JP4071453B2

JP4071453B2 - Optical disk device

Info

Publication number: JP4071453B2
Application number: JP2001129910A
Authority: JP
Inventors: 節生大庭
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2001-04-26
Filing date: 2001-04-26
Publication date: 2008-04-02
Anticipated expiration: 2021-04-26
Also published as: JP2002324332A

Description

【０００１】
【発明の属する技術分野】
この発明は、例えばＣＤ−ＲドライブやＣＤ−ＲＷドライブ等の記録時ピットを形成する記録パワーとピットを形成しない再生パワーもしくは消去パワーを交互に繰り返すレーザ駆動制御回路を備えた光ディスク装置に関する。
【０００２】
【従来の技術】
一般的にレーザダイオードに戻り光が入ると戻り光により発振モードが変化してレーザノイズが増加することが知られている。
光ディスクのように反射光を取り扱う光ディスク装置では、そのレーザダイオードへの戻り光の影響を考慮する必要があり、そのレーザノイズを下げる方法として、レーザ発光に２００ＭＨｚ〜５００ＭＨｚ程度の高周波を重畳する手段が一般的な光ディスク装置では用いられている。
例えば、特開平５−１９７９９４号公報に記載された技術では、半導体レーザにおいて、フォーカスサーボ系によるフォーカス制御引き込み時には、高周波重畳回路による高周波電流の重畳量を多くすることにより、フォーカス引き込み時の戻り光量の変動に対して安定した半導体レーザの発光パワーが得られるレーザノイズ低減回路が示されている。
【０００３】
また、特開平６−２２３３９９号公報に記載された技術では、レーザノイズ低減に必要不可欠な高周波重畳手段を半導体レーザのケース内で信号検出手段と同一ウェハ上に形成することで、光ヘッドの小型化をはかる装置が示されている。一方、レーザダイオードの出力限界から記録パワーでの発光時には高周波を重畳しない、もしくは再生時より小さい振幅の高周波を重畳することが一般的な記録可能な光ディスクでは行われる。
その前者の例としては、上記特開平６−２２３３９９号公報に記載された技術においては、光ディスクの記録と再生の動作モードにより、高周波のＯＮ／ＯＦＦができる構成が示されている。
また、後者の例としては、特開２０００−１４９３０２号公報に記録と再生の動作モードにより高周波重畳の重畳周波数や重畳振幅を変える構成が示されている。
【０００４】
ここで、レーザダイオードの（駆動電流）対（発光パワー）の関係は高周波重畳の量によって変化する。
図１５及び図１６は、それぞれレーザーダイオードの駆動電流と発光パワーである出射パワーの関係を示した線図である。
図１５に示すように、記録時、高周波を重畳しない記録パワーと高周波を重畳した再生パワーを交互に繰り返した場合、再生パワーは高周波を重畳した状態で制御される為、再生パワー分の駆動電流は高周波を重畳した時のレーザーダイオードの（レーザ駆動電流）対（レーザ出射パワー：発光パワー）の関係より決定される。
一方、記録パワーで発光時高周波を重畳しない場合もしくは少ない量の高周波を重畳した場合は再生パワー分の電流はもっと大きい値であるが、その分は供給されないので、結局再生パワー分の電流に加算すべき記録パワー分の電流が図１６に示したように大きく見えてしまう。つまり記録パワー分の電流効率（図中の真の効率）に誤差（図中の誤差を含んだ効率）が生じてしまうことになる。
【０００５】
ＣＤ−ＲやＣＤ−ＲＷディスクに書きこみを行うＣＤ−ＲドライブやＣＤ−ＲＷドライブの場合、ディスク感度が大きく異なるディスクに対して記録品質を維持するために、パワーを可変していわゆる試し書きを行い、そこを再生することで最適な記録パワーを決定する。
ＣＤ−Ｒ／ＲＷディスクの規格書であるオレンジブックでは一回の試し書き領域を１５セクターとし、各セクターで異なるパワーで記録し、そこを再生して最適記録パワーを決定する方法が示されている。
このように、試し書き領域はフォーマットで規格化されている為、記録速度の高速化にともなって、試し書き時間が短くつまり一つのパワーでの記録時間が短くなってしまう。参考までにＣＤの１セクターは一倍速時１／７５秒である。
【０００６】
【発明が解決しようとする課題】
しかしながら、当然２倍速で１／７５秒の半分、４倍速で更にその半分と記録速度があがるにつれて一パワーの記録時間が短くなる。
ここで、正しい電流効率が求められていないとパワーをある値からある値に変える場合、最初に与える光源の駆動電流に誤差があるため、所望のパワーに達するのに時間がかかってしまう。
従来は上記のような誤差があっても記録速度が遅いため、所望のパワーに達することができたが、記録速度がどんどん早くなり、所望のパワーに達する前に一記録パワー期間が終了してしまう不具合が発生し、その結果、最適な記録パワーが得られず記録品質が低下してしまうという問題があった。
上述した特開平６−２２３３９９号公報や特開２０００−１４９３０２号公報に記載された技術では、これらの記録速度が速くなった場合が十分考慮されていなかった。
【０００７】
あるいは、ＺｏｎｅＣＬＶ記録などである位置から記録速度と共に記録パワーを変更する場合、変更のパワーが早く所望のパワーに達しないと達するまでの時間は記録品質が低下してしまうという問題もあった。
この発明は上記の課題を解決するためになされたものであり、記録速度が速い場合のテスト記録の際に設定パワーと実際の発光パワーのずれによる記録品質の低下を防ぐことを第１の目的とする。
【０００８】
また、特開平１０−３１２５７０号公報に記載された技術には、ＣＤ−ＲＷとＣＤ−Ｒの半導体レーザ駆動制御回路を共通化する装置において、ＣＤ−Ｒの記録時、第１のパワーＰ１と第２のパワーＰ２を制御し、その第２のパワーＰ２を制御している時の電流Ｉ２に所定の比をかけて求めた電流Ｉ３をレーザ駆動回路に与えることで簡易に第３のパワーＰ３を制御する装置が示されている。
しかしながら、このような装置では、高周波重畳の重畳量によって電流効率に誤差を生じることに対する考慮がされておらず、従って正しい第３のパワーＰ３が設定されず、ＣＤ−Ｒの様に第２のパワーＰ２と第３のパワーＰ３の比が記録品質に大きく寄与するシステムでは記録品質の低下を招くことになるという問題があった。
【０００９】
さらに、特開２０００−３０２７６号公報に記載された技術には、高速応答性及び高精度サンプリングパルスの生成を必要とすることなしに光ビームのパワーを正確かつ速やかに制御する装置において、記録波形の第１のパワーＰ１時の光出力検出回路の出力をボトムホールド回路で、第３のパワーＰ３時の光出力検出回路の出力をピークホールド回路で各々ホールドし、予め設定された第１のパワーＰ１，第２のパワーＰ２，第３のパワーＰ３の比率に基づいて第２のパワーＰ２の駆動電流を決定することで高速記録時サンプルホールドの難しい第２のパワーＰ２のレベルを制御する装置が示されている。
しかしながら、このような装置では、高周波重畳の重畳量によって電流効率に誤差を生じることに対する考慮がされておらず、従って正しい第２のパワーＰ２が設定されず、ＣＤ−Ｒの様に第２のパワーＰ２と第３のパワーＰ３の比が記録品質に大きく寄与するシステムでは記録品質の低下を招くことになるという問題があった。
そこで、２値のサンプルにより３値のパワーを容易に制御するシステムにおいても良好な記録品質を得られるようにすることを第２の目的とする。
【００１０】
また、レーザダイオードの（駆動電流）対（出射パワー）の関係は光ディスクの戻り光がある状態と無い状態で大きく異なる。これは、とりわけホログラムレーザの様にレーザダイオードと信号検出の受光素子が同一パッケージ内に納まり、レーザへの戻り光量が多い場合に顕著になる。従って上記駆動電流差Ｉ差を求める期間としては、フォーカスサーボ系によってフォーカスオン状態で行うのが望ましい。
そこで、駆動電流差Ｉ差をより正確に求められるようにすることを第３の目的とする。
【００１１】
さらに、上述のようにレーザノイズを低減する為に高周波を重畳する手段を取ると、その高周波の重畳をしない場合、あるいは重畳しても少ない量を重畳する場合、最悪の状態ではフォーカス信号にレーザノイズが乗るため、フォーカスサーボ系がフォーカスオン状態を保持できず、フォーカスが外れてしまう可能性がある。なお、通常の状態ではフォーカスサーボが維持できない状態になることはないが、光ディスクが粗悪な場合あるいは外乱が生じた場合等に上述のような状態が発生する可能性がある。
そこで、フォーカス状態が維持できなくなった場合でもリトライによって救済して駆動電流差Ｉ差を求められるようにすることを第４の目的とする。
【００１２】
また、通常の状態ではレーザノイズが高周波重畳により低減できていない状態でも、一般的な装置の場合、フォーカスオン状態が維持できなくなることはないが、外乱が生じた場合や光ディスクが粗悪な場合、レーザノイズによってフォーカス信号もいわゆるノイズマージンが少ないため、最悪の状態ではフォーカスオン状態が維持できなくなる可能性がある。
一時的な外乱等であれば上述の様にリトライすることによって回避することができるが、継続的な外乱や粗悪な光ディスクの場合、リトライしても駆動電流差Ｉ差が求められない可能性がある。
そこで、フォーカス状態でＩ差が求められなかった場合でも、駆動電流差Ｉ差とは異なる値の駆動電流値差ＦｏＩ差によって簡易的に駆動電流差Ｉ差を求め、擬似的に正しい補正効率を求められるようにすることを第５の目的とする。
【００１３】
さらに、年々、ＣＤ−Ｒ／ＲＷ装置は記録速度の高速化が図られ、それに伴って大きな記録パワーも必要になってきている。
ここで、記録パワーを大きくとることは、当然レーザの駆動電流も大きくする必要があり、記録時の第１のパワーと第２のパワーをスイッチングすることにより、ノイズレベルの増大を引き起こしている。
記録時のサーボ信号の検出を再生パワー発光時にサンプルし、記録パワー発光時にホールドすることによって検出する装置において、上記記録パワーの増大した時に検出信号のＳ／Ｎを稼ぐため、記録時の再生パワーを大きくして信号成分を大きくすることによってＳ／Ｎを稼ぐ手段が一般的に取られる。
例えば、特開平８−１０２０７８号公報に記載された技術では、記録時記録パワーに応じてウォブル信号を再生する再生パワーを変化させる装置が示されている。
【００１４】
しかしながら、ここで駆動電流差Ｉ差はパワーによって異なる為、記録時の再生パワーを再生時の発光パワーから可変する場合、再生時の発光パワーで高周波を重畳する／しないで求めた駆動電流差Ｉ差を補正効率の算出に用いると、補正効率が正しく求められないという問題が生じる。
そこで、再生時の発光パワーと記録時の再生パワーが異なる場合でも補正効率を正しく求められるようにすることを第６の目的とする。
さらにまた、レーザダイオードの（駆動電流）対（出射パワー）の関係は温度依存性があるため、上記記録前に求めた駆動電流差Ｉ差が若干ではあるが、レーザの記録中の自己加熱によって変化してしまうという問題が生じる。
そこで、補正効率を高精度に求められるようにすることを第７の目的とする。
【００１５】
【課題を解決するための手段】
この発明は上記の第１の目的を達成するため、レーザダイオード等の光源と、その光源への電流供給手段と、上記光源の発光出力レベルをモニタする光出力検出手段と、記録動作時、上記光源によって第１のパワーＰ１とそれよりも高い第２のパワーＰ２の発光を交互に繰り返して光ディスクにデータを記録する光ディスク装置であって、上記電流供給手段は、上記第１のパワーＰ１での発光分の電流Ｉ１と上記第２のパワーＰ２と上記第１のパワーＰ１の差分の電流Ｉ２とを加算して出力する手段と、上記第１のパワーＰ１時に高周波電流Ｉｈｆを上記電流Ｉ１に重畳する手段と、上記第２のパワーＰ２時に上記高周波電流Ｉｈｆの重畳をオフもしくは異なる電流Ｉｈｆ２に切り替える手段を有し、記録動作時、上記第２のパワーＰ２による発光時に上記光出力検出手段によってモニタした発光出力レベルＶｍ２をホールドする手段と、上記第１のパワーＰ１による発光時に上記光出力検出手段によってモニタした発光出力レベルＶｍ１をホールドする手段と、上記各手段によってホールドした発光出力レベルＶｍ１と発光出力レベルＶｍ２とをそれぞれ所望の値になるように上記電流供給手段を制御する制御手段と、記録時に上記第１のパワーＰ１による発光時に高周波を重畳し、上記第２のパワーＰ２では高周波を重畳しないようにするかもしくは重畳しても上記第１のパワーＰ１による発光時に重畳する高周波と異なる量を重畳するようにし、記録前に上記第１のパワーＰ１のレベルで高周波を重畳した第１発光期間と、上記第１のパワーＰ１のレベルで高周波を重畳しない発光期間もしくは記録時の上記第２のパワーＰ２の出力時に重畳する量の高周波を重畳した上記第１のパワーＰ１のレベルでの発光期間である第２発光期間とを設け、上記第１発光期間と上記第２発光期間とにおける上記光源の駆動電流差Ｉ差を保持し、上記第２のパワーＰ２による発光時もしくは発光後、上記第２のパワーＰ２の駆動電流の補正効率η＝（Ｐ２−Ｐ１）／（Ｉ２−Ｉ差）を求め、上記第２のパワーＰ２の変更時、変更後の第２のパワーＰ２′の初期電流Ｉ２′＝（Ｐ２′−Ｐ１）／η＋Ｉ差を求めて決定する手段を備えた光ディスク装置を提供する。
【００１６】
