recording, the more the synchronization occurs on the playback device side. The following performance can be improved. However, when the frequency of recording the synchronization signal is increased, the area allocated for data recording is reduced accordingly, and the recording capacity of the optical disk is reduced.
[0014]
Even in the method disclosed in Japanese Patent Application Laid-Open No. 11-316951, if the recording of the synchronization signal is interrupted and the recording of the data is interrupted, there is a problem in that the recording capacity decreases if an attempt is made to improve the tracking performance of the synchronization. is there.
[0015]
One way to solve this problem is to acquire synchronization roughly using the dedicated synchronization pattern recorded at a low frequency, and then synchronize with high precision using the phase information obtained by demodulating the signal modulated with data. A method of capturing is conceivable.
[0016]
However, with this method, the recording capacity of the optical disk can be increased, but there is a problem that the configuration of the reproducing apparatus becomes complicated. Further, in this method, in order to acquire synchronization with high accuracy by data, it is necessary to be able to decode data with a certain degree of accuracy even with coarse synchronization acquisition using a synchronization pattern. When the accuracy of synchronization acquisition decreases, it becomes difficult to correctly decode the data, so that the synchronization accuracy may be significantly reduced.
[0017]
The present invention has been made in consideration of the above points. For example, a plurality of series of modulation signals are generated using orthogonal carrier wave signals, and a groove or the like is generated by a recording signal obtained by adding the modulation signals of the plurality of lines. Information recording apparatus, information recording medium, and information reproducing apparatus capable of reliably capturing synchronously by preventing a decrease in recording capacity with a simple configuration when recording desired data by changing the recording medium It is.
[0018]
[Means for Solving the Problems]
  In order to solve such a problem, the invention of claim 1 is applied to an information recording apparatus, and a recording signal is generated by adding a synchronization signal, which is a reproduction reference of a data transfer clock, to a modulation signal. The recording medium is irradiated with a recording beam, and a change in the information recording surface due to the irradiation of the recording beam is formed.Further, the modulation means generates a carrier wave signal from a plurality of sine wave signals and / or cosine wave signals having a frequency that is an integral multiple of the frequency of the predetermined reference signal, and corresponds to each of the plurality of sine wave signals and / or cosine wave signals. A plurality of sub-modulation signals are generated by modulation with a bit string synchronized with the data transfer clock, and a plurality of sub-modulation signals are added to generate a modulation signal. The synchronizing signal is a sine wave signal having a frequency lower than the frequency of the plurality of sine wave signals and / or cosine wave signals and having an integer multiple of the frequency of the reference signal.
[0019]
  And claims7In the present invention, the present invention is applied to an information recording medium, a recording signal is generated by adding a synchronization signal which is a reproduction reference of a data transfer clock to a modulation signal, and information recording by irradiation of a recording beam in accordance with the recording signal The data is recorded by changing the surface.Further, the modulation means generates a carrier wave signal from a plurality of sine wave signals and / or cosine wave signals having a frequency that is an integral multiple of the frequency of the predetermined reference signal, and corresponds to each of the plurality of sine wave signals and / or cosine wave signals. A plurality of sub-modulation signals are generated by modulation with a bit string synchronized with the data transfer clock, and a plurality of sub-modulation signals are added to generate a modulation signal. The synchronizing signal is a sine wave signal having a frequency lower than the frequency of the plurality of sine wave signals and / or cosine wave signals and having an integer multiple of the frequency of the reference signal.
[0020]
  And claims12In this invention, the present invention is applied to an information reproducing apparatus, and a synchronizing signal which is a reproduction reference of a data transfer clock is added to a modulated signal.TheA recording signal is generated, and a clock is generated by changing the frequency according to the control signal for an information recording medium on which data is recorded by changing the information recording surface by irradiation of a recording beam according to the recording signal. Then, the phase of the clock and the reproduction signal are compared, and a control signal is generated based on the phase comparison result, thereby synchronizing the clock with the synchronization signal included in the reproduction signal.At this time, the recording medium generates a carrier wave signal with a plurality of sine wave signals and cosine wave signals having a frequency that is an integral multiple of the frequency of the predetermined reference signal by the modulation means, and generates the plurality of sine wave signals and cosine wave signals. A plurality of sub-modulated signals are generated by modulation with a bit string synchronized with the corresponding data transfer clock, and a plurality of sub-modulated signals are added to generate a modulated signal. Further, the synchronization signal is a sine wave signal having a frequency lower than the frequencies of the plurality of sine wave signals and the cosine wave signal and having a frequency that is an integral multiple of the frequency of the reference signal. Here, the control signal generating means for generating the clock includes a sine wave signal generating means for generating a sine wave signal synchronized with the clock, and a cosine wave signal for generating a cosine wave signal having a phase difference of 90 degrees with respect to the sine wave signal. A generating means, a sine wave multiplication means for multiplying the reproduction signal by the sine wave signal and outputting the multiplication result by the sine wave, and a cosine wave for multiplying the reproduction signal by the cosine wave signal and outputting the multiplication result by the cosine wave. Multiplying means, integrating sine wave multiplication result with clock as reference and outputting sine wave integration result, and integrating cosine wave multiplication result with clock as cosine wave A cosine wave integrating means for outputting the integration result and a comparing means for comparing the integration results of the sine wave and the cosine wave are provided, and a control signal is generated based on the comparison result of the comparing means..
