JPH0453046A - Magneto-optical recording medium - Google Patents
Magneto-optical recording mediumInfo
- Publication number
- JPH0453046A JPH0453046A JP16209890A JP16209890A JPH0453046A JP H0453046 A JPH0453046 A JP H0453046A JP 16209890 A JP16209890 A JP 16209890A JP 16209890 A JP16209890 A JP 16209890A JP H0453046 A JPH0453046 A JP H0453046A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic
- magneto
- recording
- film
- magnetic film
- 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
- 230000005291 magnetic effect Effects 0.000 claims abstract description 132
- 239000000758 substrate Substances 0.000 claims abstract description 18
- 230000004907 flux Effects 0.000 abstract description 14
- 230000005415 magnetization Effects 0.000 abstract description 7
- 230000005381 magnetic domain Effects 0.000 description 8
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 2
- 239000004417 polycarbonate Substances 0.000 description 2
- 239000004926 polymethyl methacrylate Substances 0.000 description 2
- 239000004593 Epoxy Substances 0.000 description 1
- 229910003271 Ni-Fe Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229910000889 permalloy Inorganic materials 0.000 description 1
- 239000012994 photoredox catalyst Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、レーザー光等の光により情報を光磁気記録し
、磁気再生する光磁気記録媒体に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording medium in which information is magneto-optically recorded using light such as a laser beam and reproduced magnetically.
光磁気記録媒体としての光磁気ディスク１３は、第２図
に示すように、基本的に透明な基板３上に磁性膜５を形
成したものであり、これに磁界変調により情報の記録を
行う場合、一定強度のレーザー光１を対物レンズ２でス
ポット状に集光して、上記基板側３から磁性膜５に照射
する。そして、照射領域の温度をキュリー温度近傍まで
昇温しで磁性膜５の抗磁力を低下させ、この状態で記録
情報に応じて反転する磁界を記録用磁気ヘッド７より上
記照射領域に印加することによって、磁性膜４の磁化（
矢印で示されている）を反転させ、情報の記録が行われ
る。一方、情報の再生を行う場合、記録時よりも弱い一
定強度のレーザー光ｌを、上記と同様に対物レンズ２で
スポット状に集光して、上記基板側３から磁性膜５に照
射する。As shown in FIG. 2, a magneto-optical disk 13 as a magneto-optical recording medium basically has a magnetic film 5 formed on a transparent substrate 3, and when information is recorded on this by magnetic field modulation. A laser beam 1 of a constant intensity is focused into a spot by an objective lens 2, and is irradiated onto the magnetic film 5 from the substrate side 3. Then, the temperature of the irradiated area is raised to near the Curie temperature to lower the coercive force of the magnetic film 5, and in this state, a magnetic field that reverses depending on the recorded information is applied to the irradiated area from the recording magnetic head 7. The magnetization of the magnetic film 4 (
(indicated by an arrow) is reversed to record information. On the other hand, when reproducing information, a laser beam l having a constant intensity weaker than that during recording is focused into a spot by the objective lens 2 and irradiated onto the magnetic film 5 from the substrate side 3 in the same manner as described above.
そして、反射光における偏光面の回転を検出することに
より、情報の再生が行われる。Information is then reproduced by detecting the rotation of the plane of polarization in the reflected light.
上記磁界変調による光磁気記録において、記録周波数を
高くすると、第１３回日本応用磁気学会学術講演概要集
（１，９８９）第１９８頁に記載されているように、光
磁気ディスク１３上の磁区形状は、三日月型となること
が知られている。すなわち、第３図に示すように、光磁
気ディスク１３上のトラック１６が、光ビームスポット
１４に対して左方向く図の矢印方向）に回転している場
合、光ビームスポット１４内の昇温領域は左側から冷え
て行き、それに伴って抗磁力も大きくなって行く。そし
て、抗磁力が記録用磁気ヘッドの印加磁界よりも大きく
なるまで温度が下がると、磁化は印加磁界の方向に揃わ
なくなり、直前の情報を記憶することになる。このため
、磁区１５・・・の形状は、光ビームスポット１４の左
側の形状を反映して、図のように、左に凸の三日月型に
なっている。In magneto-optical recording using the above magnetic field modulation, when the recording frequency is increased, the shape of the magnetic domain on the magneto-optical disk 13 changes as described in the 13th Japan Society of Applied Magnetics Academic Conference Abstracts (1,989), page 198. is known to be crescent-shaped. That is, as shown in FIG. 3, when the track 16 on the magneto-optical disk 13 is rotating to the left with respect to the light beam spot 14 (in the direction of the arrow in the figure), the temperature within the light beam spot 14 increases. The area cools from the left side, and the coercive force increases accordingly. Then, when the temperature drops until the coercive force becomes larger than the applied magnetic field of the recording magnetic head, the magnetization is no longer aligned in the direction of the applied magnetic field, and the immediately previous information is stored. Therefore, the shape of the magnetic domains 15... reflects the shape of the left side of the light beam spot 14, and has a crescent shape convex to the left as shown in the figure.