また、上記の第２の目的を達成するため、レーザダイオード等の光源と、その光源への電流供給手段と、上記光源の発光出力レベルをモニタする光出力検出手段と、記録動作時、上記光源によって第１のパワーＰ１とそれよりも高い第２のパワーＰ２とさらにそれよりも高い第３のパワーＰ３の発光を行って光ディスクにデータを記録する光ディスク装置であって、上記電流供給手段は、上記第１のパワーＰ１での発光分の電流Ｉ１と上記第２のパワーＰ２と上記第１のパワーＰ１の差分の電流Ｉ２と上記第３のパワーＰ３と上記第２のパワーＰ２の差分の電流Ｉ３とを加算して出力する手段と、上記第１のパワーＰ１時に高周波電流Ｉｈｆを上記電流Ｉ１に重畳する手段と、上記第２のパワーＰ２及び上記第３のパワーＰ３時に上記高周波電流Ｉｈｆの重畳をオフもしくは異なる電流Ｉｈｆ２に切り替える手段とを有し、記録動作時、上記第２のパワーＰ２による発光時に上記光出力検出手段によってモニタした発光出力レベルＶｍ２をホールドする手段と、上記第１のパワーＰ１による発光時に上記光出力検出手段によってモニタした発光出力レベルＶｍ１をホールドする手段と、その各手段によってホールドした発光出力レベルＶｍ１と発光出力レベルＶｍ２とをそれぞれ所望の値になるように上記電流供給手段を制御する制御手段と、記録時に上記第１のパワーＰ１による発光時に高周波を重畳し、上記第２のパワーＰ２及び上記第３のパワーＰ３では上記第１のパワーＰ１による発光時に重畳する高周波と異なる量を重畳するかもしくは重畳しないようにし、記録前に上記第１のパワーＰ１のレベルで高周波を重畳した第１発光期間と、上記第１のパワーＰ１のレベルで高周波を重畳しない発光期間もしくは記録時の上記第２のパワーＰ２及び上記第３のパワーＰ３の出力時に重畳する量の高周波を重畳した上記第１のパワーＰ１のレベルでの発光期間である第２発光期間とを設け、上記第１発光期間と上記第２発光期間とにおける上記光源の駆動電流差Ｉ差を保持し、上記第２のパワーＰ２による発光時、上記第２のパワーＰ２の駆動電流の補正効率η＝（Ｐ２−Ｐ１）／（Ｉ２−Ｉ差）を求め、上記第３のパワーＰ３の発光を行う為の駆動電流Ｉ３＝（Ｐ３−Ｐ２）／補正効率を求めて決定して上記電流供給手段に与える手段を備えた光ディスク装置を提供する。
【００１７】
さらに、レーザダイオード等の光源と、その光源への電流供給手段と、上記光源の発光出力レベルをモニタする光出力検出手段と、記録動作時、上記光源によって第１のパワーＰ１とそれよりも高い第２のパワーＰ２とさらにそれより高い第３のパワーＰ３の発光を行って光ディスクにデータを記録する光ディスク装置であって、上記電流供給手段は、上記第１のパワーＰ１での発光分の電流Ｉ１と上記第２のパワーＰ２と上記第１のパワーＰ１の差分の電流Ｉ２と上記第３のパワーＰ３と上記第２のパワーＰ２の差分の電流Ｉ３とを加算して出力する手段と、上記第１のパワーＰ１時に高周波電流Ｉｈｆを上記電流Ｉ１に重畳する手段と、上記第２のパワーＰ２及び上記第３のパワーＰ３時に上記高周波電流Ｉｈｆの重畳をオフもしくは異なる電流Ｉｈｆ２に切り替える手段とを有し、記録動作時、上記第３のパワーＰ３による発光時に上記光出力検出手段によってモニタした発光出力レベルＶｍ３をホールドする手段と、上記第１のパワーＰ１による発光時に上記光出力検出手段によってモニタした発光出力レベルＶｍ１をホールドする手段と、その各手段によってホールドした発光出力レベルＶｍ１と発光出力レベルＶｍ３とをそれぞれ所望の値になるように上記電流供給手段を制御する制御手段と、記録時に上記第１のパワーＰ１による発光時に高周波を重畳し、上記第２のパワーＰ２及び上記第３のパワーＰ３では上記第１のパワーＰ１による発光時に重畳する高周波と異なる量を重畳するかもしくは高周波を重畳しないようにし、記録前に上記第１のパワーＰ１のレベルで高周波を重畳した第１発光期間と、上記第１のパワーＰ１のレベルで高周波を重畳しない発光期間もしくは記録時の上記第２のパワーＰ２及び上記第３のパワーＰ３の出力時に重畳する量の高周波を重畳した上記第１のパワーＰ１のレベルでの発光期間である第２発光期間とを設け、上記第１発光期間と上記第２発光期間とにおける上記光源の駆動電流差もしくはその駆動電流Ｉ差に比例した比例値である駆動電流差Ｉ差を保持し、上記第３のパワーＰ３による発光時、上記第３のパワーＰ３の駆動電流の補正効率η＝（Ｐ３−Ｐ１）／（Ｉ２＋Ｉ３−Ｉ差）を求め、上記第２のパワーＰ２の発光を行う為の駆動電流Ｉ２＝（Ｐ２−Ｐ１）／補正効率＋Ｉ差と上記第３のパワーＰ３の発光を行う為の駆動電流Ｉ３＝（Ｐ３−Ｐ２）／補正効率とを求めて決定して上記電流供給手段に与える手段を備えた光ディスク装置にするとよい。
【００１８】
また、上記の第３の目的を達成するため、上記のような記載の光ディスク装置において、上記駆動電流差Ｉ差を保持する為の記録前に上記第１のパワーＰ１のレベルで高周波を重畳した第１発光期間と、上記第１のパワーＰ１のレベルで高周波を重畳しない発光期間もしくは記録時の上記第２のパワーＰ２の出力時に重畳する量の高周波を重畳した上記第１のパワーＰ１での発光期間である第２発光期間とを、フォーカスサーボ系によってフォーカスオンさせた状態で行うようにした光ディスク装置を提供する。
【００１９】
さらに、上記の第４の目的を達成するため、上記のような光ディスク装置において、上記第１のパワーＰ１のレベルで高周波を重畳しない発光期間もしくは記録時の上記第２のパワーＰ２の出力時に重畳する量の高周波を重畳した上記第１のパワーＰ１での発光期間である第２発光期間において、上記フォーカスサーボ系によってフォーカスオンを維持できなくなってフォーカスオフ状態になってしまった場合、上記フォーカスサーボ系によって再度フォーカスオン状態にして上記駆動電流差Ｉ差を取得するようにした光ディスク装置を提供する。
【００２０】
また、上記の第５の目的を達成するため、上記のような光ディスク装置において、フォーカスオフ状態の期間に上記第１のパワーＰ１のレベルで高周波を重畳した第３発光期間と、上記第１のパワーＰ１のレベルで高周波を重畳しない発光期間もしくは記録時の上記第２のパワーＰ２の出力時に重畳する量の高周波を重畳した上記第１のパワーＰ１のレベルでの発光期間である第４発光期間とを設け、上記第３発光期間と上記第４発光期間とにおける上記光源の駆動電流差ＦｏＩ差を保持し、上記フォーカスオン状態で上記駆動電流差Ｉ差を取得する発光期間に上記フォーカスサーボ系によるフォーカスオン状態が維持できなくなってフォーカスオフ状態になって上記駆動電流差Ｉ差が求められない場合もしくは上記再度の駆動電流差Ｉ差の取得によっても求められない場合、上記駆動電流差Ｉ差を上記駆動電流差ＦｏＩ差を一定倍した値に決定するようにした光ディスク装置を提供する。
【００２１】
さらに、上記の第６の目的を達成するため、上記のような記載の光ディスク装置において、再生時の発光パワーと記録時の上記第１のパワーＰ１が異なる場合、記録前の上記駆動電流差Ｉ差を求める際に再生時の発光パワーから記録時の上記第１のパワーＰ１にパワー変更後に上記駆動電流差Ｉ差を求めるようにした光ディスク装置を提供する。
【００２２】
さらにまた、上記の第７の目的を達成するため、上記のような光ディスク装置において、記録時、上記第１のパワーＰ１の発光時に高周波を重畳しない期間もしくは重畳しても上記第２のパワーＰ２及び上記第３のパワーＰ３時に重畳する量の高周波を重畳する期間を記録時に設けるようにした光ディスク装置を提供する。
【００２３】
【発明の実施の形態】
以下、この発明の実施形態を図面に基づいて具体的に説明する。
図１は、この発明の一実施形態である光ディスク装置の構成を示すブロック図である。
この光ディスク装置は、一度だけ書き込み可能なＣＤフォーマットに準拠したディスクであるＣＤ−Ｒ（ＣＤ−Ｒｅｃｏｒｄａｂｌｅ）ディスクに対するデータの記録と再生を行うＣＤ−Ｒドライブである。
ＣＤ（ＣｏｍｐａｃｔＤｉｓｃ），ＣＤ−ＲＯＭ，ＣＤ−Ｒ等の光ディスク１は光ディスク基板上にデータ列をピットと呼ばれる穴の有無で表現し、これにレーザ光をあててその反射光変化でデータを読み取る。このデータ列はレコードの様に光ディスク基板上に螺旋状にならべられており、その螺旋状に配された線をトラックと呼んでいる。隣り合うトラック間の距離は１．６ミクロンである。
【００２４】
さて、光ディスク１は、スピンドルモータ（ＳｐｉｎｄｌｅＭｏｔｏｒ）２によって回転駆動される。
スピンドルモータ２は、モータドライバ（ＭｏｔｏｒＤｒｉｖｅｒ）３とサーボ部（Ｓｅｒｖｏ）４によって一定速度になるように制御される。
光ピックアップ（ＰｉｃｋＵｐ）５は、図示を省略した公知技術の半導体レーザ（ＬａｓｅｒＤｉｏｄｅ）光源，レンズ等の光学系，レーザ光の焦点が光ディスクに合うようにレンズの位置を光ディスクと垂直方向に動かす機構であるフォーカスアクチュエータ，レーザ光の焦点がトラックをトレースするように光ディスクの半径方向（スレッジ方向）にレンズを動かす機構であるトラックアクチュエータ，受光素子及びポジションセンサ等を内蔵したものであり、レーザ光を光ディスク１に照射する。
【００２５】
また、光ピックアップ５全体は、同じく図示を省略したシークモータによってスレッジ方向に移動可能である。これらフォーカスアクチュエータ，トラックアクチュエータ，シークモータは、受光素子，ポジションセンサから得られた信号に基づいてモータドライバ３とサーボ部４によってレーザスポットが目的の場所に位置するように制御される。
データ読み出しの場合、光ピックアップ５で得られた再生信号はリードアンプ（ＲｅａｄＡｍｐ）６で増幅されてイコライザ処理や２値化（デジタル化）された後，ＣＤデコーダ（ＣＤＤｅｃｏｄｅｒ）７に入力されてＥＦＭ復調される。
【００２６】
ＥＦＭはＥｉｇｈｔｔｏＦｏｕｒｔｅｅｎＭｏｄｕｌａｔｉｏｎの略であり、光ディスク１には光学的に再生または記録し易いように８ｂｉｔデータを１４ｂｉｔのデータに変調したデータが書かれている。
ＥＦＭ復調されたデータはデインタリーブ（並べ替え直し）とエラー訂正の処理を受ける。その後、このデータはバッファマネージャ（ＢｕｆｆｅｒＭａｎａｇｅｒ）８によって一旦バッファＲＡＭ（ＢｕｆｆｅｒＲＡＭ）９に蓄えられ、セクタデータとしてそろった段階でＡＴＡＰＩ，ＳＣＳＩ等のインタフェース（Ｉ／Ｆ）１０を介してホストコンピュータに一気に送られる。
音楽データの場合、ＣＤデコーダ７から出てきたデータはＤ／Ａコンバータ１１に入力され、アナログのオーディオ信号が取り出される。
【００２７】
データ書き込み時は、Ｉ／Ｆ１０を通してホストコンピュータから送られてきたデータはバッファマネージャ８によって一旦バッファＲＡＭ９に蓄えられる。バッファＲＡＭ９にある程度データが貯まったところで書き込みを開始するが、その前にレーザスポットを書き込み開始地点に位置させなければならない。
この地点は、トラックの蛇行によって予め光ディスク１に刻まれているウォブル信号により求められる。ウォブル信号にはＡＴＩＰと呼ばれる絶対時間情報が含まれており、ＡＴＩＰデコーダ１２によってその情報が取り出せる。また、ＡＴＩＰデコーダ１２が生成する同期信号はＣＤエンコーダ１３に入力され、正確な位置でのデータの書き出しを可能にしている。
【００２８】
バッファＲＡＭ９のデータは、ＣＤ−ＲＯＭエンコーダ１４やＣＤエンコーダ１３でエラー訂正コードの不可やインタリーブ（並べ替え）が行われた後にＥＦＭ変調され、レーザコントローラ回路（ＬａｓｅｒＣｏｎｔｒｏｌｌｅｒ）１５，光ピックアップ５を介して光ディスク１に記録される。
ＲＯＭ１６は、ＣＰＵ１８がこの光ディスク装置におけるデータの記録及び再生の制御を行う際のプログラムを格納する読み出し専用メモリである。
ＲＡＭ１７は、ＣＰＵ１８がこの光ディスク装置におけるデータの記録及び再生の制御を行う際の作業領域である読み書き可能なメモリである。
ＣＰＵ１８は、この光ディスク装置におけるデータの記録及び再生の制御を行う。
このような光ディスク装置の上記レーザコントローラ回路１５がこの発明に係わる特徴を有する。
【００２９】
（１）この発明の請求項１に係わる実施例
図２は、図１に示したレーザコントローラ回路１５の内部構成と光ピックアップ５に搭載されたＬＤ及びＬＤの出射パワーをモニタする為の素子であるＰＤ（ＰｈｏｔｏＤｅｔｅｃｔｏｒ）の構成とを示したブロック図である。
図３は、図２に示したＰＤ２１の入射光量に対する出力電流の変化を示す線図である。
ＬＤ２０から出射されたレーザ光の一部はパワーモニタであるＰＤ２１に入射される。ここでＰＤ２１は、図３に示すように、レーザ光の入射光量に比例した電流を出力する。
【００３０】
ＣＤ−Ｒに記録を行う際には、ＬＤ２０からは第１のパワーＰ１と第１のパワーＰ１よりも高い第２のパワー０２が繰り返し出射される。第１のパワーＰ１と第２のパワーＰ２の出射する時間は記録するＥＦＭ信号に基づいたものである。
つまり、出射される時間はある単位をＴとすると、Ｔの３〜１１のうちの整数倍された長さである。実際には３〜１１のうちの整数倍の時間長を記録品質をよくするため、若干短くあるいは若干長くしたりするが、この発明の主旨と関係ないのでその説明は省略する。
第１のパワーＰ１は、一般的には光ディスク１からデータ（情報）を読み出すときの再生パワーＰｒであり、第２のパワーＰ２は光ディスク１の記録膜である有機色素に十分な熱を与え光ディスク１に良好なピットを形成する記録パワーＰｗである。
【００３１】
図４は、図２に示したＬＤ２０から出射される発光波形を示す波形図である。
同図において、時間ｔライトスタートより前の波形が光ディスク１からデータを読み出す場合の発光波形であり、時間ｔライトスタートより後の波形が光ディスク１にデータを書き込む場合の発光波形である。
データを読み出す場合、ＬＤ２０からは一般的に１ｍＷ以下（より具体的には０．４ｍＷ等）の再生パワーＰｒが一定光量で出力される。
一方、記録時は再生パワーＰｒと記録パワーＰｗの発光が繰り返される。
記録パワーＰｗは、一般に数ｍＷ〜数１０ｍＷである（より具体的には５ｍＷ〜４０ｍＷの間で実際に試し書き込みを行って記録特性が良いパワーが選ばれる）。記録パワーＰｗも再生パワーＰｒと同様にＡＰＣ制御され、一定光量が保たれる。すなわち、この再生パワーＰｒが上記第１のパワーＰ１に、記録パワーＰｗが上記第２のパワーＰ２にそれぞれ相当する。
【００３２】
次に、図２に基づいて上記ＡＰＣ制御について説明する。
まず、ＰＤ２１に入射されたレーザ光は光電変換によって光量に比例した電流のかたちで出力される。つまり、ＬＤ２０から出射されるレーザ光が図４に示したような発光波形の場合、図４の縦軸を電流に置き換えたような波形が出力される。次にＩ／Ｖ変換器（Ｉ／Ｖ変換回路）２２によって電流を電圧に変換する。