[0021]
  According to the configuration of claim 1If the recorded signal isThe recording signal can be multiplexed and recorded, thereby preventing a decrease in recording capacity as in the case of recording data by interrupting the recording of data, and the synchronization can be reliably captured with a simple configuration. it can.
[0022]
  And claims7Depending on the configuration ofThe sameIn the period signalAccurate playbackThe recording signal is multiplexed and recorded, whereby the recording capacity is prevented from being lowered as in the case where the recording of the data is interrupted and the synchronization signal is recorded, and the synchronization can be reliably acquired with a simple configuration.
[0023]
  Claim 12With this configuration, the clock can be reproduced with reference to the synchronization signal that is multiplexed and recorded on the recording signal, thereby reducing the recording capacity as in the case of recording the synchronization signal by interrupting the data recording. Therefore, synchronization can be reliably acquired with a simple configuration.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
[0025]
(1) Configuration of the embodiment
FIG. 2 is a block diagram showing the optical disc apparatus according to the embodiment of the present invention. The optical disc apparatus 1 records the digital information DINFO supplied from the information source 3 on the disc master 2 by modulation of the laser beam L 1 applied to the disc master 2.
[0026]
In the optical disc manufacturing process, after developing the master disc 2 on which the digital information DINFO is recorded in this way, a mother disc is created by electroforming, and a stamper is created from this 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 prepare an optical disk.
[0027]
Here, the information source 3 is constituted by a digital tape recorder, for example, and outputs digital information DINFO by a digital audio signal, a digital video signal or the like by parallel data having a predetermined number of bits.
[0028]
In this optical disc apparatus 1, the bit number conversion circuit 4 divides this digital information DINFO into every 4 bits and outputs 4-bit parallel digital signals DD0 to DD3. The recording signal generation circuit 5 generates and outputs a recording signal RS whose signal level continuously changes according to the digital signals DD0 to DD3.
[0029]
The laser light source 6 is composed of, for example, a gas laser or the like, and emits a laser beam L0. The optical modulator 7 is composed of, for example, an AOM (Acoustic Optical Modulator), and modulates and outputs the intensity of the laser beam in accordance with the recording signal RS output from the recording signal generation circuit 5.
[0030]
Thus, the laser beam L1 whose intensity is modulated by the recording signal RS is bent toward the disc master 2 by a mirror (not shown), and is focused on the disc master 2 by the objective lens 8. The mirror and the objective lens 8 are sequentially moved from the inner peripheral side to the outer peripheral side of the disc master 2 in synchronization with the rotation of the disc master 2 by a thread mechanism (not shown), whereby the optical disc apparatus 1 is exposed by the laser beam L1. The position is sequentially displaced toward the outer periphery of the disc master 2.
[0031]
The spindle motor 10 rotates the disk master 2 and outputs an FG signal FG whose signal level rises at every predetermined rotation angle from an FG signal generation circuit held at the bottom. The spindle servo circuit 11 drives the spindle motor 10 so that the frequency of the FG signal FG becomes a predetermined frequency according to the exposure position of the disk master 2, thereby rotating the disk master 2 at a predetermined rotational speed. .
[0032]
As a result, on the disc master 2, the irradiation locus of the laser beam L1 is formed in a spiral shape, and a groove is formed from the exposure locus. Further, in the exposure process, the intensity of the laser beam L1 is modulated by the recording signal RS whose signal level continuously changes in accordance with the digital signals DD0 to DD3. Digital information DINFO is recorded by changing the width.
[0033]
FIG. 1 is a block diagram showing the recording signal generation circuit 5. In the recording signal generation circuit 5, the oscillator 13 generates and outputs the data transfer clock CK1 of the digital signals DD0 to DD3 with the frequency f0. Accordingly, the digital signals DD0 to DD3 are input to the recording signal generation circuit 5 in synchronization with the data transfer clock CK1.
[0034]
The level conversion circuits (LT) 14A to 14D latch each bit of the digital signals DD0 to DD3 on the basis of the data transfer clock CK1, and the signal level of each bit based on the TTL level is centered on 0 [V]. The signal levels of the digital signals DD0 to DD3 are converted and output so as to change between a predetermined negative voltage and positive voltage. In this embodiment, the negative side voltage and the positive side voltage are set to -1 [V] and 1 [V], respectively.
[0035]
The subcarrier generation circuits 15A and 15B are composed of, for example, a PLL (Phase Locked Loop) circuit that operates based on the data transfer clock CK1 and a low-pass filter, and the data transfer clock CK1 changes from low level to high level. At timing t = 0, a sine wave signal SC1 and a cosine wave signal SC2 having a frequency f1 that is twice the frequency f0 of the data transfer clock CK1 represented by the following equations are generated.
[0036]
[Expression 1]

[0037]
The subcarrier generation circuits 16A and 16B are composed of, for example, a PLL (Phase Locked Loop) circuit that operates on the basis of the data transfer clock CK1 and a low-pass filter, and the data transfer clock CK1 changes from a low level to a high level. At timing t = 0, a sine wave signal SC3 and a cosine wave signal SC4 having a frequency f2 that is three times the frequency f0 of the data transfer clock CK1 represented by the following equations are generated and output.
[0038]
[Expression 2]

[0039]
The multiplication circuit 17A multiplies the output signal of the level conversion circuit 14A by the sine wave signal SC1, thereby generating and outputting the amplitude modulation signal M1 of the least significant bit DD0 of the digital signals DD0 to DD3. The multiplication circuit 17B multiplies the output signal of the level conversion circuit 14B by the cosine wave signal SC2, thereby the lowest order of the digital signals DD0 to DD3 having a narrowly orthogonal relationship with respect to the amplitude modulation signal by the multiplication circuit 17A. To generate and output an amplitude modulation signal M2 of the first bit DD1.
[0040]
The multiplication circuit 18A multiplies the output signal of the level conversion circuit 14C and the sine wave signal SC3, thereby generating and outputting the amplitude modulation signal M3 of the bit DD2 of the lower-order second bit of the digital signals DD0 to DD3. The multiplication circuit 18B multiplies the output signal of the level conversion circuit 14D by the cosine wave signal SC4, so that the highest order of the digital signals DD0 to DD3 having a narrowly orthogonal relationship with the amplitude modulation signal by the multiplication circuit 18A. An amplitude modulation signal M4 of bit DD3 is generated and output.
[0041]
As a result, the amplitude modulation signals M1 to M4 output from the multiplication circuits 17A to 18B are respectively expressed by the following equations. Here, A1 to A4 are constants of value 1 or value -1 corresponding to the logical values of bits DD0 to DD3, respectively.
[0042]
[Equation 3]

[0043]
The adder circuit 19 adds the modulation signals M1 and M2 of the multiplication circuits 17A and 17B, which are orthogonal to each other with the carrier frequency f1, and outputs a modulation signal MA based on orthogonal modulation. The adder circuit 20 adds the modulation signals M3 and M4 of the multiplication circuits 18A and 18B that are orthogonal to each other with the carrier frequency f2, and outputs a modulation signal MB by orthogonal modulation.
[0044]
As a result, the modulation signals MA and MB are 45 degrees and 135 degrees in phase with respect to the original sine wave signals SC1 and SC3, depending on the logical values of the bits DD0, DD1 and DD2 and DD3 of the digital signals DD0 to DD3, respectively. 225 degrees and 315 degrees are keyed and output, and the amplitude is 2 of the original sine wave signals SC1 and SC3.^1/2 Will be output.
[0045]
The synchronization signal generation circuit 23 is configured by, for example, a low-pass filter, and generates a synchronization signal SYNC that is a sine wave having a frequency f0 by removing a harmonic component of the data transfer clock CK1 output from the oscillator 13. Further, at this time, the synchronization signal generation circuit 23 generates this synchronization signal so that the amplitude of the synchronization signal SYNC is larger than the amplitude of the modulation signals MA and MB, and thereby the data transfer clock CK1 is changed from the low level to the high level. The timing for changing to the level is set to t = 0, and a synchronization signal SYNC represented by the following equation is output to the subsequent adder circuit 22. Here, the amplitude of the synchronization signal SYNC is set to a value of 10 by comparison with the equation (3).
[0046]
[Expression 4]

[0047]
The addition circuit 22 adds the addition signals MA and MB and the synchronization signal SYNC from the addition circuits 19 and 20, and outputs the result.
[0048]
The signal level correction circuit 24 corrects the output signal level of the adder circuit 22 so that the light amount of the laser beam L1 output from the optical modulator 7 is proportional to the output signal level of the adder circuit 22 thus obtained. To generate a recording signal RS. Specifically, the signal level correction circuit 24 has a predetermined gain so as to compensate for the non-linearity of the optical modulator 7 and so that the laser beam L1 is almost completely shielded by the bottom value in the output signal of the adder circuit 22. The output signal of the adder circuit 22 is amplified by AA to give an offset voltage BB. As a result, the signal level correction circuit 24 outputs a recording signal RS represented by the following equation.
[0049]
[Equation 5]

[0050]
FIG. 3 is a perspective view showing an optical disc produced from the disc master 2 exposed in this way. In the disc master 2, the light quantity of the laser beam L1 is modulated by the recording signal RS using the sine wave signal and the cosine wave signal as a carrier wave signal, and the exposure is performed continuously by the width corresponding to the light quantity of the laser beam L1. An exposure locus is formed by recording the digital information DINFO as a change in the information recording surface. Thus, the optical disk 30 is formed such that the groove corresponding to the exposure locus is formed in a spiral shape, and the width of the groove changes according to the recording signal RS. As a result, on the optical disc 30, the continuous change of the information recording surface due to the irradiation of the laser beam L1 is formed by the groove, and the digital information DINFO is recorded.
[0051]
FIG. 4 is a block diagram showing an optical disc apparatus for reproducing the optical disc 30. As shown in FIG. In the optical disc device 31, the spindle motor 32 rotates the optical disc 30 and outputs an FG signal FG2 whose signal level rises at every predetermined rotation angle from the FG signal generation circuit held at the bottom. The spindle servo circuit 33 drives the spindle motor 32 so that the frequency of the FG signal FG2 becomes a predetermined frequency in accordance with the laser beam irradiation position of the optical pickup 34 with respect to the optical disk 30, thereby causing the optical disk 30 to rotate at a predetermined rotational speed. It is driven by rotation.
[0052]
The optical pickup 34 is a so-called three-beam optical pickup applied to a compact disc player or the like, and generates -1st order, 0th order, and + 1st order diffracted light from a laser beam of a semiconductor laser by a diffraction grating, and an objective lens. Thus, the diffracted light is condensed on the optical disk 30. The optical pickup 34 receives the return light of the diffracted light by a predetermined light receiving element, performs current-voltage conversion processing on the light reception result, and performs matrix calculation, so as to respond to the tracking error amount with respect to the track center which is the center of the groove. The tracking error signal TE whose signal level changes, the focus error signal FE whose signal level changes according to the focus error amount, and the reproduction signal SU whose signal level changes according to the groove width are output.
[0053]
The biaxial servo circuit 35 moves the objective lens of the optical pickup 34 according to the tracking error signal TE and the focus error signal FE output from the optical pickup 34, thereby executing processing for tracking control and focus control.
[0054]
The reproduction signal correction circuit 36 removes a component corresponding to the bias voltage added by the signal level correction circuit 24 by removing a direct current component from the reproduction signal SU output from the optical pickup 34, and then amplifies it with a predetermined gain. As a result, a reproduction signal GRF represented by the following equation is output in comparison with equations (3) to (5). Here, AS is a constant representing the amplitude.
[0055]
[Formula 6]

