JP2004070977A

JP2004070977A - Optical pickup and disk drive device

Info

Publication number: JP2004070977A
Application number: JP2002224425A
Authority: JP
Inventors: Takeshi Tanimoto; 谷本　豪
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 2002-08-01
Filing date: 2002-08-01
Publication date: 2004-03-04

Abstract

【課題】部品点数の削減による小型化を図ると共に性能の向上を図る。
【解決手段】発光素子１４から出射された異なる波長を有するレーザー光を互いに直交する偏光方向の光に変換する偏光方向変換手段２２と、該偏光方向変換手段を透過された第１の波長を有するレーザー光のみを回折すると共に第１の回折角度で回折する第１の回折手段２３と、偏光方向変換手段を透過された第２の波長を有するレーザー光のみを回折すると共に第１の回折角度とは異なる第２の回折角度で回折する第２の回折手段２４とを設け、異なる波長を有するレーザー光の０次光及び±１次光の各受光エリア２１ａ、２１ｂ、２１ｂにおけるスポット中心がそれぞれ略一致するように、第１の回折手段と第２の回折手段による回折角度θを決定した。
【選択図】　　　　　図２An object of the present invention is to reduce the number of parts to reduce the size and improve the performance.
A polarization direction converting means for converting laser beams having different wavelengths emitted from a light emitting element into light having polarization directions orthogonal to each other, and having a first wavelength transmitted through the polarization direction converting means. A first diffraction means for diffracting only the laser light and diffracting the light at a first diffraction angle, and diffracting only the laser light having the second wavelength transmitted through the polarization direction changing means, and Is provided with second diffracting means 24 for diffracting at different second diffraction angles, and the center of the spot in each of the light receiving areas 21a, 21b, 21b of the 0th-order light and ± 1st-order light of the laser light having different wavelengths is substantially The diffraction angles θ by the first diffraction means and the second diffraction means were determined so as to match.
[Selection] Fig. 2

