JP2004171680A

JP2004171680A - Optical head device

Info

Publication number: JP2004171680A
Application number: JP2002336870A
Authority: JP
Inventors: Yoshio Hayashi; 善雄林
Original assignee: Nidec Sankyo Corp
Current assignee: Nidec Sankyo Corp
Priority date: 2002-11-20
Filing date: 2002-11-20
Publication date: 2004-06-17

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical head device capable of surely preventing an optical recording medium from being damaged even when a shock is applied to the optical recording medium. <P>SOLUTION: If the optical recording medium 2 is shocked when an objective lens 3 is positioned at an outer circumferential side of the optical recording medium 2, and the optical recording medium 2 collides with a protective member 5, a disk chuck mechanism 6 comes off due to the large moment to push up the optical recording medium 2, and the optical recording medium 2 comes into contact with the protective member 5 in a tilted posture. In this case also, the upper surface of the protective member 5 has a cross section formed of a horizontal part 51 on the inner circumferential side and an outer circumferential part 52 having a form continuously rounded from this horizontal part 51, therefore, even if the optical recording medium 2 is in the tilted posture, the contact area with the protective member 5 is large and the contact pressure is small. Therefore, the optical recording medium 2 is surely protected against damaging. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、光記録媒体の記録、再生に用いられる光ヘッド装置に関するものである。さらに詳しくは、対物レンズの外周縁に重なる保護部材の構成に対するものである。
【０００２】
【従来の技術】
ＣＤ−ＲＯＭ（ＣｏｍｐａｃｔＤｉｓｋＲｅａｄＯｎｌｙＭｅｍｏｒｙ）、ＣＤ−Ｒ（ＣｏｍｐａｃｔＤｉｓｋＲｅｃｏｒｄａｂｌｅ）、ＣＤ−ＲＷ（ＣｏｍｐａｃｔＤｉｓｋＲｅｗｒｉｔａｂｌｅ）、ＤＶＤ−ＲＯＭ（ＤｉｇｉｔａｌＶｅｒｓａｔｉｌｅＤｉｓｋＲｅａｄＯｎｌｙＭｅｍｏｒｙ）、ＤＶＤ−ＲＷ（ＤｉｇｉｔａｌＶｅｒｓａｔｉｌｅＤｉｓｋＲｅａｄＯｎｌｙＭｅｍｏｒｙ）、ＤＶＤ−ＲＷ（Ｒｅｗｒｉｔａｂｌｅ）などの光記録媒体に対する記録あるいは再生には、図４（Ａ）に示すように、光源からの出射光を光記録媒体に収束させる対物レンズ３と、この対物レンズ３が載置されるレンズ保持部１１を備えたレンズホルダ１０とを有する光ヘッド装置が用いられる。