[0056]
The synchronization signal reproduction circuit 37 reproduces and outputs the data transfer clock CK1 from the reproduction signal GRF thus obtained, and the data reproduction circuit 38 performs signal processing of the reproduction signal GRF based on the data transfer clock CK1. Digital information DINFO is reproduced and output.
[0057]
FIG. 5 is a block diagram showing the synchronization signal reproduction circuit 37. The synchronization signal reproduction circuit 37 is configured by a PLL (Phase Locked Loop) circuit. That is, in the synchronization signal regeneration circuit 37, a voltage controlled oscillator (VCO: Voltage Controlled Oscillator) 40 generates and outputs the data transfer clock CK1 with the frequency varied according to the control voltage VC, and the phase detection circuit 41 The phase difference between the synchronization signal included in the reproduction signal GRF and the data transfer clock CK1 is detected, and the detection result is output as the phase difference signal PE. The loop filter 42 limits the band of the phase difference signal PE and amplifies the phase difference signal PE with a predetermined gain to generate a control voltage VC, and outputs the control voltage VC to the voltage controlled oscillation circuit 40. Thus, the synchronization signal regeneration circuit 37 regenerates the data transfer clock CK1 by forming a feedback loop so that the data transfer clock CK1 is synchronized with the synchronization signal included in the regeneration signal GRF.
[0058]
Therefore, in the phase detection circuit 41, the sine wave signal generation circuit 45 performs data transfer on the assumption that the data transfer clock CK1 is synchronized with the synchronization signal of the reproduction signal GRF by limiting the band of the data transfer clock CK1. A timing at which the signal level of the clock CK1 rises is set to a time point t = 0, and a sine wave signal CC1 represented by the following equation is generated.
[0059]
[Expression 7]

[0060]
Similarly, the cosine wave signal generation circuit 46 limits the band of a rectangular wave signal that is shifted in phase by ¼ phase with respect to the data transfer clock CK1, so that the data transfer clock CK1 is synchronized with the synchronization signal of the reproduction signal GRF. Assuming that the signal level of the data transfer clock CK1 rises at time t = 0, a cosine wave signal CC2 represented by the following equation is generated.
[0061]
[Equation 8]

[0062]
Multiplication circuits 47 and 48 multiply the reproduction signal GRF by the sine wave signal CC1 and cosine wave signal CC2, respectively, and the integration circuits 49 and 50 integrate and output the multiplication results of the multiplication circuits 47 and 48. Thus, the multiplication circuit 47 and the integration circuit 49, the multiplication circuit 48 and the integration circuit 59 constitute a synchronous detection circuit, respectively, and detect the in-phase components of the sine wave signal CC1 and the cosine wave signal CC2 included in the reproduction signal GRF, respectively. And output. The integration circuits 49 and 50 are reset at the cycle of the data transfer clock CK1, so that the integration value does not increase beyond a predetermined value.
[0063]
That is, if the phase difference between the sine wave signal CC1 and the synchronizing signal component included in the reproduction signal GRF is Δθ, the time error Δt corresponding to the phase difference Δθ is expressed by the following equation.
[0064]
[Equation 9]

[0065]
Here, when the timing at which the signal level of the data transfer clock CK1 rises is set to the time point t = 0, the integration result PS by the integration circuit 49 is expressed by the following equation.
[0066]
[Expression 10]

[0067]
Here, when the data transfer clock CK1 is synchronized with the synchronization signal of the reproduction signal GRF, the frequencies f1 and f2 are integer multiples of the frequency f0 of the data transfer clock CK1, so When A4 is constant and the integration interval is an integral multiple of the data transfer clock CK1, the integration result of the first term to the fourth term on the right side in equation (10) is 0. Even if the constants A1 to A4 change in the integration interval due to noise or the like, the integration result of the first term to the fourth term on the right side of the equation (10) is practically compared to the integration result of the right side and the fifth term. Observed as a sufficiently small value. Thereby, the equation (10) can be approximated as the following equation. However, T0 is a constant by integration.
[0068]
## EQU11 ##

[0069]
As a result, in the integration result PS of the integration circuit 49, a signal level in phase with the sine wave signal CC1 included in the reproduction signal GRF is detected. On the other hand, the integration result PC of the integration circuit 50 is similarly expressed by the following equation.
[0070]
[Expression 12]

[0071]
As a result, as in the case of the sine wave signal CC1, the equation (12) can be approximated as shown in the following equation, whereby the integration result PC of the integration circuit 50 has a cosine wave signal CC2 included in the reproduction signal GRF. An in-phase signal level is detected.
[0072]
[Formula 13]

[0073]
The phase comparison circuit 51 obtains an arc tangent from the integration results PS and PC and outputs it as a phase difference signal PE. That is, the phase difference signal PE is expressed by the following equation.
[0074]
[Expression 14]

[0075]
Thus, the phase difference signal PE indicates the phase difference between the synchronization signal included in the reproduction signal GRF and the data transfer clock CK1. As a result, the synchronization signal reproduction circuit 37 forms a feedback loop so that the phase difference signal PE becomes 0 level, and synchronizes the data transfer clock CK1 with the synchronization signal included in the reproduction signal GRF. .
[0076]
FIG. 6 is a block diagram showing the data reproduction circuit 38. The subcarrier generation circuits 60A and 60B are composed of, for example, a PLL (Phase Locked Loop) circuit, and the timing at which the signal level of the data transfer clock CK1 rises with respect to the data transfer clock CK1 as time t = 0 is expressed by the following equation: A sine wave signal SW1 and a cosine wave signal SW2 having a frequency f1 represented by
[0077]
[Expression 15]

