JP4002355B2

JP4002355B2 - Objective lens driving device and optical pickup with the same

Info

Publication number: JP4002355B2
Application number: JP01874999A
Authority: JP
Inventors: 美智雄三浦; 昭雄矢部; 順羽藤
Original assignee: Hitachi Media Electronics Co Ltd
Current assignee: Hitachi Consumer Electronics Co Ltd
Priority date: 1999-01-27
Filing date: 1999-01-27
Publication date: 2007-10-31
Anticipated expiration: 2019-01-27
Also published as: JP2000215479A

Description

【０００１】
【発明の属する技術分野】
本発明は、光ディスク装置に用いられる対物レンズ駆動装置およびそれを備えた光ピッアップに関するものである。
【０００２】
【従来の技術】
光ディスク装置に用いられる対物レンズ駆動装置の一例として、例えば特開平８−２５５３６４号公報のものが知られている。
【０００３】
図７、図８、図９はその従来技術による基本的な対物レンズ駆動装置の弾性支持部材固定部の構成を示したものである。図７（ａ），（ｂ）はホルダ正面図及びＣ−Ｃ断面図、図８は図７におけるＤ部拡大図、図９は弾性支持部材８が理想的に配置されたとき〔同図（ａ）〕と偏心して配置されたとき〔同図（ｂ）〕の弾性支持部材８の変形状態のＤ部拡大図を示す。
【０００４】
図７から図９に示す弾性支持部材固定部以外は、図１に示す本発明の対物レンズ駆動装置とほぼ同様な構成となっている。すなわち、対物レンズ１はレンズホルダ２上面に配置され、このレンズホルダ２の外周にフォーカシングコイル３が巻回され、レンズホルダ２側面にトラッキングコイル４が貼付けられている。
【０００５】
４本の平行な直線状の弾性支持部材８は、その一端をレンズホルダ２に、他端をホルダ５を経由して支持基板９に固定され、対物レンズ１が配置されているレンズホルダ２は、フォーカシング方向、トラッキング方向に移動可能となる状態にて弾性支持されている。ホルダ５の中には弾性支持部材８の共振を減衰させる粘弾性剤が充填されている。
【０００６】
弾性支持部材８の一端が固定されている支持基板９はホルダ５に接着固定され、ホルダ５はヨーク７の一部に配置されている。前記フォーカシングコイル３、トラッキングコイル４を流れる駆動電流は、ヨーク７とマグネット６（６ａ，６ｂ）から構成される磁気回路によって発生する磁束に作用するように配置されている。
【０００７】
フォーカシング制御時には、光ディスク記録面の面振れに対応して、フォーカシングコイル３に電流を供給して対物レンズ１を光軸方向に動作させ、光ビームのスポットを光ディスク記録面上に追従させることができる。トラッキング制御時には、光ディスクのトラックの偏芯、蛇行に対応して、トラッキングコイル４に電流を供給して対物レンズ１を光軸と直角方向に動作させ、光ビームのスポットを光ディスクのトラック上に追従させることができる。これらの動作時に発生する弾性支持部材８の不要共振はホルダ５に充填されている粘弾性剤により減衰され、安定した動作を得ることができる。
【０００８】
【発明が解決しようとする課題】
近年、光ディスク装置においては高記録密度化が進められている。高記録密度化を実現する一つの方法に、光ビームをより細く絞り込み、光ディスクの記録面上でのスポット径を小さくする方法がある。このスポット径は、光ビームの波長をλ、対物レンズ１の開口数をＮＡとすると、（λ／ＮＡ）に比例する。
【０００９】
そのため一般的には光ビームの波長λを小さくし、かつ、対物レンズ１の開口数（ＮＡ）を従来よりも大きな値とすることにより、光ビームを細く絞り込み、高記録密度化に対応する方法が主流となっている。対物レンズ１のＮＡを大きくすることにより光ビームをより細く絞り込むことが可能となる反面、光ディスクと対物レンズ１との傾きによる光学特性劣化は顕著になる特性を有している。
【００１０】
従って、４本の弾性支持部材８（８ａ，８ｂ，８ｃ，８ｄ）には４本ともほぼ同じ弾性変形をすることが求められる。すなわち、前記対物レンズ１が配置されている可動部がフォーカシング方向、トラッキング方向に変位した場合でも、４本の弾性支持部材８が同じように変形し、前記可動部を必要以上に傾けることのないことが要求される。
【００１１】
従来の対物レンズ駆動装置は図９に示すように、ホルダ５に設けられたすり鉢状のホルダ穴５ａに弾性支持部材８が貫通され、さらに支持基板９に配置された支持基板穴９ａを貫通し、支持基板９表面にて半田によって固定されていた。しかし、この対物レンズ駆動装置の場合、図８、図９に示すように、実際に弾性支持部材８が固定されている支持基板９端面と弾性支持部材８が貫通しているホルダ穴５ａの間に、支持基板９の厚さ分の隙間が介在している。
【００１２】
従って、対物レンズ１が配置された可動部がフォーカシング方向及びトラッキング方向に変位した場合、弾性支持部材８は支持基板９表面（図中、固定点）から弾性変形を開始するので、ホルダ穴５ａ端と弾性支持部材８との距離は変化する。弾性支持部材８が貫通するホルダ穴５ａが十分大きく、かつ、弾性支持部材８がそのほぼ中心を通過して固定されている場合は問題はないが、図９（ｂ）に示すように偏って固定配置された場合、上記可動部の変位によって弾性支持部材８の弾性変形領域でホルダ穴５ａ端に接触し、その結果、４本の弾性支持部材８のうち数本のみが不自然な強制変位を受けることになる。そのため対物レンズ１が配置された可動部はある方向に傾き、対物レンズ１と光ディスクとの相対角度が大きくずれる問題があった。
【００１３】
また、この問題を回避するために、弾性支持部材８をホルダ穴５ａ中心を通過するように固定するには、専用の組立治工具にて弾性支持部材８を位置決め固定する必要があり、組立作業性が悪い。
【００１４】