ここでの出力電圧を再生パワーに対応したものをＶ（Ｐｒ）、記録パワーに対応したものをＶ（Ｐｗ）とする。すなわち、このＶ（Ｐｒ）が上記発光出力レベルＶｍ１に、Ｖ（Ｐｗ）が上記発光出力レベルＶｍ２にそれぞれ相当する。
この出力は再生時は、Ｖ（Ｐｒ）レベルのみの信号であるが、記録時はＶ（Ｐｒ）とＶ（Ｐｗ）が交互に変化する信号のため、Ｓ／Ｈ回路Ｒ（ボトムホールド回路でも良い）２３とＳ／Ｈ回路Ｗ（ピークホールド回路でも良い）２４によってＶ（Ｐｒ）とＶ（Ｐｗ）に分離される。
【００３３】
サンプル信号Ｒは、再生時は常にＳ／Ｈ回路Ｒ２３内のスイッチＳＷをオン（ＯＮ）にする信号であり、記録時は記録時の再生パワーレベルが出射されている期間あるいはそれよりも若干短い期間のみＳ／Ｈ回路Ｒ２３内のスイッチＳＷをオンにし、記録パワーレベルが出射されている期間はＳ／Ｈ回路Ｒ２３内のスイッチＳＷをオフ（ＯＦＦ）にし、Ｓ／Ｈ回路Ｒ２３内のコンデンサＣで再生パワーレベルに対応した電圧Ｖ（Ｐｒ）のみ取り出すようにコントロールされる信号である。
【００３４】
一方、サンプル信号Ｗは、再生時は常にＳ／Ｈ回路Ｗ２４内のスイッチＳＷをオフ（ＯＦＦ）にする信号であり、記録時は記録時の記録パワーレベルが出射されている期間あるいはそれよりも若干短い期間のみＳ／Ｈ回路Ｗ２４内のスイッチＳＷをオン（ＯＮ）にし、記録時の再生パワーレベルが出射されている期間はＳ／Ｈ回路Ｗ２４内のスイッチＳＷをオフ（ＯＦＦ）にし、Ｓ／Ｈ回路Ｗ２４内のコンデンサＣで記録パワーレベルに対応した電圧Ｖ（Ｐｗ）のみ取り出すようにコントロールされる信号である。
このサンプルホールドで分離された各Ｖ（Ｐｒ）及びＶ（Ｐｗ）は、それぞれＡ／Ｄ変換器Ｒ２５とＡ／Ｄ変換器Ｗ２６によってデータの形にされ、ＣＰＵ１８に入力として与えられる。その各々のデータをＡＤ（Ｐｒ）とＡＤ（Ｐｗ）とする。
【００３５】
ＣＰＵ１８は、ＡＤ（Ｐｒ）及びＡＤ（Ｐｗ）がそれぞれ所望の値（基準値Ｒと基準値Ｗ）になる様にＤ／Ａ変換器Ｒ２７及びＤ／Ａ変換器Ｗ２８に出力するデータを可変する。その各々のデータをＤＡ（Ｐｒ）とＤＡ（Ｐｗ）とする。
Ｄ／Ａ変換器Ｒ２７とＤ／Ａ変換器Ｗ２８の各出力はそれぞれＶ／Ｉ変換器Ｒ２９とＶ／Ｉ変換器Ｗ３０によって電流に変換及び電流増幅され電流加算器３１に入力される。
電流加算器３１で加算された電流はＬＤ２０に流れ、ＬＤ２０からレーザ光が出射される。この出射光がＰＤ２１に入射されるため、誤差増幅器を中心にフィードバックループが形成される。
上記のように構成されたフィードバックループにより、基準値によって決定される一定パワーがＬＤ２０から出射されることになる。
【００３６】
実際には、この基準値と出射パワーの関係を光ディスク装置の製造工程などにおいて求めておく。あるいは、決めた基準値と出射パワーの関係になるように調整する。このＬＤ２０から出射されるパワーが一定になるように制御することをＡＰＣ（ＡｕｔｏＰｏｗｅｒＣｏｎｔｒｏｌ）という。ＬＤ２０から出射するパワーを可変したい場合はこの基準値を可変することにより実現できる。
Ｖ／Ｉ変換器Ｒ２９の出力に挿入されたスイッチＳＷは、ＬＤ２０からレーザ光を出射する際にはオン（ＯＮ）にし、Ｖ／Ｉ変換器Ｗ３０の出力に挿入されたスイッチＳＷは、記録時の記録パワーレベルの期間のみオン（ＯＮ）にするライトパルス信号によりコントロールされる。
各スイッチＳＷの制御信号、つまりサンプル信号Ｒ，サンプル信号Ｗ，ライトパルス信号は、図１に示したＣＤエンコーダ１３によって出力される信号である。
【００３７】
さて、以上で定常的な発光状態に関して説明したが、次に、ＬＤ２０からレーザ光が出射されていない状態から再生パワーレベルが出射される場合、及び再生パワーレベルのみの出射状態から記録時の出射波形が出射される場合について説明する。
図５は、ＣＰＵ１８から出力するＶｒの変化を示す波形図である。
図６は、ＣＰＵ１８から出力するＶｗの変化を示す波形図である。
まず、図５に示すように、ＬＤ２０からレーザ光が出射されていない状態ではＶ（Ｐｒ）＝０である。次に再生パワーで発光を開始する場合には、再生発光スタートでＣＰＵ１８からのＤＡ（Ｐｒ）を０にした状態で、ＬＤドライバ部のＬＤオン信号でスイッチＳＷをオンにする。当然Ｖ（Ｐｒ）＝０なので、ＣＰＵ１８は基準値Ｒに比べてＡＤ（Ｐｒ）が小さいので、ＤＡ（Ｐｒ）を徐々に上げていき、いずれＡＤ（Ｐｒ）が基準値Ｒ（ＶｒｅｆＲ）と等しくなり、その後ＣＰＵ１８はＡＤ（Ｐｒ）が基準値Ｒになるように維持する。
【００３８】
同様にして、図６に示すように、再生パワーレベルのみの出射状態から、記録時の出射波形が出射される場合も、サンプルホールド回路のスイッチのＯＮ／ＯＦＦの繰り返しやＬＤドライバ部のライトパルス信号によるＯＮ／ＯＦＦの繰り返しはあるが、同様にＡＤ（Ｐｗ）は０からＤＡ（Ｐｗ）の増加に伴い大きくなり、いずれＡＤ（Ｐｗ）が基準値Ｗ（ＶｒｅｆＷ）と等しくなり、その後ＣＰＵ１８はＡＤ（Ｐｒ）が基準値Ｗを維持するように制御する。
また、図２では再生パワー時高周波を重畳する高周波重畳回路３２の出力をＬＤ２０に重畳するようにした構成にしている。
【００３９】
なお、高周波重畳回路３２の出力に設けられたスイッチＳＷによってライトパルス信号に連動して記録パワー時にオフにして再生パワー時にオンにする構成としている。また、ライトパルス信号で高周波重畳をオフにする構成にしているが、ライトパルス時、高周波の重畳をオフにせず、重畳量を可変する場合、ライトパルス信号によって高周波重畳回路３２の出力を抵抗分圧等により減衰させるか、あるいは高周波重畳回路を２つ用意しておいてこれを切り替えるか、あるいは図示を省略した高周波重畳回路の内部の発振器の出力の電流ゲインを切りかえる構成にする必要がある。
【００４０】
ここで、上述したように高周波重畳のＯＮ／ＯＦＦでＬＤ２０の（駆動電流）対（出射パワー）の関係が図１５に示したように変化する。
そこで、図４に示したリード期間に図２に示した高周波重畳回路３２の出力をオフにする機構を設けて、ＡＰＣを行うことにより、高周波重畳ＯＮ時のＤＡ（ＰｒＯＮ）と高周波重畳ＯＦＦ時のＤＡ（ＰｒＯＦＦ）を取得し、その差ＤＡ（Ｐｒ差）＝ＤＡ（ＰｒＯＦＦ）−ＤＡ（ＰｒＯＮ）を求めておく。
次にライト発光を開始してＡＰＣ制御を行い、ＤＡ（Ｐｗ）よりライトパワーの電流効率を取得する。
この際、補正効率η＝（Ｐｗ−Ｐｒ）／（ＤＡ（Ｐｗ）−ＤＡ（Ｐｒ差）×α）によって算出して、図２のＣＰＵ１８内の図示を省略したメモリ内に保持する。なお、上記αは、図２において再生パワー制御側と記録パワー側で電流ゲインが異なる場合に、算出したＤＡ（Ｐｒ差）を記録パワー側の電流ゲインに換算する為の係数である。
【００４１】
上記Ｄ／Ａ変換器は、正式にはＤｉｇｉｔａｌｔｏＡｎａｌｏｇ変換器であり、デジタル値、例えば１０００００００（１６進数で８０ｈｅｘ）をアナログ値（例えば２．０［Ｖ］）に変換する回路である。
ＬＤ（ＬａｓｅｒＤｉｏｄｅ）２０は、電流で駆動する素子であり、例えば４０ｍＡ長して１ｍＷ出射する素子である。
したがって、図２において、Ｄ／Ａ変換器Ｒ２７とＤ／Ａ変換器Ｗ２８の出力先にそれぞれＶ／Ｉ変換器（電圧→電流変換器）Ｒ２９とＶ／Ｉ変換器Ｗ３０を設けている。
ここで、一般的にレーザ光の駆動に用いられるＶ／Ｉ変換器において何ボルト入力されると何ｍＡ出力するかというのは、再生パワー駆動用と記録パワー駆動用では感度が違う場合が一般的である。再生パワーは駆動電流が記録パワーに比べて小さくて済むからである。
【００４２】
例えば、再生パワー用は２Ｖ入力で４０ｍＡ、記録パワー用は２Ｖ入力で８０ｍＡ等である。
つまり、同じデジタル値（上記ＤＡ（＊＊））、例えば８０ｈｅｘでも駆動できる電流は４０ｍＡと８０ｍＡとデジタル値に対する感度が異なる。
例えば、再生パワー２０ｍＡ分を記録パワー側の電流の一部として流す場合はデジタル値としては再生パワーのデジタル値４０ｈｅｘに対して記録パワーのデジタル値２０ｈｅｘで良いわけであり、結局再生パワーのデジタル値を記録パワーのデジタル値に換算する場合はその感度差をかけてやる必要がある。これを上記係数αにしている。
上述の例ではライトパワーの方が感度が２倍なので係数αは１／２になる。
つまり、ＤＡ（Ｐｗ）とＤＡ（Ｐｒ）の単位が違うので、この係数αによって合わせるのである。
【００４３】
次に、試し書き時あるいはＺｏｎｅＣＬＶ記録などで、記録パワーを変更する場合、上記補正効率ηを用い、例えば（Ｐｗ−Ｐｒ）を２倍にする場合、ＤＡ（Ｐｗ２倍）は、ＤＡ（Ｐｗ２倍）＝２×（Ｐｗ−Ｐｒ）／補正効率＋ＤＡ（Ｐｒ差）×αより算出する。
以上の構成により、記録パワー可変時も最終的にＡＰＣにより整定した時のパワーとほぼ同等のパワーで発光ができるので、試し書き時に一パワーでの記録時間が短い場合でもＡＰＣ制御が追従できる。
また、ＺｏｎｅＣＬＶで記録パワー切り替えた際に切り替え後も所望のパワーで記録が開始できるので切り替え個所の記録品質を維持できる。
【００４４】
このようにして、記録パワーの駆動電流の効率を正確に求めることができ、ライトパワーを可変して記録する場合、次のパワーに変更した際、最終的にほぼ制御されたパワーに近いパワー値から発光が開始できるので、高速記録時など試し書きの一パワー記録時間が短い場合などでも、最終的な制御パワーに達する為、試し書きが正しく行え、記録品質を維持することができる。
【００４５】
（２）この発明の請求項２に係わる実施例
図７は、図１に示したレーザコントローラ回路１５の内部構成と光ピックアップ５に搭載されたＬＤ及びＬＤの出射パワーをモニタする為の素子であるＰＤの構成との他の例を示したブロック図である。
同図に示した回路構成では、図２に示した回路にピークパワーの電流を加算して出力するための回路を追加している。
ここでピークパワーについて説明する。
図８は、ＣＤ−Ｒドライブにおいて光ディスクにデータ記録時実際にレーザ光源より出射される発光の説明図である。
この発光の仕方はＣＤ−Ｒの規格であるオレンジブックに示されている。
【００４６】
図８に示す様に、記録パワーの前縁でライトパワーより高いピークパワーでの発光期間を設け、出だしの部分はとりわけ強いパワーで急峻に色素の熱をあげれるように多少持ち上げる。
図７の回路では、上記回路にＤ／Ａ変換器Ｐ３３とＶ／Ｉ変換器Ｐ３４とスイッチＳＷを設けており、ピークパワーはＳ／Ｈ回路によってＶ（Ｐｐ）を取り出すことをせず、Ｄ／Ａ変換器Ｐ３３とＶ／Ｉ変換器Ｐ３４によってＤＡ（Ｐｗ）の算出によってＤＡ（Ｐｐ）を求める制御を行う構成にしている。そして、上述と同様にして補正効率ηを求め、その補正効率ηを用いてＤＡ（Ｐｐ）＝（Ｐｐ−Ｐｗ）／補正効率ηを算出してＤ／Ａ変換器Ｐ３３にデータ出力を行う。
【００４７】
このようにして、第１のパワーと第２のパワーでの高周波重畳の重畳量の違いによる再生パワー駆動電流の差で第２のパワーの駆動電流の効率を補正するようにしたので、第２のパワーの制御で決定されるＩ２より正しくＩ３が求められ、従って、２値のサンプルにより３値のパワーを容易に制御するシステムにおいても所望のＰ２とＰ３の比が得られ、記録品質の低下を防ぐことができる。
【００４８】
（３）この発明の請求項３に係わる実施例
図９は、図１に示したレーザコントローラ回路１５の内部構成と光ピックアップ５に搭載されたＬＤ及びＬＤの出射パワーをモニタする為の素子であるＰＤの構成とのさらに他の例を示したブロック図である。
同図に示した回路構成では、図２に示した回路のＳ／Ｈ回路Ｗ２４及びＡ／Ｄ変換器Ｗ２６をそれぞれピークパワー検出用のピークホールド回路Ｐ３５とＡ／Ｄ変換器Ｐ３６に変更している。
上述と同様にして、ピークホールド回路Ｐ３５で保持した値はＡ／Ｄ変換器Ｐ３６によってデータＡＤ（Ｐｐ）に変換されてＣＰＵ１８で処理可能になる。
ＣＰＵ１８は、ＤＡ（Ｐｒ差）を上述と同様にして求め、保持しておく。
【００４９】
ＤＡ（Ｐｒ）は、高周波重畳ＯＮ時の駆動電流しか流されていないので、ＤＡ（Ｐｗ）には高周波ＯＦＦと高周波ＯＮの差ＤＡ（Ｐｒ差）が余分に流されることになる。
したがって、ＤＡ（Ｐｗ）からＤＡ（Ｐｒ差）を引いたものとＤＡ（Ｐｐ）が同じ値になるようにすると良い。
つまり、ＤＡ（Ｐｐ）とＤＡ（Ｐｗ）とＤＡ（Ｐｒ差）を用いて、ＤＡ（Ｐｐ）＝ＤＡ（Ｐｗ）−ＤＡ（Ｐｒ差）とした状態を維持してＡＰＣを行い、補正効率η＝（Ｐｐ−Ｐｒ）／（ＤＡ（Ｐｐ）＋ＤＡ（Ｐｗ）−ＤＡ（Ｐｒ差））として求め、ＤＡ（Ｐｐ）＝（Ｐｐ−Ｐｗ）／補正効率η，ＤＡ（Ｐｗ）＝（Ｐｗ−Ｐｒ）／補正効率＋ＤＡ（Ｐｒ差）として求めて決定する。
【００５０】
このようにして、第１のパワーと第２及び第３のパワーでの高周波重畳の重畳量の違いによる再生パワー駆動電流の差で第３のパワーの駆動電流の効率を補正するようにしたので、第３のパワーの制御で決定される電流値より正しく電流Ｉ３及びＩ２を求めることができ、従って、２値のサンプルにより３値のパワーを制御するシステムにおいても所望の第２のパワーＰ２と第３のパワーＰ３の比が得られ、記録品質の低下を防ぐことができる。
【００５１】
（４）この発明の請求項４に係わる実施例
図１０は、この発明の請求項４に係わる処理を示すフローチャート図である。この処理は、駆動電流差Ｉ差を求めて決定するものであり、上記図２，図７，図９に示した回路において実施することができる。
ステップ（図中「Ｓ」で示す）１で最初にＤ／Ａ変換器に０をセットして、ＤＡ（Ｐｒ）を０にした状態にし、ステップ２でＬＤＯＮ信号をオンにし、ステップ３で所望の再生パワーになるようにＤＡ（Ｐｒ）を増加させてＡＤ（Ｐｒ）が基準値Ｒになるまでインクリメントさせる。
ステップ４でフォーカス引き込みを行い、ステップ５でＡＤ（Ｐｒ）が基準値Ｒとなった後はこの関係を維持するようにＤＡ（Ｐｒ）を増減させて再生パワーのＡＰＣを続ける。次にフォーカスサーボをオン（ＯＮ）にした後、ＡＰＣにより維持されているＤＡ（Ｐｒ）をＤＡ（ＰｒＯＮ）として保持する。
【００５２】