[0078]
The multiplication circuits 61A and 61B multiply the sine wave signal SW1, the cosine wave signal SW2, and the reproduction signal GRF, respectively. The integration circuits 62A and 62B are reset by the data transfer clock CK1, and integrate and output the multiplication results of the multiplication circuits 61A and 61B. Thereby, the multiplication circuit 61A and the integration circuit 62A, the multiplication circuit 61B and the integration circuit 62B constitute a synchronous detection circuit, respectively, and detect the in-phase components of the sine wave signal SW1 and the cosine wave signal SW2 included in the reproduction signal GRF, respectively. And output. Thereby, the integration circuits 62A and 62B output integration results dem1 and dem2 represented by the following equations, respectively.
[0079]
[Expression 16]

[0080]
[Expression 17]

[0081]
Thus, A1 and A2 are constants of value 1 or value -1 corresponding to the logical values of the bits DD0 and DD1 of the digital signals DD0 to DD4, respectively. Therefore, in the integration results dem1 and dem2, these lower side 2 It can be seen that it indicates the logical value of the bit.
[0082]
Level conversion circuits (LT) 64A and 64B convert the signal levels of the integration results dem1 and dem2 into TTL levels and output them.
[0083]
The subcarrier generation circuits 65A and 65B are configured by, for example, a PLL circuit, and the frequency expressed by the following equation with the timing at which the signal level of the data transfer clock CK1 rises at time t = 0 with reference to the data transfer clock CK1. A sine wave signal SW3 and a cosine wave signal SW4 of f1 are respectively generated and output.
[0084]
[Formula 18]

[0085]
Multiplication circuits 66A and 66B multiply the sine wave signal SW3 and the cosine wave signal SW4 by the reproduction signal GRF, respectively. The integration circuits 67A and 67B are reset by the data transfer clock CK1, integrate the multiplication results of the multiplication circuits 66A and 66B, and output the result. Thus, the multiplication circuit 66A and the integration circuit 67A, the multiplication circuit 66B and the integration circuit 67B constitute a synchronous detection circuit, respectively, and detect the in-phase components of the sine wave signal SW3 and the cosine wave signal SW4 included in the reproduction signal GRF, respectively. And output. Thereby, the integration circuits 67A and 67B output integration results dem3 and dem4 represented by the following equations, respectively.
[0086]
[Equation 19]

[0087]
[Expression 20]