さらに最近では、弾性支持部材８の位置決めをホルダ穴５ａの径を小さくし、このホルダ穴５ａによって行う方法が用いられている。この場合上述したように、弾性支持部材８とホルダ穴５ａ端とのクリアランスはもともと小さくなり、対物レンズ１が配置されている可動部が変位すると、弾性支持部材８は支持基板９表面から弾性変形を開始するため、必ず支持基板９の厚さ分離れた位置に位置するホルダ穴５ａ端に弾性支持部材８の弾性変形領域の一部が接触することになる。そのため結果的に対物レンズ１をフォーカシング方向、トラッキング方向に変位させたとき、対物レンズ１は予期せぬ方向に予期せぬ量傾くことになり、光ディスクからの良好な信号の読み取り、あるいは書き込みが不可能になるという問題があった。
【００１５】
このように従来の対物レンズ駆動装置は、４本の弾性支持部材８の固定端付近において、弾性変形を開始する位置、すなわち半田によって支持固定されている点と離れた位置に、弾性支持部材８を位置決めするホルダ５に配置された小さなホルダ穴５ａが配置されていた。そのため対物レンズ１が配置された可動部がフォーカシング方向及びトラッキング方向に変位した場合、弾性支持部材８の固定端以外の弾性変形領域の部分がホルダ５と接触し、対物レンズ１が傾いてしまう。
【００１６】
その結果、対物レンズ１の傾動動作による光ディスク上の光スポットに光学的な歪みである収差が発生し、正確に光ディスクから信号を読み出せない、あるいは書き込めないという問題があった。
【００１７】
本発明は、上記課題を解決するためになされたもので、対物レンズが配置された可動部をフォーカシング方向及びトラッキング方向に変位させても、弾性支持部材は本来の弾性変形を行い、ホルダ穴端などの障害物に接触することなく結果として対物レンズが設計した通りに動作し、必要以上に傾き難い対物レンズ駆動装置およびそれを備えた光ピッアップを実現することを目的としている。
【００１８】
【課題を解決するための手段】
上記目的を達成するために、第１の手段は、
光ビームを光ディスク上に集光させる対物レンズおよびその対物レンズを保持するレンズホルダを含む可動部と、その可動部に一端が固定されて前記可動部を弾性支持する複数の弾性支持部材と、その弾性支持部材の少なくとも一部を包囲したホルダと、前記弾性支持部材の他端が固定される支持基板と、前記対物レンズを保持して、前記可動部を少なくとも対物レンズの光軸方向と対物レンズの光軸に対してほぼ直角方向に駆動する駆動手段とを備えた対物レンズ駆動装置を対象とするものである。
【００１９】
そして前記支持基板と前記ホルダとが一体に接合され、前記ホルダは前記支持基板と嵌合される凸部を有し、前記支持基板は前記凸部と嵌合される穴部を有し、前記ホルダに内部から前記凸部の方向に前記弾性支持部材を貫通させる貫通穴が設けられ、該貫通穴は少なくとも一部がテーパ形状でありテーパ面が貫通穴端面から開始される形状を有し、前記弾性支持部材は前記支持基板に半田により固定され、その半田によって固定された前記弾性支持部材の弾性変形開始点が前記ホルダの貫通穴端面と略一致するように構成したことを特徴とする。
【００２０】
また上記目的を達成するために、第２の手段は、
光ビームを光ディスク上に集光させる対物レンズおよびその対物レンズを保持するレンズホルダを含む可動部と、その可動部に一端が固定されて前記可動部を弾性支持する複数の弾性支持部材と、その弾性支持部材の少なくとも一部を包囲し、かつ前記弾性支持部材の共振を減衰させる粘弾性剤が充填されたホルダと、前記弾性支持部材の他端が固定される支持基板と、前記対物レンズを保持して、前記可動部を少なくとも対物レンズの光軸方向と対物レンズの光軸に対してほぼ直角方向に駆動する駆動手段とを備えた対物レンズ駆動装置を対象とするものである。
【００２１】
そして前記支持基板と前記ホルダとが一体に接合され、前記ホルダは前記支持基板と嵌合される凸部を有し、前記支持基板は前記凸部と嵌合される穴部を有し、前記ホルダに内部から前記凸部の方向に前記弾性支持部材を貫通させる貫通穴が設けられ、該貫通穴は少なくとも一部がテーパ形状でありテーパ面が貫通穴端面から開始される形状を有し、前記弾性支持部材は前記支持基板に半田により固定され、その半田によって固定された前記弾性支持部材の弾性変形開始点が前記ホルダの貫通穴端面と略一致するように構成したことを特徴とする。
【００２２】
また第３の手段は、第１または第２の手段において、前記可動部を光ディスクのトラッキング方向に対して傾動駆動可能な駆動手段をも有することを特徴とする。
【００２３】
また第４の手段は、第３の手段において、前記弾性支持部材が６本の棒状の弾性支持部材で構成されていることを特徴とする。
【００２４】
また第５の手段は、第１ないし第４の手段のいずれかにおいて、前記支持基板と嵌合される前記凸部を第１の凸部としたときに、前記ホルダは前記第１の凸部の周囲に前記支持基板を受ける第２の凸部を有し、前記第１の凸部と前記第２の凸部の段差は前記支持基板の板厚に略等しいことを特徴とする。
【００２５】
また第６の手段は、第５の手段において、前記第１の凸部と前記第２の凸部との間に凹部がほぼリング状に形成されていることを特徴とする。
【００２６】
また第７の手段は、第１ないし第６の手段のいずれかにおいて、前記ホルダが液晶ポリマーで構成されていることを特徴とする。
また第８の手段は、光ピックアップにおいて第１ないし第７の手段のいずれかの対物レンズ駆動装置を備えたことを特徴とする。
【００２７】
【発明の実施の形態】
以下、図面を用いて本発明の実施の形態について説明する。本発明による対物レンズ駆動装置の第１の実施形態について図１ないし図５を用いて説明する。
【００２８】
図１は本発明による第１の実施形態を示した対物レンズ駆動装置全体の斜視図、図２は本発明の要部となるホルダ５、支持基板の斜視図、図３（ａ），（ｂ）はホルダ５正面図及びＡ−Ａ断面図、図４は図３におけるＢ部拡大図、図５（ａ），（ｂ）は弾性支持部材８が理想的に配置されたときと、偏って配置されたときのＢ部拡大図である。
【００２９】
図１ないし図５において、対物レンズ１はレンズホルダ２の上面に配置されている。レンズホルダ２には、対物レンズ１をほぼその巻中心としてフォーカシングコイル３が巻回され、フォーカシングコイル３の光ディスク接線方向の両側には、トラッキングコイル４がレンズホルダ２に掛かるように配置されている。また、ヨーク７とマグネット６から構成される磁気回路は、これらフォーカシングコイル３及びトラッキングコイル４の有効部分を挟み込むように配置されている。
【００３０】
対物レンズ１、レンズホルダ２、フォーカシングコイル３、トラッキングコイル４等から構成される可動部は４本の弾性支持部材８（８ａ，８ｂ，８ｃ，８ｄ）で支持されており、その弾性支持部材８の一端は可動部に固定されている。また、前記弾性支持部材８は導電性材料で構成され、可動部に配置された前記フォーカシングコイル３及び前記トラッキングコイル４とそれぞれ電気的に接続されて、固定部から前記導電性弾性支持部材８を経由して前記フォーカシングコイル３及び前記トラッキングコイル４に電流を供給することができる。
【００３１】
前記弾性支持部材８の他端は、ホルダ５に設けられたホルダ穴５ａを経由し、支持基板９に設けられた支持基板穴９ａを貫通して、支持基板９の表面にて半田によって固定されている。ホルダ５は前記弾性支持部材８の一部を包囲する構造になっており、かつ、この弾性支持部材８を包囲している部分には粘弾性剤が充填され、この粘弾性剤により弾性支持部材８に発生する不要共振を減衰させる構成となっている。
【００３２】
ホルダ５と支持基板９とは接着剤などによって一体に接合されている。また、弾性支持部材８が貫通するホルダ５のホルダ穴５ａの周囲は凸状に突き出ており、この突出している凸部５ｂの周囲にはリング状に凹部（溝）５ｃが形成され、接着剤溜まりとなっている。このリング状の凹部５ｃの周囲には支持基板９の受面となる受面５ｄが構成されており、少なくともこの受面５ｄで支持基板９と接合されている。
【００３３】
ホルダ５と支持基板９の形状を図２、図４で詳細に示す。図に示すように、ホルダ５から出た凸部５ｂは支持基板９に設けられた弾性支持部材８貫通用の支持基板穴９ａに嵌合し、ホルダ５に設けられた弾性支持部材８貫通用のホルダ穴５ａ端面が支持基板９の半田付け面と略同一の面となっている。また、ホルダ５に設けられている弾性支持部材８貫通用のホルダ穴５ａは、その径が弾性支持部材８の外径とほぼ同じ径（僅かに大きい径）で構成されており、弾性支持部材８の固定部側の位置決めをこのホルダ穴５ａで行っている。
【００３４】
これにより、支持基板９の半田面で半田によって固定された弾性支持部材８の弾性変形開始点はホルダ５の弾性支持部材８用のホルダ穴５ａ端面とほぼ一致することになるので、弾性支持部材８が弾性変形をしても弾性支持部材８の固定点とホルダ５の弾性支持部材８用のホルダ穴５ａ端面が一致しており、弾性支持部材８の弾性領域部分がホルダ５に接触することがない。また、ホルダ５には薄肉部が存在するため、ホルダ５は流動性の良い液晶ポリマー（ＬＣＰ）で構成されている。
【００３５】
また、ホルダ５の弾性支持部材８用のホルダ穴５ａ径が小さく、かつ、支持基板９上の半田面が略一致しているため、半田によりホルダ穴５ａが閉じるため、中に充填されている粘弾性剤を硬化させる工程においても、このホルダ穴５ａから粘弾性剤が漏れ出すこともなく、生産性に優れている。
【００３６】
次にこの実施形態に係る対物レンズ駆動装置の動作について説明する。
光ディスクの上下の面振れに対して光ピックアップでは光学的にフォーカシングエラー信号を作成し、この信号に応じてフォーカシング駆動回路からフォーカシングコイル３に適切な駆動電流が導電性弾性支持部材８を介して供給され、対物レンズ１によって集光された光ビームの光スポットが常に光ディスクの記録面上に位置するようにフォーカシング制御が行われる。
【００３７】
トラックの蛇行、偏芯に対しても光ピックアップでは光学的にトラッキングエラー信号を作成し、この信号に応じてトラッキング駆動回路からトラッキングコイル４に適切な駆動電流が、導電性弾性支持部材８を介して供給され、対物レンズ１によって集光された光ビームの光スポットが常に光ディスクのトラック上に位置するようにトラッキング制御が行われる。このようにしてフォーカシング制御、トラッキング制御が行われ、光ディスクから信号を読み取ることが可能となる。
【００３８】
一方、光ディスクから読み取った信号には、主に光ディスクと対物レンズ１との相対傾き角度によってその大きさが左右される時間軸方向の誤差（ジッター）が含まれている。従って、フォーカシング方向、トラッキング方向に動作しても対物レンズ１の傾き角度が初期傾き角度に対して変化しにくい特性が要求される。図示しないが、本発明による対物レンズ駆動装置においては、磁気回路を構成するヨーク７、マグネット６、及びトラッキングコイル４、フォーカシングコイル３の構成を適切に設定し、対物レンズ１を傾けるトルクが発生し難い構成となっている。
【００３９】
対物レンズ１をフォーカシング方向あるいはトラッキング方向に変位させる場合、対物レンズ１が配置されている可動部を弾性支持している弾性支持部材８は、支持基板９に半田によって固定されている固定点をその境界点として弾性変形を開始する。図５はこの状態を示しており、弾性支持部材８の固定点の位置は支持基板９にもられた半田によって左右される。
【００４０】
しかし、本発明の第１の実施形態では、ホルダ５の弾性支持部材８貫通用兼位置決め用ホルダ穴５ａの端面が支持基板９の表面とほぼ同一面となっているため、弾性支持部材８の弾性変形開始点はホルダ穴５ａ端面とほぼ一致している。従って、この点を境界として弾性支持部材８が弾性変形を開始しても、ホルダ穴５ａ端面に弾性支持部材８が接触することがなく、４本の弾性支持部材８はほぼ同じ変形を行うことが可能となる。
【００４１】
また図５（ｂ）に示すように、弾性支持部材８がホルダ穴５ａの中心から偏って取り付けられている場合においても、上述の通り、弾性支持部材８の固定点とホルダ穴５ａ端とが一致しているので、仮に弾性支持部材８がホルダ穴５ａ端に接触していても、それは弾性支持部材８の固定部であって弾性変形領域ではない。従って、可動部がフォーカシング方向及びトラッキング方向に変位しても、４本の弾性支持部材８はほぼ理想的な弾性変形をするので、結果的に対物レンズ１を傾けることがない。
【００４２】