Description

【０００１】
【発明の属する技術分野】
本発明は光ピックアップ及びディスクドライブ装置についての技術分野に関する。詳しくは、２種類の異なるディスク状記録媒体に対する情報信号の記録及び／又は再生を行う光ピックアップ及びこれを備えたディスクドライブ装置において、性能の向上を図ると共に部品点数の削減による小型化を図る技術分野に関する。
【０００２】
【従来の技術】
ディスク状記録媒体に対する情報信号の記録や再生を行うディスクドライブ装置があり、このようなディスクドライブ装置は、ディスクテーブルに装着されるディスク状記録媒体の半径方向へ移動し該ディスク状記録媒体に対して対物レンズを介してレーザー光を照射する光ピックアップを備えている。
【０００３】
以下に、従来のディスクドライブ装置の光ピックアップに設けられた光学系の一例を示す（図８参照）。
【０００４】
光ピックアップの図示しない移動ベースには、所要の各光学要素、即ち、第１の発光素子ａ、第２の発光素子ｂ、第１のグレーティングｃ、第２のグレーティングｄ、第１のビームスプリッターｅ、第２のビームスプリッターｆ、コリメーターレンズｇ、立ち上げミラーｈ、対物レンズｉ、調整レンズｊ及び受光素子ｋが搭載されている。
【０００５】
第１の発光素子ａ及び第１のグレーティングｃは、第１のディスク状記録媒体、例えば、ＣＤ（Ｃｏｍｐａｃｔ　Ｄｉｓｃ）ｘ専用の光学素子であり、第１の発光素子ａからは７８０ｎｍの波長を有するレーザー光が出射される。
【０００６】
一方、第２の発光素子ｂ及び第２のグレーティングｄは、第２のディスク状記録媒体、例えば、ＤＶＤ（Ｄｉｇｉｔａｌ　Ｖｅｒｓａｔｉｌｅ　Ｄｉｓｃ）ｙ専用の光学素子であり、第２の発光素子ｂからは６５０ｎｍの波長を有するレーザー光が出射される。
【０００７】
以上のような光学系において、ＣＤｘに対して情報信号の記録や再生が行われるときには、第１の発光素子ａからレーザー光が出射されて第１のグレーティングｃによってレーザー光が０次光と±１次光とに回折され、順に第１のビームスプリッターｅ、第２のビームスプリッターｆ、コリメーターレンズｇ、立ち上げミラーｈ及び対物レンズｉを介してＣＤｘの記録面にレーザー光が照射される。レーザー光はＣＤｘの記録面で反射され、順に対物レンズｉ、立ち上げミラーｈ、コリメーターレンズｇ、第２のビームスプリッターｆ、第１のビームスプリッターｅ及び調整レンズｊを介して受光素子ｋに入射される。受光素子ｋに入射されたレーザー光は、０次光Ｓａと±１次光Ｓｂ、Ｓｂとがそれぞれ受光素子ｋの３つの受光エリアｌ、ｍ、ｎのそれぞれ略中央部で受光される（図９参照）。
【０００８】
一方、ＤＶＤｙに対して情報信号の記録や再生が行われるときには、第２の発光素子ｂからレーザー光が出射されて第２のグレーティングｄによってレーザー光が０次光と±１次光とに回折され、順に第２のビームスプリッターｆ、コリメーターレンズｇ、立ち上げミラーｈ及び対物レンズｉを介してＤＶＤｙの記録面にレーザー光が照射される。照射されたレーザー光はＤＶＤｙの記録面で反射され、順に対物レンズｉ、立ち上げミラーｈ、コリメーターレンズｇ、第２のビームスプリッターｆ、第１のビームスプリッターｅ及び調整レンズｊを介して受光素子ｋに入射される。受光素子ｋに入射されたレーザー光は、ＣＤｘの場合と同様に、０次光Ｓｃと±１次光Ｓｄ、Ｓｄとがそれぞれ受光素子ｋの３つの受光エリアｌ、ｍ、ｎのそれぞれ略中央部で受光される（図９参照）。
【０００９】
【発明が解決しようとする課題】
ところで、レーザー光の回折角度θ（０次光と±１次光とが為す角度）は、グレーティングの格子ピッチ（グレーティングの溝間の間隔）をＰｄとし、レーザー光の波長をλとすると、Ｓｉｎθ＝λ／Ｐｄで表され、回折角度θは波長λに対してグレーティングの格子ピッチＰｄを定めることにより所望の値に設定することができる。従って、上記した従来のディスクドライブ装置においては、第１のグレーティングｃと第２のグレーティングｄの格子ピッチをそれぞれ固有の値に定めることにより、第１の発光素子ａ又は第２の発光素子ｂから出射される各レーザー光の回折角度を所望の値に設定し、０次光Ｓａ、Ｓｃと±１次光Ｓｂ、Ｓｂ、Ｓｄ、Ｓｄとをそれぞれ受光素子ｋの３つの受光エリアｌ、ｍ、ｎのそれぞれ略中央部で受光させることができる（図９参照）。
【００１０】
ところが、上記した従来のディスクドライブ装置にあっては、２種類のディスク状記録媒体ＣＤｘ、ＤＶＤｙに対応した発光素子ａ、ｂ、ビームスプリッターｅ、ｆに加え、各レーザー光の回折角度を固有の値に設定するために２つのグレーティングｃ、ｄを設けており、部品点数が多く、また、各光学要素を配置するための大きなスペースが必要であるため、光ピックアップの大型化を来たしているという問題がある。
【００１１】
そこで、別の従来のディスクドライブ装置として、異なる波長を有する２種類のレーザー光を出射する１つの発光素子と１つのグレーティングを用いて光学系を構成したものがある。従って、このような光学系にあっては、グレーティングが１つであり、７８０ｎｍの波長を有するレーザー光と６５０ｎｍの波長を有するレーザー光とも同一のグレーティングによって回折される。
【００１２】
しかしながら、このように各波長を有するレーザー光を同一のグレーティングによって回折させるようにすると、一方のレーザー光の０次光Ｓｅと±１次光Ｓｆ、Ｓｆを受光素子の各受光エリアｏ、ｐ、ｑの中央部で受光させ、他方のレーザー光の０次光Ｓｇを０次光Ｓｅが受光される受光エリアｏの中央部に合わせるようにすると、他方のレーザー光の±１次光Ｓｈ、Ｓｈが受光素子の各受光エリアｐ、ｑから外れ（図１０参照）、他方のレーザー光についてのフォーカシングの誤差信号及びトラッキングの誤差信号の検出ができない。
【００１３】
従って、異なる波長を有する２種類のレーザー光を出射する１つの発光素子と１つのグレーティングを用いて光学系を構成した場合には、各レーザー光を受光するための２つの受光素子が必要となってしまう。
【００１４】
一方、異なる波長を有する２種類のレーザー光を出射する１つの発光素子と１つのグレーティングを用いて構成した光学系において、例えば、６５０ｎｍの波長のレーザー光の０次光のみを使用し±１次光を使用しない所謂１ビームの対応とすることも可能である。ところが、この場合には、ＤＶＤ（ＤＶＤビデオ、ＤＶＤ−ＲＯＭ）に対する情報信号の再生は可能であるが、情報信号の記録ができなくなり、また、ＤＶＤ−ＲＡＭに対しては情報信号の記録及び再生の双方ともできなくなり、使用可能なディスク状記録媒体の種類が限定されてしまうという不都合がある。
【００１５】
そこで、本発明光ピックアップ及びディスクドライブ装置は、上記した問題点を克服し、部品点数の削減による小型化を図ると共に性能の向上を図ることを課題とする。
【００１６】
【課題を解決するための手段】
本発明光ピックアップ及びディスクドライブ装置は、上記した課題を解決するために、２種類の異なるディスク状記録媒体へ向けて該各ディスク状記録媒体に対応した第１の波長及び第２の波長を有するレーザー光を出射する発光素子と、該発光素子から出射された第１の波長を有するレーザー光の偏光方向と第２の波長を有するレーザー光の偏光方向とを互いに直交する偏光方向の光に変換する偏光方向変換手段と、該偏光方向変換手段を透過された第１の波長を有するレーザー光のみを回折すると共に第１の回折角度で回折する第１の回折手段と、偏光方向変換手段を透過された第２の波長を有するレーザー光のみを回折すると共に第１の回折角度とは異なる第２の回折角度で回折する第２の回折手段と、第１の波長を有するレーザー光及び第２の波長を有するレーザー光を各レーザー光の進行方向に応じて反射し又は透過するビームスプリッターと、第１の回折手段又は第２の回折手段によって回折され各ディスク状記録媒体で反射された第１の波長を有するレーザー光と第２の波長を有するレーザー光の光軸を一致させる光軸合成素子と、該光軸合成素子によって光軸が一致された第１の波長を有するレーザー光と第２の波長を有するレーザー光が入射されると共にレーザー光の０次光と±１次光とを各別に受光する３つの受光エリアを有する受光素子とを設け、第１の波長を有するレーザー光の０次光及び±１次光の各受光エリアにおけるスポット中心と、第２の波長を有するレーザー光の０次光及び±１次光の各受光エリアにおけるスポット中心とがそれぞれ略一致するように、第１の回折手段による回折角度と第２の回折手段による回折角度とを決定したものである。
【００１７】
別の本発明光ピックアップ及びディスクドライブ装置は、上記した課題を解決するために、２種類の異なるディスク状記録媒体へ向けて該各ディスク状記録媒体に対応した第１の波長及び第２の波長を有するレーザー光を出射する発光素子と、該発光素子から出射された第１の波長を有するレーザー光の偏光方向と第２の波長を有するレーザー光の偏光方向とを互いに直交する偏光方向の光に変換する偏光方向変換手段と、該偏光方向変換手段を透過された第１の波長を有するレーザー光のみを回折すると共に第１の回折角度で回折する第１の回折手段と、偏光方向変換手段を透過された第２の波長を有するレーザー光のみを所定の回折効率で回折する第２の回折手段と、第１の波長を有するレーザー光及び第２の波長を有するレーザー光を各レーザー光の進行方向に応じて反射し又は透過するビームスプリッターと、第１の回折手段又は第２の回折手段によって回折され各ディスク状記録媒体で反射された第１の波長を有するレーザー光と第２の波長を有するレーザー光の光軸を一致させる光軸合成素子と、該光軸合成素子によって光軸が一致された第１の波長を有するレーザー光と第２の波長を有するレーザー光が入射されると共にレーザー光の０次光と±１次光とを各別に受光する３つの受光エリアを有する受光素子とを設け、第１の波長を有するレーザー光の０次光及び±１次光の各受光エリアにおけるスポット中心と、第２の波長を有するレーザー光の０次光及び±１次光の各受光エリアにおけるスポット中心とがそれぞれ略一致するように、第１の回折手段による回折角度と第２の回折手段による回折角度とを決定したものである。
【００１８】
従って、本発明光ピックアップ及びディスクドライブ装置にあっては、同一の発光素子から出射された異なる波長を有する２種類のレーザー光が同一の受光素子の受光エリアで受光される。
【００１９】
【発明の実施の形態】
以下に、本発明光ピックアップ及びディスクドライブ装置の実施の形態を添付図面を参照して説明する。
【００２０】
ディスクドライブ装置１は、外筐２内に所要の各部材及び各機構が配置されて成る（図１参照）。
【００２１】
外筐２内にはシャーシ３が配置され、該シャーシ３に図示しないスピンドルモーターが取り付けられている。スピンドルモーターのモーター軸にはディスクテーブル４が固定されている。
【００２２】
シャーシ３には配置孔３ａが形成され、ディスクテーブル４が配置孔３ａを介してシャーシ３の上方へ突出されている。
【００２３】
シャーシ３の下面側には、リードスクリュー５とガイド軸６、６とが平行な状態で配置されている。シャーシ３の配置孔３ａには、光ピックアップ７がディスクテーブル４に装着されるディスク状記録媒体１００の半径方向へ移動可能な状態で配置されている。
【００２４】
光ピックアップ７は移動ベース８と該移動ベース８に設けられた所要の光学要素（光学素子）と移動ベース８上に支持された対物レンズ駆動装置９とを有し、移動ベース８の両端部がそれぞれガイド軸６、６に摺動自在に支持されている。移動ベース８に設けられた図示しないナット部材がリードスクリュー５に螺合され、移動ベース８に取り付けられた図示しない送りモーターによってリードスクリュー５が回転されると、ナット部材がリードスクリュー５の回転方向に応じた方向へ送られ、光ピックアップ７がガイド軸６、６に案内されてディスクテーブル４に装着されるディスク状記録媒体１００の半径方向へ移動される。
【００２５】
対物レンズ駆動装置９は固定部１０と該固定部１０に複数のサスペンション１１、１１、・・・を介して移動可能に支持された可動部１２とを有し、該可動部１２に対物レンズ１３が保持されている（図１参照）。
【００２６】
移動ベース８には、所要の各光学要素が配置されている（図２参照）。
【００２７】
光学要素としては、発光素子１４、光回折素子１５、ビームスプリッター１６、コリメーターレンズ１７、立ち上げミラー１８、対物レンズ駆動装置９に設けられた対物レンズ１３、光軸合成素子１９、調整レンズ２０及び受光素子２１等であり、これらの各光学要素によってディスクドライブ装置１の光学系が構成される。
【００２８】
発光素子１４は異なる波長を有するレーザー光を発光する２つの発光点を有し、第１の発光点からは、例えば、７８０ｎｍの波長（第１の波長）を有するレーザー光が出射され、第２の発光点からは、例えば、６５０ｎｍの波長（第２の波長）を有するレーザー光が出射される。一方のディスク状記録媒体１００、即ち、ＣＤ１００ａに対する情報信号の記録又は再生が行われるときには、第１の発光点から７８０ｎｍの波長を有するレーザー光が出射され、他方のディスク状記録媒体１００、即ち、ＤＶＤ１００ｂに対する情報信号の記録又は再生が行われるときには、第２の発光点から６５０ｎｍの波長を有するレーザー光が出射される。
【００２９】
発光素子１４の第１の発光点と第２の発光点とは所定の間隔を置いて配置されており、第２の波長を有するレーザー光は上記した光学系の光軸上に一致されているが、第１の波長を有するレーザー光は光学系の光軸上からずれている。　光回折素子１５は、偏光方向変換手段として機能する１／２波長板２２と、第１の回折手段として機能する第１のグレーティング２３と、第２の回折手段として機能する第２のグレーティング２４とが順に接合されて構成されている（図３参照）。
【００３０】
１／２波長板２２は、第１の波長を有するレーザー光に対してはπ、第２の波長を有するレーザー光に対してはπ／２の位相差を発生させ、各レーザー光の偏光方向を互いに直交する方向へ変換する。
【００３１】
第１のグレーティング２３のレーザー光の光軸方向における一方の面は、複数の溝が形成された回折面２３ａとして形成され、第２のグレーティング２４のレーザー光の光軸方向における一方の面は、複数の溝が形成された回折面２４ａとして形成されている。
【００３２】
第１のグレーティング２３及び第２のグレーティング２４は、それぞれ特定の偏光方向のレーザー光のみを回折し、その偏光方向と直交する偏光方向のレーザー光は回折せず透過板として機能する。例えば、第１のグレーティング２３は１／２波長板２２によって偏光方向が変換された第１の波長を有するレーザー光のみを回折して０次光と±１次光とを生成し、第２のグレーティング２４は１／２波長板２２によって偏光方向が変換された第２の波長を有するレーザー光のみを回折して０次光と±１次光とを生成する。
【００３３】
第１のグレーティング２３及び第２のグレーティング２４にあっては、それぞれ格子ピッチが固有の値に設定され、回折角度が互いに異なるように設計されている。
【００３４】
第１のグレーティング２３及び第２のグレーティング２４は、第１の波長を有するレーザー光又は第２の波長を有するレーザー光をそれぞれ所定の回折効率で回折する。この回折効率は、使用されるディスク状記録媒体の種類に応じた最適の値に設定されている。
【００３５】
ビームスプリッター１６は、例えば、反射型であり、発光素子１４から出射されたレーザー光を分離面１６ａで反射してコリメーターレンズ１７へ導き、ディスク状記録媒体１００で反射されたレーザー光の戻り光を透過して光軸合成素子１９へ導く機能を有する。
【００３６】
コリメーターレンズ１７は入射されたレーザー光の光束を平行光束にする機能を有し、立ち上げミラー１８はレーザー光を反射して対物レンズ１３又はコリメーターレンズ１７へ導く機能を有し、対物レンズ１３は入射されたレーザー光をディスク状記録媒体１００の記録トラック上に集光させる機能を有する。
【００３７】
光軸合成素子１９は、光学系の光軸上からずれた第１の波長を有するレーザー光の光軸方向を補正し、受光素子２１の所定の受光点に入射させる機能を有している。
【００３８】
調整レンズ２０はレーザー光の倍率を調整するためのレンズである。
【００３９】
受光素子２１は、レーザー光の０次光と±１次光とをそれぞれ受光する３つの受光エリア２１ａ、２１ｂ、２１ｂを有している（図４参照）。受光エリア２１ａは０次光を受光するエリアであり、受光エリア２１ｂ、２１ｂはそれぞれ＋１次光と−１次光を受光するエリアである。
【００４０】
以上のように構成された光学系において、発光素子１４から第１の波長を有するレーザー光が出射されると、出射されたレーザー光は光回折素子１５の１／２波長板２２によって偏光方向が変換され第１のグレーティング２３によって回折角度θ１で回折されて０次光と±１次光が生成される（図３に回折の様子を破線で示す。）。このとき、第１の波長を有するレーザー光は第２のグレーティング２４によっては回折されず透過されるだけである。レーザー光はビームスプリッター１６の分離面１６ａで反射されてコリメーターレンズ１７によって平行光束とされ、立ち上げミラー１８で立ち上げられて対物レンズ１３を介してディスクテーブル４に装着されたＣＤ１００ａの記録面に照射される。ＣＤ１００ａの記録面に照射されたレーザー光は、該記録面で反射されて戻り光として再び対物レンズ１３、立ち上げミラー１８及びコリメーターレンズ１７を介してビームスプリッター１６に入射される。ビームスプリッター１６に入射された戻り光は、ビームスプリッター１６の分離面１６ａを透過され、光軸合成素子１９によって光軸方向が補正されて調整レンズ２０を介して受光素子２１に入射される。
【００４１】
受光素子２１に入射された第１の波長を有するレーザー光は、回折された０次光が受光エリア２１ａで受光され、±１次光がそれぞれ受光エリア２１ｂ、２１ｂで受光される。
【００４２】
光ピックアップ７にあっては、第１の波長を有するレーザ光の０次光Ｓｍａと±１次光Ｓｓａ、Ｓｓａの各スポット中心がそれぞれ受光エリア２１ａ、２１ｂ、２１ｂの中央に略一致するように、第１のグレーティング２３による回折角度が設計されている。従って、受光素子２１に入射された第１の波長を有するレーザー光は、０次光Ｓｍａと±１次光Ｓｓａ、Ｓｓａの各スポット中心がそれぞれ受光エリア２１ａ、２１ｂ、２１ｂの中央に略一致した状態で受光される（図４参照）。
【００４３】
受光素子２１に戻り光が入射されると、受光エリア２１ａで受光された０次光Ｓｍａに基づいてＣＤ１００ａに対する情報信号の読取が行われる。同時に、受光エリア２１ｂ、２１ｂで受光された±１次光Ｓｓａ、Ｓｓａに基づいてフォーカシングの誤差信号及びトラッキングの誤差信号の検出が行われ、この検出結果に基づいて対物レンズ駆動装置９の可動部１２が固定部１３に対して変位されてフォーカシング調整及びトラッキング調整が行われる。
【００４４】
一方、発光素子１４から第２の波長を有するレーザー光が出射されると、出射されたレーザー光は光回折素子１５の１／２波長板２２によって偏光方向が変換され第２のグレーティング２４によって回折角度θ２で回折されて０次光と±１次光が生成される（図３に回折の様子を実線で示す。）。このとき、第２の波長を有するレーザー光は第１のグレーティング２３によっては回折されず透過されるだけである。レーザー光はビームスプリッター１６の分離面１６ａで反射されてコリメーターレンズ１７によって平行光束とされ、立ち上げミラー１８で立ち上げられて対物レンズ１３を介してディスクテーブル４に装着されたＤＶＤ１００ｂの記録面に照射される。ＤＶＤ１００ｂの記録面に照射されたレーザー光は、該記録面で反射されて戻り光として再び対物レンズ１３、立ち上げミラー１８及びコリメーターレンズ１７を介してビームスプリッター１６に入射される。ビームスプリッター１６に入射された戻り光は、ビームスプリッター１６の分離面１６ａを透過され、光軸合成素子１９及び調整レンズ２０を介して受光素子２１に入射される。
【００４５】
受光素子２１に入射された第２の波長を有するレーザー光は、回折された０次光が受光エリア２１ａで受光され、±１次光がそれぞれ受光エリア２１ｂ、２１ｂで受光される。
【００４６】
光ピックアップ７にあっては、第２の波長を有するレーザ光の０次光Ｓｍｂと±１次光Ｓｓｂ、Ｓｓｂの各スポット中心がそれぞれ受光エリア２１ａ、２１ｂ、２１ｂの中央に略一致するように、第２のグレーティング２４による回折角度が設計されている。従って、受光素子２１に入射された第２の波長を有するレーザー光は、０次光Ｓｍｂと±１次光Ｓｓｂ、Ｓｓｂの各スポット中心がそれぞれ受光エリア２１ａ、２１ｂ、２１ｂの中央に略一致した状態で受光される（図４参照）。
【００４７】
受光素子２１に戻り光が入射されると、受光エリア２１ａで受光された０次光Ｓｍｂに基づいてＤＶＤ１００ｂに対する情報信号の読取が行われる。同時に、受光エリア２１ｂ、２１ｂで受光された±１次光Ｓｓｂ、Ｓｓｂに基づいてフォーカシングの誤差信号及びトラッキングの誤差信号の検出が行われ、この検出結果に基づいて対物レンズ駆動装置９の可動部１２が固定部１３に対して変位されてフォーカシング調整及びトラッキング調整が行われる。
【００４８】
以上に記載した通り、光ピックアップ７にあっては、光回折素子１５の１／２波長板２２によって波長の異なるレーザー光の偏光方向を互いに直交する方向に変換し、偏光方向が変換されたレーザー光を第１のグレーティング２３又は第２のグレーティング２４によって選択的に回折するようにしている。
【００４９】
従って、異なる波長を有するレーザー光に対して共通の発光素子１４、光回折素子１５、ビームスプリッター１６及び受光素子２１を用いることができ、部品点数の削減及びこれによる各光学要素の省スペース化による光ピックアップ７の小型化を図ることができる。
【００５０】
また、異なる波長を有する２種類のレーザー光について、それぞれ０次光と±１次光の各スポット中心を受光素子２１の各受光エリア２１ａ、２１ｂ、２１ｂの各中央に略一致させることができるため、各種のＣＤ（ＣＤーＲＯＭ、ＣＤーＲ、ＣＤーＲＷ等）、ＤＶＤ（ＤＶＤビデオ、ＤＶＤーＲＯＭ、ＤＶＤーＲ、ＤＶＤーＲＡＭ等）に対する情報信号の記録及び再生を行うことができ、使用可能なディスク状記録媒体１００の種類が増加し、光ピックアップ７の性能の向上を図ることができる。
【００５１】
さらに、第１のグレーティング２３の第１の波長を有するレーザー光についての回折効率及び第２のグレーティング２４の第２の波長を有するレーザー光についての回折効率は、使用されるディスク状記録媒体の種類に応じて最適の値に設定すればよいため、設計の自由度が高く光ピックアップ７の性能の向上を図ることができる。
【００５２】
加えて、１／２波長板２２と第１のグレーティング２３と第２のグレーティング２４とを接合して光回折素子１５を構成しているため、接合した分の省スペース化を図ることができ、光ピックアップ７の一層の小型化を図ることができる。
【００５３】
尚、上記には、１／２波長板２２と第１のグレーティング２３と第２のグレーティング２４とを接合した例を示したが、こられの各部を適宜離間して配置することも可能である。
【００５４】
また、上記には、７８０ｎｍの波長を第１の波長とし、６５０ｎｍを第２の波長として説明したが、６５０ｎｍの波長が第１の波長であると共に７８０ｎｍが第２の波長であってもよい。
【００５５】