【０００３】
ここで、対物レンズ３の外周縁には、リング状の保護部材９が重ねられており、図４（Ｂ）に示すように、衝撃などによって光記録媒体２がレンズホルダ１０に衝突しようしたときでも、光記録媒体は、保護部材９と接触するようになっている。
【０００４】
ここで、光記録媒体２が静止している時の衝突は、衝突によって光記録媒体２に傷がついてもその範囲が狭く、かつ、保護部材９があれば、傷の発生を小さく抑えることができる。これに対して、光記録媒体２が回転している時の衝突は、光記録媒体２に円周状の擦り傷を発生させる危険性が高く、このような傷は、連続したデータ破壊の原因となるので、重大な問題点となる。
【０００５】
このため、保護部材９は、対物レンズ３の保護と併せて、光記録媒体２の保護という重要な機能を担っており、ゴムや弾性樹脂などといった弾性を備えた材料で構成されている。なお、保護部材９としては、光記録媒体２の回転方向と直交する方向に配置して、衝突時においても読み取り信号の再生を可能にしたものもある。いずれにしても、保護部材９は、断面矩形であり、衝撃などによって光記録媒体２がレンズホルダ１０に衝突したとき、図４（Ｂ）、および図４（Ｃ）に一点鎖線で示すように、光記録媒体２は、保護部材９の水平な上面９１と接触することになる（例えば、特許文献１、２参照）。
【０００６】
【特許文献１】
特開２０００−２０９７７（図１）
【特許文献２】
特開２００２−２２２５３５（図３）
【０００７】
【発明が解決しようとする課題】
このように構成した光ヘッド装置において、光記録媒体２の内周側に対物レンズ３が位置しているときに光記録媒体２に衝撃が加わって、光記録媒体２が保護部材５と衝突したときには、光記録媒体２に作用するモーメントが小さいので、ディスクチャッキング機構６が外れることがないため、図４（Ｂ）、および図４（Ｃ）を参照して説明したように、光記録媒体２は、保護部材９の水平な上面９１と十分な接触面積をもって接触する。このため、接触圧が小さいので、光記録媒体２に傷が付かない。
【０００８】
しかしながら、図４（Ｄ）に示すように、光記録媒体２の外周側に対物レンズ３が位置しているときに光記録媒体２に衝撃が加わって光記録媒体２が保護部材５９に衝突すると、光記録媒体２にはそれを押し上げようとする大きなモーメントが加わるので、ディスクチャッキング機構６が外れ、図４（Ｃ）に二点鎖線で示すように、光記録媒体２が傾いた姿勢で保護部材９の外周側の角部分９２に接触することになる。この状態では保護部材９と光記録媒体２との接触面積が極めて狭く、接触圧が大きいため、光記録媒体２に傷が付いてしまうという問題点がある。
【０００９】
以上の問題点に鑑みて、本発明の課題は、光記録媒体に衝撃が加わったときでも、光記録媒体に傷が付くのを確実に防止することのできる光ヘッド装置を提供することにある。
【００１０】
【課題を解決するための手段】
上記課題を解決するため、本発明では、光源からの出射光を光記録媒体に収束させる対物レンズと、該対物レンズが載置されるレンズ保持部を備えたレンズホルダと、前記対物レンズの外周縁を覆う保護部材とを有する光ヘッド装置において、前記保護部材は、上面から外周側面にかけてＲ形状をもつ断面形状を有していることを特徴とする。
【００１１】
本発明では、保護部材は、上面から外周側面にかけてＲ形状をもつ断面形状を有しているため、光記録媒体が斜めに傾いた姿勢で保護部材と接触した場合でも、保護部材と光記録媒体とが接する部分の面積が広く、接触圧が小さい。従って、光記録媒体に傷が付くのを確実に防止することができる。
【００１２】
本発明において、前記保護部材の上面は、内周側が水平部分になっており、当該水平部分からＲ形状をもつ外周部分が連続して形成された断面形状を有していることが好ましい。このように構成すると、光記録媒体が水平姿勢のまま保護部材に接しても、このとき接するのは、保護部材の上面の水平部分である。それ故、保護部材と光記録媒体とが接する部分の面積が広く、接触圧が小さいので、光記録媒体に傷が付くのを確実に防止することができる。
【００１３】
本発明において、前記保護部材がリング状の場合、当該保護部材の周方向の全体が前記Ｒ形状の外周部分をもつ断面形状を有していることが好ましい。
【００１４】
本発明において、前記保護部材がリング状であり、周方向の一部が前記Ｒ形状の外周部分をもつ断面形状を有している構成であってもよい。