この三日月型の磁区１５の大きさは、光ビームスポット
１４よりも小さく、記録周波数を高くすることにより、
さらに小さくなる。したがって、記録周波数を高くする
と、記録密度を上げることができる。The size of this crescent-shaped magnetic domain 15 is smaller than the light beam spot 14, and by increasing the recording frequency,
It gets even smaller. Therefore, by increasing the recording frequency, the recording density can be increased.
ところが、上記従来の構成では、記録周波数を高くして
高密度記録した場合、光ビームスポット１４内に複数の
磁区１５・・・が存在することになり、このために、反
射光における偏光面の回転を検出することにより情報を
再生することは困難になるという問題点を有している。However, in the conventional configuration described above, when high-density recording is performed by increasing the recording frequency, a plurality of magnetic domains 15 exist within the light beam spot 14, which causes the polarization plane of the reflected light to change. The problem is that it is difficult to reproduce information by detecting rotation.
本発明の光磁気記録媒体は、上記の課題を解決するため
に、透明な基体上に磁性膜を形成し、レーザー光等の光
により情報を記録する光磁気記録媒体において、上記基
体と磁性膜の間に軟磁性層が設けられていることを特徴
としている。In order to solve the above problems, the magneto-optical recording medium of the present invention is a magneto-optical recording medium in which a magnetic film is formed on a transparent substrate and information is recorded using light such as a laser beam. It is characterized in that a soft magnetic layer is provided in between.
上記の構成によれば、基体と磁性膜の間に軟磁性層を設
けたので、例えば主磁極と補助磁極を備えた再生用磁気
ヘッドにより情報を再生する場合、磁性膜から出て主磁
極に入った磁束は、補助磁極から出た後、軟磁性層を通
って容易に磁性膜の元の位置に戻ることができる。この
ため、磁性膜５から出た磁束の多くが主磁極に入って来
ることになり、再生出力が増加する。これにより、高密
度記録された情報を効率的に再生できる。According to the above structure, since the soft magnetic layer is provided between the base and the magnetic film, when reproducing information using a magnetic reproducing head equipped with a main magnetic pole and an auxiliary magnetic pole, for example, the soft magnetic layer comes out from the magnetic film and reaches the main magnetic pole. After the entered magnetic flux exits from the auxiliary magnetic pole, it can easily return to its original position in the magnetic film through the soft magnetic layer. Therefore, most of the magnetic flux emitted from the magnetic film 5 enters the main magnetic pole, increasing the reproduction output. Thereby, information recorded at high density can be efficiently reproduced.
本発明の一実施例を第１図に基づいて説明すれば、以下
のとおりである。なお、従来例の図面で示した部材と同
一の機能を有する部材には、同一の符号を付記する。An embodiment of the present invention will be described below based on FIG. Note that members having the same functions as those shown in the drawings of the conventional example are given the same reference numerals.
本発明の光磁気記録媒体としての光磁気ディスク１３は
、第１図に示すように、透明な基板３（基体）上に、面
内磁化を通しやすい高透磁率の軟磁性体からなる軟磁性
層４と、磁性１１５とを順次形成して構成になっている
。また、らせん状の案内溝（図示されていない）が、基
板３の軟磁性層４側に形成されている。As shown in FIG. 1, the magneto-optical disk 13 as a magneto-optical recording medium of the present invention is made of a soft magnetic material made of a soft magnetic material with high magnetic permeability that easily passes in-plane magnetization on a transparent substrate 3 (substrate). The structure is such that the layer 4 and the magnetic layer 115 are sequentially formed. Further, a spiral guide groove (not shown) is formed on the soft magnetic layer 4 side of the substrate 3.