ステップ６で高周波重畳の出力をオフ（ＯＦＦ）にし、ステップ７で再生パワーＡＰＣによって維持されているＤＡ（Ｐｒ）をＤＡ（ＰｒＯＦＦ）として保持する。ステップ８でＤＡ（ＰｒＯＮ）とＤＡ（ＰｒＯＦＦ）の差ＤＡ（Ｐｒ差）を保持し、記録パワー発光時の補正効率算出時に前記ＤＡ（Ｐｒ差）を用いる。
ステップ９で高周波重畳の出力をオン（ＯＮ）にして、次のステップへ進む。
このようにして、光ディスク有無の差により、また光ディスクの反射率の違いにより駆動電流差Ｉ差に違いが生じるが、記録前のフォーカスＯＮ状態で駆動電流差Ｉ差を求めるようにしたので、より正確に駆動電流差Ｉ差を取得することができ、従って補正効率ηを正しく求めることができ、上記図２，図７，図９に示した回路を備えた光ディスク装置において、記録品質を良好に維持することが可能になる。
【００５３】
（５）この発明の請求項５に係わる実施例
図１１は、この発明の請求項５に係わる処理を示すフローチャート図である。
この処理では、高周波重畳ＯＦＦ後のフォーカス（Ｆｏｃｕｓ）外れ判定処理を追加しており、フォーカス外れが検出された場合に再度フォーカス引き込みから行うようにしている。
ステップ（図中「Ｓ」で示す）１１で最初にＤ／Ａ変換器に０をセットして、ＤＡ（Ｐｒ）を０にした状態にし、ステップ１２でＬＤＯＮ信号をオンにし、ステップ１３で所望の再生パワーになるようにＤＡ（Ｐｒ）を増加させてＡＤ（Ｐｒ）が基準値Ｒになるまでインクリメントさせる。
ステップ１４でフォーカス引き込みを行い、ステップ１５でＡＤ（Ｐｒ）が基準値Ｒとなった後はこの関係を維持するようにＤＡ（Ｐｒ）を増減させて再生パワーのＡＰＣを続ける。次にフォーカスサーボをオン（ＯＮ）にした後、ＡＰＣにより維持されているＤＡ（Ｐｒ）をＤＡ（ＰｒＯＮ）として保持する。
【００５４】
ステップ１６で高周波重畳の出力をオフ（ＯＦＦ）にし、ステップ１７でフォーカス外れか否かを判断し、フォーカス外れならステップ１４へ戻って上記処理を繰り返し、フォーカス外れでなければ、ステップ１８で再生パワーＡＰＣによって維持されているＤＡ（Ｐｒ）をＤＡ（ＰｒＯＦＦ）として保持する。ステップ１９でＤＡ（ＰｒＯＮ）とＤＡ（ＰｒＯＦＦ）の差ＤＡ（Ｐｒ差）を保持し、記録パワー発光時の補正効率算出時に前記ＤＡ（Ｐｒ差）を用いる。
ステップ２０で高周波重畳の出力をオン（ＯＮ）にして次のステップへ進む。
このようにして、駆動電流差Ｉ差を求める際、フォーカスサーボが外れてしまった場合、駆動電流差Ｉ差が求められない可能性があるが、上述のようにしてリトライを行う様にしたので、駆動電流差Ｉ差を求めることができ、上述の補正効率を正しく求めることができ、上記図２，図７，図９に示した回路を備えた光ディスク装置において、記録品質を良好に維持することが可能になる。
【００５５】
（６）この発明の請求項６に係わる実施例
図１２は、この発明の請求項６に係わる処理を示すフローチャート図である。
この処理では、フォーカス引き込み前に高周波重畳ＯＮとＯＦＦのＤＡ（Ｐｒ）を各々取得し、ＤＡ（Ｐｒ差ＯＦＦ）を算出する。
また、フォーカス引き込み後の高周波重畳ＯＦＦでフォーカス外れが検出された場合はＤＡ（Ｐｒ差）はＤＡ（Ｐｒ差ＯＦＦ）に定数をかけたものとして保持し、高周波重畳ＯＮの状態に戻し、以降のルーチンに進むようにしている。
ステップ（図中「Ｓ」で示す）３１で最初にＤ／Ａ変換器に０をセットして、ＤＡ（Ｐｒ）を０にした状態にし、ステップ３２でＬＤＯＮ信号をオンにし、ステップ３３で所望の再生パワーになるようにＤＡ（Ｐｒ）を増加させてＡＤ（Ｐｒ）が基準値Ｒになるまでインクリメントさせる。
【００５６】
ステップ３４でＡＤ（Ｐｒ）が基準値Ｒとなった後はこの関係を維持するようにＤＡ（Ｐｒ）を増減させて再生パワーのＡＰＣを続ける。次にフォーカスサーボをオン（ＯＮ）にした後、ＡＰＣにより維持されているＤＡ（Ｐｒ）をＤＡ（ＰｒＯＮ）として保持する。
ステップ３５で高周波重畳の出力をオフ（ＯＦＦ）にし、ステップ３６でＡＤ（Ｐｒ）＝基準値ＲになるＤＡ（Ｐｒ）をＤＡ（ＰｒＯＦＦ）として保持する。
ステップ３７でＤＡ（ＰｒＯＦＦ）とＤＡ（ＰｒＯＮ）の差ＤＡ（Ｐｒ差ＯＦＦ）を保持し、ステップ３８で高周波重畳の出力をオン（ＯＮ）にし、ステップ３９でフォーカス引き込みを行い、ステップ４０でＡＤ（Ｐｒ）＝基準値ＲになるＤＡ（Ｐｒ）をＤＡ（ＰｒＯＮ）として保持する。
【００５７】
ステップ４１で高周波重畳の出力をオフ（ＯＦＦ）にし、ステップ４２でフォーカス外れか否かを判断し、フォーカス外れならステップ４６へ進んでＤＡ（Ｐｒ差ＯＦＦ）×αを保持し、記録パワー発光時の補正効率算出時にそのＤＡ（Ｐｒ差）を用いる。
ステップ４２でフォーカス外れでなければ、ステップ４３で再生パワーＡＰＣによって維持されているＤＡ（Ｐｒ）をＤＡ（ＰｒＯＦＦ）として保持する。ステップ４４でＤＡ（ＰｒＯＦＦ）とＤＡ（ＰｒＯＮ）の差ＤＡ（Ｐｒ差）を保持し、記録パワー発光時の補正効率算出時に前記ＤＡ（Ｐｒ差）を用いる。
ステップ４５で高周波重畳の出力をオン（ＯＮ）にして次のステップへ進む。
【００５８】
なお、上述の処理では、一度のフォーカス外れでステップ４６へ進むようにしたが、複数回のフォーカスＯＮ状態での高周波重畳ＯＦＦ時のＤＡ（Ｐｒ）を求める為のリトライを行うようにしても良い。
このようにして、上述の光ディスク装置において継続的な外乱や粗悪光ディスクの場合、リトライしても駆動電流差Ｉ差が求められない可能性があり、このようにフォーカス状態で駆動電流差Ｉ差が求められなかった場合でも、駆動電流差Ｉ差とは異なる値の駆動電流差ＦｏＩ差を事前に実験等により求めた駆動電流差ＦｏＩ差と駆動電流差Ｉ差の関係より一定倍して簡易的に駆動電流差Ｉ差を求め、擬似的に正しい補正効率を求めて記録品質を維持することができる。
【００５９】
（７）この発明の請求項７に係わる実施例
図１３は、この発明の請求項７に係わる処理を示すフローチャート図である。
この処理は、上記図２，図７，図９に示した回路において実施することができる。この処理では、フォーカス引き込み後、記録時の再生パワーＡＰＣによってＡＤ（Ｐｒ）を維持する値になるようにＤＡ（Ｐｒ）を制御し、再生パワーを記録時の再生パワーに変更する。このＡＰＣによって維持されているＤＡ（Ｐｒ）をＤＡ（ＰｒＯＮ）として保持する。
次に、同再生パワーのまま高周波重畳をオフにし、再生パワーＡＰＣによって維持されているＤＡ（Ｐｒ）をＤＡ（ＰｒＯＦＦ）として保持する。
このＤＡ（ＰｒＯＮ）とＤＡ（ＰｒＯＦＦ）の差ＤＡ（Ｐｒ差）を保持しておき、記録パワー発光時の補正効率算出時に上記ＤＡ（Ｐｒ差）を用いる。
【００６０】
ステップ（図中「Ｓ」で示す）５１で最初にＤ／Ａ変換器に０をセットして、ＤＡ（Ｐｒ）を０にした状態にし、ステップ５２でＬＤＯＮ信号をオンにし、ステップ５３で所望の再生パワーになるようにＤＡ（Ｐｒ）を増加させてＡＤ（Ｐｒ）が基準値Ｒになるまでインクリメントさせる。
ステップ５４でフォーカス引き込みを行い、ステップ５５でＡＤ（Ｐｒ）が基準値Ｒとなった後はこの関係を維持するようにＤＡ（Ｐｒ）を増減させて再生パワーのＡＰＣを続ける。次にフォーカスサーボをオン（ＯＮ）にした後、ＡＰＣにより維持されているＤＡ（Ｐｒ）をＤＡ（ＰｒＯＮ）として保持する。
【００６１】
ステップ５６で高周波重畳の出力をオフ（ＯＦＦ）にし、ステップ５７で再生パワーＡＰＣによって維持されているＤＡ（Ｐｒ）をＤＡ（ＰｒＯＦＦ）として保持する。ステップ５８でＤＡ（ＰｒＯＦＦ）とＤＡ（ＰｒＯＮ）の差ＤＡ（Ｐｒ差）を保持し、記録パワー発光時の補正効率算出時に前記ＤＡ（Ｐｒ差）を用いる。ステップ５９で高周波重畳の出力をオン（ＯＮ）にし、ステップ６０でＡＤ（Ｐｒ）を増加させてＡＤ（Ｐｒ）が基準値ＲになるまでＤＡ（Ｐｒ）を調整し、次のステップへ進む。
このようにして、記録前に記録時再生パワーで高周波を重畳する／しない（重畳しても異なる量）で駆動電流値差Ｉ差を求めることにより、正しく補正効率が求まり、従って上述の光ディスク装置で再生時の発光パワーと記録時の再生パワーが異なる場合でも、良好な記録品質を維持することができる。
【００６２】
（８）この発明の請求項８に係わる実施例
図１４は、この発明の請求項８に係わる処理を示すフローチャート図である。
この処理は、上記図２，図７，図９に示した回路において実施することができる。この処理では、記録中に駆動電流値差Ｉ差を更新する。
通常記録時は再生パワーレベルで信号検出等を行う為レーザーノイズ低減の為、高周波が重畳されている状態であり、再生パワーはＡＰＣされている。この状態でステップ７１で現在制御されているＤＡ（Ｐｒ）をＤＡ（ＰｒＯＮ記録）として保持し、ステップ７２で高周波重畳をオフ（ＯＦＦ）にし、ステップ７３で再生パワーＡＰＣにより求まるＤＡ（Ｐｒ）をＤＡ（ＰｒＯＦＦ記録）として保持し、ステップ７４でＤＡ（Ｐｒ差）＝ＤＡ（ＰｒＯＦＦ記録）−ＤＡ（ＰｒＯＮ記録）として算出してＤＡ（Ｐｒ差）を更新する。その後、ステップ７５で高周波重畳をオン（ＯＮ）にし、再生パワー時高周波が重畳される状態に戻し、通常の記録状態に戻る。
【００６３】
このルーチンの処理を定期的に行うことによって、記録時の温度上昇による駆動電流値差Ｉ差を適時更新して正しい補正効率を求めることができる。
また、以上の処理では再生パワー時高周波重畳ＯＮ，記録パワー時高周波重畳ＯＦＦに関して説明をしたが、記録パワー時高周波重畳ＯＮでも、再生パワー時より少ない量の重畳量を重畳する場合も同様に実施することができる。
このようにして、上述の光ディスク装置においてレーザ光の記録中の自己加熱によって変化する（駆動電流）対（出射パワー）の関係に対応し、例えば定期的に記録中に駆動電流値差Ｉ差を再度求め直すことによって、より正確な補正効率を取得することができ、したがって、記録品質をより高精度に維持することができる。
【００６４】
【発明の効果】
以上説明してきたように、この発明の請求項１の光ディスク装置によれば、記録速度が速い場合のテスト記録の際に設定パワーと実際の発光パワーのずれによる記録品質の低下を防ぐことができる。
また、この発明の請求項２又は３の光ディスク装置によれば、２値のサンプルにより３値のパワーを容易に制御するシステムにおいても良好な記録品質を得られるようにすることができる。
さらに、この発明の請求項４の光ディスク装置によれば、駆動電流差Ｉ差をより正確に求めることができる。
【００６５】
また、この発明の請求項５の光ディスク装置によれば、フォーカス状態が維持できなくなった場合でもリトライによって救済して駆動電流差Ｉ差を求めることができる。
さらに、この発明の請求項６の光ディスク装置によれば、フォーカス状態でＩ差が求められなかった場合でも擬似的に正しい補正効率を求めることができる。
また、この発明の請求項７の光ディスク装置によれば、再生時の発光パワーと記録時の再生パワーが異なる場合でも補正効率を正しく求めることができる。
さらに、この発明の請求項８の光ディスク装置によれば、補正効率を高精度に求めることができる。
【図面の簡単な説明】
【図１】この発明の一実施形態である光ディスク装置の構成を示すブロック図である。
【図２】図１に示したレーザコントローラ回路１５の内部構成を示すブロック図である。
【図３】図２に示したＰＤ２１の入射光量に対する出力電流の変化を示す線図である。
【図４】図２に示したＬＤ２０から出射される発光波形を示す波形図である。
【図５】図２に示したＣＰＵ１８から出力するＶｒの変化を示す波形図である。
【図６】図２に示したＣＰＵ１８から出力するＶｗの変化を示す波形図である。
【図７】図１に示したレーザコントローラ回路１５の内部構成と光ピックアップ５に搭載されたＬＤ及びＬＤの出射パワーをモニタする為の素子であるＰＤの構成との他の例を示したブロック図である。
【図８】ＣＤ−Ｒドライブにおいて光ディスクにデータ記録時実際にレーザ光源より出射される発光の説明図である。
【図９】図１に示したレーザコントローラ回路１５の内部構成と光ピックアップ５に搭載されたＬＤ及びＬＤの出射パワーをモニタする為の素子であるＰＤの構成とのさらに他の例を示したブロック図である。
【図１０】この発明の請求項４に係わる処理を示すフローチャート図である。
【図１１】この発明の請求項５に係わる処理を示すフローチャート図である。
【図１２】この発明の請求項６に係わる処理を示すフローチャート図である。
【図１３】この発明の請求項７に係わる処理を示すフローチャート図である。
【図１４】この発明の請求項８に係わる処理を示すフローチャート図である。
【図１５】レーザーダイオードの駆動電流と発光パワーである出射パワーの関係を示した線図である。
【図１６】同じくレーザーダイオードの駆動電流と発光パワーである出射パワーの関係を示した線図である。
【符号の説明】
１：光ディスク２：スピンドルモータ
３：モータドライバ４：サーボ部
５：光ピックアップ６：リードアンプ
７：ＣＤデコーダ８：バッファマネージャ
９：バッファＲＡＭ１０：インタフェース（Ｉ／Ｆ）
１１：Ｄ／Ａコンバータ１２：ＡＴＩＰデコーダ
１３：ＣＤエンコーダ１４：ＣＤ−ＲＯＭエンコーダ
１５：レーザコントローラ回路
１６：ＲＯＭ１７：ＲＡＭ
１８：ＣＰＵ２０：ＬＤ
２１：ＰＤ２２：Ｉ／Ｖ変換器
２３：Ｓ／Ｈ回路Ｒ２４：Ｓ／Ｈ回路Ｗ
２５：Ａ／Ｄ変換器Ｒ２６：Ａ／Ｄ変換器Ｗ
２７：Ｄ／Ａ変換器Ｒ２８：Ｄ／Ａ変換器Ｗ
２９：Ｖ／Ｉ変換器Ｒ３０：Ｖ／Ｉ変換器Ｗ
３１：電流加算器３２：高周波重畳回路
３３：Ｄ／Ａ変換器Ｐ３４：Ｖ／Ｉ変換器Ｐ
３５：ピークホールド回路Ｐ３６：Ａ／Ｄ変換器Ｐ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc apparatus provided with a laser drive control circuit that alternately repeats recording power for forming recording pits and reproducing power or erasing power for not forming pits, such as a CD-R drive and a CD-RW drive.
[0002]
[Prior art]
In general, it is known that when return light enters a laser diode, the oscillation mode is changed by the return light and laser noise increases.
In an optical disk apparatus that handles reflected light, such as an optical disk, it is necessary to consider the influence of return light to the laser diode. As a method for reducing the laser noise, there is a means for superimposing a high frequency of about 200 MHz to 500 MHz on laser light emission. It is used in a general optical disc apparatus.
For example, in the technique described in Japanese Patent Laid-Open No. 5-197994, in a semiconductor laser, when a focus control is pulled by a focus servo system, the amount of high frequency current superimposed by a high frequency superimposing circuit is increased to increase the amount of return light at the time of focus pulling. A laser noise reduction circuit capable of obtaining a stable emission power of a semiconductor laser with respect to the fluctuation of the above is shown.
[0003]
In the technique described in Japanese Patent Laid-Open No. 6-223399, the high-frequency superimposing means indispensable for laser noise reduction is formed on the same wafer as the signal detection means in the semiconductor laser case, thereby reducing the size of the optical head. An apparatus for achieving the conversion is shown. On the other hand, from a laser diode output limit, a high frequency is not superimposed at the time of light emission with recording power, or a high frequency with a smaller amplitude than that at the time of reproduction is superimposed on a general recordable optical disc.
As an example of the former, in the technique described in the above-mentioned Japanese Patent Application Laid-Open No. 6-223399, there is shown a configuration in which high frequency can be turned on / off according to the operation mode of recording and reproduction of an optical disc.
As an example of the latter, Japanese Patent Laid-Open No. 2000-149302 discloses a configuration in which the superposition frequency and superposition amplitude of high frequency superposition are changed depending on the recording and reproduction operation modes.
[0004]
Here, the relationship between (driving current) and (light emission power) of the laser diode varies depending on the amount of high frequency superposition.
FIGS. 15 and 16 are graphs showing the relationship between the driving current of the laser diode and the emission power, which is the light emission power, respectively.
As shown in FIG. 15, during recording, when recording power that does not superimpose high frequencies and reproduction power that superimposes high frequencies are alternately repeated, the reproduction power is controlled in a state where high frequencies are superimposed. Is determined from the relationship of (laser drive current) versus (laser emission power: emission power) of the laser diode when a high frequency is superimposed.
On the other hand, if the recording power does not superimpose the high frequency during light emission or if a small amount of high frequency is superimposed, the current for the playback power is a larger value, but that amount is not supplied, so it will eventually be added to the current for the playback power. The current corresponding to the recording power to be viewed appears large as shown in FIG. That is, an error (efficiency including an error in the figure) occurs in the current efficiency (true efficiency in the figure) for the recording power.
[0005]
In the case of a CD-R drive or CD-RW drive that writes to a CD-R or CD-RW disc, so as to maintain recording quality for discs with greatly different disc sensitivities, so-called trial writing with variable power is possible. To determine the optimum recording power.
The Orange Book, which is the standard for CD-R / RW discs, shows a method for determining the optimum recording power by setting each trial writing area to 15 sectors, recording with different power in each sector, and reproducing the recorded area. Yes.
Thus, since the test writing area is standardized by the format, the test writing time is shortened, that is, the recording time with one power is shortened as the recording speed is increased. For reference, one sector of a CD is 1/75 second at 1x speed.
[0006]
[Problems to be solved by the invention]
However, as a matter of course, the recording time of one power is shortened as the recording speed is increased to half of 1/75 second at double speed and further half of that at quadruple speed.
Here, when the power is changed from a certain value to a certain value unless the correct current efficiency is required, it takes time to reach the desired power because there is an error in the drive current of the light source to be applied first.
Conventionally, the recording speed was slow even with the above errors, so the desired power could be reached, but the recording speed became faster and one recording power period ended before reaching the desired power. As a result, there has been a problem that the optimum recording power cannot be obtained and the recording quality is deteriorated.
In the techniques described in Japanese Patent Laid-Open Nos. 6-223399 and 2000-149302 described above, the case where these recording speeds are increased is not sufficiently taken into consideration.
[0007]
Alternatively, when the recording power is changed together with the recording speed from a position such as ZoneCLV recording, there is a problem that the recording quality is deteriorated until the change power reaches the desired power quickly.
The present invention has been made to solve the above-mentioned problems, and a first object of the present invention is to prevent a decrease in recording quality due to a deviation between a set power and an actual light emission power during test recording when the recording speed is high. And
[0008]
Further, in the technique described in Japanese Patent Laid-Open No. 10-31570, in a device that shares a CD-RW and a CD-R semiconductor laser drive control circuit, the first power P1 is recorded when a CD-R is recorded. The second power P2 is controlled, and a current I3 obtained by multiplying the current I2 when the second power P2 is controlled by a predetermined ratio is given to the laser drive circuit, so that the third power P3 can be easily obtained. A device for controlling is shown.
However, in such a device, no consideration is given to the occurrence of an error in current efficiency due to the amount of superposition of high-frequency superposition, and therefore the correct third power P3 is not set, and the second like the CD-R. In a system in which the ratio of the power P2 and the third power P3 greatly contributes to the recording quality, there is a problem that the recording quality is deteriorated.
[0009]
Further, the technique described in Japanese Patent Laid-Open No. 2000-30276 discloses a recording waveform in an apparatus that accurately and quickly controls the power of a light beam without requiring generation of a high-speed response and a high-precision sampling pulse. The output of the optical output detection circuit at the time of the first power P1 is held by the bottom hold circuit, and the output of the optical output detection circuit at the time of the third power P3 is held by the peak hold circuit, respectively. An apparatus for controlling the level of the second power P2, which is difficult to sample and hold at the time of high-speed recording, by determining the drive current of the second power P2 based on the ratio of P1, the second power P2, and the third power P3. It is shown.
However, in such a device, no consideration is given to the occurrence of an error in current efficiency due to the amount of superposition of high-frequency superposition, and therefore the correct second power P2 is not set, and the second like the CD-R. In a system in which the ratio of the power P2 and the third power P3 greatly contributes to the recording quality, there is a problem that the recording quality is deteriorated.
Therefore, a second object is to obtain a good recording quality even in a system in which ternary power is easily controlled by binary samples.
[0010]
In addition, the relationship between the (driving current) versus (output power) of the laser diode is greatly different between the state with and without the return light of the optical disk. This is particularly noticeable when the laser diode and the light receiving element for signal detection are housed in the same package, such as a hologram laser, and the amount of light returning to the laser is large. Therefore, it is desirable that the period for obtaining the drive current difference I difference is in a focus-on state by the focus servo system.
Therefore, a third object is to obtain the drive current difference I difference more accurately.
[0011]
Furthermore, if the means for superimposing the high frequency to reduce the laser noise as described above is taken, if the superposition of the high frequency is not performed, or if a small amount is superimposed even if it is superimposed, the laser will be added to the focus signal in the worst state. Because of noise, the focus servo system cannot maintain the focus-on state, and the focus may be lost. In the normal state, the focus servo cannot be maintained, but the above-described state may occur when the optical disk is bad or a disturbance occurs.
Accordingly, a fourth object is to provide a drive current difference I difference by remedying even when the focus state cannot be maintained.
[0012]
Moreover, even in a state where laser noise cannot be reduced by high frequency superposition in a normal state, in the case of a general device, the focus on state can not be maintained, but when a disturbance occurs or the optical disk is bad, Since the focus signal also has a small so-called noise margin due to laser noise, the focus on state may not be maintained in the worst state.
If it is a temporary disturbance or the like, it can be avoided by retrying as described above. However, in the case of a continuous disturbance or a bad optical disc, there is a possibility that the drive current difference I difference may not be obtained even after retrying. is there.
Therefore, even when the I difference is not obtained in the focus state, the drive current difference I difference is simply obtained by the drive current value difference FoI difference different from the drive current difference I difference, and the pseudo correct correction efficiency is obtained. The fifth object is to be required.
[0013]
Furthermore, the recording speed of CD-R / RW devices has been increased year by year, and accordingly, a large recording power has been required.
Here, increasing the recording power naturally requires increasing the laser driving current, and switching the first power and the second power during recording causes an increase in noise level.
In a device that detects the detection of servo signals during recording when reproducing power is emitted and holds it when recording power is emitted, in order to earn the S / N of the detection signal when the recording power increases, the reproducing power during recording Generally, means for increasing S / N by increasing the signal component is taken.
For example, in the technique described in Japanese Patent Laid-Open No. 8-102078, an apparatus for changing the reproduction power for reproducing a wobble signal according to the recording power at the time of recording is shown.
[0014]
However, since the drive current difference I difference varies depending on the power, when the reproduction power during recording is varied from the light emission power during reproduction, the drive current difference I obtained without superimposing high frequency with the light emission power during reproduction is determined. When the difference is used for calculating the correction efficiency, there arises a problem that the correction efficiency cannot be obtained correctly.
Accordingly, it is a sixth object of the present invention to make it possible to correctly obtain the correction efficiency even when the light emission power during reproduction is different from the reproduction power during recording.
Furthermore, since the relationship between (driving current) and (emitted power) of the laser diode is temperature-dependent, the difference in driving current difference I obtained before the recording is slight, but due to self-heating during laser recording. The problem of changing.
Accordingly, a seventh object is to obtain the correction efficiency with high accuracy.
[0015]
[Means for Solving the Problems]
In order to achieve the first object, the present invention provides a light source such as a laser diode, a current supply means for the light source, a light output detection means for monitoring the light emission output level of the light source, An optical disc apparatus for recording data on an optical disc by alternately repeating light emission of a first power P1 and a second power P2 higher than that by a light source, wherein the current supply means has the first power P1 A means for adding and outputting the light emission current I1, the second power P2 and the difference current I2 of the first power P1, and a high-frequency current Ihf superimposed on the current I1 during the first power P1. And means for switching off the superposition of the high-frequency current Ihf at the second power P2 or switching to a different current Ihf2, and the second power P2 during the recording operation. Means for holding the light emission output level Vm2 monitored by the light output detection means at the time of light emission, means for holding the light emission output level Vm1 monitored by the light output detection means at the time of light emission by the first power P1, and each of the above means A control means for controlling the current supply means so that the light emission output level Vm1 and the light emission output level Vm2 held by each of them are set to desired values, and a high frequency is superimposed at the time of light emission by the first power P1 during recording, In the second power P2, the high frequency is not superimposed, or even if it is superimposed, an amount different from the high frequency superimposed at the time of light emission by the first power P1 is superimposed, and the first power P1 is recorded before recording. The first light emission period in which the high frequency is superimposed on the level and the high frequency is not superimposed on the level of the first power P1. The light-emitting period or at the time of recording The second power P2 And a second light emission period that is a light emission period at the level of the first power P1 superposed on the amount of high frequency that is superimposed at the time of output, and driving the light source in the first light emission period and the second light emission period The current difference I difference is maintained, and the correction efficiency η = (P2−P1) / (I2−I difference) of the driving current of the second power P2 is obtained during or after light emission by the second power P2. There is provided an optical disc apparatus comprising means for obtaining and determining a difference between initial currents I2 ′ = (P2′−P1) / η + I of the second power P2 ′ after the change when the second power P2 is changed.
[0016]
In order to achieve the second object, a light source such as a laser diode, current supply means for the light source, light output detection means for monitoring the light emission output level of the light source, and the light source during recording operation The optical disc apparatus records the data on the optical disc by emitting light of the first power P1, the second power P2 higher than that, and the third power P3 higher than that, wherein the current supply means includes: The current I1 corresponding to the light emission at the first power P1, the current I2 that is the difference between the second power P2 and the first power P1, the current that is the difference between the third power P3 and the second power P2. Means for adding and outputting I3, means for superimposing the high frequency current Ihf on the current I1 at the time of the first power P1, and high frequency at the time of the second power P2 and the third power P3. Means for switching the superimposition of the current Ihf off or switching to a different current Ihf2, and holding the light emission output level Vm2 monitored by the light output detection means during light emission by the second power P2 during recording operation; A means for holding the light emission output level Vm1 monitored by the light output detection means during light emission by the first power P1, and a light emission output level Vm1 and a light emission output level Vm2 held by the respective means are respectively set to desired values. And a control means for controlling the current supply means, and a high frequency is superimposed upon light emission by the first power P1 during recording, and light emission by the first power P1 is performed at the second power P2 and the third power P3. Sometimes superimpose or do not superimpose an amount that differs from the high frequency that is superimposed. A first light emission period in which a high frequency is superimposed at the level of the first power P1, and a light emission period in which a high frequency is not superimposed at the level of the first power P1, or the second power P2 and the third power P3 at the time of recording. And a second light emission period that is a light emission period at the level of the first power P1 superposed on the amount of high frequency that is superimposed at the time of output, and driving the light source in the first light emission period and the second light emission period The current difference I difference is held, and when light is emitted with the second power P2, the driving current correction efficiency η = (P2-P1) / (I2-I difference) of the second power P2 is obtained, and the third There is provided an optical disc apparatus provided with means for obtaining and determining drive current I3 = (P3−P2) / correction efficiency for emitting light of power P3.
[0017]
Further, a light source such as a laser diode, a current supply means for the light source, a light output detection means for monitoring the light emission output level of the light source, and a first power P1 higher than that by the light source during recording operation. An optical disc apparatus for recording data on an optical disc by emitting light of a second power P2 and a third power P3 higher than the second power P2, wherein the current supply means is a current for light emission at the first power P1. Means for adding and outputting the current I2 of the difference between I1, the second power P2, the first power P1, the current I3 of the difference between the third power P3 and the second power P2, and Means for superimposing the high-frequency current Ihf on the current I1 at the first power P1, and off or different superposition of the high-frequency current Ihf at the second power P2 and the third power P3. Means for switching to the current Ihf2, and means for holding the light emission output level Vm3 monitored by the light output detection means during light emission by the third power P3 during recording operation, and light emission by the first power P1 The current supply means is controlled so that the light emission output level Vm1 monitored by the light output detection means is sometimes held, and the light emission output level Vm1 and the light emission output level Vm3 held by the respective means are respectively set to desired values. And a control means for superimposing a high frequency when light is emitted by the first power P1 during recording, and the second power P2 and the third power P3 are different from the high frequency superimposed when light is emitted by the first power P1. Or the high frequency is not superimposed, and the level of the first power P1 is set before recording. In the first light emission period in which the high frequency is superimposed and the light emission period in which the high frequency is not superimposed at the level of the first power P1, or the amount to be superimposed in the output of the second power P2 and the third power P3 at the time of recording. A second light emission period which is a light emission period at the level of the first power P1 with a high frequency superimposed thereon is provided, and the drive current difference of the light source or the drive current I between the first light emission period and the second light emission period. A drive current difference I difference which is a proportional value proportional to the difference is held, and when light is emitted by the third power P3, the drive current correction efficiency η = (P3−P1) / (I2 + I3−) of the third power P3. Drive current I2 = (P2−P1) / correction efficiency + I difference for performing light emission of the second power P2 and drive current I3 = (light emission of the third power P3) = (I difference). P3-P2) / Correction effect Determine seeking bets may be in the optical disc apparatus having means for providing to said current supplying means.
[0018]
In order to achieve the third object, in the optical disk apparatus described above, a high frequency is superimposed at the level of the first power P1 before recording for maintaining the drive current difference I difference. In the first power P1 in which the first light emission period and the light emission period in which the high frequency is not superimposed at the level of the first power P1 or the amount of high frequency superimposed in the output of the second power P2 during recording are superimposed. Provided is an optical disc apparatus in which a second light emission period, which is a light emission period, is performed in a state where focus is turned on by a focus servo system.
[0019]
Further, in order to achieve the fourth object, in the optical disc apparatus as described above, the superimposition is performed at the time of outputting the second power P2 during recording or the light emission period when the high frequency is not superimposed at the level of the first power P1. When the focus servo system cannot maintain the focus on in the second light emission period, which is the light emission period with the first power P1 in which the amount of high frequency is superimposed, the focus servo is turned off. There is provided an optical disc apparatus in which the focus current is again turned on by a system to acquire the drive current difference I difference.
[0020]
In order to achieve the fifth object, in the optical disc apparatus as described above, a third light emission period in which a high frequency is superimposed at the level of the first power P1 in the period of the focus off state, and the first A light emission period in which the high frequency is not superimposed at the level of the power P1, or a light emission period at the level of the first power P1 in which the amount of the high frequency superimposed at the time of output of the second power P2 at the time of recording is superimposed. The focus servo system is held during the light emission period in which the drive current difference FoI difference of the light source in the third light emission period and the fourth light emission period is held and the drive current difference I difference is acquired in the focus on state. If the focus on state cannot be maintained and the focus off state cannot be obtained and the drive current difference I difference cannot be obtained, or the drive current difference I difference If it obtained neither determined by, to provide an optical disk device in which the driving current difference I-difference so as to determine a value obtained by a predetermined multiplying the drive current difference FoI difference.
[0021]
Furthermore, in order to achieve the sixth object, in the optical disk apparatus described above, when the light emission power during reproduction and the first power P1 during recording are different, the drive current difference I before recording is There is provided an optical disc apparatus in which, when the difference is obtained, the drive current difference I difference is obtained after the power is changed from the light emission power during reproduction to the first power P1 during recording.
[0022]
Furthermore, in order to achieve the seventh object, in the optical disc apparatus as described above, the second power P2 is recorded even when a high frequency is not superimposed at the time of recording or when the first power P1 is emitted or even when it is superimposed. And an optical disk apparatus in which a period for superimposing an amount of high frequency superimposed at the time of the third power P3 is provided during recording.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an optical disc apparatus according to an embodiment of the present invention.
This optical disk apparatus is a CD-R drive that records and reproduces data on a CD-R (CD-Recordable) disk that is a disk that conforms to a CD format that can be written only once.
An optical disc 1 such as a CD (Compact Disc), a CD-ROM, or a CD-R represents a data string on the optical disc substrate by the presence or absence of a hole called a pit, and reads data by applying a laser beam to this and changing the reflected light. . This data string is arranged in a spiral on the optical disk substrate like a record, and the line arranged in the spiral is called a track. The distance between adjacent tracks is 1.6 microns.
[0024]
Now, the optical disk 1 is rotationally driven by a spindle motor 2.
The spindle motor 2 is controlled by a motor driver (Motor Driver) 3 and a servo unit (Servo) 4 so as to have a constant speed.
The optical pickup (Pick Up) 5 moves the position of the lens in a direction perpendicular to the optical disc so that the optical system such as a well-known semiconductor laser (Laser Diode) light source, lens, etc., not shown, and the laser beam is focused on the optical disc. A focus actuator that is a mechanism, a track actuator that is a mechanism that moves the lens in the radial direction (sledge direction) of the optical disc so that the focal point of the laser beam traces the track, a light receiving element, a position sensor, etc. Is irradiated onto the optical disc 1.
[0025]
The entire optical pickup 5 can be moved in the sledge direction by a seek motor (not shown). These focus actuator, track actuator, and seek motor are controlled by the motor driver 3 and the servo unit 4 so that the laser spot is positioned at a target location based on signals obtained from the light receiving element and the position sensor.
In the case of data reading, the reproduction signal obtained by the optical pickup 5 is amplified by a read amplifier (Read Amp) 6 and is equalized or binarized (digitized), and then input to a CD decoder (CD Decoder) 7. And EFM demodulated.
[0026]
EFM is an abbreviation for “Eight to Fourteen Modulation”, and data obtained by modulating 8-bit data into 14-bit data is written on the optical disc 1 so as to be easily reproduced or recorded optically.
The EFM demodulated data undergoes deinterleaving (reordering) and error correction processing. After that, this data is temporarily stored in a buffer RAM 9 by a buffer manager 8 and is sent to a host computer via an interface (I / F) 10 such as ATAPI or SCSI at the stage where the data is gathered. Sent at once.
In the case of music data, the data output from the CD decoder 7 is input to the D / A converter 11 and an analog audio signal is extracted.
[0027]
At the time of data writing, data sent from the host computer through the I / F 10 is temporarily stored in the buffer RAM 9 by the buffer manager 8. Writing starts when a certain amount of data is stored in the buffer RAM 9, but before that, the laser spot must be positioned at the writing start point.
This point is obtained by a wobble signal preliminarily carved on the optical disc 1 by meandering tracks. The wobble signal includes absolute time information called ATIP, which can be extracted by the ATIP decoder 12. The synchronization signal generated by the ATIP decoder 12 is input to the CD encoder 13 so that data can be written at an accurate position.
[0028]
The data in the buffer RAM 9 is EFM-modulated after the error correction code is disabled or interleaved (rearranged) by the CD-ROM encoder 14 or the CD encoder 13, and passes through the laser controller circuit (Laser Controller) 15 and the optical pickup 5. To be recorded on the optical disc 1.
The ROM 16 is a read-only memory that stores a program when the CPU 18 controls recording and reproduction of data in the optical disc apparatus.
The RAM 17 is a readable / writable memory that is a work area when the CPU 18 controls data recording and reproduction in the optical disc apparatus.
The CPU 18 controls data recording and reproduction in the optical disk apparatus.
The laser controller circuit 15 of such an optical disc apparatus has the characteristics according to the present invention.
[0029]
(1) Embodiment according to claim 1 of the present invention
FIG. 2 is a block diagram showing the internal configuration of the laser controller circuit 15 shown in FIG. 1 and the configuration of the LD (Photo Detector) that is an element for monitoring the LD mounted on the optical pickup 5 and the emission power of the LD. FIG.
FIG. 3 is a diagram showing a change in the output current with respect to the incident light amount of the PD 21 shown in FIG.
Part of the laser light emitted from the LD 20 is incident on the PD 21 which is a power monitor. Here, as shown in FIG. 3, the PD 21 outputs a current proportional to the amount of incident laser light.
[0030]
When recording on the CD-R, the LD 20 repeatedly emits the first power P1 and the second power 02 higher than the first power P1. The emission time of the first power P1 and the second power P2 is based on the EFM signal to be recorded.
In other words, the emission time is a length that is an integral multiple of 3 to 11 of T, where T is a certain unit. Actually, the time length that is an integral multiple of 3 to 11 is slightly shortened or slightly lengthened in order to improve the recording quality.
The first power P1 is generally the reproduction power Pr when reading data (information) from the optical disk 1, and the second power P2 applies sufficient heat to the organic dye that is the recording film of the optical disk 1, and the optical disk 1 is a recording power Pw for forming a good pit.
[0031]
FIG. 4 is a waveform diagram showing a light emission waveform emitted from the LD 20 shown in FIG.
In the figure, the waveform before the time t write start is a light emission waveform when data is read from the optical disc 1, and the waveform after the time t write start is a light emission waveform when data is written to the optical disc 1.
When reading data, the LD 20 generally outputs a reproduction power Pr of 1 mW or less (more specifically, 0.4 mW or the like) with a constant light amount.
On the other hand, during recording, light emission of the reproduction power Pr and the recording power Pw is repeated.
The recording power Pw is generally several mW to several tens mW (more specifically, a power with good recording characteristics is selected by actually performing test writing between 5 mW and 40 mW). The recording power Pw is also APC controlled in the same manner as the reproduction power Pr, and a constant light quantity is maintained. That is, this Reproduction power Pr Is in the first power P1, Recording power Pw Corresponds to the second power P2.
[0032]
Next, the APC control will be described with reference to FIG.
First, the laser light incident on the PD 21 is output in the form of a current proportional to the amount of light by photoelectric conversion. That is, when the laser beam emitted from the LD 20 has a light emission waveform as shown in FIG. 4, a waveform is output in which the vertical axis in FIG. 4 is replaced with a current. Next, the I / V converter (I / V conversion circuit) 22 converts the current into a voltage.
Here, the output voltage corresponding to the reproduction power is V (Pr), and the output voltage corresponding to the recording power is V (Pw). That is, V (Pr) corresponds to the light emission output level Vm1 and V (Pw) corresponds to the light emission output level Vm2.
This output is a signal of only the V (Pr) level at the time of reproduction, but since V (Pr) and V (Pw) change alternately at the time of recording, the S / H circuit R (even in the bottom hold circuit) It is separated into V (Pr) and V (Pw) by an S / H circuit W (may be a peak hold circuit) 24.
[0033]
The sample signal R is a signal that always turns on the switch SW in the S / H circuit R23 during reproduction, and during recording, the reproduction power level during recording is emitted or slightly shorter than that. Only during the period, the switch SW in the S / H circuit R23 is turned on, and during the period when the recording power level is emitted, the switch SW in the S / H circuit R23 is turned off and the capacitor C in the S / H circuit R23 is turned off. The signal is controlled so as to extract only the voltage V (Pr) corresponding to the reproduction power level.
[0034]
On the other hand, the sample signal W is a signal that always turns off the switch SW in the S / H circuit W24 during reproduction, and during recording, the recording power level at the time of recording is emitted or longer than that. The switch SW in the S / H circuit W24 is turned on only during a short period, and the switch SW in the S / H circuit W24 is turned off during the period when the reproduction power level at the time of recording is emitted. / H This signal is controlled so that only the voltage V (Pw) corresponding to the recording power level is taken out by the capacitor C in the circuit W24.
Each V (Pr) and V (Pw) separated by the sample and hold is converted into data by an A / D converter R25 and an A / D converter W26, respectively, and provided to the CPU 18 as an input. The data is AD (Pr) and AD (Pw).
[0035]
The CPU 18 changes the data to be output to the D / A converter R27 and the D / A converter W28 so that AD (Pr) and AD (Pw) have desired values (reference value R and reference value W), respectively. . The respective data are assumed to be DA (Pr) and DA (Pw).
The outputs of the D / A converter R27 and the D / A converter W28 are converted into current and amplified by the V / I converter R29 and the V / I converter W30, respectively, and input to the current adder 31.
The current added by the current adder 31 flows to the LD 20 and laser light is emitted from the LD 20. Since this emitted light is incident on the PD 21, a feedback loop is formed around the error amplifier.
A constant power determined by the reference value is emitted from the LD 20 by the feedback loop configured as described above.
[0036]
Actually, the relationship between the reference value and the emission power is obtained in the manufacturing process of the optical disk device. Or it adjusts so that it may become the relationship between the decided reference value and output power. Controlling the power emitted from the LD 20 to be constant is called APC (Auto Power Control). If it is desired to vary the power emitted from the LD 20, it can be realized by varying this reference value.
The switch SW inserted in the output of the V / I converter R29 is turned on when emitting laser light from the LD 20, and the switch SW inserted in the output of the V / I converter W30 is used for recording. This is controlled by a write pulse signal that is turned on only during the recording power level period.
The control signals of each switch SW, that is, the sample signal R, the sample signal W, and the write pulse signal are signals output by the CD encoder 13 shown in FIG.
