JP2621200B2 - Objective lens actuator - Google Patents
Objective lens actuatorInfo
- Publication number
- JP2621200B2 JP2621200B2 JP62195501A JP19550187A JP2621200B2 JP 2621200 B2 JP2621200 B2 JP 2621200B2 JP 62195501 A JP62195501 A JP 62195501A JP 19550187 A JP19550187 A JP 19550187A JP 2621200 B2 JP2621200 B2 JP 2621200B2
- Authority
- JP
- Japan
- Prior art keywords
- objective lens
- lens actuator
- shaft
- magnetic circuit
- base
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、光学式記録再生装置の記録再生ヘッド等に
用いられる対物レンズアクチュエータに関する。Description: TECHNICAL FIELD The present invention relates to an objective lens actuator used for a recording / reproducing head of an optical recording / reproducing apparatus.
従来の対物レンズアクチュエータの一例を第２図に示
す。この例では、対物レンズ１は、基台10に設置された
軸７に対しての回転および軸方向の摺動により、二次元
運動を実現する。通常、対物レンズアクチュエータは、
中立点保持のため基台に対してバネ支持される。この
時、対物レンズアクチュエータは共振点を持ち、駆動力
に対する対物レンズアクチュエータの機械的振幅の周波
数特性は第４図のようになる。すなわち、共振周波数f0
において振幅は異常に大きくなりサーボ引き込み時に不
安定になりやすい。この共振を抑制するために各種の対
策が施される。たとえば、ある種のゴム等で作られるこ
とが多いバネ支持部11にダンピング性を持たせたりす
る。この時の、対物レンズアクチュエータの振幅の周波
数特性は第５図のようになり、共振周波数f0における振
幅はおさえられる。しかし、これらの方法ではその材料
に依存するところが大きく特性のばらつきは避けられな
い。また、第２図のアクチュエータの場合、軸７の可動
体２との摩擦が対物レンズアクチュエータの制御特性を
低下させてしまう。FIG. 2 shows an example of a conventional objective lens actuator. In this example, the objective lens 1 realizes a two-dimensional movement by rotation with respect to a shaft 7 mounted on a base 10 and sliding in an axial direction. Usually, the objective lens actuator is
The spring is supported by the base for holding the neutral point. At this time, the objective lens actuator has a resonance point, and the frequency characteristic of the mechanical amplitude of the objective lens actuator with respect to the driving force is as shown in FIG. That is, the resonance frequency f 0
In this case, the amplitude becomes abnormally large and tends to become unstable at the time of servo pull-in. Various measures are taken to suppress this resonance. For example, the spring support portion 11, which is often made of a certain kind of rubber or the like, has a damping property. At this time, the frequency characteristic of the objective lens actuator amplitude is as shown in FIG. 5, the amplitude is suppressed at the resonant frequency f 0. However, these methods largely depend on the material, and variability in characteristics cannot be avoided. In addition, in the case of the actuator shown in FIG. 2, the friction of the shaft 7 with the movable body 2 degrades the control characteristics of the objective lens actuator.
そこで本発明はこのような問題点を解決するためのも
ので、対物レンズを含む可動体と摺動する軸をヨークと
してふくむ磁気回路を構成し、この磁気回路の磁場によ
って軸と可動体との間に磁性流体を保持することによ
り、対物レンズアクチュエータの共振を抑制し、同時に
摩擦も低減させようとするものである。Therefore, the present invention is intended to solve such a problem, and comprises a magnetic circuit including a movable body including an objective lens and a shaft that slides as a yoke, and the magnetic field of the magnetic circuit causes the shaft to be movable. By holding the magnetic fluid in between, the resonance of the objective lens actuator is suppressed, and at the same time, the friction is also reduced.
本発明の対物レンズアクチュエータは、基台に固定さ
れた支軸と、対物レンズが搭載されるとともにコイルが
設けられており、このコイルと磁気回路により前記支軸
に対して回転、摺動される可動体と、を有し、 前記磁気回路は、少なくとも前記基台と前記支軸とイ
ンナーヨークと磁石とにより構成され、前記支軸と前記
可動体との間には磁性流体が充填されてなることを特徴
とする。The objective lens actuator of the present invention is provided with a spindle fixed to a base, an objective lens, and a coil. The coil and a magnetic circuit rotate and slide with respect to the spindle. A movable body, wherein the magnetic circuit includes at least the base, the support shaft, an inner yoke, and a magnet, and a magnetic fluid is filled between the support shaft and the movable body. It is characterized by the following.
また、前記磁石は前記基台と前記インナーヨークとの
間に配置されてなることを特徴とする。Further, the magnet is disposed between the base and the inner yoke.