上記の光磁気ディスク１３を用いて、主磁極型の磁気ヘ
ッドにより情報を再生する場合の光磁気ディスク装置の
構成例を同図に併せて示す。The figure also shows an example of the configuration of a magneto-optical disk device in which information is reproduced by a main pole type magnetic head using the magneto-optical disk 13 described above.
本実施例の光磁気ディスク装置では、レーザー光ｌを集
光する対物レンズ２が基板３側に配置されている。再生
用磁気へラド６と記録用磁気ヘッド７はコの字型をした
磁気コア８に一体化して設けられており、記録用磁気へ
ラド７は光磁気ディスク１３を挟んで光ビームスポット
１４に対向するように配置されている。再生用磁気ヘッ
ド６の磁気コア８の断面は上記光ビームスポット１４よ
りも小さくなるように設定されており、この回りに再生
用コイル９が巻かれて、主磁極１１を形成している。一
方、記録用磁気へラド７の磁気コア８の断面は光ビーム
スポット１４よりも大きくなるように設定されており、
この回りに記録用コイル１０が巻かれて、補助磁極１２
を形成している。In the magneto-optical disk device of this embodiment, an objective lens 2 for condensing the laser beam 1 is arranged on the substrate 3 side. The reproducing magnetic head 6 and the recording magnetic head 7 are integrated into a U-shaped magnetic core 8, and the recording magnetic head 7 is directed to the light beam spot 14 with the magneto-optical disk 13 in between. are arranged to face each other. The cross section of the magnetic core 8 of the reproducing magnetic head 6 is set to be smaller than the optical beam spot 14, and a reproducing coil 9 is wound around it to form a main magnetic pole 11. On the other hand, the cross section of the magnetic core 8 of the recording magnetic helad 7 is set to be larger than the light beam spot 14,
A recording coil 10 is wound around this, and an auxiliary magnetic pole 12
is formed.
上記の構成において、光磁気ディスク１３は再生用磁気
ヘッド８から記録用磁気ヘッド７の方向（図の右方向）
へ回転駆動される。そして、磁界変調記録を行う場合、
−型強度のレーザー光ｌが対物レンズ２により集光され
、光磁気ディスク１３の基板３側から光ビームスポット
１４として照射され、照射領域の磁性膜５がキエリー温
度近傍まで加熱され、抗磁力が低下する。この状態で、
駆動電流が記録用コイル１０に供給されて記録用磁気ヘ
ッド７から記録情報に応じて高周波数で反転する磁界が
上記照射領域全体に印加され、光ビームスポット１４よ
りも小さい領域に高密度記録が行われる。なお、記録は
上記案内溝からなるトラックのランド部に対して行われ
る。In the above configuration, the magneto-optical disk 13 is moved in the direction from the reproducing magnetic head 8 to the recording magnetic head 7 (rightward in the figure).
is driven to rotate. When performing magnetic field modulation recording,
- type intensity laser beam l is focused by the objective lens 2 and irradiated as a light beam spot 14 from the substrate 3 side of the magneto-optical disk 13, the magnetic film 5 in the irradiated area is heated to near the Chierly temperature, and the coercive force is increased. descend. In this state,
A drive current is supplied to the recording coil 10, and a magnetic field that reverses at a high frequency according to the recording information is applied from the recording magnetic head 7 to the entire irradiation area, and high-density recording is performed in an area smaller than the light beam spot 14. It will be done. Note that recording is performed on the land portion of the track consisting of the guide groove.
一方、情報の再生時、レーザー光１の照射が止められ、
磁気再生が行われる。すなわち、磁性膜５から出た磁束
は、再生用磁気ヘッド６の主磁極１１から再生用コイル
９に導かれ、光磁気ディスクの回転に伴うこの磁束の時
間変化により、再生用コイル９の両端に記録情報に応じ
て反転する誘導起電力が発生し、再生信号として出力さ
れる。On the other hand, when reproducing information, the irradiation of laser light 1 is stopped,
Magnetic reproduction takes place. That is, the magnetic flux emitted from the magnetic film 5 is guided from the main pole 11 of the magnetic head 6 for reproduction to the coil 9 for reproduction, and due to the time change of this magnetic flux accompanying the rotation of the magneto-optical disk, it is applied to both ends of the coil 9 for reproduction. An induced electromotive force is generated that is inverted according to the recorded information, and is output as a reproduction signal.
