JP2697007B2 - Objective lens actuator - Google Patents
Objective lens actuatorInfo
- Publication number
- JP2697007B2 JP2697007B2 JP26653488A JP26653488A JP2697007B2 JP 2697007 B2 JP2697007 B2 JP 2697007B2 JP 26653488 A JP26653488 A JP 26653488A JP 26653488 A JP26653488 A JP 26653488A JP 2697007 B2 JP2697007 B2 JP 2697007B2
- Authority
- JP
- Japan
- Prior art keywords
- objective lens
- coil
- lens actuator
- optical axis
- permanent magnet
- 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 - Lifetime
Links
Landscapes
- Optical Recording Or Reproduction (AREA)
Description
【発明の詳細な説明】 〔従来の技術〕 従来、この種の対物レンズアクチュエータは、光ディ
スク面に光スポットを正確にあてるため、フォーカスを
調整するフォーカシングと位置ずれを調整するトラッキ
ングを行なう。このため、対物レンズアクチュエータ
は、磁力線を発生する永久磁石と、光軸方向に駆動力を
発生するフォーカシングコイルおよび光軸に対し垂直方
向に駆動力を発生するトラッキングコイルの２つのコイ
ルと、そのコイルの駆動力に対し、反力を発生するバネ
材とを有している。Description of the Related Art [0002] Conventionally, an objective lens actuator of this type performs focusing for adjusting a focus and tracking for adjusting a position shift in order to accurately place a light spot on an optical disk surface. For this purpose, the objective lens actuator is composed of two coils: a permanent magnet that generates a line of magnetic force, a focusing coil that generates a driving force in the optical axis direction, and a tracking coil that generates a driving force in a direction perpendicular to the optical axis. And a spring member that generates a reaction force with respect to the driving force.
第６図に、従来例の外観図を示す。 FIG. 6 shows an external view of a conventional example.
レンズホルダ20は、棒状のバネ材10によって支持さ
れ、対物レンズ１を保持している。レンズホルダ20に設
けられた開口穴内には、ヨーク2A,2Bが、これらヨーク2
A,2Bと対向位置には永久磁石13A,13Bが配設されてお
り、レンズホルダの永久磁石13A,13Bの対向部および側
部に設けられたトラックコイル4a,4b,5a,5bおよびフォ
ーカスコイル６との磁気作用によりレンズのトラッキン
グ移動およびフォーカシング移動が行われる。第４図に
トラックコイル4a,4bと永久磁石による磁界の関係を示
す。The lens holder 20 is supported by the rod-shaped spring material 10 and holds the objective lens 1. In the opening hole provided in the lens holder 20, the yokes 2A and 2B
Permanent magnets 13A and 13B are disposed at positions facing A and 2B, respectively, and track coils 4a, 4b, 5a and 5b and focus coils provided at the facing and side portions of the permanent magnets 13A and 13B of the lens holder. The tracking and focusing movements of the lens are performed by the magnetic action with the lens 6. FIG. 4 shows the relationship between the track coils 4a and 4b and the magnetic field generated by the permanent magnet.
上述した従来の対物レンズアクチュエータは、次のよ
うな問題点がある。The above-mentioned conventional objective lens actuator has the following problems.
トラックコイル4a,4b,5a,5bは、永久磁石13a,13bの発
生する磁界において、２つの方向の電流成分、即ち、ト
ラッキングのための駆動力となる光軸に平行な成分（Ｙ
方向）と、光軸方向と垂直方向の成分（Ｘ方向）とをも
つ（第４図参照）。一般に、Ｘ方向（光軸と直角方向）
に流れる電流成分はコイルの対向辺で互いに逆方向であ
るため両電流により生ずる磁気力は互いに相殺されなけ
ればならない。このため第７図に示す永久磁石の磁束密
度の分布に対し、第８図Ａのような関係でコイルを配置
している。しかし、フォーカシング等の動作により、ト
ラックコイル4a,4b,5a,5bの光軸方向の移動が起きる
と、第８図ＢまたはＣのように磁石中心からコイル中心
位置がずれると、トラックコイル4a,4b,5a,5bの２つの
辺で、異なる大きさの磁気力が発生し、モーメントによ
り対物レンズアクチュエータにずれが生じる。The track coils 4a, 4b, 5a, 5b generate current components in two directions in the magnetic field generated by the permanent magnets 13a, 13b, that is, a component parallel to the optical axis serving as a driving force for tracking (Y
Direction) and a component (X direction) perpendicular to the optical axis direction (see FIG. 4). Generally, in the X direction (perpendicular to the optical axis)
Current components flowing in opposite directions on the opposite sides of the coil, the magnetic forces generated by both currents must cancel each other. For this reason, the coils are arranged in the relationship shown in FIG. 8A with respect to the distribution of the magnetic flux density of the permanent magnet shown in FIG. However, when the track coils 4a, 4b, 5a, 5b move in the optical axis direction due to an operation such as focusing, when the coil center position is shifted from the magnet center as shown in FIG. 8B or C, the track coils 4a, Magnetic forces of different magnitudes are generated on the two sides 4b, 5a, 5b, and the moment causes a displacement of the objective lens actuator.
本発明の対物レンズアクチュエータは、特に、フォー
カシングを行なう第１のコイルと、トラッキングを行な
う第２のコイルと、これら２つのコイルに対し磁界を与
える永久磁石とを有し、前記第２のコイルが前記磁界内
で矩形状である対物レンズアクチュエータにおいて、前
記第２のコイルの駆動力の中心付近に前記第１のコイル
に平行な線に沿って少なくとも１つの凹部を設けた高透
磁率の材料の板を前記永久磁石のコイルに対向する面に
接着したことを特徴としている。The objective lens actuator of the present invention has, in particular, a first coil for performing focusing, a second coil for performing tracking, and a permanent magnet for applying a magnetic field to these two coils. In the objective lens actuator having a rectangular shape in the magnetic field, a material having high magnetic permeability in which at least one concave portion is provided near a center of a driving force of the second coil along a line parallel to the first coil. A plate is bonded to a surface of the permanent magnet facing the coil.
次に本発明について図面を参照して説明する。 Next, the present invention will be described with reference to the drawings.
第１図は、本発明の一実施例の斜視図を示す。 FIG. 1 shows a perspective view of one embodiment of the present invention.
レンズホルダ20に取付けられた対物レンズ１は、その
光軸方向及び光軸と直交する方向（トラッキング方向）
に移動可能に４本のバネ10により、ベース100に保持さ
れている。The objective lens 1 attached to the lens holder 20 has an optical axis direction and a direction orthogonal to the optical axis (tracking direction).
And is held on the base 100 by four springs 10 so as to be movable.
対物レンズ光軸に直交する方向に磁極を有する永久磁
石3A,3Bを対物レンズ光軸を挟持する様に配置し永久磁
石3A,3Bとセンタヨーク2A,2Bの間に矩形状に差込んだト
ラックコイル4a,4b及び5a,5bを配した構成の対物レンズ
アクチュエータにおいて前記永久磁石3A,3B表面に対物
レンズ１の光軸と直交する方向でトラックコイル3A,3B
の光軸方向中心近傍に矩形ミゾを有した鉄板50,51を着
接した構成を有している。Tracks in which permanent magnets 3A and 3B having magnetic poles in the direction orthogonal to the optical axis of the objective lens are arranged so as to sandwich the optical axis of the objective lens, and are inserted in a rectangular shape between the permanent magnets 3A and 3B and the center yokes 2A and 2B. In the objective lens actuator having the coils 4a, 4b and 5a, 5b, the track coils 3A, 3B are disposed on the surfaces of the permanent magnets 3A, 3B in a direction perpendicular to the optical axis of the objective lens 1.
And iron plates 50 and 51 having rectangular grooves near the center of the optical axis direction.
永久磁石3A,3Bとセンタヨーク2A,2B間の、磁束密度分
布は第２図に示す実測値より矩形ミゾを有する鉄板50,5
1を着接した事により中心部近傍の磁束密度分布が凹状
に減少する。これにより、第３図Ａに示す様に前記磁束
密度分布の中のトラックコイルが磁束密度分布の中心に
位置する場合と第３図Ｂ、上方に位置する場合、及び第
３図Ｃ下方向に位置する場合、それぞれにおいて、図中
トラックコイル上方断面部と、下方断面部に受ける磁束
密度変化が少なくなる。したがって、第４図に示す様に
トラックコイルに電流が流れる事により、発生するモー
メントは第５図に示す様にモーメントM1及びモーメント
M2となるがその差が少なくなり互いに打ち消し合う事と
なる。The magnetic flux density distribution between the permanent magnets 3A, 3B and the center yokes 2A, 2B is shown in FIG.
The magnetic flux density distribution in the vicinity of the central portion is reduced in a concave shape by attaching 1. Thus, as shown in FIG. 3A, when the track coil in the magnetic flux density distribution is located at the center of the magnetic flux density distribution, in FIG. 3B, when it is located above, and in FIG. In each case, the change in magnetic flux density applied to the upper cross section and the lower cross section of the track coil in FIG. Therefore, a current flows through the tracking coils as shown in FIG. 4, the moment generated moments M 1 and moment as shown in FIG. 5
The M 2 becomes a that cancel each other becomes the difference is less.
この様に、上記構成によれば、レンズホルダ20に発生
する不要な回動モーメントは極めて少なくなり、トラッ
クコイルの光軸と平行に電流が流れる事により発生する
光軸と直交する力の成分のみが、有効となり良好なトラ
ッキング動作特性が得られる。As described above, according to the above configuration, unnecessary rotation moment generated in the lens holder 20 is extremely reduced, and only a component of a force orthogonal to the optical axis generated by current flowing in parallel with the optical axis of the track coil is generated. Is effective, and good tracking operation characteristics can be obtained.