【００１５】
本発明において、前記保護部材の表面の断面形状は、中心近傍が略水平であって、最外周が水平部分から略５°のＲ形状になっていることが好ましい。このように構成すると、前記保護部材は、光記録媒体が傾いたときでも当該光記録媒体の傾きが５°以下であるときには常に前記Ｒ形状の外周部分が光記録媒体に接することになる。すなわち、光記録媒体駆動装置においては、光記録媒体の上面にはカバーなどが配置され、光記録媒体が傾いたときには光記録媒体がカバーなどに当たるため、光記録媒体の傾きは、最大でも５°位に制限されている。従って、保護部材については光記録媒体の傾きが５°以下であるときに常にＲ形状の外周部分が光記録媒体に接するように形成しておけばよい。
【００１６】
【発明の実施の形態】
以下に図面を参照して本発明を適用した光ヘッド装置を説明する。
【００１７】
図１（Ａ）、（Ｂ）はそれぞれ、軸摺動回動型アクチュエータを備えた光ヘッド装置を模式的に示す説明図、およびワイヤーサスペンジョン型アクチュエータを備えた光ヘッド装置の説明図である。図２（Ａ）〜（Ｄ）はそれぞれ、本発明を適用した光ヘッド装置に用いた保護部材などの説明図、光記録媒体が水平姿勢のまま保護部材と衝突する様子を示す説明図、保護部材の断面形状を拡大して示す説明図、および光記録媒体が斜めに傾いた姿勢で保護部材と衝突する様子を示す説明図である。
【００１８】
図１（Ａ）に示す軸摺動回動型アクチュエータを備えた光ヘッド装置は、光記録媒体の半径方向に走査可能なフレーム２０上に、レンズホルダ２２が支軸２１に支持された状態にある。レンズホルダ２２は、磁気駆動回路によって、トラッキング駆動時には、矢印Ｔ１で示すように、支軸２１周りに回動可能であるとともに、フォーカシング駆動時には、矢印Ｆ１で示すように、支軸２１に沿って摺動可能である。
【００１９】
また、図１（Ｂ）に示すワイヤーサスペンジョン型アクチュエータを備えた光ヘッド装置は、光記録媒体２の半径方向に走査可能なフレーム３０上で、例えば、４本のワイヤー３１でレンズホルダ３２が支持された状態にある。レンズホルダ３２は、磁気駆動回路によって、トラッキング駆動時には、矢印Ｔ２で示すように、ワイヤー３１の変形によりトラッキング方向に変位可能であるとともに、フォーカシング駆動時には、矢印Ｆ２で示すように、ワイヤー３１の変形によりフォーカシング方向に変位可能である。
【００２０】
これらいずれのタイプの光ヘッド装置においても、図２（Ａ）に示すように、レンズホルダ１０はレンズ保持部１１を備えており、このレンズ保持部１１には、光源からの出射光を光記録媒体に収束させる対物レンズ３が搭載されている。また、対物レンズ３の外周縁には、ゴムや弾性樹脂などといった弾性材料からなるリング状の保護部材５が重ねられ、かつ、接着固定されている。このため、図２（Ｂ）に示すように、衝撃などによって光記録媒体２がレンズホルダ１０や対物レンズ３に衝突しようとしたときでも、光記録媒体は、保護部材９と接触する。
【００２１】
このように構成した光ヘッド装置において、保護部材５は、図２（Ｃ）に示すように、全周にわたって上面から外周側面にかけてＲ形状をもつ断面形状を有している。すなわち、保護部材５の上面は、内周側が水平部分５１になっており、この水平部分５１からＲ形状をもつ外周部分５２が連続して形成された断面形状を有している。すなわち、保護部材５の表面の断面形状は、中心近傍が略水平であって、最外周が水平部分から略５°のＲ形状になっている。従って、保護部材５の上面には屈曲部分などがなく、なだらかな形状を有している。
【００２２】
このように構成した光ヘッド装置において、図２（Ｂ）に示すように、光記録媒体２の内周側に対物レンズ３が位置しているときに光記録媒体２に衝撃が加わって光記録媒体２が保護部材５と衝突したときでも、光記録媒体２に作用するモーメントが小さいので、ディスクチャッキング機構６が外れることがない。従って、光記録媒体２は、水平姿勢のまま保護部材５の上面に接するが、このとき接するのは、保護部材５の上面内周側の水平部分５１である。それ故、保護部材５と光記録媒体２とが接する部分の面積が広いので、接触圧が小さく、光記録媒体２に傷が付くのを確実に防止することができる。
【００２３】