このとき、主磁極１１の磁気コア８断面は光ビームスポ
ットよりも小さく設定されているので、光ビームスポッ
ト１４よりも小さい領域に高密度記録されている情報を
再生できる。At this time, since the cross section of the magnetic core 8 of the main pole 11 is set smaller than the light beam spot, information recorded at high density in an area smaller than the light beam spot 14 can be reproduced.
本発明では、基板３と磁性膜５の間に高透磁率の軟磁性
層４を設けたので、磁性膜５から出て主磁極１１に入っ
た磁束は、補助磁極１２から軟磁性層４を通って容易に
元の位置に戻ることができる。このため、記録層５から
出た磁束が効率的に主磁極１１に入ることになり、再生
出力が増加する。In the present invention, since the soft magnetic layer 4 with high magnetic permeability is provided between the substrate 3 and the magnetic film 5, the magnetic flux that exits the magnetic film 5 and enters the main magnetic pole 11 is transferred from the auxiliary magnetic pole 12 to the soft magnetic layer 4. You can easily return to your original position. Therefore, the magnetic flux emitted from the recording layer 5 efficiently enters the main pole 11, increasing the reproduction output.
なお、情報の再生時、記録用磁気ヘッド７に対向した磁
性ｗＩ５上の磁区からも、磁束が補助磁極１２を通して
再生用コイル９に導かれるが、補助磁極１２の断面は記
録磁区の大きさよりも充分大きいので、全体としてこの
磁束はあまり時間変化しない。このため、再生用コイル
９の両端に発生ずる誘導起電力は、はとんど再生用磁気
ヘッド６に対向した磁性膜５上の磁区からの磁束の時間
変化によるものであり、記録用磁気ヘッド５の影響は、
はとんどない。When reproducing information, magnetic flux is also guided from the magnetic domain on the magnetic wI5 facing the recording magnetic head 7 to the reproduction coil 9 through the auxiliary magnetic pole 12, but the cross section of the auxiliary magnetic pole 12 is larger than the size of the recording magnetic domain. Since it is sufficiently large, this magnetic flux as a whole does not change much over time. Therefore, the induced electromotive force generated at both ends of the reproduction coil 9 is mainly due to the time change of the magnetic flux from the magnetic domain on the magnetic film 5 facing the reproduction magnetic head 6, and The influence of 5 is
There is no way.
また、本実施例の再生用磁気ヘッド６と記録用磁気ヘッ
ド７は、１つの磁気コア８に一体化して設けられている
ので、両者の相対的な位置決め精度が向上している。こ
のため、高密度記録・再生を行うときの磁気ヘッドの位
置決めが容易になると共に、部品点数が減り、磁気ヘッ
ドの構成が簡素化し、装置が小型化している。Further, since the reproducing magnetic head 6 and the recording magnetic head 7 of this embodiment are integrated into one magnetic core 8, the relative positioning accuracy of the two is improved. Therefore, positioning of the magnetic head during high-density recording/reproduction is facilitated, the number of parts is reduced, the configuration of the magnetic head is simplified, and the device is made smaller.
上記光磁気ディスクの基板３としては、具体的には例え
ば、ガラス、ＰＣ（ポリカーボネイト）、ＡＰＯ（アモ
ルファスポリオレフィン）、ＰＭＭＡ、（ポリメチルメ
タアクリレイト）、エポキシ等が用いられる。As the substrate 3 of the magneto-optical disk, specifically, for example, glass, PC (polycarbonate), APO (amorphous polyolefin), PMMA, (polymethyl methacrylate), epoxy, etc. are used.
また、軟磁性層４には、例えば、Ｆｅ、Ｎｉ−Ｆｅ合金
（パーマロイ）等が使用される。Further, for the soft magnetic layer 4, for example, Fe, Ni-Fe alloy (permalloy), etc. are used.