[0088]
Level conversion circuits (LT) 68A and 68B convert the signal levels of the integration results dem3 and dem4 into TTL levels and output them.
[0089]
The bit number conversion circuit 69 sequentially latches the output signals of the level conversion circuits 64A to 68B on the basis of the data transfer clock CK1 to reproduce 4-bit parallel data. Further, contrary to the bit number conversion circuit 69 in the optical disc apparatus 1, the bit number conversion circuit 69 returns the 4-bit parallel data to the original arrangement, thereby reproducing and outputting the digital information DINFO.
[0090]
(2) Operation of the embodiment
In the above configuration, the digital information DINFO output from the information source 3 (FIG. 2) is converted into 4-bit parallel digital signals DD0 to DD3 by the bit number conversion circuit 4. The digital signals DD0 to DD3 (FIG. 1) are sequentially input to the recording signal generating circuit 5 successively at timing synchronized with the data transfer clock CK1, where the signal levels are respectively referred to the 0 level by the level converting circuits 14A to 14D. The signal level is corrected so as to change.
[0091]
In the recording signal generation circuit 5, with the data transfer clock CK1 as a reference, the frequencies f1 and f2 are twice and three times the frequency f0 of the data transfer clock CK1, and have a predetermined phase with respect to the data transfer clock CK1. The sine wave signals SC1 and SC3 and the cosine wave signals SC2 and SC4 held in the relationship are generated. In the multiplication circuits 17A to 17D, these sine wave signals and cosine wave signals SC1 to SC4 are converted to level conversion circuits 14A to 14D, respectively. The output signal is multiplied.
[0092]
As a result, the recording signal generation circuit 5 uses four carrier waves of sine wave signals and cosine wave signals SC1 to SC4 of frequencies f1 and f2 as carrier waves, and keys each carrier wave by each bit string of the digital signals DD0 to DD3. Then, amplitude modulation signals M1 to M4 are generated by the bit strings of the digital signals DD0 to DD3.
[0093]
In the recording signal generation circuit 5, modulation signals M1 and M2, M3 and M4 related to the same carrier frequency are added in addition circuits 19 and 20, respectively, thereby generating quadrature amplitude modulation signals MA and MB related to vector synthesis. The Further, the modulation signals MA and MB are added by the adder circuit 22 to generate a modulation signal for multiplexing, so that the bottom level becomes 0 level and the signal level changes, and the nonlinearity of the optical modulator 7 As a result, the signal level of the modulation signal is corrected by the signal level correction circuit 24 to generate the recording signal RS.
[0094]
At this time, the recording signal generation circuit 5 is held in a fixed phase relationship with the data transfer clock CK1 (that is, held in a fixed phase relationship with the sine wave signals and cosine wave signals SC1 to SC4 via the data transfer clock CK1). A sine wave signal having the same frequency f0 as that of the data transfer clock CK1 is generated by the synchronization signal generation circuit 23, and this sine wave signal is superimposed on the modulation signal by the addition circuit 22 as the synchronization signal SYNC. As a result, in the optical disc apparatus 1, the synchronization signal SYNC based on the sine wave signal is multiplexed on the recording signal RS due to the continuous signal level change.
[0095]
At this time, the synchronization signal SYNC is added to the modulation signal with a larger amplitude than the other modulation signals M1 to M4. As a result, the recording signal RS is generated such that the change in the signal waveform due to the synchronization signal SYNC is greatly observed with respect to the change in the signal waveform due to the other modulation signals M1 to M4.
[0096]
In the optical disc apparatus 1, the intensity of the laser beam L0 emitted from the laser light source 6 is modulated by the operation of the optical modulator 7 based on the recording signal RS generated in this way, and the resulting laser beam L1 The light is condensed on the rotating disc master 2. Thus, in the optical disc apparatus 1, digital information DINFO formed by superimposing the synchronization signal SYNC as a change in the continuous width of the exposure locus is recorded on the disc master 2.
[0097]
In the disc master 2 generated in this way, a mother disk is created through electroforming and the like after development processing, and a disk substrate is mass-produced through a series of processing using the mother disc. In the disk substrate thus generated, a groove is formed in the exposure locus on the disk master 2, and a reflective film, a protective film, etc. are formed on the side where the groove is formed, and the optical disk 30 (FIG. 3) is formed. Mass production. Accordingly, in the optical disc 30, a groove, which is a guide groove for the laser beam, is formed by this groove, and the groove width is formed so as to change according to the recording signal RS.
[0098]
As a result, in the optical disc 30, it is possible to reliably capture synchronization by preventing a decrease in recording capacity as in the case of recording data by interrupting data recording.
[0099]
That is, in the optical disc 30, the reproduction signal SU whose signal level changes according to the width of the groove is detected from the reception result of the return light obtained by irradiating the laser beam in the optical disc apparatus 31 (FIG. 4). The reproduction signal GRF equivalent to the output signal (FIG. 1) of the addition circuit 22 during recording is detected by correcting the signal level in the reproduction signal correction circuit 36.
[0100]
In the optical disk device 31, this reproduction signal GRF is input to the synchronization signal reproduction circuit 37, and here, the sine wave signal CC1 and the cosine wave are based on the data transfer clock CK1 output from the voltage control type oscillation circuit 40 (FIG. 5). The signal CC2 is generated, and the reproduction signal GRF is multiplied by the sine wave signal CC1 and the cosine wave signal CC2, and the multiplication results are integrated by the integration circuits 49 and 50, whereby the sine wave signal CC1 and cosine included in the reproduction signal GRF are obtained. The signal level in phase with the wave signal CC2 is detected. In the optical disc device 31, the phase difference of the data transfer clock CK1 with respect to the synchronization signal SYNC included in the reproduction signal GRF is detected by the phase comparison circuit 51 from the signal level detected in this way, and this phase difference is detected via the loop filter 42. The frequency of the data transfer clock CK1 in the voltage controlled oscillation circuit 40 is corrected so that the data transfer clock CK1 is synchronized with the synchronization signal SYNC included in the reproduction signal GRF. As a result, in the optical disc apparatus 31, the synchronization signal reproducing circuit 37 having the PLL circuit configuration can acquire the synchronization by the synchronization signal SYNC continuously recorded on the optical disc 30, and can surely acquire the synchronization with a simple configuration. .
[0101]
Further, at this time, the frequency f0 of the synchronization signal SYNC is set to the basic frequency, and the frequencies f1 and f2 of the sine wave signal and cosine wave signal for data transfer are set to 2 times and 3 times the integral frequency of the basic frequency f0. By setting, when the data transfer clock CK1 is synchronized with the synchronization signal SYNC, it is possible to prevent the integration results in the integration circuits 49 and 50 from being affected by the modulation signals generated by the data transfer. As a result, in this embodiment, even if the synchronization signal is multiplexed and recorded on the modulation signal, the synchronization can be reliably acquired.
[0102]