これに対して、図２（Ｄ）に示すように、光記録媒体２の外周側に対物レンズ３が位置しているときに光記録媒体２に衝撃が加わって光記録媒体２が保護部材５と衝突すると、光記録媒体２を押し上げようとするモーメントが大きいので、ディスクチャッキング機構６が外れ、光記録媒体２が傾いた姿勢で保護部材５と接する。但し、本形態において、保護部材５の外周部分５２は、上面から外周側面にかけてＲ形状をもつ断面形状を有しているため、傾いた姿勢の光記録媒体２であっても、保護部材５との接触面積が広く、接触圧が小さい。このため、光記録媒体２に傷が付くのを確実に防止することができる。
【００２４】
ここで、光記録媒体駆動装置においては、光記録媒体２の上面にはカバー（図示せず）などが配置され、光記録媒体２が傾いたときには光記録媒体２がカバーに当たるため、光記録媒体２の傾きは、最大でも５°位に制限されている。従って、保護部材５については光記録媒体２の傾きが５°以下であるときに常にＲ形状の外周部分５２が光記録媒体２に接するように形成してある。
【００２５】
このように本形態によれば、光記録媒体２に衝撃が加わって、光記録媒体２が水平姿勢のまま保護部材５に衝突した場合、および光記録媒体２が斜めに傾いた姿勢で保護部材５に接触した場合のいずれにおいても、保護部材５と光記録媒体２とが接する部分の面積が広いため、光記録媒体２に傷が付くのを確実に防止することができる。
【００２６】
（その他の実施の形態）
なお、上記形態では、リング状の保護部材２において、周方向の全体がＲ形状の外周部分をもつ断面形状を有している構成であったが、リング状の保護部材において、周方向の一部がＲ形状の外周部分をもつ断面形状を有している構成であってもよい。
【００２７】
例えば、図１（Ｂ）に示すワイヤーサスペンジョン型アクチュエータに用いる保護部材５においては、図３（Ａ）、（Ｂ）に示すように、トラッキング方向と直交する側（タンジェント方向／矢印ＴＡで示す）では、内周側が水平部分５１になっており、この水平部分５１からＲ形状をもつ外周部分５２が連続して形成された断面形状を有している一方、図３（Ａ）、（Ｃ）に示すように、トラッキング方向（矢印Ｔで示す）においては、矩形の断面形状を有している構成であってもよい。
【００２８】
【発明の効果】
以上説明したように、本発明によれば、光記録媒体に衝撃が加わって、光記録媒体が斜めに傾いた姿勢で保護部材に衝突した場合でも、保護部材と光記録媒体とが接する部分の面積が広いため、光記録媒体に傷が付くのを確実に防止することができる。
【図面の簡単な説明】
【図１】（Ａ）、（Ｂ）はそれぞれ、軸摺動回動型アクチュエータを備えた光ヘッド装置を模式的に示す説明図、およびワイヤーサスペンジョン型アクチュエータを備えた光ヘッド装置の説明図である。
【図２】（Ａ）〜（Ｄ）はそれぞれ、本発明を適用した光ヘッド装置に用いた保護部材などの説明図、光記録媒体が水平姿勢のまま保護部材と衝突する様子を示す説明図、保護部材の断面形状を拡大して示す説明図、および光記録媒体が斜めに傾いた姿勢で保護部材と衝突する様子を示す説明図である。
【図３】（Ａ）〜（Ｃ）はそれぞれ、本発明を適用した別の光ヘッド装置に用いた保護部材などの説明図、この保護部材をトラッキング方向と直交する方向に切断したときの断面図、および保護部材をトラッキング方向に切断したときの断面図である。
【図４】（Ａ）〜（Ｄ）はそれぞれ、従来の光ヘッド装置に用いた保護部材などの説明図、光記録媒体が水平姿勢のまま保護部材と衝突する様子を示す説明図、保護部材の断面形状を拡大して示す説明図、および光記録媒体が斜めに傾いた姿勢で保護部材と衝突する様子を示す説明図である。
【符号の説明】
３対物レンズ
５保護部材
６チャッキング機構
１０レンズホルダ
１１レンズ保持部
５１保護部材の上面の水平部
５２保護部材のＲ形状をもつ外周部分[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical head device used for recording and reproducing on an optical recording medium. More specifically, the present invention relates to a configuration of a protective member overlapping an outer peripheral edge of an objective lens.
[0002]
[Prior art]
CD-ROMs (Compact Disk Read Only Memory), CD-Rs (Compact Disk Recordable), CD-RWs (Compact Disk Rewritable), DVD-ROMs (Digital Versatile Daily Digital Read-Only-Rek-Nearly-Dry-Release) For recording or reproduction on an optical recording medium such as a memory (Memory) or a DVD-RW (Rewritable), as shown in FIG. 4A, an objective lens 3 for converging light emitted from a light source to the optical recording medium, and the objective lens 3 An optical head device having a lens holder 10 having a lens holding portion 11 on which the lens 3 is placed is used.
[0003]
Here, a ring-shaped protective member 9 is superimposed on the outer peripheral edge of the objective lens 3, and as shown in FIG. 4B, when the optical recording medium 2 tries to collide with the lens holder 10 due to impact or the like. However, the optical recording medium comes into contact with the protection member 9.
[0004]
Here, the collision when the optical recording medium 2 is stationary is small even if the optical recording medium 2 is damaged by the collision, and if the protective member 9 is provided, it is possible to reduce the occurrence of the damage. it can. On the other hand, a collision when the optical recording medium 2 is rotating has a high risk of causing circumferential scratches on the optical recording medium 2, and such a scratch is a cause of continuous data destruction. This is a serious problem.
[0005]
For this reason, the protection member 9 has an important function of protecting the optical recording medium 2 as well as protecting the objective lens 3 and is made of an elastic material such as rubber or elastic resin. Some of the protection members 9 are arranged in a direction perpendicular to the rotation direction of the optical recording medium 2 so that a read signal can be reproduced even at the time of collision. In any case, the protection member 9 has a rectangular cross section, and when the optical recording medium 2 collides with the lens holder 10 due to an impact or the like, as shown by a dashed line in FIGS. 4B and 4C. The optical recording medium 2 comes into contact with the horizontal upper surface 91 of the protection member 9 (for example, see Patent Documents 1 and 2).
[0006]
[Patent Document 1]
JP 2000-20977 (FIG. 1)
[Patent Document 2]
JP-A-2002-225535 (FIG. 3)
[0007]
[Problems to be solved by the invention]
In the optical head device thus configured, when the objective lens 3 is located on the inner peripheral side of the optical recording medium 2, an impact is applied to the optical recording medium 2, and the optical recording medium 2 collides with the protective member 5. Since the moment acting on the optical recording medium 2 is sometimes small, the disc chucking mechanism 6 does not come off, and as described with reference to FIGS. 4B and 4C, 2 contacts the horizontal upper surface 91 of the protection member 9 with a sufficient contact area. Therefore, the contact pressure is small, and the optical recording medium 2 is not damaged.
[0008]
However, as shown in FIG. 4D, when the optical recording medium 2 is impacted by the impact when the objective lens 3 is located on the outer peripheral side of the optical recording medium 2 and the optical recording medium 2 collides with the protective member 59, Since a large moment is applied to the optical recording medium 2 to push it up, the disc chucking mechanism 6 comes off, and the optical recording medium 2 is tilted as shown by a two-dot chain line in FIG. It comes into contact with the corner portion 92 on the outer peripheral side of the protection member 9. In this state, there is a problem that the contact area between the protective member 9 and the optical recording medium 2 is extremely small and the contact pressure is large, so that the optical recording medium 2 is damaged.
[0009]
In view of the above problems, an object of the present invention is to provide an optical head device that can reliably prevent an optical recording medium from being damaged even when an impact is applied to the optical recording medium. .
[0010]
[Means for Solving the Problems]
In order to solve the above problems, according to the present invention, an objective lens for converging light emitted from a light source to an optical recording medium, a lens holder including a lens holding portion on which the objective lens is mounted, and an external lens outside the objective lens In an optical head device having a protection member covering a peripheral edge, the protection member has a cross-sectional shape having an R shape from an upper surface to an outer peripheral side surface.
[0011]
In the present invention, since the protection member has a cross-sectional shape having an R shape from the top surface to the outer peripheral side surface, even when the optical recording medium comes into contact with the protection member in an obliquely inclined posture, the protection member and the optical recording medium can be used. And the contact pressure is small. Therefore, it is possible to reliably prevent the optical recording medium from being damaged.
[0012]
In the present invention, it is preferable that the upper surface of the protective member has a horizontal portion on the inner peripheral side, and has a cross-sectional shape in which an outer peripheral portion having an R shape is continuously formed from the horizontal portion. With this configuration, even if the optical recording medium comes into contact with the protection member in a horizontal posture, the contact at this time is a horizontal portion on the upper surface of the protection member. Therefore, since the area where the protective member and the optical recording medium are in contact with each other is large and the contact pressure is small, it is possible to reliably prevent the optical recording medium from being damaged.
[0013]
In the present invention, when the protective member has a ring shape, it is preferable that the entire circumferential direction of the protective member has a cross-sectional shape having the R-shaped outer peripheral portion.
[0014]
In the present invention, the protection member may be ring-shaped, and may have a configuration in which a part in a circumferential direction has a cross-sectional shape having the R-shaped outer peripheral portion.
[0015]
In the present invention, it is preferable that the cross-sectional shape of the surface of the protection member is substantially horizontal near the center and approximately 5 ° from the horizontal portion at the outermost periphery. With this configuration, even when the optical recording medium is inclined, when the inclination of the optical recording medium is 5 ° or less, the outer peripheral portion of the R shape is in contact with the optical recording medium. That is, in the optical recording medium driving device, a cover or the like is disposed on the upper surface of the optical recording medium, and when the optical recording medium is inclined, the optical recording medium hits the cover or the like. Is restricted to the second place. Therefore, the protective member may be formed so that the outer peripheral portion of the R shape is always in contact with the optical recording medium when the inclination of the optical recording medium is 5 ° or less.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an optical head device to which the present invention is applied will be described with reference to the drawings.
[0017]
1A and 1B are an explanatory diagram schematically showing an optical head device provided with a shaft sliding and rotating actuator and an explanatory diagram of an optical head device provided with a wire suspension type actuator, respectively. FIGS. 2A to 2D are explanatory views of a protective member and the like used in an optical head device to which the present invention is applied, an explanatory view showing a state in which an optical recording medium collides with a protective member in a horizontal posture, and FIG. FIG. 3 is an explanatory diagram showing an enlarged cross-sectional shape of the member, and an explanatory diagram showing a state in which the optical recording medium collides with a protective member in an obliquely inclined posture.
[0018]
An optical head device provided with a shaft sliding rotation type actuator shown in FIG. 1A has a lens holder 22 supported on a support shaft 21 on a frame 20 that can scan in the radial direction of an optical recording medium. is there. The lens holder 22 is rotatable around the support shaft 21 as shown by an arrow T1 during tracking drive by the magnetic drive circuit, and is moved along the support shaft 21 as shown by an arrow F1 during focusing drive during tracking drive. It can slide.
[0019]
The optical head device including the wire suspension type actuator shown in FIG. 1B has a lens holder 32 supported by, for example, four wires 31 on a frame 30 that can scan in the radial direction of the optical recording medium 2. It has been done. The lens holder 32 can be displaced in the tracking direction by the deformation of the wire 31 as shown by the arrow T2 during the tracking drive by the magnetic drive circuit, and deformed by the deformation of the wire 31 during the focusing drive as shown by the arrow F2 during the focusing drive. Can be displaced in the focusing direction.
[0020]
In any of these types of optical head devices, as shown in FIG. 2A, the lens holder 10 includes a lens holding portion 11, and the lens holding portion 11 records light emitted from a light source by optical recording. An objective lens 3 for focusing on a medium is mounted. A ring-shaped protective member 5 made of an elastic material such as rubber or elastic resin is superimposed on the outer peripheral edge of the objective lens 3 and is adhered and fixed. Therefore, as shown in FIG. 2B, even when the optical recording medium 2 attempts to collide with the lens holder 10 or the objective lens 3 due to an impact or the like, the optical recording medium comes into contact with the protective member 9.
[0021]
In the optical head device thus configured, as shown in FIG. 2C, the protection member 5 has an R-shaped cross section from the top surface to the outer peripheral side surface over the entire circumference. That is, the upper surface of the protection member 5 has a horizontal portion 51 on the inner peripheral side, and has a cross-sectional shape in which an outer peripheral portion 52 having an R shape is continuously formed from the horizontal portion 51. That is, the cross-sectional shape of the surface of the protective member 5 is substantially horizontal near the center, and the outermost periphery has an R shape of approximately 5 ° from the horizontal portion. Therefore, the upper surface of the protection member 5 has no bent portion and the like, and has a gentle shape.
[0022]
In the optical head device configured as described above, as shown in FIG. 2B, when the objective lens 3 is located on the inner peripheral side of the optical recording medium 2, a shock is applied to the optical recording medium 2 to perform optical recording. Even when the medium 2 collides with the protection member 5, the moment acting on the optical recording medium 2 is small, so that the disk chucking mechanism 6 does not come off. Therefore, the optical recording medium 2 comes into contact with the upper surface of the protection member 5 while keeping the horizontal posture, but at this time, the horizontal portion 51 on the inner peripheral side of the upper surface of the protection member 5 is in contact. Therefore, since the area of the portion where the protective member 5 and the optical recording medium 2 are in contact with each other is large, the contact pressure is small and the optical recording medium 2 can be reliably prevented from being damaged.
[0023]
On the other hand, as shown in FIG. 2D, when the objective lens 3 is located on the outer peripheral side of the optical recording medium 2, an impact is applied to the optical recording medium 2 and the optical recording medium 2 is moved to the protective member 5. When the collision occurs, the moment to push up the optical recording medium 2 is large, so that the disk chucking mechanism 6 comes off and the optical recording medium 2 comes into contact with the protective member 5 in an inclined posture. However, in the present embodiment, since the outer peripheral portion 52 of the protective member 5 has an R-shaped cross section from the upper surface to the outer peripheral side surface, even if the optical recording medium 2 is inclined, the outer peripheral portion 52 is Has a large contact area and a small contact pressure. Therefore, it is possible to reliably prevent the optical recording medium 2 from being damaged.
[0024]
Here, in the optical recording medium driving device, a cover (not shown) or the like is disposed on the upper surface of the optical recording medium 2, and when the optical recording medium 2 is inclined, the optical recording medium 2 hits the cover. The inclination of 2 is limited to about 5 ° at the maximum. Therefore, the protection member 5 is formed such that the R-shaped outer peripheral portion 52 is always in contact with the optical recording medium 2 when the inclination of the optical recording medium 2 is 5 ° or less.
[0025]
As described above, according to the present embodiment, when the optical recording medium 2 collides with the protective member 5 in a horizontal posture due to an impact applied to the optical recording medium 2, and when the optical recording medium 2 is inclined obliquely, In any case where the optical recording medium 2 contacts the optical recording medium 2, it is possible to reliably prevent the optical recording medium 2 from being damaged because the area where the protective member 5 contacts the optical recording medium 2 is large.