さらに、上記には、第１のグレーティング２３と第２のグレーティング２４とを各別に形成した例を示したが、例えば、第１のグレーティング２３の回折面２３ａと第２のグレーティング２４の回折面２４ａとをレーザー光の光軸方向における両面に有するような複合回折手段２５を形成し、該複合回折手段２５と１／２波長板２２とを接合し、光回折素子１５Ａとすることもできる（図５参照）。このような互いに反対側の面にそれぞれ回折面２３ａ、２４ａが形成された複合回折手段２５を有する光回折素子１５Ａを用いることにより、一層の省スペース化による光ピックアップ７の小型化を図ることができる。
【００５６】
尚、光回折素子１５Ａの場合にあっても、複合回折手段２５と１／２波長板２２とを適宜離間して配置することが可能である。
【００５７】
次に、第２の回折手段として、第２の波長を有するレーザー光のみを所定の回折効率で回折する深溝グレーティングを用いた例について説明する（図６及び図７参照）。
【００５８】
光回折素子１５Ｂは、偏光方向変換手段として機能する１／２波長板２２と、第１の回折手段として機能する第１のグレーティング２３と、第２の回折手段として機能する深溝グレーティング２６とが順に接合されて構成されている（図６参照）。
【００５９】
深溝グレーティング２６は、その回折面２６ａの溝が、第２の波長を有するレーザー光のみを所定の回折効率で回折する深さに形成されている。
【００６０】
図７は、グレーティングの溝の深さと回折効率との関係を、７８０ｎｍの波長を有するレーザー光及び６５０ｎｍの波長を有するレーザー光について示したグラフ図である。実線は７８０ｎｍの波長を有するレーザー光の０次光についてのデーターであり、点線は７８０ｎｍの波長を有するレーザー光の±１次光についてのデーターであり、１点鎖線は６５０ｎｍの波長を有するレーザー光の０次光についてのデーターであり、２点鎖線は６５０ｎｍの波長を有するレーザー光の±１次光についてのデーターである。
【００６１】
図７に示す通り、溝の深さと回折効率とは各レーザー光（回折光）毎に一定の相関関係があり、深溝グレーティング２６の溝の深さは、第２の波長を有するレーザー光のみを回折する溝の深さ、例えば、図７にＡで示す約６μｍとされている。従って、深溝グレーティング２６を用いた場合には、７８０ｎｍの波長を有するレーザー光は回折されず、６５０ｎｍの波長を有するレーザー光のみが所定の回折効率で回折される。
【００６２】
このように深溝グレーティング２６を用いた場合には、第１の波長を有するレーザー光の回折効率を決定することにより、第２の波長を有するレーザー光の回折効率が溝の深さに依存して一義的に定められる。
【００６３】
第１のグレーティング２３及び深溝グレーティング２６にあっては、それぞれ格子ピッチが固有の値に設定され、回折角度が互いに異なるように設計されている。
【００６４】
第２の回折手段として深溝グレーティング２６が用いられた光学系において、発光素子１４から第１の波長を有するレーザー光が出射されると、出射されたレーザー光は光回折素子１５Ｂの第１のグレーティング２３によって０次光と±１次光が生成される。このとき、第１の波長を有するレーザー光は深溝グレーティング２６によっては回折されず透過されるだけである。
【００６５】
一方、発光素子１４から第２の波長を有するレーザー光が出射されると、出射されたレーザー光は光回折素子１５Ｂの深溝グレーティング２６によって回折されて０次光と±１次光が生成される。このとき、第２の波長を有するレーザー光は第１のグレーティング２３によっては回折されず透過されるだけである。
【００６６】
光回折素子１５Ｂにあっても、第１の波長を有するレーザー光及び第２の波長を有するレーザー光の各０次光と±１次光の各スポット中心がそれぞれ受光エリア２１ａ、２１ｂ、２１ｂの中央に略一致するように、第１のグレーティング２３及び深溝グレーティング２６による回折角度が設計されている。従って、光回折素子１５Ｂを有する光学系にあっても、光回折素子１５を有する上記した光学系と同様に、受光素子２１に入射された第１の波長を有するレーザー光及び第２の波長を有するレーザー光は、各０次光と±１次光の各スポット中心がそれぞれ受光エリア２１ａ、２１ｂ、２１ｂの中央に略一致した状態で受光される。
【００６７】
尚、上記には、７８０ｎｍの波長を第１の波長とし、６５０ｎｍを第２の波長として説明したが、６５０ｎｍの波長が第１の波長であると共に７８０ｎｍが第２の波長であってもよい。第１の波長が６５０ｎｍであり、第２の波長が７８０ｎｍである場合には、光回折素子１５Ｂの深溝グレーティング２６の溝の深さは、第１の波長を有するレーザー光のみを回折する溝の深さ、例えば、図７にＢで示す約１．３μｍとされている。従って、この場合には、６５０ｎｍの波長を有するレーザー光は回折されず、７８０ｎｍの波長を有するレーザー光のみが所定の回折効率で回折される。
【００６８】
このように第２の波長を有するレーザー光の回折効率を決定することにより、第１の波長を有するレーザー光の回折効率が溝の深さに依存して一義的に定められる。
【００６９】
以上に記載した通り、光回折素子１５Ｂが用いられた場合にあっても、第１の波長を有するレーザー光と第２の波長を有するレーザー光が、第１のグレーティング２３又は深溝グレーティング２６によって選択的に回折される。
【００７０】
従って、異なる波長を有するレーザー光に対して共通の発光素子１４、光回折素子１５、ビームスプリッター１６及び受光素子２１を用いることができ、部品点数の削減及びこれによる各光学要素の省スペース化による光ピックアップ７の小型化を図ることができる。
【００７１】
また、異なる波長を有する２種類のレーザー光について、それぞれ０次光と±１次光の各スポット中心を受光素子２１の各受光エリア２１ａ、２１ｂ、２１ｂの各中央に略一致させることができるため、各種のＣＤ（ＣＤーＲＯＭ、ＣＤーＲ、ＣＤーＲＷ等）、ＤＶＤ（ＤＶＤビデオ、ＤＶＤーＲＯＭ、ＤＶＤーＲ、ＤＶＤーＲＡＭ等）に対する情報信号の記録及び再生を行うことができ、使用可能なディスク状記録媒体１００の種類が増加し、光ピックアップ７の性能の向上を図ることができる。
【００７２】
さらに、１／２波長板２２と第１のグレーティング２３と深溝グレーティング２６とを接合して光回折素子１５Ｂを構成しているため、接合した分の省スペース化を図ることができ、光ピックアップ７の一層の小型化を図ることができる。
【００７３】
尚、上記には、１／２波長板２２と第１のグレーティング２３と深溝グレーティング２６とを接合した例を示したが、こられの各部を適宜離間して配置することも可能である。
【００７４】
また、光回折素子１５Ｂにあっても、光回折素子１５Ａのように、第１のグレーティング２３の回折面２３ａと深溝グレーティング２６の回折面２６ａとをレーザー光の光軸方向における両面に有するような複合回折手段を含む構成としてもよい。
【００７５】
上記した実施の形態において示した各部の具体的な形状及び構造は、何れも本発明を実施する際の具体化のほんの一例を示したものにすぎず、これらによって本発明の技術的範囲が限定的に解釈されることがあってはならないものである。
【００７６】
【発明の効果】
以上に記載したところから明らかなように、請求項１に記載した発明によれば、異なる波長を有するレーザー光に対して共通の発光素子、ビームスプリッター及び受光素子を用いることができ、部品点数の削減及びこれによる各光学要素の省スペース化による光ピックアップの小型化を図ることができる。
【００７７】
また、異なる波長を有する２種類のレーザー光について、それぞれ０次光と±１次光の各スポット中心を受光素子の各受光エリアの各中央に略一致させることができるため、各種のディスク状記録媒体に対する情報信号の記録及び再生を行うことができ、使用可能なディスク状記録媒体の種類が増加し、光ピックアップの性能の向上を図ることができる。
【００７８】
さらに、第１の回折手段の第１の波長を有するレーザー光についての回折効率及び第２の回折手段の第２の波長を有するレーザー光についての回折効率を、使用されるディスク状記録媒体の種類に応じて最適の値に設定すればよいため、設計の自由度が高く光ピックアップの性能の向上を図ることができる。
【００７９】
請求項２に記載した発明によれば、接合した分の省スペース化を図ることができ、光ピックアップの一層の小型化を図ることができる。
【００８０】
請求項３に記載した発明によれば、一層の省スペース化による光ピックアップの小型化を図ることができる。
【００８１】
請求項４に記載した発明によれば、なお一層の省スペース化による光ピックアップの小型化を図ることができる。
【００８２】
請求項５に記載した発明によれば、異なる波長を有するレーザー光に対して共通の発光素子、ビームスプリッター及び受光素子を用いることができ、部品点数の削減及びこれによる各光学要素の省スペース化による光ピックアップの小型化を図ることができる。
【００８３】
また、異なる波長を有する２種類のレーザー光について、それぞれ０次光と±１次光の各スポット中心を受光素子の各受光エリアの各中央に略一致させることができるため、各種のディスク状記録媒体に対する情報信号の記録及び再生を行うことができ、使用可能なディスク状記録媒体の種類が増加し、光ピックアップの性能の向上を図ることができる。
【００８４】
請求項６に記載した発明によれば、接合した分の省スペース化を図ることができ、光ピックアップの一層の小型化を図ることができる。
【００８５】
請求項７に記載した発明によれば、一層の省スペース化による光ピックアップの小型化を図ることができる。
【００８６】
請求項８に記載した発明によれば、なお一層の省スペース化による光ピックアップの小型化を図ることができる。
【００８７】
請求項９に記載した発明によれば、異なる波長を有するレーザー光に対して共通の発光素子、ビームスプリッター及び受光素子を用いることができ、部品点数の削減及びこれによる各光学要素の省スペース化によるディスクドライブ装置の小型化を図ることができる。
【００８８】
また、異なる波長を有する２種類のレーザー光について、それぞれ０次光と±１次光の各スポット中心を受光素子の各受光エリアの各中央に略一致させることができるため、各種のディスク状記録媒体に対する情報信号の記録及び再生を行うことができ、使用可能なディスク状記録媒体の種類が増加し、ディスクドライブ装置の性能の向上を図ることができる。
【００８９】
さらに、第１の回折手段の第１の波長を有するレーザー光についての回折効率及び第２の回折手段の第２の波長を有するレーザー光についての回折効率を、使用されるディスク状記録媒体の種類に応じて最適の値に設定すればよいため、設計の自由度が高くディスクドライブ装置の性能の向上を図ることができる。
【００９０】
請求項１０に記載した発明によれば、接合した分の省スペース化を図ることができ、ディスクドライブ装置の一層の小型化を図ることができる。
【００９１】
請求項１１に記載した発明によれば、一層の省スペース化によるディスクドライブ装置の小型化を図ることができる。
【００９２】
請求項１２に記載した発明によれば、なお一層の省スペース化によるディスクドライブ装置の小型化を図ることができる。
【００９３】
請求項１３に記載した発明によれば、異なる波長を有するレーザー光に対して共通の発光素子、ビームスプリッター及び受光素子を用いることができ、部品点数の削減及びこれによる各光学要素の省スペース化によるディスクドライブ装置の小型化を図ることができる。
【００９４】
また、異なる波長を有する２種類のレーザー光について、それぞれ０次光と±１次光の各スポット中心を受光素子の各受光エリアの各中央に略一致させることができるため、各種のディスク状記録媒体に対する情報信号の記録及び再生を行うことができ、使用可能なディスク状記録媒体の種類が増加し、ディスクドライブ装置の性能の向上を図ることができる。
【００９５】
請求項１４に記載した発明によれば、接合した分の省スペース化を図ることができ、ディスクドライブ装置の一層の小型化を図ることができる。
【００９６】
請求項１５に記載した発明によれば、一層の省スペース化によるディスクドライブ装置の小型化を図ることができる。
【００９７】
請求項１６に記載した発明によれば、なお一層の省スペース化によるディスクドライブ装置の小型化を図ることができる。
【図面の簡単な説明】
【図１】図２乃至図７と共に本発明の実施の形態を示すものであり、本図はディスクドライブ装置の概略斜視図である。
【図２】光ピックアップに設けられた光学系の構成を示す概念図である。
【図３】光回折素子の構成を拡大して示す概念図である。
【図４】受光素子の受光エリアの状態を示す概念図である。
【図５】別の光回折素子の構成を拡大して示す概念図である。
【図６】さらに別の光回折素子の構成を拡大して示す概念図である。
【図７】グレーティングの溝の深さと回折効率との関係を示すグラフ図である。
【図８】従来の光ピックアップに設けられた光学系の構成を示す概念図である。
【図９】従来の光ピックアップにおいて、各レーザー光の各スポット中心が受光素子の受光エリアの中央に略一致されている状態を示す概念図である。
【図１０】従来の光ピックアップにおいて、一方のレーザー光の±１次光が受光素子の受光エリアから外れた状態を示す概念図である。
【符号の説明】
１…ディスクドライブ装置、４…ディスクテーブル、７…光ピックアップ、１３…対物レンズ、１４…発光素子、１６…ビームスプリッター、１９…光軸合成素子、２１…受光素子、２１ａ…受光エリア、２１ｂ…受光エリア、２２…１／２波長板（偏光方向変換手段）、２３…第１のグレーティング（第１の回折手段）、２３ａ…回折面、２４…第２のグレーティング（第２の回折手段）、２４ａ…回折面、２５…複合回折手段、２６…深溝グレーティング（第２の回折手段）、２６ａ…回折面、１００…ディスク状記録媒体、１００ａ…ＣＤ（ディスク状記録媒体）、１００ｂ…ＤＶＤ（ディスク状記録媒体）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the technical field of an optical pickup and a disk drive. More specifically, in an optical pickup for recording and / or reproducing information signals on and from two different types of disk-shaped recording media, and a disk drive device including the same, a technique for improving the performance and reducing the number of components to reduce the size. About the field.
[0002]
[Prior art]
2. Description of the Related Art There is a disk drive device that records and reproduces information signals on and from a disk-shaped recording medium. Such a disk drive device moves in a radial direction of a disk-shaped recording medium mounted on a disk table and moves the disk-shaped recording medium. And an optical pickup for irradiating a laser beam through an objective lens.
[0003]
An example of an optical system provided in an optical pickup of a conventional disk drive device is shown below (see FIG. 8).
[0004]
On a moving base (not shown) of the optical pickup, required optical elements, that is, a first light emitting element a, a second light emitting element b, a first grating c, a second grating d, and a first beam splitter e are provided. , A second beam splitter f, a collimator lens g, a rising mirror h, an objective lens i, an adjustment lens j, and a light receiving element k.
[0005]
The first light emitting element a and the first grating c are optical elements dedicated to a first disk-shaped recording medium, for example, a CD (Compact Disc) x, and have a wavelength of 780 nm from the first light emitting element a. Laser light is emitted.
[0006]
On the other hand, the second light emitting element b and the second grating d are optical elements dedicated to a second disk-shaped recording medium, for example, a DVD (Digital Versatile Disc) y, and have a wavelength of 650 nm from the second light emitting element b. A laser beam having a wavelength is emitted.
[0007]
In the optical system as described above, when recording or reproducing an information signal with respect to CDx, a laser beam is emitted from the first light emitting element a and the first grating c converts the laser beam into 0th-order light. The light is diffracted into the primary light, and the recording surface of the CDx is irradiated with the laser beam through the first beam splitter e, the second beam splitter f, the collimator lens g, the rising mirror h, and the objective lens i in order. . The laser light is reflected by the recording surface of the CDx, and is sequentially transmitted to the light receiving element k via the objective lens i, the rising mirror h, the collimator lens g, the second beam splitter f, the first beam splitter e, and the adjustment lens j. Incident. In the laser light incident on the light receiving element k, the zero-order light Sa and the ± first-order lights Sb and Sb are received at substantially the center of each of the three light receiving areas l, m and n of the light receiving element k (see FIG. 9).
[0008]
On the other hand, when information signals are recorded or reproduced on DVDy, laser light is emitted from the second light emitting element b, and the laser light is diffracted by the second grating d into zero-order light and ± first-order light. Then, the recording surface of the DVDy is irradiated with laser light through the second beam splitter f, the collimator lens g, the rising mirror h, and the objective lens i in order. The irradiated laser light is reflected by the recording surface of the DVDy, and is sequentially received via the objective lens i, the rising mirror h, the collimator lens g, the second beam splitter f, the first beam splitter e, and the adjustment lens j. The light is incident on the element k. As in the case of CDx, the laser light incident on the light receiving element k is such that the 0th-order light Sc and the ± 1st-order lights Sd and Sd are respectively substantially at the centers of the three light receiving areas l, m and n of the light receiving element k. The light is received by the section (see FIG. 9).