Further, by making the amplitude of the synchronization signal SYNC larger than that of other modulation signals, the phase difference signal PE can be obtained with a high S / N ratio when the synchronization is acquired by the PLL circuit configuration in this way, This also makes it possible to capture the synchronization easily and reliably.
[0103]
In the optical disc apparatus 31, the digital information DINFO is reproduced with reference to the data transfer clock CK1 generated in this way. That is, in the optical disk device 31 (FIG. 6), the sine wave signals SW1, SW3 and cosine wave signals SW2, SW4 equivalent to the sine wave signals SC1, SC3, cosine wave signals SC2, SC4 generated during recording from the data transfer clock CK1. Are generated by the subcarrier generation circuits 60A, 60B, 65A and 65B, and the multiplication results of the sine wave signals SW1 and SW3, the cosine wave signals SW2 and SW4 and the reproduction signal GRF are generated by the multiplication circuits 61A, 61B, 66A and 66B. Is done.
[0104]
The multiplication results of the multiplication circuits 61A, 61B, 66A, 66B are integrated by the integration circuits 62A, 62B, 67A, 67B, respectively, with the period of the data transfer clock CK1, thereby the bits DD0 to DD3 of the digital signals DD0 to DD3. Integration results dem1 to dem4 whose signal level changes according to the logical value are detected. Further, the integration results dem1 to dem4 are converted to the TTL level by the level conversion circuits 64A to 68B, and then latched by the bit number conversion circuit 69 to reproduce the original digital signals DD0 to DD3, and the digital signals DD0 to DD3 are reproduced. The bit arrangement is corrected and the original digital information DINFO is reproduced.
[0105]
(3) Effects of the embodiment
According to the above configuration, a plurality of series of modulation signals are generated using orthogonal carrier wave signals, and the groove width is continuously changed by a recording signal obtained by adding the modulation signals of the plurality of lines. When recording this data, by adding the synchronization signal, which is the reproduction reference of the data transfer clock, to the recording signal and recording it, it is possible to prevent the recording capacity from being lowered and reliably capture the synchronization with a simple configuration. .
[0106]
At this time, with the synchronization signal as a reference, a modulation signal is generated by a sine wave signal and a cosine wave signal having a frequency that is an integral multiple of the frequency of the synchronization signal. Synchronization can be acquired by a signal.
[0107]
Also, by increasing the amplitude of the synchronization signal compared to the amplitude of the modulation signal, it is possible to acquire the synchronization with a high SN ratio on the reproduction side, and this can also ensure the synchronization acquisition with a simple configuration.
[0108]
(4) Other embodiments
In the above-described embodiment, the case where the recording signal is generated by generating and adding the modulation signal by the two sets of orthogonal sine wave signal and cosine wave signal has been described, but the present invention is not limited to this. In the case where the amplitude modulation signal is generated and recorded by a plurality of sets of reference signals of various numbers, the present invention is further applied to the case where only the sine wave signal or the cosine wave signal is amplitude modulated and recorded, etc. The same effect as the embodiment can be obtained.
[0109]
In the above-described embodiment, the case where the modulation signal is generated and recorded by the orthogonal sine wave signal and cosine wave signal has been described. However, the present invention is not limited to this, and SN sufficient for data reproduction in each system is described. If the ratio can be ensured, the application of such an orthogonal relationship can be eliminated.
[0110]
In the above-described embodiment, the case where the modulation signal is generated by amplitude-modulating the orthogonal sine wave signal and cosine wave signal has been described. However, the present invention is not limited to this, and the modulation signal is generated by frequency modulation. For example, the present invention can be widely applied.
[0111]
In the above embodiment, the case where desired data is recorded by changing the groove width has been described. However, the present invention is not limited to this, and the meandering of the groove, the meandering of the groove wall surface, and the change of the depth of the groove. In the case of recording by the method, the present invention is widely applied to a case where a long and narrow continuous protrusion (projection) having a shape opposite to the groove is formed, and recording is performed by meandering of the projection, meandering of the wall surface, and change in height. be able to.
[0112]
In the above embodiment, the case where desired data is recorded by the change of the groove width as a continuous change of the information recording surface has been described. However, the present invention is not limited to this and is applied to, for example, a magneto-optical disk. Thus, the present invention can be widely applied to recording desired data by changing the width of a region magnetized to a predetermined polarity, meandering, or the like as a continuous change of the information recording surface.
[0113]
In the above-described embodiment, the case where desired data is recorded by the groove as a continuous change of the information recording surface has been described. However, the present invention is not limited to this, and the above-described recording signal is converted to PWM (Pulse Width Modulation). ) And the like, and the recording signal is converted into a binary signal, and the laser beam is turned on / off by this recording signal to record the desired data by the pit row. Further, the desired data is recorded by the mark row. It can be widely applied to cases.
[0114]
In the above-described embodiment, the case where desired data is recorded by laser beam irradiation has been described. However, the present invention is not limited to this, and the case where desired data is recorded by an electron beam instead of a laser beam. Can also be widely applied.
[0115]
In the above-described embodiment, the case where desired data is recorded on an optical disk, which is a disk-shaped information recording medium, has been described. However, the present invention is not limited to this, and desired data is recorded on a card-shaped information recording medium. The present invention can be widely applied to recording desired data on information recording media having various shapes, such as recording.
[0116]
【The invention's effect】
As described above, according to the present invention, for example, a plurality of series of modulation signals are generated using a plurality of orthogonal carrier signals, and a groove or the like is changed by a recording signal obtained by adding the plurality of modulation signals. When recording this data, the recording reference signal is added to the recording signal and the recording reference signal is added to the recording signal, so that the recording capacity can be prevented from being lowered and the synchronization can be reliably acquired with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a recording signal generation circuit applied to an optical disc apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram showing an optical disc apparatus according to an embodiment of the present invention.
3 is a perspective view showing an optical disc by the optical disc apparatus of FIG. 2. FIG.
4 is a block diagram showing an optical disc apparatus that reproduces the optical disc of FIG. 3; FIG.
5 is a block diagram showing a synchronization signal reproduction circuit of the optical disc apparatus of FIG. 4. FIG.
6 is a block diagram showing a data reproduction circuit of the optical disc apparatus of FIG. 4. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 31 ... Optical disk apparatus, 2 ... Disc master, 3 ... Information source, 5 ... Recording signal generation circuit, 7 ... Optical modulator, 30 ... Optical disk, 37 ... Synchronous signal reproduction circuit, 38 ... ... Data recovery circuit