[0037]
Now, the steady light emission state has been described above. Next, when the reproduction power level is emitted from the state where the laser beam is not emitted from the LD 20 and when the reproduction is performed from the emission state of only the reproduction power level during recording. A case where a waveform is emitted will be described.
FIG. 5 is a waveform diagram showing changes in Vr output from the CPU 18.
FIG. 6 is a waveform diagram showing changes in Vw output from the CPU 18.
First, as shown in FIG. 5, V (Pr) = 0 in a state where laser light is not emitted from the LD 20. Next, when the light emission is started at the reproduction power, the switch SW is turned on by the LD on signal of the LD driver section in a state where DA (Pr) from the CPU 18 is set to 0 at the start of the reproduction light emission. Naturally, since V (Pr) = 0, the CPU 18 has a smaller AD (Pr) than the reference value R, so DA (Pr) is gradually increased, and eventually AD (Pr) becomes equal to the reference value R (VrefR). After that, the CPU 18 maintains AD (Pr) at the reference value R.
[0038]
Similarly, as shown in FIG. 6, even when the output waveform at the time of recording is output from the output state of only the reproduction power level, ON / OFF repetition of the switch of the sample hold circuit and the write pulse of the LD driver unit Although there is ON / OFF repetition depending on the signal, similarly, AD (Pw) increases as DA (Pw) increases from 0, and eventually AD (Pw) becomes equal to the reference value W (VrefW). AD (Pr) is controlled so as to maintain the reference value W.
In FIG. 2, the output of the high frequency superimposing circuit 32 that superimposes the high frequency during reproduction power is superposed on the LD 20.
[0039]
The switch SW provided at the output of the high frequency superimposing circuit 32 is configured to be turned off at the recording power and turned on at the reproducing power in conjunction with the write pulse signal. Further, although the high frequency superimposition is turned off by the write pulse signal, when the superposition of the high frequency is not turned off and the superposition amount is varied during the write pulse, the output of the high frequency superposition circuit 32 is divided by the resistance by the write pulse signal. It is necessary to attenuate by pressure or the like, or to prepare two high-frequency superposition circuits and switch them, or to switch the current gain of the output of the oscillator inside the high-frequency superposition circuit (not shown).
[0040]
Here, as described above, the relationship between (driving current) and (driving power) of the LD 20 changes as shown in FIG.
Therefore, by providing a mechanism for turning off the output of the high frequency superposition circuit 32 shown in FIG. 2 during the read period shown in FIG. 4 and performing APC, DA (PrON) at the time of high frequency superposition ON and at the time of high frequency superposition OFF DA (PrOFF) is obtained, and the difference DA (Pr difference) = DA (PrOFF) −DA (PrON) is obtained in advance.
Next, light emission is started, APC control is performed, and current efficiency of write power is acquired from DA (Pw).
At this time, the correction efficiency η = (Pw−Pr) / (DA (Pw) −DA (Pr difference) × α) is calculated and stored in the memory in the CPU 18 in FIG. Note that α is a coefficient for converting the calculated DA (Pr difference) to a recording power side current gain when the current gain is different between the reproduction power control side and the recording power side in FIG.
[0041]
The D / A converter is formally a Digital to Analog converter and is a circuit that converts a digital value, for example, 10000000 (80 hex in hexadecimal) into an analog value (for example, 2.0 [V]).
The LD (Laser Diode) 20 is an element driven by current, and is an element that emits 1 mW with a length of 40 mA, for example.
Therefore, in FIG. 2, a V / I converter (voltage → current converter) R29 and a V / I converter W30 are provided at the output destinations of the D / A converter R27 and the D / A converter W28, respectively.
Here, in general, how many volts are input in a V / I converter used for driving a laser beam and how many mA is output is generally in the case where the sensitivity is different between driving for reproducing power and driving for recording power. Is. This is because the reproduction power requires a smaller drive current than the recording power.
[0042]
For example, the reproduction power is 40 mA at 2 V input, and the recording power is 80 mA at 2 V input.
That is, the current that can be driven even with the same digital value (above DA (**)), for example, 80 hex, has a sensitivity to the digital value of 40 mA and 80 mA.
For example, when a reproduction power of 20 mA is supplied as a part of the current on the recording power side, the digital value may be a recording power digital value of 20 hex with respect to a reproducing power digital value of 40 hex. When converting to a digital value of recording power, it is necessary to multiply the sensitivity difference. This is the coefficient α.
In the above example, the write power is twice as sensitive, so the coefficient α is ½.
That is, since the units of DA (Pw) and DA (Pr) are different, they are matched by this coefficient α.
[0043]
Next, when the recording power is changed during trial writing or ZoneCLV recording, the correction efficiency η is used. For example, when (Pw−Pr) is doubled, DA (Pw2 times) is DA (Pw2 times). ) = 2 × (Pw−Pr) / correction efficiency + DA (Pr difference) × α.
With the above configuration, even when the recording power is variable, light can be emitted with a power almost equal to the power finally set by APC, so that APC control can follow even when the recording time with one power is short during trial writing.
Further, when the recording power is switched by ZoneCLV, recording can be started with a desired power even after switching, so that the recording quality at the switching portion can be maintained.
[0044]
In this way, it is possible to accurately determine the drive current efficiency of the recording power, and when recording with variable write power, when changing to the next power, the power value that is close to the finally controlled power value. Since the light emission can be started from the beginning, even when the power recording time for one trial writing is short, such as during high-speed recording, the final control power is reached, so that the trial writing can be performed correctly and the recording quality can be maintained.
[0045]
(2) Embodiment according to claim 2 of the present invention
FIG. 7 is a block diagram showing another example of the internal configuration of the laser controller circuit 15 shown in FIG. 1 and the configuration of the PD mounted on the optical pickup 5 and the PD that is an element for monitoring the emission power of the LD. FIG.
In the circuit configuration shown in the figure, a circuit for adding and outputting a peak power current to the circuit shown in FIG. 2 is added.
Here, the peak power will be described.
FIG. 8 is an explanatory diagram of light emission actually emitted from the laser light source when data is recorded on the optical disk in the CD-R drive.
This light emission method is shown in the Orange Book which is a CD-R standard.
[0046]
As shown in FIG. 8, a light emission period with a peak power higher than the write power is provided at the leading edge of the recording power, and the protruding portion is slightly raised so that the heat of the dye can be raised sharply with a particularly strong power.
In the circuit of FIG. 7, the D / A converter P33, the V / I converter P34, and the switch SW are provided in the above circuit, and the peak power does not extract V (Pp) by the S / H circuit. Control is performed to obtain DA (Pp) by calculating DA (Pw) by the / A converter P33 and V / I converter P34. Then, the correction efficiency η is obtained in the same manner as described above, DA (Pp) = (Pp−Pw) / correction efficiency η is calculated using the correction efficiency η, and data is output to the D / A converter P33.
[0047]
In this way, the efficiency of the drive current of the second power is corrected by the difference in the reproduction power drive current due to the difference in the amount of superposition of the high frequency superposition between the first power and the second power. I3 is obtained more accurately than I2 determined by controlling the power of the recording medium. Therefore, even in a system in which the ternary power is easily controlled by the binary sampling, a desired ratio of P2 and P3 can be obtained and the recording quality is lowered. Can be prevented.
[0048]
(3) Embodiment according to claim 3 of the present invention
FIG. 9 shows still another example of the internal configuration of the laser controller circuit 15 shown in FIG. 1 and the configuration of the PD mounted on the optical pickup 5 and the PD that is an element for monitoring the emission power of the LD. It is a block diagram.
In the circuit configuration shown in the figure, the S / H circuit W24 and the A / D converter W26 of the circuit shown in FIG. 2 are changed to a peak hold circuit P35 for detecting peak power and an A / D converter P36, respectively. Yes.
In the same manner as described above, the value held by the peak hold circuit P35 is converted into data AD (Pp) by the A / D converter P36 and can be processed by the CPU 18.
The CPU 18 obtains DA (Pr difference) in the same manner as described above and holds it.
[0049]
Since DA (Pr) is supplied with only the driving current when the high frequency superposition is ON, the difference DA (Pr difference) between the high frequency OFF and the high frequency ON is additionally supplied to DA (Pw).
Therefore, it is preferable that DA (Pp) is equal to DA (Pw) minus DA (Pr difference).
That is, APC is performed using DA (Pp), DA (Pw), and DA (Pr difference) while maintaining the state of DA (Pp) = DA (Pw) −DA (Pr difference), and correction efficiency η = (Pp−Pr) / (DA (Pp) + DA (Pw) −DA (Pr difference)), and DA (Pp) = (Pp−Pw) / correction efficiency η, DA (Pw) = (Pw−Pr) ) / Correction efficiency + DA (Pr difference).
[0050]
In this way, the efficiency of the drive current of the third power is corrected by the difference in the reproduction power drive current due to the difference in the amount of high frequency superposition between the first power and the second and third powers. Therefore, the currents I3 and I2 can be obtained correctly from the current value determined by the control of the third power. Therefore, even in a system in which the ternary power is controlled by the binary samples, the desired second power P2 and The ratio of the third power P3 can be obtained, and the deterioration of the recording quality can be prevented.
[0051]
(4) Embodiment according to claim 4 of the present invention
FIG. 10 is a flowchart showing processing according to claim 4 of the present invention. This process is performed by determining the drive current difference I difference and can be implemented in the circuits shown in FIGS.
In step (indicated by “S” in the figure), first, 0 is set in the D / A converter so that DA (Pr) is set to 0. In step 2, the LD ON signal is turned on. DA (Pr) is increased so that the desired reproduction power is obtained, and incremented until AD (Pr) reaches the reference value R.
At step 4, focus pull-in is performed, and after AD (Pr) reaches the reference value R at step 5, DA (Pr) is increased or decreased so as to maintain this relationship, and APC of the reproduction power is continued. Next, after the focus servo is turned on (ON), DA (Pr) maintained by APC is held as DA (PrON).
[0052]
In step 6, the high frequency superimposition output is turned off (OFF), and in step 7, DA (Pr) maintained by the reproduction power APC is held as DA (PrOFF). In step 8, the difference DA (Pr difference) between DA (PrON) and DA (PrOFF) is held, and the DA (Pr difference) is used when calculating the correction efficiency during recording power emission.
In step 9, the high frequency superimposition output is turned on (ON), and the process proceeds to the next step.
In this way, a difference occurs in the drive current difference I due to the difference in presence or absence of the optical disc and the difference in the reflectivity of the optical disc, but since the drive current difference I difference is obtained in the focus ON state before recording, The drive current difference I difference can be accurately obtained, and therefore the correction efficiency η can be obtained correctly. In the optical disc apparatus provided with the circuits shown in FIGS. 2, 7, and 9, the recording quality is improved. It becomes possible to maintain.
[0053]
(5) Embodiment according to claim 5 of the present invention
FIG. 11 is a flowchart showing processing according to claim 5 of the present invention.
In this processing, focus out-of-focus determination processing after high-frequency superimposition OFF is added, and when out-of-focus is detected, the focus pull-in is performed again.
In step (indicated by “S” in the figure) 11, first, 0 is set in the D / A converter so that DA (Pr) is set to 0. In step 12, the LD ON signal is turned on. DA (Pr) is increased so that the desired reproduction power is obtained, and incremented until AD (Pr) reaches the reference value R.
At step 14, focus pull-in is performed, and after AD (Pr) becomes the reference value R at step 15, DA (Pr) is increased or decreased so as to maintain this relationship, and APC of reproduction power is continued. Next, after the focus servo is turned on (ON), DA (Pr) maintained by APC is held as DA (PrON).
[0054]
In step 16, the output of high frequency superimposition is turned off (OFF). In step 17, it is determined whether or not the focus is out of focus. If it is out of focus, the process returns to step 14 and the above processing is repeated. DA (Pr) maintained by APC is held as DA (PrOFF). In step 19, the difference DA (Pr difference) between DA (PrON) and DA (PrOFF) is held, and the DA (Pr difference) is used when calculating the correction efficiency during recording power emission.
In step 20, the output of high frequency superimposition is turned on (ON) and the process proceeds to the next step.
In this way, when the drive current difference I difference is obtained, if the focus servo is lost, the drive current difference I difference may not be obtained. However, the retry is performed as described above. Thus, the drive current difference I difference can be obtained, and the above-described correction efficiency can be obtained correctly. In the optical disc apparatus provided with the circuits shown in FIGS. 2, 7, and 9, the recording quality is satisfactorily maintained. It becomes possible.
[0055]
(6) Embodiment according to claim 6 of the present invention
FIG. 12 is a flowchart showing processing according to claim 6 of the present invention.
In this process, high-frequency superimposition ON and OFF DA (Pr) are respectively acquired before focus pull-in, and DA (Pr difference OFF) is calculated.
In addition, when out-of-focus is detected with high-frequency superimposition OFF after focus pull-in, DA (Pr difference) is held as DA (Pr difference OFF) multiplied by a constant and returned to the high-frequency superposition ON state. I am trying to proceed to the routine.
In step (indicated by “S” in the figure) 31, first, the D / A converter is set to 0, DA (Pr) is set to 0, the LD ON signal is turned on in step 32, and in step 33. DA (Pr) is increased so that the desired reproduction power is obtained, and incremented until AD (Pr) reaches the reference value R.
[0056]
After AD (Pr) reaches the reference value R in step 34, DA (Pr) is increased or decreased so as to maintain this relationship, and APC of the reproduction power is continued. Next, after the focus servo is turned on (ON), DA (Pr) maintained by APC is held as DA (PrON).
In step 35, the output of high frequency superimposition is turned off (OFF), and in step 36, DA (Pr) where AD (Pr) = reference value R is held as DA (PrOFF).
In step 37, the difference DA (Pr difference OFF) between DA (PrOFF) and DA (PrON) is held. In step 38, the output of high frequency superimposition is turned on (ON). In step 39, the focus is pulled in. DA (Pr) where (Pr) = reference value R is held as DA (PrON).
[0057]
In step 41, the output of the high frequency superimposition is turned off (OFF). In step 42, it is determined whether or not the focus is out of focus. If it is out of focus, the process proceeds to step 46, and DA (Pr difference OFF) × α is held. The DA (Pr difference) is used when calculating the correction efficiency.
If not out of focus in step 42, DA (Pr) maintained by the reproduction power APC is held as DA (PrOFF) in step 43. In step 44, the difference DA (Pr difference) between DA (PrOFF) and DA (PrON) is held, and the DA (Pr difference) is used when calculating the correction efficiency during recording power emission.
In step 45, the output of the high frequency superimposition is turned on (ON) and the process proceeds to the next step.
[0058]
In the above-described processing, the process proceeds to step 46 with one out of focus. However, a retry may be performed to obtain DA (Pr) at the time of high frequency superposition OFF in a plurality of focus ON states. .
In this way, in the case of a continuous disturbance or a bad optical disk in the optical disk device described above, there is a possibility that the drive current difference I difference may not be obtained even after retrying. Even if it is not obtained, the drive current difference FoI difference having a value different from the drive current difference I difference is simply multiplied by a fixed value from the relationship between the drive current difference FoI difference and the drive current difference I difference obtained in advance through experiments or the like. Thus, the drive current difference I difference is obtained, and the correct correction efficiency is obtained in a pseudo manner to maintain the recording quality.