[0009]
[Problems to be solved by the invention]
By the way, the diffraction angle θ of laser light (the angle formed by the 0th-order light and ± 1st-order light) is given by: = Λ / Pd, and the diffraction angle θ can be set to a desired value by determining the grating pitch Pd of the grating with respect to the wavelength λ. Therefore, in the above-described conventional disk drive device, by setting the grating pitch of the first grating c and the grating pitch of the second grating d to unique values, the first light emitting element a or the second light emitting element b The diffraction angle of each emitted laser beam is set to a desired value, and the 0th order light Sa, Sc and the ± 1st order light Sb, Sb, Sd, Sd are respectively received in three light receiving areas 1, m, The light can be received substantially at the center of each of n (see FIG. 9).
[0010]
However, in the above-mentioned conventional disk drive device, in addition to the light-emitting elements a and b and the beam splitters e and f corresponding to the two types of disk-shaped recording media CDx and DVDy, the diffraction angle of each laser beam is unique. Since two gratings c and d are provided to set the values, the number of parts is large, and a large space for arranging each optical element is required, so that the size of the optical pickup is increased. There's a problem.
[0011]
Therefore, as another conventional disk drive device, there is one in which an optical system is configured using one light emitting element that emits two types of laser lights having different wavelengths and one grating. Therefore, in such an optical system, there is one grating, and both a laser beam having a wavelength of 780 nm and a laser beam having a wavelength of 650 nm are diffracted by the same grating.
[0012]
However, when the laser light having each wavelength is diffracted by the same grating in this way, the 0th-order light Se and the ± 1st-order lights Sf, Sf of one of the laser lights are converted into the respective light receiving areas o, p, q is received at the center of the other laser beam, and the 0th-order light Sg of the other laser beam is adjusted to the center of the light receiving area o where the 0th-order light Se is received. Deviates from the respective light receiving areas p and q of the light receiving element (see FIG. 10), and it is impossible to detect a focusing error signal and a tracking error signal for the other laser beam.
[0013]
Therefore, when an optical system is configured using one light emitting element that emits two types of laser lights having different wavelengths and one grating, two light receiving elements for receiving each laser light are required. Would.
[0014]
On the other hand, in an optical system configured using one light emitting element that emits two types of laser beams having different wavelengths and one grating, for example, only the 0th-order light of a laser beam having a wavelength of 650 nm is used and ± 1st-order It is also possible to use a so-called one beam that does not use light. However, in this case, it is possible to reproduce the information signal from the DVD (DVD video, DVD-ROM), but it is not possible to record the information signal, and to record and reproduce the information signal from the DVD-RAM. However, there is a disadvantage that the types of disk-shaped recording media that can be used are limited.
[0015]
Therefore, it is an object of the present invention to overcome the above-mentioned problems, to reduce the number of parts, to reduce the size, and to improve the performance.
[0016]
[Means for Solving the Problems]
In order to solve the above-described problems, the optical pickup and the disk drive device of the present invention have a first wavelength and a second wavelength corresponding to each of the disk-shaped recording media toward two different types of disk-shaped recording media. A light-emitting element that emits laser light, and the polarization direction of the laser light having the first wavelength and the polarization direction of the laser light having the second wavelength emitted from the light-emitting element are converted into lights having polarization directions orthogonal to each other. Polarization direction converting means, a first diffraction means for diffracting only a laser beam having a first wavelength transmitted through the polarization direction converting means and diffracting at a first diffraction angle, and transmitting the polarization direction converting means. Second diffracting means for diffracting only the laser beam having the second wavelength and diffracting the laser beam at a second diffraction angle different from the first diffraction angle, and a laser beam having the first wavelength And a beam splitter that reflects or transmits the laser light having the second wavelength according to the traveling direction of each laser light, and is diffracted by the first diffraction means or the second diffraction means and reflected by each disk-shaped recording medium. Optical axis synthesizing element for matching the optical axes of the laser light having the first wavelength and the laser light having the second wavelength, and the laser light having the first wavelength whose optical axis is matched by the optical axis synthesizing element. And a light-receiving element having three light-receiving areas for receiving laser light having a second wavelength and receiving the 0th-order light and ± 1st-order light of the laser light separately, and having a first wavelength. The spot centers in the light receiving areas of the zero-order light and the ± first-order light of the light substantially coincide with the spot centers in the light-receiving areas of the zero-order light and the ± first-order light of the laser light having the second wavelength. Sea urchin is obtained by determining the diffraction angle by the diffraction angle by the first diffraction means second diffraction means.
[0017]
According to another aspect of the present invention, there is provided an optical pickup and a disk drive device that aim at two different types of disk-shaped recording media, and a first wavelength and a second wavelength corresponding to each of the disk-shaped recording media. A light emitting element that emits a laser beam having a first wavelength and light that has a polarization direction perpendicular to the polarization direction of the laser beam having a first wavelength and the laser beam having a second wavelength emitted from the light emitting element. Polarization direction converting means, a first diffraction means for diffracting only a laser beam having a first wavelength transmitted through the polarization direction converting means and diffracting at a first diffraction angle, and a polarization direction converting means A second diffracting means for diffracting only the laser light having the second wavelength transmitted through the laser beam with a predetermined diffraction efficiency, and a laser light having the first wavelength and a laser light having the second wavelength. A beam splitter that reflects or transmits the laser beam according to the traveling direction of the laser beam, and a laser beam having a first wavelength diffracted by the first or second diffracting unit and reflected by each disk-shaped recording medium. An optical axis combining element for matching the optical axes of the laser lights having the two wavelengths, and a laser beam having the first wavelength and a laser light having the second wavelength whose optical axes are matched by the optical axis combining element are incident. A light receiving element having three light receiving areas for separately receiving the 0th order light and the ± 1st order light of the laser light, and the 0th order light and the ± 1st order light of the laser light having the first wavelength are provided. The diffraction angle by the first diffraction means so that the center of the spot in each light receiving area substantially coincides with the center of the spot in each light receiving area of the zero-order light and the ± first-order light of the laser light having the second wavelength. When it is obtained by determining the diffraction angle by the second diffraction means.
[0018]
Therefore, in the optical pickup and the disk drive of the present invention, two types of laser beams having different wavelengths emitted from the same light emitting element are received by the same light receiving area of the same light receiving element.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of an optical pickup and a disk drive device according to the present invention will be described with reference to the accompanying drawings.
[0020]
The disk drive device 1 has required members and mechanisms arranged in an outer casing 2 (see FIG. 1).
[0021]
A chassis 3 is disposed in the outer casing 2, and a spindle motor (not shown) is attached to the chassis 3. The disk table 4 is fixed to the motor shaft of the spindle motor.
[0022]
An arrangement hole 3a is formed in the chassis 3, and the disk table 4 projects above the chassis 3 through the arrangement hole 3a.
[0023]
A lead screw 5 and guide shafts 6, 6 are arranged on the lower surface side of the chassis 3 in parallel. The optical pickup 7 is arranged in the arrangement hole 3 a of the chassis 3 so as to be movable in the radial direction of the disk-shaped recording medium 100 mounted on the disk table 4.
[0024]
The optical pickup 7 has a moving base 8, required optical elements (optical elements) provided on the moving base 8, and an objective lens driving device 9 supported on the moving base 8. Each is slidably supported by a guide shaft 6,6. When a nut member (not shown) provided on the moving base 8 is screwed into the lead screw 5 and the lead screw 5 is rotated by a feed motor (not shown) attached to the moving base 8, the nut member rotates in the rotation direction of the lead screw 5. The optical pickup 7 is guided by the guide shafts 6 and 6 and is moved in the radial direction of the disk-shaped recording medium 100 mounted on the disk table 4.
[0025]
The objective lens driving device 9 has a fixed part 10 and a movable part 12 movably supported by the fixed part 10 via a plurality of suspensions 11, 11,. Are held (see FIG. 1).
[0026]
Required optical elements are arranged on the moving base 8 (see FIG. 2).
[0027]
The optical elements include a light emitting element 14, an optical diffraction element 15, a beam splitter 16, a collimator lens 17, a rising mirror 18, an objective lens 13 provided in an objective lens driving device 9, an optical axis combining element 19, and an adjusting lens 20. And a light receiving element 21 and the like, and these optical elements constitute an optical system of the disk drive device 1.
[0028]
The light emitting element 14 has two light emitting points that emit laser lights having different wavelengths, and a laser light having a wavelength of 780 nm (first wavelength) is emitted from the first light emitting point, For example, a laser beam having a wavelength of 650 nm (second wavelength) is emitted from the light emitting point. When recording or reproducing an information signal on one disk-shaped recording medium 100, that is, the CD 100a, a laser beam having a wavelength of 780 nm is emitted from the first light emitting point, and the other disk-shaped recording medium 100, that is, When recording or reproducing an information signal with respect to the DVD 100b, a laser beam having a wavelength of 650 nm is emitted from the second light emitting point.
[0029]
The first light emitting point and the second light emitting point of the light emitting element 14 are arranged at a predetermined interval, and the laser light having the second wavelength coincides with the optical axis of the optical system described above. However, the laser light having the first wavelength is shifted from the optical axis of the optical system. The optical diffraction element 15 includes a half-wave plate 22 functioning as a polarization direction conversion unit, a first grating 23 functioning as a first diffraction unit, and a second grating 24 functioning as a second diffraction unit. Are sequentially joined (see FIG. 3).
[0030]
The half-wave plate 22 generates a phase difference of π with respect to the laser light having the first wavelength and π / 2 with respect to the laser light having the second wavelength, and the polarization direction of each laser light. Are converted to directions orthogonal to each other.
[0031]
One surface of the first grating 23 in the optical axis direction of the laser beam is formed as a diffraction surface 23a having a plurality of grooves, and one surface of the second grating 24 in the optical axis direction of the laser beam is It is formed as a diffraction surface 24a having a plurality of grooves.
[0032]
Each of the first grating 23 and the second grating 24 diffracts only a laser beam in a specific polarization direction, and functions as a transmission plate without diffracting a laser beam in a polarization direction orthogonal to the polarization direction. For example, the first grating 23 diffracts only the laser light having the first wavelength whose polarization direction has been converted by the half-wave plate 22 to generate 0th-order light and ± 1st-order light, and The grating 24 diffracts only the laser light having the second wavelength, the polarization direction of which has been changed by the half-wave plate 22, to generate zero-order light and ± first-order light.
[0033]
The first grating 23 and the second grating 24 are designed such that the grating pitch is set to a unique value and the diffraction angles are different from each other.
[0034]
The first grating 23 and the second grating 24 diffract the laser light having the first wavelength or the laser light having the second wavelength, respectively, with a predetermined diffraction efficiency. This diffraction efficiency is set to an optimum value according to the type of the disk-shaped recording medium used.
[0035]
The beam splitter 16 is, for example, a reflection type, and reflects the laser light emitted from the light emitting element 14 on the separation surface 16a to guide it to the collimator lens 17, and returns the laser light reflected on the disk-shaped recording medium 100. And a function of guiding the light to the optical axis combining element 19.
[0036]
The collimator lens 17 has a function of converting the light beam of the incident laser light into a parallel light beam, and the rising mirror 18 has a function of reflecting the laser light and guiding it to the objective lens 13 or the collimator lens 17. Reference numeral 13 has a function of condensing the incident laser light on a recording track of the disc-shaped recording medium 100.
[0037]
The optical axis combining element 19 has a function of correcting the optical axis direction of the laser light having the first wavelength shifted from the optical axis of the optical system and causing the laser light to enter a predetermined light receiving point of the light receiving element 21.
[0038]
The adjustment lens 20 is a lens for adjusting the magnification of the laser beam.
[0039]
The light receiving element 21 has three light receiving areas 21a, 21b, and 21b that receive the 0th order light and the ± 1st order light of the laser light, respectively (see FIG. 4). The light receiving area 21a is an area for receiving the 0th order light, and the light receiving areas 21b and 21b are areas for receiving the + 1st order light and the -1st order light respectively.
[0040]
In the optical system configured as described above, when the laser light having the first wavelength is emitted from the light emitting element 14, the emitted laser light is polarized by the half-wave plate 22 of the optical diffraction element 15. The light is converted and diffracted at the diffraction angle θ1 by the first grating 23 to generate 0th-order light and ± 1st-order light (the state of diffraction is shown by broken lines in FIG. 3). At this time, the laser beam having the first wavelength is only transmitted through the second grating 24 without being diffracted. The laser light is reflected by the separation surface 16 a of the beam splitter 16, converted into a parallel light beam by the collimator lens 17, raised by the raising mirror 18, and recorded on the CD 100 a mounted on the disk table 4 via the objective lens 13. Is irradiated. The laser light applied to the recording surface of the CD 100a is reflected by the recording surface and returns as a return light to the beam splitter 16 via the objective lens 13, the rising mirror 18 and the collimator lens 17 again. The return light that has entered the beam splitter 16 is transmitted through the separation surface 16 a of the beam splitter 16, the optical axis direction is corrected by the optical axis combining element 19, and is incident on the light receiving element 21 via the adjustment lens 20.
[0041]
With respect to the laser light having the first wavelength incident on the light receiving element 21, the diffracted zero-order light is received by the light receiving area 21a, and the ± first-order lights are received by the light receiving areas 21b and 21b, respectively.
[0042]
In the optical pickup 7, the center of each spot of the zero-order light Sma and the ± first-order lights Ssa and Ssa of the laser light having the first wavelength is substantially coincident with the center of the light receiving areas 21a, 21b and 21b, respectively. The diffraction angle by the first grating 23 is designed. Therefore, in the laser beam having the first wavelength incident on the light receiving element 21, the center of each spot of the zero-order light Sma and the ± first-order lights Ssa and Ssa substantially coincide with the centers of the light receiving areas 21a, 21b, and 21b, respectively. Light is received in this state (see FIG. 4).
[0043]
When the return light is incident on the light receiving element 21, an information signal is read from the CD 100a based on the zero-order light Sma received by the light receiving area 21a. At the same time, a focusing error signal and a tracking error signal are detected based on the ± primary lights Ssa and Ssa received in the light receiving areas 21b and 21b, and the movable part of the objective lens driving device 9 is detected based on the detection results. Focusing adjustment and tracking adjustment are performed by displacing 12 with respect to the fixed portion 13.
[0044]
On the other hand, when the laser light having the second wavelength is emitted from the light emitting element 14, the emitted laser light is changed in polarization direction by the half-wave plate 22 of the optical diffraction element 15 and diffracted by the second grating 24. The light is diffracted at the angle θ2 to generate 0th-order light and ± 1st-order light (the state of diffraction is shown by a solid line in FIG. 3). At this time, the laser light having the second wavelength is not diffracted by the first grating 23 and is merely transmitted. The laser light is reflected by the separation surface 16 a of the beam splitter 16, converted into a parallel light beam by the collimator lens 17, raised by the rising mirror 18, and recorded on the DVD 100 b mounted on the disk table 4 via the objective lens 13. Is irradiated. The laser beam applied to the recording surface of the DVD 100b is reflected by the recording surface and returns to the beam splitter 16 via the objective lens 13, the rising mirror 18 and the collimator lens 17 as return light. The return light that has entered the beam splitter 16 is transmitted through the separation surface 16a of the beam splitter 16, and is incident on the light receiving element 21 via the optical axis combining element 19 and the adjustment lens 20.
[0045]
With respect to the laser light having the second wavelength incident on the light receiving element 21, the diffracted zero-order light is received in the light receiving area 21a, and the ± first-order lights are received in the light receiving areas 21b and 21b, respectively.
[0046]
In the optical pickup 7, the center of each spot of the zero-order light Smb and the ± first-order lights Ssb and Ssb of the laser light having the second wavelength is substantially coincident with the centers of the light receiving areas 21a, 21b and 21b, respectively. , The diffraction angle by the second grating 24 is designed. Therefore, in the laser light having the second wavelength incident on the light receiving element 21, the center of each spot of the 0th order light Smb and the ± 1st order lights Ssb and Ssb substantially coincide with the centers of the light receiving areas 21a, 21b and 21b, respectively. The light is received in this state (see FIG. 4).
[0047]
When the return light is incident on the light receiving element 21, an information signal is read from the DVD 100b based on the zero-order light Smb received by the light receiving area 21a. At the same time, an error signal for focusing and an error signal for tracking are detected based on the ± first-order lights Ssb, Ssb received in the light receiving areas 21b, 21b, and based on the detection results, the movable portion of the objective lens driving device 9 Focusing adjustment and tracking adjustment are performed by displacing 12 with respect to the fixed portion 13.
[0048]
As described above, in the optical pickup 7, the half-wave plate 22 of the optical diffraction element 15 converts the polarization directions of the laser beams having different wavelengths into directions orthogonal to each other, and converts the polarization direction of the laser light. Light is selectively diffracted by the first grating 23 or the second grating 24.
[0049]
Therefore, it is possible to use the common light emitting element 14, the light diffraction element 15, the beam splitter 16 and the light receiving element 21 for laser light having different wavelengths, thereby reducing the number of parts and thereby saving the space of each optical element. The size of the optical pickup 7 can be reduced.
[0050]
In addition, for two types of laser beams having different wavelengths, the center of each spot of the 0th-order light and ± 1st-order light can be made to substantially coincide with each center of each of the light receiving areas 21a, 21b, 21b of the light receiving element 21. Record and reproduce information signals on various CDs (CD-ROM, CD-R, CD-RW, etc.) and DVDs (DVD-Video, DVD-ROM, DVD-R, DVD-RAM, etc.) The types of the disk-shaped recording media 100 that can be used are increased, and the performance of the optical pickup 7 can be improved.
[0051]
Further, the diffraction efficiency of the first grating 23 for the laser light having the first wavelength and the diffraction efficiency of the second grating 24 for the laser light having the second wavelength depend on the type of the disc-shaped recording medium used. Can be set to an optimum value in accordance with the condition (1), the design flexibility is high, and the performance of the optical pickup 7 can be improved.
[0052]
In addition, since the optical diffraction element 15 is formed by joining the half-wave plate 22, the first grating 23, and the second grating 24, the joint can be saved in space. The size of the optical pickup 7 can be further reduced.
[0053]
In the above description, an example in which the half-wave plate 22, the first grating 23, and the second grating 24 are joined has been described. However, these parts may be appropriately separated from each other. .
[0054]
In the above description, the wavelength of 780 nm is the first wavelength and the wavelength of 650 nm is the second wavelength. However, the wavelength of 650 nm may be the first wavelength and the wavelength of 780 nm may be the second wavelength.
[0055]
Further, in the above description, an example is shown in which the first grating 23 and the second grating 24 are separately formed. For example, the diffraction surface 23a of the first grating 23 and the diffraction surface 24a of the second grating 24 are shown. Is formed on both sides in the optical axis direction of the laser light, and the composite diffraction means 25 and the half-wave plate 22 are joined to form an optical diffraction element 15A (FIG. 5). By using the optical diffraction element 15A having the compound diffraction means 25 in which the diffraction surfaces 23a and 24a are formed on the opposite surfaces, respectively, the size of the optical pickup 7 can be further reduced by further space saving. it can.
[0056]
Note that, even in the case of the optical diffraction element 15A, the composite diffraction means 25 and the half-wavelength plate 22 can be appropriately separated from each other.
[0057]
Next, an example in which a deep groove grating that diffracts only a laser beam having a second wavelength with a predetermined diffraction efficiency is used as the second diffraction means will be described (see FIGS. 6 and 7).
[0058]
The light diffraction element 15B includes a half-wave plate 22 functioning as a polarization direction conversion unit, a first grating 23 functioning as a first diffraction unit, and a deep groove grating 26 functioning as a second diffraction unit. They are joined together (see FIG. 6).
[0059]
The deep groove grating 26 has a groove on the diffraction surface 26a formed at a depth such that only the laser beam having the second wavelength is diffracted at a predetermined diffraction efficiency.
[0060]
FIG. 7 is a graph showing the relationship between the grating depth and the diffraction efficiency for a laser beam having a wavelength of 780 nm and a laser beam having a wavelength of 650 nm. The solid line is the data for the 0th order light of the laser light having the wavelength of 780 nm, the dotted line is the data for the ± first order light of the laser light having the wavelength of 780 nm, and the dashed line is the laser light having the wavelength of 650 nm. , And the two-dot chain line is data for the ± 1st order laser light having a wavelength of 650 nm.
[0061]
As shown in FIG. 7, there is a certain correlation between the depth of the groove and the diffraction efficiency for each laser beam (diffraction light), and the depth of the groove of the deep groove grating 26 is determined only by the laser beam having the second wavelength. The depth of the groove to be diffracted is, for example, about 6 μm indicated by A in FIG. Therefore, when the deep groove grating 26 is used, laser light having a wavelength of 780 nm is not diffracted, and only laser light having a wavelength of 650 nm is diffracted at a predetermined diffraction efficiency.
[0062]
When the deep groove grating 26 is used, the diffraction efficiency of the laser light having the second wavelength is determined depending on the depth of the groove by determining the diffraction efficiency of the laser light having the first wavelength. It is determined uniquely.
[0063]
The first grating 23 and the deep groove grating 26 are designed such that the grating pitch is set to a specific value and the diffraction angles are different from each other.
[0064]
In the optical system using the deep groove grating 26 as the second diffraction means, when the laser light having the first wavelength is emitted from the light emitting element 14, the emitted laser light is converted into the first grating of the optical diffraction element 15B. 23 generates zero-order light and ± first-order light. At this time, the laser light having the first wavelength is only transmitted through the deep groove grating 26 without being diffracted.
[0065]
On the other hand, when the laser light having the second wavelength is emitted from the light emitting element 14, the emitted laser light is diffracted by the deep groove grating 26 of the optical diffraction element 15B to generate 0th-order light and ± 1st-order light. . At this time, the laser light having the second wavelength is not diffracted by the first grating 23 and is merely transmitted.
[0066]
Even in the optical diffraction element 15B, the center of each spot of the 0th-order light and the ± 1st-order light of the laser light having the first wavelength and the laser light having the second wavelength respectively correspond to the light receiving areas 21a, 21b, 21b. The diffraction angle by the first grating 23 and the deep groove grating 26 is designed to substantially coincide with the center. Therefore, even in the optical system having the light diffraction element 15B, similarly to the above-described optical system having the light diffraction element 15, the laser light having the first wavelength and the second wavelength that have entered the light receiving element 21 are used. The laser beam is received in a state where the center of each spot of each of the 0th order light and ± 1st order light substantially coincides with the center of the light receiving areas 21a, 21b, 21b, respectively.
[0067]
In the above description, the wavelength of 780 nm is the first wavelength and the wavelength of 650 nm is the second wavelength. However, the wavelength of 650 nm may be the first wavelength and the wavelength of 780 nm may be the second wavelength. When the first wavelength is 650 nm and the second wavelength is 780 nm, the depth of the groove of the deep groove grating 26 of the optical diffraction element 15B is equal to the depth of the groove that diffracts only the laser light having the first wavelength. The depth is, for example, about 1.3 μm indicated by B in FIG. Therefore, in this case, the laser light having a wavelength of 650 nm is not diffracted, and only the laser light having a wavelength of 780 nm is diffracted with a predetermined diffraction efficiency.
[0068]
By determining the diffraction efficiency of the laser light having the second wavelength in this manner, the diffraction efficiency of the laser light having the first wavelength is uniquely determined depending on the depth of the groove.
[0069]
As described above, even when the optical diffraction element 15B is used, the laser light having the first wavelength and the laser light having the second wavelength are selected by the first grating 23 or the deep groove grating 26. Is diffracted.
[0070]