なお、本実施例のように再生用磁気ヘッド６により再生
する場合、光ビームを必要としないので、基板３と磁性
膜５の間に不透明層があってもよく、上記のように軟磁
性層４が不透明でもかまわない。この場合、記録時、レ
ーザー光１は軟磁性層４に吸収されて、軟磁性層４が加
熱されることになるが、軟磁性層４は薄いので、熱伝導
により磁性膜５も加熱されるため、支障なく記録を行な
える。Note that in the case of reproduction using the reproduction magnetic head 6 as in this embodiment, since a light beam is not required, an opaque layer may be provided between the substrate 3 and the magnetic film 5, and a soft magnetic layer may be provided between the substrate 3 and the magnetic film 5 as described above. It doesn't matter if 4 is opaque. In this case, during recording, the laser beam 1 is absorbed by the soft magnetic layer 4 and the soft magnetic layer 4 is heated, but since the soft magnetic layer 4 is thin, the magnetic film 5 is also heated by heat conduction. Therefore, recording can be performed without any problems.
磁性１１！５には、例えば、ＴｂＦｅＣｏ、ＤｙＦｅＣ
ｏ、ＧｄＴｂＦｅ、、ＭｎＢｔ、、ＭｎＢ１Ｃｕ、Ｐｔ
Ｃｏ、ＰｔＭｎＳｂ等の垂直磁化膜が用いられる。また
、Ｃｒｙ、等の面内磁化膜を使用しても、上記垂直磁化
膜と同様にして、再生出力が増加する。Magnetism 11!5 includes, for example, TbFeCo, DyFeC
o, GdTbFe, , MnBt, , MnB1Cu, Pt
A perpendicular magnetization film such as Co, PtMnSb, etc. is used. Further, even if an in-plane magnetization film such as Cry is used, the reproduction output increases in the same way as the above-mentioned perpendicular magnetization film.
なお、以上の実施例では、光磁気記録媒体として、光磁
気ディスク１３について説明したが、光磁気カードや光
磁気テープ等にも応用される。In the above embodiments, the magneto-optical disk 13 has been described as the magneto-optical recording medium, but the present invention can also be applied to magneto-optical cards, magneto-optical tapes and the like.
本発明の光磁気記録媒体は、以上のように、基体と磁性
膜の間に軟磁性層を設けたので、例えば主磁極と補助磁
極とを備えた再生用磁気ヘッドにより情報を再生する場
合、磁性膜から出て主磁極に入った磁束は、補助磁極か
ら出た後、軟磁性層を通って容易に磁性膜の元の位置に
戻ることができる。このため、磁性膜から出た磁束の多
くが主磁極に入って来ることになり、再生出力が増加す
る。これにより、高密度記録された情報を効率的に再生
できるという効果を奏する。As described above, in the magneto-optical recording medium of the present invention, since the soft magnetic layer is provided between the base and the magnetic film, when information is reproduced using a reproducing magnetic head having a main magnetic pole and an auxiliary magnetic pole, for example, The magnetic flux that has exited the magnetic film and entered the main magnetic pole can easily return to its original position in the magnetic film through the soft magnetic layer after exiting from the auxiliary magnetic pole. Therefore, most of the magnetic flux emitted from the magnetic film enters the main magnetic pole, increasing the reproduction output. This has the effect that information recorded at high density can be efficiently reproduced.
第１図は本発明の一実施例を示すものであり、光磁気デ
ィスクと磁気ヘッド周辺の概略の構成図である。
第２図及び第３図は従来例を示すものである。
第２図は、光磁気ディスクと記録用磁気ヘッド周辺の概
略の構成図である。
第３図は、光磁気ディスク上の磁区形状を示す説明図で
ある。
３は基板（基体）、４は軟磁性層、５は磁性膜６は再生
用磁気ヘッド、７は記録用磁気ヘッド、８は磁気コア、
１１は主磁極、１２は補助磁極１３は光磁気ディスク（
光磁気記録媒体）である。
特許出願人 シャープ 株式会社第
図FIG. 1 shows one embodiment of the present invention, and is a schematic diagram of the structure around a magneto-optical disk and a magnetic head. FIGS. 2 and 3 show conventional examples. FIG. 2 is a schematic configuration diagram of the magneto-optical disk and the vicinity of the recording magnetic head. FIG. 3 is an explanatory diagram showing the shape of magnetic domains on a magneto-optical disk. 3 is a substrate (substrate), 4 is a soft magnetic layer, 5 is a magnetic film 6 is a reproducing magnetic head, 7 is a recording magnetic head, 8 is a magnetic core,
11 is a main magnetic pole, 12 is an auxiliary magnetic pole 13 is a magneto-optical disk (
magneto-optical recording medium). Patent applicant: Sharp Co., Ltd.
Claims (1)
により情報を記録する光磁気記録媒体において、 上記基体と磁性膜の間に軟磁性層が設けられていること
を特徴とする光磁気記録媒体。[Claims] 1. In a magneto-optical recording medium in which a magnetic film is formed on a transparent substrate and information is recorded using light such as a laser beam, a soft magnetic layer is provided between the substrate and the magnetic film. A magneto-optical recording medium characterized by:
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2162098A JP2559156B2 (en) | 1990-06-20 | 1990-06-20 | Magneto-optical recording / reproducing device |
| CA002043995A CA2043995C (en) | 1990-06-13 | 1991-06-06 | Magneto-optical recording/reproducing device |
| US07/713,742 US5202862A (en) | 1990-06-13 | 1991-06-11 | Magneto-optical recording and reproducing device having integrally formed recording and reproducing magnetic heads |
| DE69133223T DE69133223T2 (en) | 1990-06-13 | 1991-06-13 | Magneto-optical recording / reproducing device |
| EP91305374A EP0461907B1 (en) | 1990-06-13 | 1991-06-13 | Magneto-optical recording/reproducing device |
| EP97203052A EP0827143B1 (en) | 1990-06-13 | 1991-06-13 | Magneto-optical recording/reproducing device |
| DE69129280T DE69129280T2 (en) | 1990-06-13 | 1991-06-13 | Magneto-optical recording / playback device |
| US08/000,271 US5325344A (en) | 1990-06-13 | 1993-01-04 | Magneto-optical recording and reproducing device having integrally formed recording and reproducing magnetic heads |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2162098A JP2559156B2 (en) | 1990-06-20 | 1990-06-20 | Magneto-optical recording / reproducing device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0453046A true JPH0453046A (en) | 1992-02-20 |
| JP2559156B2 JP2559156B2 (en) | 1996-12-04 |
Family
ID=15748025
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2162098A Expired - Lifetime JP2559156B2 (en) | 1990-06-13 | 1990-06-20 | Magneto-optical recording / reproducing device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2559156B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6139980A (en) * | 1997-07-02 | 2000-10-31 | Fujitsu Limited | Reading method of reading information from a recording medium and medium used therefor |
| WO2004059635A1 (en) * | 2002-12-24 | 2004-07-15 | Fujitsu Limited | Magnetooptic recording medium and method for producing the same |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57164418A (en) * | 1981-04-02 | 1982-10-09 | Ricoh Co Ltd | Vertical heat magnetic recording medium |
| JPS6171437A (en) * | 1984-09-14 | 1986-04-12 | Fujitsu Ltd | Optomagnetic disc |
| JPH01171137A (en) * | 1987-12-25 | 1989-07-06 | Hitachi Ltd | Magneto-optical recording medium |
-
1990
- 1990-06-20 JP JP2162098A patent/JP2559156B2/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57164418A (en) * | 1981-04-02 | 1982-10-09 | Ricoh Co Ltd | Vertical heat magnetic recording medium |
| JPS6171437A (en) * | 1984-09-14 | 1986-04-12 | Fujitsu Ltd | Optomagnetic disc |
| JPH01171137A (en) * | 1987-12-25 | 1989-07-06 | Hitachi Ltd | Magneto-optical recording medium |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6139980A (en) * | 1997-07-02 | 2000-10-31 | Fujitsu Limited | Reading method of reading information from a recording medium and medium used therefor |
| WO2004059635A1 (en) * | 2002-12-24 | 2004-07-15 | Fujitsu Limited | Magnetooptic recording medium and method for producing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2559156B2 (en) | 1996-12-04 |
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