Claims (14)

Modulation means for generating a modulated signal by modulating a carrier signal of a predetermined frequency by data synchronized with a predetermined data transfer clock;
Recording signal generating means for generating a recording signal by adding a synchronization signal which is a reproduction reference of the data transfer clock to the modulation signal;
Beam irradiation means for irradiating an information recording medium with the recording signal according to the recording signal and forming a change in the information recording surface by the irradiation of the recording beam;
The modulating means includes
Generating the carrier signal by a plurality of sine wave signals and / or cosine wave signals at a frequency that is an integral multiple of the frequency of a predetermined reference signal;
Modulating the plurality of sine wave signals and / or cosine wave signals with bit strings synchronized with the corresponding data transfer clocks to generate a plurality of sub-modulation signals,
Adding the plurality of sub-modulation signals to generate the modulation signal;
The synchronization signal is
The information recording apparatus, wherein the information recording apparatus is a sine wave signal having a frequency lower than a frequency of the plurality of sine wave signals and / or cosine wave signals and having an integer multiple of the frequency of the reference signal. The recording beam is
The information recording apparatus according to claim 1, wherein the information recording apparatus is a laser beam. The recording beam is
The information recording apparatus according to claim 1, wherein the information recording apparatus is an electron beam. The synchronization signal is
The information recording apparatus according to claim 1, wherein the information recording apparatus is a sine wave signal synchronized with the data transfer clock. The synchronization signal is
The information recording apparatus according to claim 1, wherein the information recording apparatus is a sine wave signal synchronized with the carrier wave signal. The synchronization signal is
The information recording apparatus according to claim 1, wherein an amplitude is set larger than an amplitude of a modulation signal by the carrier wave signal. A modulated signal is generated by modulating a carrier signal of a predetermined frequency with data synchronized with a predetermined data transfer clock,
A recording signal is generated by adding a synchronization signal which is a reproduction reference of the data transfer clock to the modulation signal,
The data is recorded by the change of the information recording surface due to the irradiation of the recording beam according to the recording signal,
The modulated signal is
The carrier signal is generated by a plurality of sine wave signals and / or cosine wave signals having a frequency that is an integral multiple of a predetermined reference signal frequency,
A plurality of sub-modulated signals are generated by modulating the plurality of sine wave signals and / or cosine wave signals with bit sequences synchronized with the corresponding data transfer clocks, respectively;
Generated by adding the plurality of sub-modulation signals;
The synchronization signal is
An information recording medium, wherein the information recording medium is a sine wave signal having a frequency lower than that of the plurality of sine wave signals and / or cosine wave signals and having an integer multiple of the frequency of the reference signal. The change of the information recording surface is
The information recording medium according to claim 7, wherein the information recording medium can be detected by a change in reflected light or a change in diffracted light obtained by irradiating a laser beam. The synchronization signal is
The information recording medium according to claim 7, wherein the information recording medium is a sine wave signal synchronized with the data transfer clock. The synchronization signal is
The information recording medium according to claim 7, wherein the information recording medium is a sine wave signal synchronized with the carrier wave signal. The synchronization signal is
The information recording medium according to claim 7, wherein an amplitude is set to be larger than an amplitude of a modulation signal by the carrier wave signal. In an information reproducing apparatus for reproducing data recorded on the information recording medium by irradiating the information recording medium with a reproducing beam,
The information recording medium is
A modulated signal is generated by modulating a carrier signal of a predetermined frequency with the data synchronized with a predetermined data transfer clock,
A recording signal is generated by adding a synchronization signal which is a reproduction reference of the data transfer clock to the modulation signal,
The data is recorded by the change of the information recording surface due to the irradiation of the recording beam according to the recording signal,
The modulated signal is
The carrier signal is generated by a plurality of sine wave signals and cosine wave signals having a frequency that is an integral multiple of the frequency of a predetermined reference signal,
A plurality of sub-modulated signals are generated by modulating the plurality of sine wave signals and cosine wave signals with bit sequences synchronized with the corresponding data transfer clocks;
Generated by adding the plurality of sub-modulation signals;
The synchronization signal is
A sine wave signal having a frequency lower than the frequency of the plurality of sine wave signals and cosine wave signals, and having an integer multiple of the frequency of the reference signal,
The information reproducing apparatus includes:
Reproduction signal detecting means for detecting a reproduction signal whose signal level changes according to the change of the information recording surface due to irradiation of the reproduction beam;
Clock generating means for generating a clock by changing the frequency according to a predetermined control signal;
Control signal generation means for synchronizing the clock with the synchronization signal included in the reproduction signal by comparing the phase of the clock with the reproduction signal and generating the control signal based on the phase comparison result;
Data reproducing means for processing the reproduction signal on the basis of the clock and reproducing the data;
The control signal generating means
Sine wave signal generating means for generating a sine wave signal synchronized with the clock;
Cosine wave signal generating means for generating a cosine wave signal having a phase difference of 90 degrees with respect to the sine wave signal;
A sine wave multiplication means for multiplying the sine wave signal by the reproduction signal and outputting a multiplication result by the sine wave;
Cosine wave multiplication means for multiplying the reproduction signal by the cosine wave signal and outputting a multiplication result by the cosine wave;
Sine wave integrating means for integrating the multiplication result by the sine wave with respect to the clock and outputting the integration result by the sine wave;
Cosine wave integrating means for integrating the multiplication result by the cosine wave with respect to the clock and outputting the integration result by the cosine wave;
Comparing means for comparing the integration results of the sine wave and cosine wave,
The information reproducing apparatus, wherein the control signal is generated based on a comparison result of the comparison means. The data reproducing means includes
A reference signal generating means for generating a demodulation reference signal having a predetermined frequency with reference to the clock;
Multiplication means for multiplying the demodulation reference signal and the reproduction signal and outputting a multiplication signal;
Integrating means for integrating the multiplication signal with respect to the clock and outputting an integration result;
The information reproducing apparatus according to claim 12, further comprising: an identification unit that sequentially identifies the integration results based on the clock and reproduces the data. The reference signal generating means includes
The reference signal for demodulation is generated by a sine wave signal and / or a cosine wave signal having different frequencies,
The multiplication means is
Multiplying the sine wave signal and / or cosine wave signal by the reproduction signal to generate a plurality of multiplication signals,
The integration means includes
Integrating each of the plurality of multiplication signals to obtain a plurality of integration results;
The identification means includes
Wherein the plurality of integration results each identified obtain a bit sequence of a plurality of systems, the information reproducing apparatus according to claim 1 3, characterized in that for reproducing the data by the bit string of the plurality of systems.

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