第１図（ａ）に本発明の対物レンズアクチュエータの
平面図を示す。対物レンズ１の二次元駆動は従来例と同
様、軸７に対する回転および軸方向の摺動により実現さ
れる。FIG. 1 (a) shows a plan view of the objective lens actuator of the present invention. Two-dimensional driving of the objective lens 1 is realized by rotation with respect to the shaft 7 and sliding in the axial direction as in the conventional example.
第１図（ｂ）に第１図（ａ）に対するａ−ａ断面図を
示す。磁気回路は磁石８、インナーヨーク６、アウター
ヨーク４からなる、ループと、磁石８、インナーヨーク
６、軸７からなるループとの２種類ある。この磁気回路
部詳細を第３図に示す。前者の磁気回路はエアギャップ
G1を含み、エアギャップG1中にはフォーカシングコイル
５およびトラッキングコイル３が配置され、これに流す
電流により対物レンズ１を２次元駆動する。後者の磁気
回路はエアギャップG2を含み、エアギャップG2中には可
動体２の軸７と摺動する軸受け部13が配置され、軸受け
部13と軸７との間には磁性流体12が充填され、エアギャ
ップG2中の磁場により保持される。従来、磁性流体を用
いてダンピング効果を狙ったものとしては実開昭58−62
450がある。これはビームを偏向させるガルバノミラー
であり、ミラーを駆動するコイルを配置する磁気回路の
エアギャップ中に磁性流体を充填するというものであ
る。しかし、この場合、可動部であるコイルと固定部で
あるヨークあるいは磁石との間のすきまは通常0.3〜0.5
mmと広いため、磁性流体の保持のためには大きな磁束密
度が必要であり、磁気回路全体が大きくなってしまう。
また、隙間が広いため強いダンピング効果は期待でき
ず、多量の磁性流体を必要とするため高コストとなり、
飛散により、ディスクや光学部品を汚してしまうことが
ある。これに対し、本発明は第１図にしめすような軸に
対する回転と軸方向の摺動により２次元駆動を実現する
対物レンズアクチュエータに対し、軸７と軸受け部13と
のすきまに磁性流体12を充填した。通常このすきまは10
〜20μｍと狭いため前述の問題は生じない。さらに、磁
性流体12の量を加減することにより、可動部に作用する
粘性力を加減することができ、また、軸７と軸受け13と
の間に発生する摩擦力に対しては、磁性流体12の潤滑効
果により、これを低減させることができる。FIG. 1 (b) is a sectional view taken along the line aa of FIG. 1 (a). There are two types of magnetic circuits: a loop composed of the magnet 8, the inner yoke 6, and the outer yoke 4, and a loop composed of the magnet 8, the inner yoke 6, and the shaft 7. FIG. 3 shows the details of the magnetic circuit section. The former magnetic circuit is an air gap
Comprises G 1, focusing coil 5 and the tracking coil 3 is disposed in the air gap G 1, and drives the objective lens 1 2 dimensions by current flowing thereto. The latter magnetic circuit includes an air gap G 2, bearing portion 13 which slides on the shaft 7 of the movable body 2 is disposed in the air gap G 2, between the bearing portion 13 and the shaft 7 ferrofluid 12 There is filled, is held by the magnetic field in the air gap G 2. Conventionally, a magnetic fluid was used to achieve a damping effect.
There are 450. This is a galvanometer mirror that deflects a beam, and fills an air gap of a magnetic circuit in which a coil for driving the mirror is disposed with a magnetic fluid. However, in this case, the clearance between the coil, which is a movable part, and the yoke or magnet, which is a fixed part, is usually 0.3 to 0.5.
Due to the large width of mm, a large magnetic flux density is required to hold the magnetic fluid, and the entire magnetic circuit becomes large.
In addition, a strong damping effect cannot be expected due to the wide gap, and a large amount of magnetic fluid is required, resulting in high cost.
Scattering may contaminate the disc and optical components. On the other hand, in the present invention, the magnetic fluid 12 is applied to the clearance between the shaft 7 and the bearing portion 13 for an objective lens actuator which realizes two-dimensional driving by rotation about the shaft and sliding in the axial direction as shown in FIG. Filled. Usually this gap is 10
The above-mentioned problem does not occur because it is as narrow as ~ 20 µm. Further, by adjusting the amount of the magnetic fluid 12, the viscous force acting on the movable portion can be adjusted, and the frictional force generated between the shaft 7 and the bearing 13 can be reduced. This can be reduced by the lubrication effect of.