[0059]
(7) Embodiment according to claim 7 of the present invention
FIG. 13 is a flowchart showing processing according to claim 7 of the present invention.
This processing can be performed in the circuits shown in FIGS. In this process, after focus pull-in, DA (Pr) is controlled so as to maintain AD (Pr) by the reproduction power APC at the time of recording, and the reproduction power is changed to the reproduction power at the time of recording. DA (Pr) maintained by this APC is held as DA (PrON).
Next, high frequency superimposition is turned off with the same reproduction power, and DA (Pr) maintained by the reproduction power APC is held as DA (PrOFF).
The difference DA (Pr difference) between DA (PrON) and DA (PrOFF) is held, and the DA (Pr difference) is used when calculating the correction efficiency during recording power emission.
[0060]
In step (indicated by “S” in the figure) 51, 0 is first set in the D / A converter so that DA (Pr) is set to 0. In step 52, the LD ON signal is turned on. DA (Pr) is increased so that the desired reproduction power is obtained, and incremented until AD (Pr) reaches the reference value R.
At step 54, the focus is pulled in. After AD (Pr) reaches the reference value R at step 55, DA (Pr) is increased or decreased so as to maintain this relationship, and APC of the reproduction power is continued. Next, after the focus servo is turned on (ON), DA (Pr) maintained by APC is held as DA (PrON).
[0061]
In step 56, the high frequency superimposition output is turned off (OFF), and in step 57, DA (Pr) maintained by the reproduction power APC is held as DA (PrOFF). In step 58, the difference DA (Pr difference) between DA (PrOFF) and DA (PrON) is held, and the DA (Pr difference) is used when calculating the correction efficiency during recording power emission. In step 59, the high frequency superimposition output is turned on (ON), and in step 60, AD (Pr) is increased to adjust DA (Pr) until AD (Pr) reaches the reference value R, and the process proceeds to the next step.
In this way, by obtaining the drive current value difference I difference with or without superposition of the high frequency with the reproduction power at the time of recording before recording (different amount even if superposed), the correction efficiency is correctly obtained, and thus the above-described optical disc apparatus is obtained. Thus, even when the light emission power during reproduction and the reproduction power during recording are different, good recording quality can be maintained.
[0062]
(8) An embodiment according to claim 8 of the present invention.
FIG. 14 is a flowchart showing processing according to claim 8 of the present invention.
This processing can be performed in the circuits shown in FIGS. In this process, the drive current value difference I difference is updated during recording.
During normal recording, signal detection and the like are performed at the reproduction power level, so that a high frequency is superimposed to reduce laser noise, and the reproduction power is APC. In this state, the currently controlled DA (Pr) is held as DA (PrON recording) in step 71, high frequency superposition is turned off in step 72, and DA (Pr) obtained from the reproduction power APC in step 73. DA (PrOFF recording) is held, and in step 74, DA (Pr difference) = DA (PrOFF recording) −DA (PrON recording) is calculated and DA (Pr difference) is updated. Thereafter, in step 75, the high frequency superimposition is turned on (ON), the state is restored to the state where the high frequency is superimposed at the reproduction power, and the normal recording state is restored.
[0063]
By periodically performing the processing of this routine, the correct correction efficiency can be obtained by updating the driving current value difference I difference due to the temperature rise during recording in a timely manner.
In the above processing, the high frequency superposition ON at the time of reproduction power and the high frequency superposition OFF at the time of recording power have been described. can do.
In this manner, in the above-described optical disc apparatus, it corresponds to the relationship of (driving current) versus (emitted power) that changes due to self-heating during recording of laser light. By calculating again, it is possible to obtain more accurate correction efficiency, and therefore it is possible to maintain the recording quality with higher accuracy.
[0064]
【The invention's effect】
As described above, according to the optical disk device of the first aspect of the present invention, it is possible to prevent the recording quality from being deteriorated due to the difference between the set power and the actual light emission power during the test recording when the recording speed is high. .
Also, according to the optical disk device of the second or third aspect of the present invention, it is possible to obtain a good recording quality even in a system in which ternary power is easily controlled by binary samples.
Furthermore, according to the optical disk device of claim 4 of the present invention, the drive current difference I difference can be obtained more accurately.
[0065]
According to the optical disk device of the fifth aspect of the present invention, even when the focus state cannot be maintained, the drive current difference I difference can be obtained by remedy by retry.
Furthermore, according to the optical disk apparatus of the sixth aspect of the present invention, it is possible to obtain pseudo correct correction efficiency even when the I difference is not obtained in the focus state.
According to the optical disk apparatus of the seventh aspect of the present invention, the correction efficiency can be obtained correctly even when the light emission power during reproduction and the reproduction power during recording are different.
Furthermore, according to the optical disk apparatus of the eighth aspect of the present invention, the correction efficiency can be obtained with high accuracy.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an optical disc apparatus according to an embodiment of the present invention.
2 is a block diagram showing an internal configuration of a laser controller circuit 15 shown in FIG. 1. FIG.
3 is a diagram showing a change in output current with respect to an incident light amount of the PD 21 shown in FIG. 2;
4 is a waveform diagram showing a light emission waveform emitted from the LD 20 shown in FIG. 2; FIG.
FIG. 5 is a waveform diagram showing changes in Vr output from a CPU 18 shown in FIG. 2;
6 is a waveform diagram showing changes in Vw output from CPU 18 shown in FIG. 2; FIG.
7 is a block diagram showing another example of the internal configuration of the laser controller circuit 15 shown in FIG. 1 and the configuration of the PD mounted on the optical pickup 5 and the PD that is an element for monitoring the emission power of the LD. FIG.
FIG. 8 is an explanatory diagram of light emission actually emitted from a laser light source when data is recorded on an optical disc in a CD-R drive.
9 shows still another example of the internal configuration of the laser controller circuit 15 shown in FIG. 1 and the configuration of the PD mounted on the optical pickup 5 and the PD that is an element for monitoring the emission power of the LD. It is a block diagram.
FIG. 10 is a flowchart showing processing according to claim 4 of the present invention;
FIG. 11 is a flowchart showing processing according to claim 5 of the present invention;
FIG. 12 is a flowchart showing processing according to claim 6 of the present invention;
FIG. 13 is a flowchart showing processing according to claim 7 of the present invention;
FIG. 14 is a flowchart showing processing according to claim 8 of the present invention;
FIG. 15 is a diagram showing the relationship between the driving current of a laser diode and the emission power, which is the emission power.
FIG. 16 is a graph showing the relationship between the driving current of the laser diode and the emission power which is the emission power.
[Explanation of symbols]
1: Optical disk 2: Spindle motor
3: Motor driver 4: Servo section
5: Optical pickup 6: Lead amplifier
7: CD decoder 8: Buffer manager
9: Buffer RAM 10: Interface (I / F)
11: D / A converter 12: ATIP decoder
13: CD encoder 14: CD-ROM encoder
15: Laser controller circuit
16: ROM 17: RAM
18: CPU 20: LD
21: PD 22: I / V converter
23: S / H circuit R 24: S / H circuit W
25: A / D converter R 26: A / D converter W
27: D / A converter R 28: D / A converter W
29: V / I converter R 30: V / I converter W
31: Current adder 32: High frequency superposition circuit
33: D / A converter P 34: V / I converter P
35: Peak hold circuit P 36: A / D converter P

Claims

A light source such as a laser diode, current supply means to the light source, light output detection means for monitoring the light emission output level of the light source,
An optical disc apparatus for recording data on an optical disc by alternately repeating light emission of a first power P1 and a higher second power P2 by the light source during a recording operation,
The current supply means adds and outputs a current I1 for light emission at the first power P1, a second power P2, and a current I2 that is the difference between the first power P1 and the first power P1; Means for superimposing the high-frequency current Ihf on the current I1 when the power P1 is 1, and means for switching the superposition of the high-frequency current Ihf off or switching to a different current Ihf2 when the second power P2.
During recording operation, means for holding the light emission output level Vm2 monitored by the light output detection means during light emission by the second power P2, and light emission output monitored by the light output detection means during light emission by the first power P1 Means for holding the level Vm1, and control means for controlling the current supply means so that the light emission output level Vm1 and the light emission output level Vm2 held by the respective means are respectively set to desired values;
A high frequency is superimposed at the time of light emission by the first power P1 at the time of recording, and a high frequency is not superimposed at the second power P2, or even if superimposed, it differs from a high frequency superimposed at the time of light emission by the first power P1. So that the amount overlaps,
A first light emission period in which a high frequency is superimposed at the level of the first power P1 before recording and a light emission period in which a high frequency is not superimposed at the level of the first power P1 or when the second power P2 is output during recording A second light emission period that is a light emission period at the level of the first power P1 on which a high frequency of the amount to be superimposed is superimposed, and a driving current difference I of the light source between the first light emission period and the second light emission period. Hold the difference,
During or after the light emission by the second power P2, the correction efficiency η = (P2−P1) / (I2−I difference) of the driving current of the second power P2 is obtained, and the change of the second power P2 An optical disc apparatus comprising means for obtaining and determining a difference between the initial current I2 '= (P2'-P1) / η + I of the second power P2 ′ after the change.

A light source such as a laser diode, current supply means to the light source, light output detection means for monitoring the light emission output level of the light source,
An optical disc apparatus for recording data on an optical disc by emitting light of a first power P1, a higher second power P2, and a higher third power P3 by the light source during a recording operation,
The current supply means includes a current I1 for light emission at the first power P1, a current I2 as a difference between the second power P2, the first power P1, the third power P3, and the second power. Means for adding and outputting the difference current I3 of the power P2, means for superposing the high-frequency current Ihf on the current I1 during the first power P1, the second power P2 and the third power P3 And sometimes means for switching off the superposition of the high-frequency current Ihf or switching to a different current Ihf2.
During recording operation, means for holding the light emission output level Vm2 monitored by the light output detection means during light emission by the second power P2, and light emission output monitored by the light output detection means during light emission by the first power P1 Means for holding the level Vm1, and control means for controlling the current supply means so that the light emission output level Vm1 and the light emission output level Vm2 held by the respective means have respective desired values;
A high frequency is superimposed at the time of light emission by the first power P1 during recording, and the second power P2 and the third power P3 are superimposed by an amount different from the high frequency superimposed at the time of light emission by the first power P1 or Do not overlap,
A first light emission period in which high frequency is superimposed at the level of the first power P1 before recording, a light emission period in which high frequency is not superimposed at the level of the first power P1, or the second power P2 and the second power during recording. And a second light emission period that is a light emission period at the level of the first power P1 on which a high frequency of an amount that is superimposed at the time of output of the third power P3 is superimposed, and in the first light emission period and the second light emission period Holding the drive current difference I difference of the light source,
In order to emit light of the third power P3 by obtaining the correction efficiency η = (P2−P1) / (I2−I difference) of the drive current of the second power P2 during the light emission by the second power P2. Drive current I3 = (P3−P2) / Optical disk apparatus comprising means for determining and determining the correction efficiency and supplying it to the current supply means.

A light source such as a laser diode, current supply means to the light source, light output detection means for monitoring the light emission output level of the light source,
An optical disc apparatus for recording data on an optical disc by emitting light of a first power P1, a higher second power P2 and a higher third power P3 by the light source during a recording operation,
The current supply means includes a current I1 for light emission at the first power P1, a current I2 as a difference between the second power P2, the first power P1, the third power P3, and the second power. Means for adding and outputting the difference current I3 of the power P2, means for superposing the high-frequency current Ihf on the current I1 during the first power P1, the second power P2 and the third power P3 And sometimes means for switching off the superposition of the high-frequency current Ihf or switching to a different current Ihf2.
During recording operation, means for holding the light emission output level Vm3 monitored by the light output detection means during light emission by the third power P3, and light emission output monitored by the light output detection means during light emission by the first power P1 Means for holding the level Vm1, and control means for controlling the current supply means so that the light emission output level Vm1 and the light emission output level Vm3 held by the respective means have respective desired values;
A high frequency is superimposed at the time of light emission by the first power P1 during recording, and the second power P2 and the third power P3 are superimposed by an amount different from the high frequency superimposed at the time of light emission by the first power P1 or Avoid superimposing high frequencies,
A first light emission period in which high frequency is superimposed at the level of the first power P1 before recording, a light emission period in which high frequency is not superimposed at the level of the first power P1, or the second power P2 and the second power during recording. And a second light emission period that is a light emission period at the level of the first power P1 on which a high frequency of an amount that is superimposed at the time of output of the third power P3 is superimposed, and in the first light emission period and the second light emission period Holding the drive current difference I difference which is a proportional value proportional to the drive current difference or the drive current I difference of the light source;
In order to emit light of the second power P2 by obtaining the correction efficiency η = (P3−P1) / (I2 + I3−I difference) of the driving current of the third power P3 at the time of light emission by the third power P3. Drive current I2 = (P2-P1) / correction efficiency + I difference and drive current I3 = (P3-P2) / correction efficiency for light emission of the third power P3 are determined and determined to supply the current An optical disc apparatus comprising means for giving to the means.

The optical disc apparatus according to any one of claims 1 to 3,
A first light emission period in which high frequency is superimposed at the level of the first power P1 and a light emission period or recording in which high frequency is not superimposed at the level of the first power P1 before recording for maintaining the drive current difference I difference. The second light emission period, which is the light emission period with the first power P1 superimposed with the amount of high frequency superimposed when the second power P2 is output, is performed in a state where the focus servo system is focused on. An optical disc apparatus characterized by that.

The optical disc apparatus according to claim 4, wherein
A light emission period in which no high frequency is superimposed at the level of the first power P1 or a light emission period at the first power P1 in which an amount of high frequency superimposed at the time of output of the second power P2 during recording is superimposed. During the light emission period, when the focus servo system cannot maintain the focus on state and the focus off state is entered, the focus servo system is set to the focus on state again to acquire the drive current difference I difference. An optical disc apparatus characterized by the above.

The optical disc apparatus according to claim 4 or 5,
A third light emission period in which a high frequency is superimposed at the level of the first power P1 during a focus off state, and a light emission period in which a high frequency is not superimposed at the level of the first power P1, or the second power P2 at the time of recording. And a fourth light emission period which is a light emission period at the level of the first power P1 superposed on the amount of high frequency superimposed at the time of output, and driving the light source in the third light emission period and the fourth light emission period During the light emission period in which the current difference FoI difference is held and the drive current difference I difference is acquired in the focus on state, the focus on state by the focus servo system cannot be maintained and the focus off state is entered and the drive current difference I difference is obtained. Is not obtained or is not obtained by obtaining the driving current difference I again, the driving current difference I difference is calculated as the driving current difference FoI difference. Optical disc apparatus characterized by being adapted to determine a constant multiplied by the value.

The optical disc apparatus according to any one of claims 1 to 6,
When the light emission power at the time of reproduction is different from the first power P1 at the time of recording, the power is changed from the light emission power at the time of reproduction to the first power P1 at the time of recording when obtaining the drive current difference I difference before recording. An optical disc apparatus characterized in that the drive current difference I difference is obtained later.

The optical disc apparatus according to any one of claims 1 to 3,
At the time of recording, a period during which the high frequency is not superimposed when the first power P1 is emitted or a period during which the high frequency is superimposed at the second power P2 and the third power P3 even when superimposed is provided at the time of recording. An optical disc apparatus characterized by that.