また図４、図５に示すように本発明では、ホルダ５に配置された支持基板９の受面５ｄは他の面から高い部分に配置されているので、ほぼ完全に受面５ｄと支持基板９とを密着させることができる。さらに、半田によってホルダ５に設けられているホルダ穴５ａがほぼ完全に閉鎖されるので、ホルダ５の内部に充填されている粘弾性剤が硬化途中に漏れ出すこともなく、安定した生産が可能となる。さらに、ホルダ５と支持基板９とを接合する接着剤は、ホルダ穴５ａ部周囲に配置されたリング状の凹部５ｃに入り込むため、塗布した接着剤が溢れてホルダ穴５ａを塞ぐことはなく、やはり安定した生産が可能となる。
このように本発明によれば、対物レンズ１が配置された可動部を支持する弾性支持部材８の固定点の位置は支持基板９の半田によって決定されるが、その位置とホルダ５に設けられた、弾性支持部材８を位置決めするためのホルダ穴５ａの位置とがほぼ一致しているため、対物レンズ１をフォーカシング方向、トラッキング方向に変位させても、弾性支持部材８の弾性変形領域はホルダ穴５ａ端に接触することがなく、従って４本の弾性支持部材８の変形状態はほぼ同一となり、所望の弾性変形を実現でき、その結果、対物レンズ１が必要以上に傾くことのない動作を実現できる。
【００４３】
図６は本発明による第２の実施形態を示した弾性支持部材８の固定部の概略を示し、同図（ａ）は正面図、同図（ｂ）は（ａ）におけるＡ−Ａ断面図である。ホルダ５のホルダ穴５ａ、支持基板９の支持基板穴９ａ周辺の形状は第１の実施形態と同じであるので、基本的な動作、作用は上述の通りである。但し、第２の実施形態では図示しないが、対物レンズ１を光ディスク半径方向に傾動動作可能な駆動手段が配置されており、また、その傾動駆動コイルが可動部に配置されている場合を想定しているので、この傾動駆動コイルに電流を供給するために導電性弾性支持部材８が２本追加され、合計６本の弾性支持部材８の構成となっている。従って、本発明の効果が第２の実施形態においても得られることは言うまでもない。
【００４４】
【発明の効果】
本発明は前述のように、支持基板とホルダとが一体に接合され、ホルダは支持基板と嵌合される凸部を有し、支持基板は凸部と嵌合される穴部を有し、ホルダに内部から凸部の方向に弾性支持部材を貫通させる貫通穴が設けられ、該貫通穴は少なくとも一部がテーパ形状でありテーパ面が貫通穴端面から開始される形状を有し、弾性支持部材は支持基板に半田により固定され、その半田によって固定された弾性支持部材の弾性変形開始点がホルダの貫通穴端面と略一致するように構成されているから、複数の弾性支持部材の弾性変形パターンを理想的に近い状態にすることが可能となり、結果的にフォーカシング動作、トラッキング動作時でも必要以上に対物レンズが傾くことがなく、光ディスクから良好な信号の読み取りあるいは書き込みが可能となる。
【００４５】
また、ホルダ穴と、支持基板上の半田付け面とがほぼ一致しているため、ホルダ穴を半田により密封することができ、その結果、ホルダ内に充填されている粘弾性剤が硬化中に漏れ出すことがなく、安定した作業性を確保することができる。
【００４６】
さらに、ホルダ穴周囲にある凸部の周りにリング状に凹部を配置し、その外側に支持基板の受面を配置しているので、支持基板とホルダを接合する際、接着剤は凹部に溜まり、接着剤の塗布量が多少増減しても、接着剤が溢れてホルダ穴を塞ぐことがなく、安定した組立て作業を実現できるなどの効果を有している。
【図面の簡単な説明】
【図１】本発明による第１の実施形態を示した対物レンズ駆動装置全体の斜視図である。
【図２】本発明の要部となるホルダ、支持基板の斜視図である。
【図３】ホルダの正面図及びＡ−Ａ断面図てある。
【図４】図３におけるＢ部の拡大図である。
【図５】弾性支持部材の非変形状態と変形状態を比較して示す図である。
【図６】本発明による第２の実施形態を示した弾性支持部材固定部の正面図及びＡ−Ａ断面図である。
【図７】従来技術におけるホルダ正面図及びＣ−Ｃ断面図である。
【図８】従来技術を説明した図７におけるＤ部拡大図である。
【図９】従来技術における弾性支持部材の非変形状態と変形状態を比較して示す図である。
【符号の説明】
１対物レンズ
２レンズホルダ
３フォーカシングコイル
４トラッキングコイル
５ホルダ
５ａホルダ穴（貫通穴）
５ｂ凸部
５ｃ凹部
５ｄ受面
６マグネット
７ヨーク
８弾性支持部材
９支持基板
９ａ支持基板穴（貫通穴）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an objective lens driving device used in an optical disk device and an optical pick-up provided with the same .
[0002]
[Prior art]
As an example of an objective lens driving device used in an optical disk device, for example, one disclosed in Japanese Patent Laid-Open No. 8-255364 is known.
[0003]
7, 8 and 9 show the configuration of the elastic support member fixing portion of the basic objective lens driving device according to the prior art. 7A and 7B are a front view of the holder and a cross-sectional view taken along the line CC, FIG. 8 is an enlarged view of a portion D in FIG. 7, and FIG. 9 is a view when the elastic support member 8 is ideally disposed [ a)] and an enlarged view of a portion D in a deformed state of the elastic support member 8 of FIG.