以上述べたように、本発明の対物レンズアクチュエー
タにおいては、軸と軸受け部との間に軸を含む磁気回路
を用いて磁性流体を保持することにより、容易に適度な
共振に対するダンピング効果を得ることができ、また、
軸と軸受けとの間に発生する摩擦力を低減させることが
できる。As described above, in the objective lens actuator of the present invention, by using a magnetic circuit including a shaft between a shaft and a bearing portion to hold a magnetic fluid, it is possible to easily obtain an appropriate damping effect on resonance. Can also be
The frictional force generated between the shaft and the bearing can be reduced.
第１図（ａ）は、本発明の対物レンズアクチュエータを
しめす平面図。 第１図（ｂ）は、第１図（ａ）におけるａ−ａ断面図。 第２図（ａ）は、従来の対物レンズアクチュエータをし
めす平面図。 第２図（ｂ）は、第２図（ａ）におけるｂ−ｂ断面図。 第３図は、本発明の対物レンズアクチュエータにおける
磁気回路断面詳細図。 第４図は、ダンピングを施さない場合の対物レンズアク
チュエータの振動振幅の周波数特性図。 第５図は、ダンピングを施した場合の対物レンズアクチ
ュエータの振動振幅の周波数特性図。 １…対物レンズ ２…可動体 ３…トラッキングコイル ４…アウターヨーク ５…フォーカシングコイル ６…インナーヨーク ７…軸 ８、９…磁石 10…基台 11…中立点保持機構 12…磁性流体 13…軸受け部 f0…共振周波数 G1，G2…エアギャップFIG. 1A is a plan view showing an objective lens actuator of the present invention. FIG. 1B is a sectional view taken along a line aa in FIG. 1A. FIG. 2A is a plan view showing a conventional objective lens actuator. FIG. 2B is a cross-sectional view taken along line bb in FIG. 2A. FIG. 3 is a detailed sectional view of a magnetic circuit in the objective lens actuator of the present invention. FIG. 4 is a frequency characteristic diagram of the vibration amplitude of the objective lens actuator when damping is not performed. FIG. 5 is a frequency characteristic diagram of the vibration amplitude of the objective lens actuator when damping is performed. DESCRIPTION OF SYMBOLS 1 ... Objective lens 2 ... Movable body 3 ... Tracking coil 4 ... Outer yoke 5 ... Focusing coil 6 ... Inner yoke 7 ... Shaft 8, 9 ... Magnet 10 ... Base 11 ... Neutral point holding mechanism 12 ... Magnetic fluid 13 ... Bearing part f 0 … Resonant frequency G 1 , G 2 … Air gap
Claims (2)
り、このコイルと磁気回路により前記支軸に対して回
転、摺動される可動体と、を有し、 前記磁気回路は、少なくとも前記基台と前記支軸とイン
ナーヨークと磁石とにより構成され、 前記支軸と前記可動体との間には磁性流体が充填されて
なることを特徴とする対物レンズアクチュエータ。1. A supporting body fixed to a base, an objective lens mounted thereon and a coil provided, and a movable body rotated and slid with respect to the supporting shaft by the coil and a magnetic circuit. Wherein the magnetic circuit includes at least the base, the support shaft, an inner yoke, and a magnet, and a magnetic fluid is filled between the support shaft and the movable body. Objective lens actuator.
との間に配置されてなることを特徴とする特許請求の範
囲第１項記載の対物レンズアクチュエータ。2. The objective lens actuator according to claim 1, wherein said magnet is disposed between said base and said inner yoke.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62195501A JP2621200B2 (en) | 1987-08-05 | 1987-08-05 | Objective lens actuator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62195501A JP2621200B2 (en) | 1987-08-05 | 1987-08-05 | Objective lens actuator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6439641A JPS6439641A (en) | 1989-02-09 |
| JP2621200B2 true JP2621200B2 (en) | 1997-06-18 |
Family
ID=16342134
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62195501A Expired - Fee Related JP2621200B2 (en) | 1987-08-05 | 1987-08-05 | Objective lens actuator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2621200B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR940002829Y1 (en) * | 1991-08-03 | 1994-04-23 | 주식회사 금성사 | Rotary head drum for vtr |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57133528A (en) * | 1981-02-13 | 1982-08-18 | Nippon Telegr & Teleph Corp <Ntt> | Optical head |
| JPS6214336A (en) * | 1985-07-12 | 1987-01-22 | Canon Inc | Optical driving device |
-
1987
- 1987-08-05 JP JP62195501A patent/JP2621200B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57133528A (en) * | 1981-02-13 | 1982-08-18 | Nippon Telegr & Teleph Corp <Ntt> | Optical head |
| JPS6214336A (en) * | 1985-07-12 | 1987-01-22 | Canon Inc | Optical driving device |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6439641A (en) | 1989-02-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |