JPS5930255A - Magnetooptic head - Google Patents
Magnetooptic headInfo
- Publication number
- JPS5930255A JPS5930255A JP13843782A JP13843782A JPS5930255A JP S5930255 A JPS5930255 A JP S5930255A JP 13843782 A JP13843782 A JP 13843782A JP 13843782 A JP13843782 A JP 13843782A JP S5930255 A JPS5930255 A JP S5930255A
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- magnetic thin
- magnetic
- light
- reflected
- 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.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
- G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
- G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
- G11B11/10532—Heads
- G11B11/10541—Heads for reproducing
- G11B11/10543—Heads for reproducing using optical beam of radiation
- G11B11/10547—Heads for reproducing using optical beam of radiation interacting with the magnetisation of an intermediate transfer element, e.g. magnetic film, included in the head
Abstract
Description
【発明の詳細な説明】
本発明は磁気記録媒体（以下、単に記録媒体と呼ぶ）上
に記録された情報を光学的に読み出す磁気−光ヘッドに
関するものであり、特に磁化の変化として高密度に記録
された情報を高効率で高分解能かつ高い信号対雑音比を
もって読み出すことができるようにしたものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic-optical head that optically reads information recorded on a magnetic recording medium (hereinafter simply referred to as a recording medium). This allows recorded information to be read out with high efficiency, high resolution, and a high signal-to-noise ratio.
従来、このような磁化情報の読み出しには、第１図に示
すような構造の磁気−光変換器が提案されている。第１
図に示す記録媒体ｌから生じた磁界によって、この媒体
ｌの表面に接近し、この媒体ｌと平行にならないように
プリズムコと２′トニより保持された磁性薄膜３が磁化
される。その磁化部分に、光源ダから偏光子５およびレ
ンズ６を経て形成した収束光を当てると、カー効果ある
いはファラデー効果によって偏光面の回転が生じ、その
出力光をレンズクより検光子ｇに導き、更に光検出器９
により情報が読み出される。Conventionally, for reading such magnetization information, a magneto-optical converter having a structure as shown in FIG. 1 has been proposed. 1st
The magnetic field generated from the recording medium 1 shown in the figure magnetizes the magnetic thin film 3 which approaches the surface of the medium 1 and is held by the prism head and the 2' edge so as not to be parallel to the medium 1. When the convergent light formed from the light source DA passes through the polarizer 5 and the lens 6 is applied to the magnetized part, the plane of polarization is rotated due to the Kerr effect or Faraday effect, and the output light is guided from the lens to the analyzer g, and further Photodetector 9
The information is read out.
しかし、この磁気−光変換器には次のような欠点がある
。However, this magneto-optical converter has the following drawbacks.
（１） 磁性Ｎ膜３の磁化を検出して電気信号に変換
するための光学系り、５μ、７．ざおよび７が複雑であ
り、その変換器の小型化やこれを高速に動かして必要な
情報トラックへアクセスすることが困難である。(1) Optical system for detecting the magnetization of the magnetic N film 3 and converting it into an electric signal, 5μ, 7. The complexity of the transducer and the difficulty in miniaturizing the transducer and moving it at high speed to access the necessary information tracks is difficult.
（，２） ７アラデー効果を用いて読み出しを行なう
ことから使用される磁性薄膜３の厚さがｚｏｏ Ｘ以下
と薄くものであるため、記録媒体／がら生じる磁界を有
効に磁性薄膜３に集めることができず、したがって、と
くに高密度に記録された情報の読み出しでは性能の低下
が生じる。(,2) Since reading is performed using the 7 Alladay effect, the thickness of the magnetic thin film 3 used is as thin as less than zooX, so the magnetic field generated by the recording medium can be effectively collected on the magnetic thin film 3. Therefore, the performance deteriorates, especially when reading information recorded at high density.
そこで、本発明の目的は、かがる欠点を排除して、記録
媒体に高密度に記録された情報を高能率で高分解能かつ
高い信号対雑音比をもって読み出し得る小型にして、高
性能の磁気−光ヘッドを提供することにある。SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate such drawbacks and to provide a compact and high-performance magnetic recording medium capable of reading out information recorded at high density on a recording medium with high efficiency, high resolution, and a high signal-to-noise ratio. - To provide an optical head.
＝かかる目的を達成するために、本発明は、透明基板上
に第１の磁性薄膜と、金属＃膜と、第一の磁性薄膜とを
′この順序で積層し、前記第一の磁性薄膜を前記第１の
磁性Ｎ膜よりも厚くしたことを特徴とするものである。= In order to achieve such an object, the present invention laminates a first magnetic thin film, a metal film, and a first magnetic thin film in this order on a transparent substrate, and stacks the first magnetic thin film on a transparent substrate. It is characterized in that it is thicker than the first magnetic N film.
以下に図面を参照して本発明の詳細な説明する。The present invention will be described in detail below with reference to the drawings.
本発明磁気−光ヘッドの構成の一例を第、２図に示す。An example of the structure of the magnetic-optical head of the present invention is shown in FIG. 2.
ここで、／／はガラスなどによる透明基板であり、その
断面の一方は放物線を形成するものとする。この側面７
．２は高い反射率をもつ金属膜（たとえば、アルミニウ
ム膜）で被覆しておく。透明基板／／上には第１の磁性
薄膜／Ｊ１非磁性金属薄膜／１１．および第一の磁性′
ｉＩｉ膜／左をこの順序で積層し、更にその第コ磁性薄
膜／左上に保護膜／乙を形成する。Here, // is a transparent substrate made of glass or the like, and one of its cross sections forms a parabola. This side 7
．． 2 is covered with a metal film (for example, an aluminum film) having a high reflectance. Transparent substrate //First magnetic thin film/J1 nonmagnetic metal thin film/11. and the first magnetism′
The iIi film/left is laminated in this order, and the protective film/B is further formed on the upper left of the comagnetic thin film.
ここで、積層された磁性薄膜／３および／３は記録媒体
／の表面に接近し、これと平行しないように保持してお
く。Here, the laminated magnetic thin films /3 and /3 are kept close to the surface of the recording medium / so as not to be parallel to it.
第一図において、記録媒体ｌがら発生した磁界ハ、厚さ
ＸＯＯＡ〜３０００ Ｘの磁性薄膜／！ｒ（たとえばパ
ーマ四イ薄膜）および厚さ１００Ｘ〜Ｊ００ Ｘの磁性
薄膜／３（たとえば鉄薄膜）をその面内方向に磁化する
。In Fig. 1, the magnetic field generated by the recording medium l is a magnetic thin film with a thickness of XOOA~3000X/! A magnetic thin film/3 (for example, an iron thin film) with a thickness of 100X to J00X is magnetized in the in-plane direction.
光源ヶからの平行光は偏光子３を透過して直線偏光光／
ｇとなり、この光／ｇは半透明鏡１０を通った後、本発
明光−磁気ヘッドの透明基板／／に入射する。透明基板
／／に入射した光束は側面７．２で反射されて、磁性薄
膜／３を透過した後、側面／コの放物線の焦点／７に収
束する。この焦点／７の位置には、反射率が高くかつ厚
さ５０八〜、ＺＯＯＡの金属薄膜／りが配置されており
、ここに収束した光束の一部は金属薄膜／りで、また残
りの光束は磁性薄膜／３で再び反射され、さらに側面／
コで反射されて平行光束／９となる。The parallel light from the light source passes through the polarizer 3 and becomes linearly polarized light/
After passing through the semi-transparent mirror 10, this light /g enters the transparent substrate // of the optical-magnetic head of the present invention. The light beam incident on the transparent substrate // is reflected by the side surface 7.2, passes through the magnetic thin film /3, and then converges at the focal point /7 of the parabola on the side surface /C. At the focal point /7, a ZOOA metal thin film with high reflectance and a thickness of 50 mm is placed, and part of the light beam converged here is absorbed by the metal thin film and the rest. The light flux is reflected again by the magnetic thin film /3 and further reflected by the side surface /3.
It is reflected by , resulting in a parallel beam of light /9.
平行光束／９は半透明鏡ＩＯで反射されてレンズクを経
て検光子ｇに入射する。検光子ｇを透過した光は光検出
器９で電気信号に変換される。The parallel light beam /9 is reflected by the semi-transparent mirror IO and enters the analyzer g through the lens. The light transmitted through the analyzer g is converted into an electrical signal by a photodetector 9.
平行光束／ｇは、透明基板／／に入射して再びこの透明
基板／／から出射するまでに記録媒体ｌから発生した磁
界によって磁化された磁性薄膜／３で反射され、または
この磁性薄膜／３を一回透過することによって、その偏
光面はカー効果およびファラデー効果によって回転する
。The parallel light flux /g is reflected by the magnetic thin film /3 magnetized by the magnetic field generated from the recording medium l, or is reflected by the magnetic thin film /3 before it enters the transparent substrate // and exits from the transparent substrate // again. By passing through once, the plane of polarization is rotated by Kerr effect and Faraday effect.
次に本発明磁気−光ヘッドを使用した場合の読み出し可
能な記録密度について述べる。記録媒体ｌとして、第３
図に示すように、Ｃ０−Ｃｒ膜のような垂直磁化膜を用
いた場合、幅すのビットを正しく読み出すためには、ｂ
以下の厚さをもつ磁性薄膜１３を用いる必要がある。例
えば、磁性薄膜１５の厚さを〃θθＡ −、？θθθＡ
とするときには、読み出し可能な線密度はｉｏθＫＢＰ
Ｉ以上となる。また、前述の各薄膜／、３．／’Ｉおよ
び／Ｓで示される積層した磁性薄膜の幅はりソグラフイ
技術によって５μｍ以下とすることができるので、読み
出し可能なトラ゛ンク密度はおよそ３００θＴＰＩとな
る。Next, the readable recording density when using the magnetic-optical head of the present invention will be described. As the recording medium l, the third
As shown in the figure, when using a perpendicular magnetization film such as a C0-Cr film, in order to correctly read the bits of the width
It is necessary to use the magnetic thin film 13 having the following thickness. For example, the thickness of the magnetic thin film 15 is set to θθA −, ? θθθA
Then, the readable linear density is ioθKBP
I or more. In addition, each of the above-mentioned thin films/, 3. Since the width of the laminated magnetic thin films indicated by /'I and /S can be reduced to 5 μm or less using the lithography technique, the readable trunk density is approximately 300θTPI.
第ｑ図は本発明磁気−光ヘッドの他の例を示し、ここで
は、各薄膜／３．／’！および／ｊと保護膜／６とから
なる積層磁性簿膜ユニット〃、コ／および、２コを７個
の透明基板／／に対して並置し、これらユニット〃、コ
／および、２ｊの各々を記録媒体ｌ上の記録トラック、
２．？、２＆およびＪの位置に対応させる。ここで、透
明基板／／に入射する光は、各ユニット曜、２／および
！、２に関連づけられた光ビーム、例えば各ユニッ）Ｊ
、、２／および二に対応する個別の光ビームあるいはこ
れらユニットをすべて光合するスリット状光ビームとす
る。かかる光ビームを透明基板／／に入射させる″こと
によって、複数本のトラック、２３゜−りおよび５の情
報を個別の光検出器、２Ａ、２７およびＨによって同時
に読み出すことができる。FIG. q shows another example of the magneto-optical head of the present invention, in which each thin film/3. /'! A laminated magnetic film unit consisting of a protective film /6 and a protective film /6 is placed side by side with respect to seven transparent substrates //, and each of these units 〃, ko/ and 2j is a recording track on a recording medium l;
2. ? , 2 & and J positions. Here, the light incident on the transparent substrate // is for each unit YO, 2/ and ! , 2, e.g. each unit) J
, 2/ and 2, or a slit-shaped light beam that combines all of these units. By making such a light beam incident on the transparent substrate //, information on a plurality of tracks 23 DEG and 5 can be read out simultaneously by individual photodetectors 2A, 27 and H.
以上述べたごとく、本発明磁気−光ヘッドは、記録媒体
ｌから発生する磁界を比較的厚い磁性薄膜／３によって
能率よく集めるとともに、磁性薄膜１５に近接する簿い
磁性薄膜／３を用いて磁気光学的に読み出すものである
。As described above, the magneto-optical head of the present invention efficiently collects the magnetic field generated from the recording medium 1 by the relatively thick magnetic thin film /3, and uses the thin magnetic thin film /3 adjacent to the magnetic thin film 15 to efficiently collect the magnetic field generated from the recording medium l. It is read out optically.
ここで、金属薄膜／４’は反射率を改善するとともに、
磁性薄膜／夕と磁性薄膜／３の磁気的相互作用を強める
働きをもつ。このため、記録媒体ｌから発生する磁界に
よって、磁性薄膜／３は強く磁化される０
この時、読み出しに用いる光の収束スポットの大きさは
、読み出しの分解能には無関係であり、磁性薄膜／３と
してファラデー効果が大きく、キュリ一温度の高い材料
（たとえば、鉄薄膜）を用いれば、読み出し時の入射光
の強度を大きくすることができることから、本発明によ
れば、大きな信号対雑音比を得ることができる。Here, the metal thin film /4' improves the reflectance and
It has the function of strengthening the magnetic interaction between the magnetic thin film/3 and the magnetic thin film/3. Therefore, the magnetic thin film/3 is strongly magnetized by the magnetic field generated from the recording medium l. At this time, the size of the convergent spot of the light used for reading is unrelated to the reading resolution; If a material with a large Faraday effect and a high Curie temperature (for example, an iron thin film) is used, the intensity of the incident light during readout can be increased, so according to the present invention, a large signal-to-noise ratio can be obtained. be able to.
さらにまた、本発明では、光の入射および出射はヘッド
に対して垂直に行われるので、光学系の構成が単純化さ
れる。Furthermore, in the present invention, since the light enters and exits perpendicularly to the head, the configuration of the optical system is simplified.
しかもまた、ヘッドの側面／、２の放物線の焦点をヘッ
ド先端部にもってくることができるため、記録媒体ｌか
ら生じる磁界によって強く磁化された磁性薄膜１３の先
端部の信号を読み出すことができ、したがって確実な読
み出しが行なわれる。Moreover, since the focus of the parabola on the side surface of the head can be brought to the tip of the head, it is possible to read the signal at the tip of the magnetic thin film 13, which is strongly magnetized by the magnetic field generated from the recording medium l. Therefore, reliable reading is performed.
さて、本発明磁気−光ヘッドでは磁性薄膜／Ｓの厚さが
Ｈｏｏ Ａの場合には、線密度１０ＯＫＢＰＩまで読み
出し出力の低下はない。従来の読み出し方法では、主磁
極の磁性膜厚の整数倍の逆数にＡる線密度で出力の大き
な減衰があるが、本発明磁気−光ヘッドではこのような
不都合を生じない。さらに、本発明による磁気−光ヘッ
ドは小型化（たとえば、直径／＊ｍＸ長さコ朋以下）で
きるため、光ファイバへの接続が可能であり、また、軽
量であるからトラッキングあるいは高速アクセスに対し
て極めて有利である。Now, in the magneto-optical head of the present invention, when the thickness of the magnetic thin film /S is Hoo A, there is no drop in readout output up to a linear density of 10 OK BPI. In the conventional readout method, there is a large attenuation of the output at a linear density A that is the reciprocal of the integer multiple of the magnetic film thickness of the main pole, but the magneto-optical head of the present invention does not suffer from this problem. Furthermore, the magneto-optical head according to the present invention can be miniaturized (for example, less than diameter/*m x length), so it can be connected to an optical fiber, and it is lightweight, making it suitable for tracking or high-speed access. This is extremely advantageous.
第夕図に示した実施例では、レンズ７によって反射光／
ｑをトラック２３．．２’ｌおよび、２左に対応して分
割し、それぞれに光検出器コ／、、、２７および２ｇを
配置することにより複数トラックに対する読み出しが可
能であり、入射光／−ざの分割という複雑な光学系は必
要でない利点がある。In the embodiment shown in FIG.
Track q23. ．． It is possible to read out multiple tracks by dividing the tracks corresponding to 2'l and 2' left and arranging photodetectors 2'l and 27 and 2g, respectively, and it is possible to read out multiple tracks. This has the advantage that no optical system is required.
第１図は従来の磁気−光変換器の構成を示す断面図、第
２図は本発明磁気−光ヘッドの構成の一例を示す断面図
、第３図は本発明磁気−光へ゛ンドを垂直磁気記録媒体
に記録された情報の読み出しに用いる場合を示す断面図
、第９図は複数の記録トラックを読み出すようにした本
発明磁気−光へラードの他の例を示す構成図である。
ｌ・・・記録媒体、
コ２．２′・・・プリズム、
３・・・磁性薄膜、
ダ・・・光源、
３・・・偏光子、
６．７・・・レンズ、
ｔ・・・検光子、
？ 、 、ｕ、 ２７． ：ｔｇ・・・光検出器、１０
・・・半透明鏡、
／か・・透明基板、
７．２・・・側面、
／３．／！；・・・磁性薄膜、
／り・・・非磁性金ＭＭ膜、
／６・・・保護膜、
／７・・・焦点、
７ｇ・・・直線偏光光、
／９・・・平行光束、
Ｊ、−／、ココ・・・ユニット１
、ｌＪ、２＜４．お・・・記録トラック。FIG. 1 is a cross-sectional view showing the configuration of a conventional magneto-optical converter, FIG. 2 is a cross-sectional view showing an example of the configuration of the magnetic-optical head of the present invention, and FIG. 3 is a cross-sectional view showing an example of the configuration of the magnetic-optical head of the present invention. FIG. 9 is a cross-sectional view showing the case where the information is read out from a magnetic recording medium, and FIG. 9 is a configuration diagram showing another example of the magnetic-optical heald according to the present invention, which is adapted to read out a plurality of recording tracks. l...recording medium, 2.2'...prism, 3...magnetic thin film, da...light source, 3...polarizer, 6.7...lens, t...detection Photon, ? , ,u, 27. :tg...photodetector, 10
...semi-transparent mirror, /...transparent substrate, 7.2...side surface, /3. /! ;...magnetic thin film, /ri...non-magnetic gold MM film, /6...protective film, /7...focal point, 7g...linearly polarized light, /9...parallel light flux, J , -/, here... unit 1 , lJ, 2<4. Oh... recording track.
Claims (1)
の磁性薄膜とをこの順序で積層し、前記第一の磁性薄膜
を前記第１の磁性薄膜よりも厚くしたことを特徴とする
磁気−光ヘッド０ ．２、特許請求の範囲第１項記載の磁気−光ヘッドにお
いて、前記第１の磁性薄膜の厚さをｉｏ。 ｒＯＡ−ＭＯＡに設定し、前記第２の磁性薄膜機とする
磁気−光ヘッド。 ３）特許請求の範囲第１項または第一項記載の磁気−光
ヘッドにおいて、前記透明基板を、その一方の側面が、
放物線へ状の断面を持つように形成したことを特徴とす
る磁気−光ヘッド０[Scope of Claims] /) A first magnetic thin film, a metal thin film, and a first magnetic thin film are laminated in this order on a transparent substrate, and the first magnetic thin film is stacked on top of the first magnetic thin film. A magneto-optical head 0. 2. In the magneto-optical head according to claim 1, the thickness of the first magnetic thin film is io. The magneto-optical head is set to rOA-MOA and serves as the second magnetic thin film machine. 3) In the magneto-optical head according to claim 1 or 1, one side surface of the transparent substrate is
A magnetic-optical head 0 characterized in that it is formed to have a parabolic cross section.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13843782A JPS5930255A (en) | 1982-08-11 | 1982-08-11 | Magnetooptic head |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13843782A JPS5930255A (en) | 1982-08-11 | 1982-08-11 | Magnetooptic head |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5930255A true JPS5930255A (en) | 1984-02-17 |
| JPH0355894B2 JPH0355894B2 (en) | 1991-08-26 |
Family
ID=15221957
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13843782A Granted JPS5930255A (en) | 1982-08-11 | 1982-08-11 | Magnetooptic head |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5930255A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL8403951A (en) * | 1983-12-29 | 1985-07-16 | Fuji Photo Film Co Ltd | METHOD AND APPARATUS FOR REPRODUCING MAGNETIC INFORMATION. |
| US5488598A (en) * | 1985-02-28 | 1996-01-30 | Canon Kabushiki Kaisha | Optical pickup using split beams impinging on different photodetector areas |
| US5689391A (en) * | 1989-12-28 | 1997-11-18 | Thomson Consumer Electronics | Magneto-optic multitrack reading head having a plurality of reflective rays |
| KR100439374B1 (en) * | 2001-09-13 | 2004-07-09 | 엘지전자 주식회사 | Optical pickup |
| KR100508418B1 (en) * | 1997-11-06 | 2005-11-24 | 후지제롯쿠스 가부시끼가이샤 | Optical Heads and Optical Disc Devices |
| JP2008290246A (en) * | 2008-08-25 | 2008-12-04 | Yamato Protec Co | Method and device for disassembling fire extinguisher |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5633781A (en) * | 1979-08-28 | 1981-04-04 | Omron Tateisi Electronics Co | Line printer |
| JPS5727450A (en) * | 1980-07-23 | 1982-02-13 | Ricoh Co Ltd | Magnetic recording medium |
-
1982
- 1982-08-11 JP JP13843782A patent/JPS5930255A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5633781A (en) * | 1979-08-28 | 1981-04-04 | Omron Tateisi Electronics Co | Line printer |
| JPS5727450A (en) * | 1980-07-23 | 1982-02-13 | Ricoh Co Ltd | Magnetic recording medium |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL8403951A (en) * | 1983-12-29 | 1985-07-16 | Fuji Photo Film Co Ltd | METHOD AND APPARATUS FOR REPRODUCING MAGNETIC INFORMATION. |
| US5488598A (en) * | 1985-02-28 | 1996-01-30 | Canon Kabushiki Kaisha | Optical pickup using split beams impinging on different photodetector areas |
| US5689391A (en) * | 1989-12-28 | 1997-11-18 | Thomson Consumer Electronics | Magneto-optic multitrack reading head having a plurality of reflective rays |
| KR100508418B1 (en) * | 1997-11-06 | 2005-11-24 | 후지제롯쿠스 가부시끼가이샤 | Optical Heads and Optical Disc Devices |
| KR100439374B1 (en) * | 2001-09-13 | 2004-07-09 | 엘지전자 주식회사 | Optical pickup |
| JP2008290246A (en) * | 2008-08-25 | 2008-12-04 | Yamato Protec Co | Method and device for disassembling fire extinguisher |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0355894B2 (en) | 1991-08-26 |
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