Therefore, it is possible to use the common light emitting element 14, the light diffraction element 15, the beam splitter 16 and the light receiving element 21 for laser light having different wavelengths, thereby reducing the number of parts and thereby saving the space of each optical element. The size of the optical pickup 7 can be reduced.
[0071]
In addition, for two types of laser beams having different wavelengths, the center of each spot of the 0th-order light and ± 1st-order light can be made to substantially coincide with each center of each of the light receiving areas 21a, 21b, 21b of the light receiving element 21. Record and reproduce information signals on various CDs (CD-ROM, CD-R, CD-RW, etc.) and DVDs (DVD-Video, DVD-ROM, DVD-R, DVD-RAM, etc.) The types of the disk-shaped recording media 100 that can be used are increased, and the performance of the optical pickup 7 can be improved.
[0072]
Further, since the half-wave plate 22, the first grating 23, and the deep groove grating 26 are joined to form the optical diffraction element 15B, the space required for the joining can be saved, and the optical pickup 7 can be saved. Can be further reduced in size.
[0073]
In the above description, an example in which the half-wave plate 22, the first grating 23, and the deep groove grating 26 are joined is shown. However, these parts may be appropriately separated from each other.
[0074]
Further, even in the optical diffraction element 15B, like the optical diffraction element 15A, the diffraction surface 23a of the first grating 23 and the diffraction surface 26a of the deep groove grating 26 are provided on both sides in the optical axis direction of the laser beam. It may be configured to include a composite diffraction means.
[0075]
The specific shapes and structures of the respective parts shown in the above-described embodiments are merely examples of the specific embodiments of the present invention, and the technical scope of the present invention is limited by these examples. It must not be interpreted in a tentative way.
[0076]
【The invention's effect】
As is clear from the above description, according to the invention described in claim 1, a common light emitting element, beam splitter, and light receiving element can be used for laser lights having different wavelengths, and the number of parts can be reduced. It is possible to reduce the size of the optical pickup by reducing the number of optical elements and the space required for each optical element.
[0077]
In addition, for two types of laser light having different wavelengths, the center of each spot of the 0th-order light and ± 1st-order light can be made to substantially coincide with each center of each light-receiving area of the light-receiving element. Information signals can be recorded on and reproduced from the medium, the types of usable disc-shaped recording media can be increased, and the performance of the optical pickup can be improved.
[0078]
Further, the diffraction efficiency of the first diffraction means for the laser light having the first wavelength and the diffraction efficiency of the second diffraction means for the laser light having the second wavelength are determined by the type of the disc-shaped recording medium used. Can be set to an optimum value according to the above, so that the degree of freedom in design is high and the performance of the optical pickup can be improved.
[0079]
According to the second aspect of the present invention, it is possible to reduce the space required for the bonding, and to further reduce the size of the optical pickup.
[0080]
According to the third aspect of the invention, it is possible to reduce the size of the optical pickup by further reducing the space.
[0081]
According to the fourth aspect of the present invention, it is possible to further reduce the size of the optical pickup by saving space.
[0082]
According to the fifth aspect of the present invention, a common light emitting element, beam splitter, and light receiving element can be used for laser beams having different wavelengths, so that the number of parts is reduced and the space of each optical element is reduced. Thus, the optical pickup can be downsized.
[0083]
In addition, for two types of laser light having different wavelengths, the center of each spot of the 0th-order light and ± 1st-order light can be made to substantially coincide with each center of each light-receiving area of the light-receiving element. Information signals can be recorded on and reproduced from the medium, the types of usable disc-shaped recording media can be increased, and the performance of the optical pickup can be improved.
[0084]
According to the sixth aspect of the present invention, it is possible to reduce the space required for the bonding, and to further reduce the size of the optical pickup.
[0085]
According to the seventh aspect of the invention, the size of the optical pickup can be reduced by further saving space.
[0086]
According to the eighth aspect of the present invention, the optical pickup can be downsized by further space saving.
[0087]
According to the ninth aspect of the present invention, a common light emitting element, beam splitter, and light receiving element can be used for laser beams having different wavelengths, thereby reducing the number of components and the space required for each optical element. , The size of the disk drive device can be reduced.
[0088]
In addition, for two types of laser light having different wavelengths, the center of each spot of the 0th-order light and ± 1st-order light can be made to substantially coincide with each center of each light-receiving area of the light-receiving element. Information signals can be recorded on and reproduced from the medium, the types of usable disk-shaped recording media can be increased, and the performance of the disk drive device can be improved.
[0089]
Further, the diffraction efficiency of the first diffraction means for the laser light having the first wavelength and the diffraction efficiency of the second diffraction means for the laser light having the second wavelength are determined by the type of the disc-shaped recording medium used. Can be set to an optimum value according to the above, so that the degree of freedom in design is high and the performance of the disk drive device can be improved.
[0090]
According to the tenth aspect, it is possible to save the space corresponding to the joined portions, and it is possible to further reduce the size of the disk drive device.
[0091]
According to the eleventh aspect, it is possible to further reduce the size of the disk drive device by further saving space.
[0092]
According to the twelfth aspect of the present invention, it is possible to reduce the size of the disk drive device by further reducing the space.
[0093]
According to the thirteenth aspect, it is possible to use a common light emitting element, a beam splitter, and a light receiving element for laser beams having different wavelengths, thereby reducing the number of components and thereby saving space for each optical element. , The size of the disk drive device can be reduced.
[0094]
In addition, for two types of laser light having different wavelengths, the center of each spot of the 0th-order light and ± 1st-order light can be made to substantially coincide with each center of each light-receiving area of the light-receiving element. Information signals can be recorded on and reproduced from the medium, the types of usable disk-shaped recording media can be increased, and the performance of the disk drive device can be improved.
[0095]
According to the fourteenth aspect, it is possible to save the space for the joined portions, and to further reduce the size of the disk drive device.
[0096]
According to the invention, the size of the disk drive device can be reduced by further space saving.
[0097]
According to the sixteenth aspect of the present invention, the size of the disk drive device can be further reduced by further saving space.
[Brief description of the drawings]
FIG. 1 shows an embodiment of the present invention together with FIG. 2 to FIG. 7, and FIG. 1 is a schematic perspective view of a disk drive device.
FIG. 2 is a conceptual diagram illustrating a configuration of an optical system provided in the optical pickup.
FIG. 3 is a conceptual diagram showing an enlarged configuration of an optical diffraction element.
FIG. 4 is a conceptual diagram showing a state of a light receiving area of a light receiving element.
FIG. 5 is a conceptual diagram showing an enlarged configuration of another optical diffraction element.
FIG. 6 is a conceptual diagram showing an enlarged configuration of still another optical diffraction element.
FIG. 7 is a graph showing the relationship between the depth of the grating groove and the diffraction efficiency.
FIG. 8 is a conceptual diagram showing a configuration of an optical system provided in a conventional optical pickup.
FIG. 9 is a conceptual diagram showing a state in which the center of each spot of each laser beam substantially coincides with the center of the light receiving area of the light receiving element in the conventional optical pickup.
FIG. 10 is a conceptual diagram showing a state in which ± primary light of one laser beam is out of a light receiving area of a light receiving element in a conventional optical pickup.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Disk drive device, 4 ... Disk table, 7 ... Optical pickup, 13 ... Objective lens, 14 ... Light emitting element, 16 ... Beam splitter, 19 ... Optical axis combining element, 21 ... Light receiving element, 21a ... Light receiving area, 21b ... Light receiving area, 22 ... 1/2 wavelength plate (polarization direction changing means), 23 ... first grating (first diffraction means), 23a ... diffraction surface, 24 ... second grating (second diffraction means), 24a: diffraction surface, 25: composite diffraction means, 26: deep groove grating (second diffraction means), 26a: diffraction surface, 100: disk-shaped recording medium, 100a: CD (disk-shaped recording medium), 100b: DVD (disk) Recording medium)