[0026]
(Other embodiments)
In the above-described embodiment, the ring-shaped protective member 2 has a configuration in which the whole in the circumferential direction has a cross-sectional shape having an R-shaped outer peripheral portion. The configuration may be such that the portion has a cross-sectional shape having an R-shaped outer peripheral portion.
[0027]
For example, in the protection member 5 used in the wire suspension type actuator shown in FIG. 1B, as shown in FIGS. 3A and 3B, the side orthogonal to the tracking direction (in the tangent direction / indicated by an arrow TA). In FIG. 3, an inner peripheral side is a horizontal portion 51, and an outer peripheral portion 52 having an R-shape has a cross-sectional shape formed continuously from the horizontal portion 51, while FIGS. 3 (A) and 3 (C). As shown in (1), a configuration having a rectangular cross section in the tracking direction (indicated by an arrow T) may be adopted.
[0028]
【The invention's effect】
As described above, according to the present invention, even when an impact is applied to the optical recording medium and the optical recording medium collides with the protective member in an obliquely inclined posture, the portion where the protective member and the optical recording medium are in contact with each other can be obtained. Since the area is large, it is possible to reliably prevent the optical recording medium from being damaged.
[Brief description of the drawings]
FIGS. 1A and 1B are an explanatory diagram schematically showing an optical head device provided with a shaft sliding and rotating type actuator, and an explanatory diagram of an optical head device provided with a wire suspension type actuator, respectively. is there.
FIGS. 2A to 2D are explanatory views of a protective member and the like used in an optical head device to which the present invention is applied, and explanatory views showing a state in which an optical recording medium collides with a protective member in a horizontal posture. FIG. 4 is an explanatory diagram showing an enlarged cross-sectional shape of the protective member, and an explanatory diagram showing a state in which the optical recording medium collides with the protective member in an obliquely inclined posture.
3A to 3C are explanatory views of a protection member and the like used in another optical head device to which the present invention is applied, and a cross section when the protection member is cut in a direction orthogonal to a tracking direction. FIG. 4 is a diagram and a cross-sectional view when the protection member is cut in the tracking direction.
FIGS. 4A to 4D are explanatory views of a protective member and the like used in a conventional optical head device, an explanatory view showing how an optical recording medium collides with a protective member in a horizontal posture, and a protective member. FIG. 4 is an explanatory diagram showing an enlarged cross-sectional shape of the optical recording medium, and an explanatory diagram showing a state in which the optical recording medium collides with a protective member in an inclined position.
[Explanation of symbols]
3 Objective lens 5 Protective member 6 Chucking mechanism 10 Lens holder 11 Lens holding part 51 Horizontal part 52 on the upper surface of protective member 52. R-shaped outer peripheral part of protective member

Claims

An optical head device having an objective lens for converging light emitted from a light source to an optical recording medium, a lens holder having a lens holding portion on which the objective lens is mounted, and a protection member for covering an outer peripheral edge of the objective lens At
The optical head device, wherein the protection member has a cross-sectional shape having an R shape from an upper surface to an outer peripheral side surface.

The top surface of the protection member according to claim 1, wherein an inner peripheral side is a horizontal portion, and an outer peripheral portion having an R shape is formed continuously from the horizontal portion. Optical head device.

3. The optical head device according to claim 1, wherein the protection member has a ring shape and has a cross-sectional shape having an outer peripheral portion of the R shape in the entire circumferential direction.

3. The optical head device according to claim 1, wherein the protection member has a ring shape, and a part in a circumferential direction has a cross-sectional shape having the R-shaped outer peripheral portion. 4.

5. The cross-sectional shape of the surface of the protective member according to any one of claims 1 to 4, wherein the vicinity of the center is substantially horizontal, and the outermost periphery has an R shape of approximately 5 ° from the horizontal portion. Optical head device.