以上説明した様に、本発明はトラックコイルを挟持す
る永久磁石にミゾを形成した鉄板を着接するという簡単
な構成で磁束密度を、大きく減少させる事なく良好なト
ラッキング動作特性を有する対物レンズアクチュエータ
を提供できる効果がある。As described above, the present invention provides an objective lens actuator having a good tracking operation characteristic without greatly reducing the magnetic flux density with a simple configuration in which a grooved iron plate is attached to a permanent magnet holding a track coil. There are effects that can be provided.
なお、本発明の効果は実施例によるアクチュエータ構
成のみならず、本例同様に光軸方向に直交する磁極を有
する対物レンズアクチュエータで光軸と平行に配置した
矩形状及びリング状のトラックコイルを該永久磁石の発
生する磁束中に配置してトラッキング動作を行う構成の
アクチュエータには、すべて同様の効果が得られる。The effect of the present invention is not only the actuator configuration according to the embodiment, but also a rectangular and ring-shaped track coil arranged in parallel with the optical axis by an objective lens actuator having a magnetic pole perpendicular to the optical axis direction as in the present embodiment. The same effect can be obtained for all actuators configured to perform the tracking operation by being arranged in the magnetic flux generated by the permanent magnet.
さらに、永久磁石に着接した鉄板に形成したミゾの形
状は本例に限定されるものではない。Furthermore, the shape of the groove formed on the iron plate that is in contact with the permanent magnet is not limited to this example.
第１図は本発明の上方斜視図、第２図は本発明の永久磁
石の磁束密度分布図、第３図は本発明の磁束密度分布中
のトラックコイル配置を示す説明図、第４図はトラック
コイルの光軸方向に対する電流の流れを示す説明図、第
５図はトラックコイルに発生する回転モーメントを示す
説明図、第６図は従来例の上方斜視図、第７図は従来例
の永久磁石の磁束密度分布図、第８図は磁束密度分布中
のトラックコイル配置を示す説明図。 １……対物レンズ、2A,2B……センタヨーク、3A,3B……
永久磁石、4a,4b,5a,5b……トラックコイル、６……フ
ォーカスコイル、10……バネ、20……レンズホルダ、5
1,52……鉄板、100……ベース。1 is an upper perspective view of the present invention, FIG. 2 is a magnetic flux density distribution diagram of the permanent magnet of the present invention, FIG. 3 is an explanatory diagram showing the arrangement of track coils in the magnetic flux density distribution of the present invention, and FIG. FIG. 5 is an explanatory view showing the flow of current in the optical axis direction of the track coil, FIG. 5 is an explanatory view showing a rotational moment generated in the track coil, FIG. 6 is an upper perspective view of the conventional example, and FIG. FIG. 8 is a diagram showing a magnetic flux density distribution of a magnet, and FIG. 8 is an explanatory diagram showing a track coil arrangement in the magnetic flux density distribution. 1 Objective lens, 2A, 2B Center yoke, 3A, 3B
Permanent magnet, 4a, 4b, 5a, 5b… track coil, 6… focus coil, 10… spring, 20… lens holder, 5
1,52 ... iron plate, 100 ... base.
Claims (1)
第１と第２のコイルにより駆動される対物レンズを介し
て、光学ヘッドから発射される光ビームのディスク面に
垂直方向の微調整（フォーカシング）とディスクの半径
方向の微調整（トラッキング）とを行なう対物レンズア
クチュエータにおいて、前記第２のコイルが前記磁界内
で矩形状であるとともに前記第２のコイルの駆動力の中
心付近に前記第１のコイルに平行な線に沿って少なくと
も１つの凹部を設けた高透磁率の材料の板を前記永久磁
石のコイルに対向する面に接着したことを特徴とする対
物レンズアクチュエータ。1. Fine adjustment of a light beam emitted from an optical head in a direction perpendicular to a disk surface via an objective lens driven by a permanent magnet and first and second coils fixed to the objective lens side. Focusing) and fine adjustment (tracking) in the radial direction of the disk in the objective lens actuator, wherein the second coil is rectangular in the magnetic field, and the second coil is located near the center of the driving force of the second coil. An objective lens actuator, wherein a plate made of a material having high magnetic permeability and having at least one concave portion provided along a line parallel to one coil is bonded to a surface of the permanent magnet facing the coil.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26653488A JP2697007B2 (en) | 1988-10-21 | 1988-10-21 | Objective lens actuator |
| US07/412,717 US5073882A (en) | 1988-09-26 | 1989-09-26 | Servo-controlled actuator with two-peak flux density distribution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26653488A JP2697007B2 (en) | 1988-10-21 | 1988-10-21 | Objective lens actuator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02113445A JPH02113445A (en) | 1990-04-25 |
| JP2697007B2 true JP2697007B2 (en) | 1998-01-14 |
Family
ID=17432206
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP26653488A Expired - Lifetime JP2697007B2 (en) | 1988-09-26 | 1988-10-21 | Objective lens actuator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2697007B2 (en) |
-
1988
- 1988-10-21 JP JP26653488A patent/JP2697007B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02113445A (en) | 1990-04-25 |
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