[0004]
Except for the elastic support member fixing portion shown in FIGS. 7 to 9, the configuration is substantially the same as that of the objective lens driving device of the present invention shown in FIG. That is, the objective lens 1 is disposed on the upper surface of the lens holder 2, the focusing coil 3 is wound around the outer periphery of the lens holder 2, and the tracking coil 4 is attached to the side surface of the lens holder 2.
[0005]
The four parallel linear elastic support members 8 have one end fixed to the lens holder 2 and the other end fixed to the support substrate 9 via the holder 5, and the lens holder 2 on which the objective lens 1 is arranged is It is elastically supported so that it can move in the focusing direction and the tracking direction. The holder 5 is filled with a viscoelastic agent that attenuates the resonance of the elastic support member 8.
[0006]
The support substrate 9 to which one end of the elastic support member 8 is fixed is bonded and fixed to the holder 5, and the holder 5 is disposed in a part of the yoke 7. The drive current flowing through the focusing coil 3 and the tracking coil 4 is arranged to act on the magnetic flux generated by the magnetic circuit composed of the yoke 7 and the magnets 6 (6a, 6b).
[0007]
At the time of focusing control, current can be supplied to the focusing coil 3 to move the objective lens 1 in the direction of the optical axis in accordance with the surface shake of the optical disk recording surface, and the light beam spot can follow the optical disk recording surface. . During tracking control, in response to the eccentricity and meandering of the optical disk track, current is supplied to the tracking coil 4 to move the objective lens 1 in a direction perpendicular to the optical axis, and the light beam spot follows the optical disk track. Can be made. Unnecessary resonance of the elastic support member 8 generated during these operations is attenuated by the viscoelastic agent filled in the holder 5, and a stable operation can be obtained.
[0008]
[Problems to be solved by the invention]
In recent years, higher recording density has been promoted in optical disc apparatuses. One method for realizing high recording density is a method of narrowing the light beam to reduce the spot diameter on the recording surface of the optical disk. This spot diameter is proportional to (λ / NA) where λ is the wavelength of the light beam and NA is the numerical aperture of the objective lens 1.
[0009]
Therefore, in general, a method for narrowing the light beam and increasing the recording density by reducing the wavelength λ of the light beam and setting the numerical aperture (NA) of the objective lens 1 to a value larger than the conventional one. Has become the mainstream. By increasing the NA of the objective lens 1, the light beam can be narrowed down more finely, but the optical characteristic deterioration due to the tilt between the optical disk and the objective lens 1 is remarkable.
[0010]
Accordingly, the four elastic support members 8 (8a, 8b, 8c, 8d) are required to undergo substantially the same elastic deformation in all four. That is, even when the movable part where the objective lens 1 is disposed is displaced in the focusing direction and the tracking direction, the four elastic support members 8 are similarly deformed, and the movable part is not tilted more than necessary. Is required.
[0011]
As shown in FIG. 9, the conventional objective lens driving device has an elastic support member 8 that passes through a mortar-shaped holder hole 5 a provided in the holder 5, and further passes through a support substrate hole 9 a that is disposed in the support substrate 9. The surface of the support substrate 9 was fixed with solder. However, in the case of this objective lens driving device, as shown in FIGS. 8 and 9, between the end face of the support substrate 9 where the elastic support member 8 is actually fixed and the holder hole 5a through which the elastic support member 8 passes. In addition, a gap corresponding to the thickness of the support substrate 9 is interposed.
[0012]
Therefore, when the movable part where the objective lens 1 is disposed is displaced in the focusing direction and the tracking direction, the elastic support member 8 starts elastic deformation from the surface of the support substrate 9 (fixed point in the figure), so the end of the holder hole 5a And the elastic support member 8 change. There is no problem when the holder hole 5a through which the elastic support member 8 penetrates is sufficiently large and the elastic support member 8 passes through its substantially center and is fixed, as shown in FIG. When fixedly arranged, the displacement of the movable part makes contact with the end of the holder hole 5a in the elastic deformation region of the elastic support member 8. As a result, only some of the four elastic support members 8 are unnatural forced displacement. Will receive. For this reason, there is a problem in that the movable portion where the objective lens 1 is disposed is inclined in a certain direction, and the relative angle between the objective lens 1 and the optical disk is greatly shifted.
[0013]
Further, in order to avoid this problem, in order to fix the elastic support member 8 so as to pass through the center of the holder hole 5a, it is necessary to position and fix the elastic support member 8 with a dedicated assembly jig. The nature is bad.
[0014]
More recently, a method has been used in which the elastic support member 8 is positioned by reducing the diameter of the holder hole 5a and using the holder hole 5a. In this case, as described above, the clearance between the elastic support member 8 and the end of the holder hole 5a is originally reduced, and when the movable portion where the objective lens 1 is disposed is displaced, the elastic support member 8 is elastically deformed from the surface of the support substrate 9. Therefore, a part of the elastic deformation region of the elastic support member 8 always comes into contact with the end of the holder hole 5a located at a position where the thickness of the support substrate 9 is separated. As a result, when the objective lens 1 is displaced in the focusing direction and the tracking direction, the objective lens 1 tilts in an unexpected amount in an unexpected direction, and reading or writing of a good signal from the optical disk is not possible. There was a problem of becoming possible.
[0015]
Thus, in the conventional objective lens driving device, the elastic support member 8 is located in the vicinity of the fixed ends of the four elastic support members 8 at a position where elastic deformation starts, that is, a position away from the point where it is supported and fixed by solder. The small holder hole 5a arrange | positioned at the holder 5 which positions is arranged. Therefore, when the movable part in which the objective lens 1 is disposed is displaced in the focusing direction and the tracking direction, the elastic deformation member other than the fixed end of the elastic support member 8 comes into contact with the holder 5 and the objective lens 1 is inclined.
[0016]
As a result, an aberration that is an optical distortion is generated in the light spot on the optical disk due to the tilting operation of the objective lens 1, and there is a problem that the signal cannot be read or written accurately from the optical disk.
[0017]
The present invention has been made in order to solve the above-described problem. Even when the movable portion where the objective lens is disposed is displaced in the focusing direction and the tracking direction, the elastic support member inherently undergoes elastic deformation, and the holder hole end As a result, the objective lens operates as designed without touching an obstacle such as an objective lens driving device that hardly tilts more than necessary, and an optical pick-up equipped with the objective lens driving device.
[0018]
[Means for Solving the Problems]
In order to achieve the above object, the first means is:
A movable part including an objective lens for condensing the light beam on the optical disc and a lens holder for holding the objective lens; a plurality of elastic support members having one end fixed to the movable part and elastically supporting the movable part; A holder surrounding at least a part of the elastic support member, a support substrate to which the other end of the elastic support member is fixed, the objective lens is held, and the movable portion is at least in the optical axis direction of the objective lens and the objective lens And an objective lens driving device having driving means for driving in a direction substantially perpendicular to the optical axis.
[0019]
And the said support substrate and the said holder are integrally joined, the said holder has a convex part fitted with the said support substrate, the said support substrate has a hole part fitted with the said convex part, The holder is provided with a through hole that penetrates the elastic support member from the inside toward the convex portion, and the through hole has a shape that is at least partially tapered and the tapered surface starts from the end surface of the through hole, The elastic support member is fixed to the support substrate by solder, and the elastic deformation start point of the elastic support member fixed by the solder is configured to substantially coincide with the end face of the through hole of the holder .
[0020]
In order to achieve the above object, the second means is:
A movable part including an objective lens for condensing the light beam on the optical disc and a lens holder for holding the objective lens; a plurality of elastic support members having one end fixed to the movable part and elastically supporting the movable part; A holder that surrounds at least a portion of the elastic support member and is filled with a viscoelastic agent that attenuates resonance of the elastic support member; a support substrate to which the other end of the elastic support member is fixed; and the objective lens The objective lens driving device is provided that includes the driving unit that holds and drives the movable portion at least in the optical axis direction of the objective lens and in a direction substantially perpendicular to the optical axis of the objective lens.
[0021]
And the said support substrate and the said holder are integrally joined, the said holder has a convex part fitted with the said support substrate, the said support substrate has a hole part fitted with the said convex part, The holder is provided with a through hole that penetrates the elastic support member from the inside toward the convex portion, and the through hole has a shape that is at least partially tapered and the tapered surface starts from the end surface of the through hole, The elastic support member is fixed to the support substrate by solder, and the elastic deformation start point of the elastic support member fixed by the solder is configured to substantially coincide with the end face of the through hole of the holder .
[0022]
Further, the third means is characterized in that in the first or second means, there is also provided drive means capable of tilting the movable portion with respect to the tracking direction of the optical disc.
[0023]
According to a fourth means, in the third means, the elastic support member is composed of six rod-like elastic support members.
[0024]
According to a fifth means, in any one of the first to fourth means, when the convex part fitted to the support substrate is the first convex part, the holder is the first convex part. There is a second projecting portion for receiving the support substrate, and a step between the first projecting portion and the second projecting portion is substantially equal to a plate thickness of the support substrate .
[0025]
The sixth means is characterized in that, in the fifth means, a concave portion is formed in a ring shape between the first convex portion and the second convex portion .
[0026]
The seventh means is characterized in that, in any one of the first to sixth means, the holder is made of a liquid crystal polymer.
The eighth means is characterized in that the optical pickup includes the objective lens driving device of any one of the first to seventh means.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. A first embodiment of an objective lens driving device according to the present invention will be described with reference to FIGS.
[0028]
FIG. 1 is a perspective view of an entire objective lens driving apparatus showing a first embodiment according to the present invention, FIG. 2 is a perspective view of a holder 5 and a support substrate, which are essential parts of the present invention, and FIGS. ) Is a front view of the holder 5 and AA sectional view, FIG. 4 is an enlarged view of a portion B in FIG. 3, and FIGS. 5 (a) and 5 (b) are biased when the elastic support member 8 is ideally arranged. It is the B section enlarged view when arranged.
[0029]
1 to 5, the objective lens 1 is disposed on the upper surface of the lens holder 2. A focusing coil 3 is wound around the lens holder 2 about the objective lens 1 as a winding center, and the tracking coil 4 is disposed on both sides of the focusing coil 3 in the tangential direction of the optical disc. . The magnetic circuit composed of the yoke 7 and the magnet 6 is arranged so as to sandwich the effective portions of the focusing coil 3 and the tracking coil 4.
[0030]
The movable portion including the objective lens 1, the lens holder 2, the focusing coil 3, the tracking coil 4, and the like is supported by four elastic support members 8 (8a, 8b, 8c, 8d), and the elastic support member 8 Is fixed to the movable part. In addition, the elastic support member 8 is made of a conductive material, and is electrically connected to the focusing coil 3 and the tracking coil 4 disposed in the movable part, and the conductive elastic support member 8 is connected from the fixed part. A current can be supplied to the focusing coil 3 and the tracking coil 4 via the via.
[0031]
The other end of the elastic support member 8 passes through a support substrate hole 9 a provided in the support substrate 9 via a holder hole 5 a provided in the holder 5 and is fixed by solder on the surface of the support substrate 9. ing. The holder 5 has a structure surrounding a part of the elastic support member 8, and a portion surrounding the elastic support member 8 is filled with a viscoelastic agent, and the elastic support member is filled with the viscoelastic agent. 8 is configured to attenuate unnecessary resonance that occurs in FIG.
[0032]
The holder 5 and the support substrate 9 are integrally joined by an adhesive or the like. Further, the periphery of the holder hole 5a of the holder 5 through which the elastic support member 8 passes protrudes in a convex shape, and a concave portion (groove) 5c is formed in a ring shape around the protruding convex portion 5b. It is a pool. A receiving surface 5d serving as a receiving surface of the support substrate 9 is formed around the ring-shaped recess 5c, and is joined to the support substrate 9 at least by the receiving surface 5d.
[0033]
The shapes of the holder 5 and the support substrate 9 are shown in detail in FIGS. As shown in the figure, the convex portion 5 b protruding from the holder 5 fits into a support substrate hole 9 a for penetrating the elastic support member 8 provided on the support substrate 9, and penetrates the elastic support member 8 provided on the holder 5. The end surface of the holder hole 5 a is substantially the same as the soldering surface of the support substrate 9. The holder hole 5a for penetrating the elastic support member 8 provided in the holder 5 has a diameter that is substantially the same as the outer diameter of the elastic support member 8 (a slightly larger diameter). The positioning of the fixed portion 8 on the side 8 is performed in the holder hole 5a.
[0034]
As a result, the elastic deformation start point of the elastic support member 8 fixed by soldering on the solder surface of the support substrate 9 substantially coincides with the end surface of the holder hole 5a for the elastic support member 8 of the holder 5, so that the elastic support member Even if 8 is elastically deformed, the fixing point of the elastic support member 8 and the end surface of the holder hole 5a for the elastic support member 8 of the holder 5 are coincident, and the elastic region portion of the elastic support member 8 is in contact with the holder 5 There is no. Moreover, since the holder 5 has a thin portion, the holder 5 is made of a liquid crystal polymer (LCP) having good fluidity.
[0035]
Moreover, since the holder hole 5a diameter for the elastic support member 8 of the holder 5 is small and the solder surface on the support substrate 9 is substantially coincident, the holder hole 5a is closed by soldering, so that the inside is filled. Even in the step of curing the viscoelastic agent, the viscoelastic agent does not leak from the holder hole 5a, and the productivity is excellent.
[0036]
Next, the operation of the objective lens driving device according to this embodiment will be described.
The optical pickup optically creates a focusing error signal with respect to the upper and lower surface fluctuations of the optical disc, and an appropriate driving current is supplied from the focusing driving circuit to the focusing coil 3 through the conductive elastic support member 8 in accordance with this signal. Then, focusing control is performed so that the light spot of the light beam collected by the objective lens 1 is always located on the recording surface of the optical disc.
[0037]
The optical pickup optically generates a tracking error signal for the meandering and eccentricity of the track, and an appropriate driving current is supplied from the tracking driving circuit to the tracking coil 4 via the conductive elastic support member 8 in accordance with this signal. Tracking control is performed so that the light spot of the light beam supplied and focused by the objective lens 1 is always positioned on the track of the optical disk. In this way, focusing control and tracking control are performed, and signals can be read from the optical disc.
[0038]
On the other hand, the signal read from the optical disc includes a time-axis direction error (jitter) whose magnitude depends mainly on the relative tilt angle between the optical disc and the objective lens 1. Therefore, there is a demand for characteristics in which the tilt angle of the objective lens 1 is less likely to change with respect to the initial tilt angle even when operated in the focusing direction and the tracking direction. Although not shown, in the objective lens driving device according to the present invention, the configuration of the yoke 7, the magnet 6, the tracking coil 4, and the focusing coil 3 constituting the magnetic circuit is appropriately set, and torque for tilting the objective lens 1 is generated. It has a difficult structure.
[0039]
When the objective lens 1 is displaced in the focusing direction or the tracking direction, the elastic support member 8 that elastically supports the movable portion on which the objective lens 1 is arranged has a fixed point fixed to the support substrate 9 by solder. Elastic deformation starts as a boundary point. FIG. 5 shows this state, and the position of the fixing point of the elastic support member 8 depends on the solder held on the support substrate 9.
[0040]
However, in the first embodiment of the present invention, since the end surface of the holder hole 5a for penetrating and positioning the elastic support member 8 of the holder 5 is substantially flush with the surface of the support substrate 9, the elastic support member 8 The elastic deformation starting point substantially coincides with the end face of the holder hole 5a. Therefore, even if the elastic support member 8 starts elastic deformation with this point as a boundary, the elastic support member 8 does not come into contact with the end face of the holder hole 5a, and the four elastic support members 8 perform substantially the same deformation. Is possible.
[0041]
Further, as shown in FIG. 5B, even when the elastic support member 8 is attached to be deviated from the center of the holder hole 5a, the fixing point of the elastic support member 8 and the end of the holder hole 5a are as described above. Therefore, even if the elastic support member 8 is in contact with the end of the holder hole 5a, it is a fixed portion of the elastic support member 8 and not an elastic deformation region. Therefore, even if the movable portion is displaced in the focusing direction and the tracking direction, the four elastic support members 8 are almost ideally elastically deformed, and as a result, the objective lens 1 is not tilted.
[0042]
In addition, as shown in FIGS. 4 and 5, in the present invention, the receiving surface 5d of the supporting substrate 9 disposed on the holder 5 is disposed at a higher portion than the other surface, so that the receiving surface 5d and the supporting substrate are almost completely disposed. 9 can be brought into close contact with each other. Furthermore, since the holder hole 5a provided in the holder 5 is almost completely closed by the solder, the viscoelastic agent filled in the holder 5 does not leak during curing, and stable production is possible. It becomes. Furthermore, since the adhesive that joins the holder 5 and the support substrate 9 enters the ring-shaped recess 5c arranged around the holder hole 5a, the applied adhesive does not overflow and block the holder hole 5a. Stable production is also possible.
As described above, according to the present invention, the position of the fixed point of the elastic support member 8 that supports the movable portion where the objective lens 1 is disposed is determined by the solder of the support substrate 9. In addition, since the position of the holder hole 5a for positioning the elastic support member 8 is substantially the same, even if the objective lens 1 is displaced in the focusing direction and the tracking direction, the elastic deformation region of the elastic support member 8 is the holder. The four elastic support members 8 do not come into contact with the end of the hole 5a, and therefore the deformation states of the four elastic support members 8 are substantially the same, and a desired elastic deformation can be realized. As a result, the objective lens 1 can be operated without tilting more than necessary. realizable.
[0043]
6A and 6B schematically show a fixing portion of the elastic support member 8 according to the second embodiment of the present invention. FIG. 6A is a front view, and FIG. 6B is a cross-sectional view taken along line AA in FIG. It is. Since the holder hole 5a of the holder 5 and the shape of the support substrate 9 around the support substrate hole 9a are the same as those in the first embodiment, the basic operation and action are as described above. However, although not shown in the second embodiment, it is assumed that driving means capable of tilting the objective lens 1 in the radial direction of the optical disk is disposed, and that the tilt driving coil is disposed in the movable portion. Therefore, two conductive elastic support members 8 are added to supply current to the tilting drive coil, and a total of six elastic support members 8 are configured. Therefore, it goes without saying that the effect of the present invention can be obtained also in the second embodiment.
[0044]
【The invention's effect】
In the present invention, as described above, the support substrate and the holder are integrally joined, the holder has a convex portion that is fitted to the support substrate, the support substrate has a hole portion that is fitted to the convex portion, The holder is provided with a through-hole that allows the elastic support member to penetrate from the inside to the convex portion, and the through-hole has a shape that is at least partially tapered and the tapered surface starts from the end surface of the through-hole, and is elastically supported. The member is fixed to the support substrate with solder, and the elastic deformation start point of the elastic support member fixed by the solder is configured to substantially coincide with the end face of the through hole of the holder. It is possible to make the pattern ideally close. As a result, the objective lens does not tilt more than necessary even during focusing and tracking operations, and good signal reading or writing from the optical disc is possible. It can become.
[0045]
In addition, since the holder hole and the soldering surface on the support substrate are substantially coincident, the holder hole can be sealed with solder. As a result, the viscoelastic agent filled in the holder is cured. Stable workability can be ensured without leakage.
[0046]
Furthermore, since the concave portion is arranged in a ring shape around the convex portion around the holder hole, and the receiving surface of the support substrate is arranged outside the convex portion, the adhesive accumulates in the concave portion when the support substrate and the holder are joined. Even if the application amount of the adhesive is slightly increased or decreased, the adhesive does not overflow and does not block the holder hole, and thus there is an effect that a stable assembling operation can be realized.
[Brief description of the drawings]
FIG. 1 is a perspective view of an entire objective lens driving device according to a first embodiment of the present invention.
FIG. 2 is a perspective view of a holder and a support substrate that are essential parts of the present invention.
FIG. 3 is a front view of the holder and a cross-sectional view taken along the line AA.
4 is an enlarged view of a portion B in FIG. 3;
FIG. 5 is a diagram showing a comparison between a non-deformed state and a deformed state of an elastic support member.
FIGS. 6A and 6B are a front view and an AA cross-sectional view of an elastic support member fixing portion according to a second embodiment of the present invention. FIGS.
FIGS. 7A and 7B are a front view of a holder and a CC cross-sectional view in the prior art.
FIG. 8 is an enlarged view of a portion D in FIG. 7 for explaining the prior art.
FIG. 9 is a diagram showing a comparison between a non-deformed state and a deformed state of an elastic support member in the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Objective lens 2 Lens holder 3 Focusing coil 4 Tracking coil 5 Holder 5a Holder hole (through hole)
5b Convex part 5c Concave part 5d Receiving surface 6 Magnet 7 Yoke 8 Elastic support member 9 Support substrate 9a Support substrate hole (through hole)

Claims

An objective lens for condensing the light beam on the optical disc, and a movable part including a lens holder for holding the objective lens;
A plurality of elastic support members having one end fixed to the movable part and elastically supporting the movable part;
A holder surrounding at least a part of the elastic support member;
A support substrate to which the other end of the elastic support member is fixed;
In an objective lens driving device comprising the driving means for holding the objective lens and driving the movable part at least in the optical axis direction of the objective lens and in a direction substantially perpendicular to the optical axis of the objective lens,
The support substrate and the holder are joined together,
The holder has a convex part fitted to the support substrate,
The support substrate has a hole to be fitted with the convex portion,
The holder is provided with a through hole that allows the elastic support member to penetrate from the inside toward the convex portion.
The through hole has a shape that is at least partially tapered and the tapered surface starts from the end surface of the through hole,
The elastic support member is fixed to the support substrate by solder;
An objective lens driving device, characterized in that an elastic deformation start point of the elastic support member fixed by the solder is substantially coincident with an end surface of the through hole of the holder .

An objective lens for condensing the light beam on the optical disc, and a movable part including a lens holder for holding the objective lens;
A plurality of elastic support members having one end fixed to the movable part and elastically supporting the movable part;
A holder that surrounds at least a portion of the elastic support member and is filled with a viscoelastic agent that attenuates resonance of the elastic support member;
A support substrate to which the other end of the elastic support member is fixed;
In an objective lens driving device comprising the driving means for holding the objective lens and driving the movable part at least in the optical axis direction of the objective lens and in a direction substantially perpendicular to the optical axis of the objective lens,
The support substrate and the holder are joined together,
The holder has a convex part fitted to the support substrate,
The support substrate has a hole to be fitted with the convex portion,
The holder is provided with a through hole that allows the elastic support member to penetrate from the inside toward the convex portion.
The through hole has a shape that is at least partially tapered and the tapered surface starts from the end surface of the through hole,
The elastic support member is fixed to the support substrate by solder;
An objective lens driving device, characterized in that an elastic deformation start point of the elastic support member fixed by the solder is substantially coincident with an end surface of the through hole of the holder .

In the objective lens driving device according to claim 1 or claim 2, wherein, the objective lens driving apparatus characterized by also having a tilt drivable drive means said movable portion with respect to the tracking direction of the optical disk.

4. The objective lens driving device according to claim 3, wherein the elastic support member is composed of six rod-shaped elastic support members.

In the objective lens driving device according to any one of claims 1 to 4, the convex portion to be fitted to the supporting substrate when the first convex portion, the holder of the first convex An objective lens having a second convex portion for receiving the support substrate around a portion, and a step between the first convex portion and the second convex portion being substantially equal to a plate thickness of the support substrate. Drive device.

6. The objective lens driving device according to claim 5, wherein a concave portion is formed in a substantially ring shape between the first convex portion and the second convex portion .

In the objective lens driving device according to any one of claims 1 to 6, the objective lens driving device, characterized in that the holder is a liquid crystal polymer.

An optical pickup comprising the objective lens driving device according to any one of claims 1 to 7.