Claims

An optical pickup that moves in a radial direction of a disk-shaped recording medium mounted on a disk table and irradiates a laser beam to the disk-shaped recording medium via an objective lens,
A light emitting element for emitting laser light having a first wavelength and a second wavelength corresponding to each of the two types of disc-shaped recording media toward two different disc-shaped recording media;
Polarization direction conversion means for converting the polarization direction of the laser light having the first wavelength and the polarization direction of the laser light having the second wavelength emitted from the light emitting element into light having polarization directions orthogonal to each other;
First diffracting means for diffracting only the laser light having the first wavelength transmitted through the polarization direction converting means and diffracting at a first diffraction angle;
A second diffracting means for diffracting only the laser light having the second wavelength transmitted through the polarization direction converting means and diffracting at a second diffraction angle different from the first diffraction angle;
A beam splitter that reflects or transmits laser light having a first wavelength and laser light having a second wavelength according to the traveling direction of each laser light,
An optical axis combining element that matches the optical axes of the laser light having the first wavelength and the laser light having the second wavelength, which are diffracted by the first diffraction means or the second diffraction means and reflected by each disk-shaped recording medium. When,
A laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes are matched by the optical axis synthesizing element are incident, and the 0th-order light and ± 1st-order light of the laser light are separately received. A light receiving element having three light receiving areas
Spot center in each light receiving area of 0th order light and ± 1st order light of laser light having the first wavelength, and spot center in each light receiving area of 0th order light and ± 1st order light of laser light having the second wavelength And a diffraction angle determined by the first diffraction means and a diffraction angle determined by the second diffraction means such that the diffraction angles substantially coincide with each other.

2. The optical pickup according to claim 1, wherein the polarization direction converting means, the first diffraction means, and the second diffraction means are joined in the optical axis direction of the laser light.

By forming the diffraction surface of the first diffraction means and the diffraction surface of the second diffraction means on both sides in the optical axis direction of the laser beam, a composite in which the first diffraction means and the second diffraction means are integrated 2. The optical pickup according to claim 1, further comprising a diffraction unit.

4. The optical pickup according to claim 3, wherein the polarization direction changing means and the composite diffraction means are joined in the optical axis direction of the laser light.

An optical pickup that moves in a radial direction of a disk-shaped recording medium mounted on a disk table and irradiates a laser beam to the disk-shaped recording medium via an objective lens,
A light emitting element for emitting laser light having a first wavelength and a second wavelength corresponding to each of the two types of disc-shaped recording media toward two different disc-shaped recording media;
Polarization direction conversion means for converting the polarization direction of the laser light having the first wavelength and the polarization direction of the laser light having the second wavelength emitted from the light emitting element into light having polarization directions orthogonal to each other;
First diffracting means for diffracting only the laser light having the first wavelength transmitted through the polarization direction converting means and diffracting at a first diffraction angle;
Second diffracting means for diffracting only the laser light having the second wavelength transmitted through the polarization direction converting means at a predetermined diffraction efficiency;
A beam splitter that reflects or transmits laser light having a first wavelength and laser light having a second wavelength according to the traveling direction of each laser light,
An optical axis combining element that matches the optical axes of the laser light having the first wavelength and the laser light having the second wavelength, which are diffracted by the first diffraction means or the second diffraction means and reflected by each disk-shaped recording medium. When,
A laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes are matched by the optical axis synthesizing element are incident, and the 0th-order light and ± 1st-order light of the laser light are separately received. A light receiving element having three light receiving areas
Spot center in each light receiving area of 0th order light and ± 1st order light of laser light having the first wavelength, and spot center in each light receiving area of 0th order light and ± 1st order light of laser light having the second wavelength And a diffraction angle determined by the first diffraction means and a diffraction angle determined by the second diffraction means such that the diffraction angles substantially coincide with each other.

6. The optical pickup according to claim 5, wherein the polarization direction changing means, the first diffraction means, and the second diffraction means are joined in an optical axis direction of the laser light.

By forming the diffraction surface of the first diffraction means and the diffraction surface of the second diffraction means on both sides in the optical axis direction of the laser beam, a composite in which the first diffraction means and the second diffraction means are integrated The optical pickup according to claim 5, further comprising a diffraction unit.

8. The optical pickup according to claim 7, wherein the polarization direction changing means and the composite diffraction means are joined in the optical axis direction of the laser light.

A disk table on which a disk-shaped recording medium is mounted and rotated, and an objective lens driving device supported on a moving base and moved in a radial direction of the disk-shaped recording medium mounted on the disk table to move the disk-shaped recording medium. An optical pickup for irradiating a laser beam through an objective lens, comprising:
The optical pickup,
A light emitting element for emitting laser light having a first wavelength and a second wavelength corresponding to each of the two types of disc-shaped recording media toward two different disc-shaped recording media;
Polarization direction conversion means for converting the polarization direction of the laser light having the first wavelength and the polarization direction of the laser light having the second wavelength emitted from the light emitting element into light having polarization directions orthogonal to each other;
First diffracting means for diffracting only the laser light having the first wavelength transmitted through the polarization direction converting means and diffracting at a first diffraction angle;
A second diffracting means for diffracting only the laser light having the second wavelength transmitted through the polarization direction converting means and diffracting at a second diffraction angle different from the first diffraction angle;
A beam splitter that reflects or transmits laser light having a first wavelength and laser light having a second wavelength according to the traveling direction of each laser light,
An optical axis combining element that matches the optical axes of the laser light having the first wavelength and the laser light having the second wavelength, which are diffracted by the first diffraction means or the second diffraction means and reflected by each disk-shaped recording medium. When,
A laser beam having a first wavelength and a laser beam having a second wavelength whose optical axes are matched by the optical axis synthesizing element are incident, and the 0th-order light and ± 1st-order light of the laser light are separately received. A light receiving element having three light receiving areas
Spot center in each light receiving area of 0th order light and ± 1st order light of laser light having the first wavelength, and spot center in each light receiving area of 0th order light and ± 1st order light of laser light having the second wavelength And a diffraction angle determined by the first diffraction means and a diffraction angle determined by the second diffraction means such that the two angles substantially coincide with each other.

10. The disk drive device according to claim 9, wherein the polarization direction conversion means, the first diffraction means, and the second diffraction means are joined in the optical axis direction of the laser light.

By forming the diffraction surface of the first diffraction means and the diffraction surface of the second diffraction means on both sides in the optical axis direction of the laser beam, a composite in which the first diffraction means and the second diffraction means are integrated The disk drive device according to claim 9, further comprising a diffraction unit.

12. The disk drive device according to claim 11, wherein the polarization direction conversion unit and the composite diffraction unit are joined in the optical axis direction of the laser light.

A disk table on which a disk-shaped recording medium is mounted and rotated, and an objective lens driving device supported on a moving base and moved in a radial direction of the disk-shaped recording medium mounted on the disk table to move the disk-shaped recording medium. An optical pickup for irradiating a laser beam through an objective lens, comprising:
The optical pickup,
A light emitting element for emitting laser light having a first wavelength and a second wavelength corresponding to each of the two types of disc-shaped recording media toward two different disc-shaped recording media;
Polarization direction conversion means for converting the polarization direction of the laser light having the first wavelength and the polarization direction of the laser light having the second wavelength emitted from the light emitting element into light having polarization directions orthogonal to each other;
First diffracting means for diffracting only the laser light having the first wavelength transmitted through the polarization direction converting means and diffracting at a first diffraction angle;
Second diffracting means for diffracting only the laser light having the second wavelength transmitted through the polarization direction converting means at a predetermined diffraction efficiency;
A beam splitter that reflects or transmits laser light having a first wavelength and laser light having a second wavelength according to the traveling direction of each laser light,
An optical axis combining element that matches the optical axes of the laser light having the first wavelength and the laser light having the second wavelength, which are diffracted by the first diffraction means or the second diffraction means and reflected by each disk-shaped recording medium. When,
The optical axis combining element receives the laser light having the first wavelength and the laser light having the second wavelength, the optical axes of which are matched with each other, and separately receives the 0th-order light and ± 1st-order light of the laser light. A light receiving element having three light receiving areas,
Spot center in each light receiving area of 0th order light and ± 1st order light of laser light having the first wavelength, and spot center in each light receiving area of 0th order light and ± 1st order light of laser light having the second wavelength And a diffraction angle determined by the first diffraction means and a diffraction angle determined by the second diffraction means such that the two angles substantially coincide with each other.

14. The disk drive device according to claim 13, wherein the polarization direction conversion means, the first diffraction means, and the second diffraction means are joined in the optical axis direction of the laser light.

By forming the diffraction surface of the first diffraction means and the diffraction surface of the second diffraction means on both sides in the optical axis direction of the laser beam, a composite in which the first diffraction means and the second diffraction means are integrated 14. The disk drive device according to claim 13, further comprising a diffraction unit.

16. The disk drive device according to claim 15, wherein the polarization direction converting means and the composite diffraction means are joined in the direction of the optical axis of the laser light.