JPH026121B2 - - Google Patents
Info
- Publication number
- JPH026121B2 JPH026121B2 JP56060630A JP6063081A JPH026121B2 JP H026121 B2 JPH026121 B2 JP H026121B2 JP 56060630 A JP56060630 A JP 56060630A JP 6063081 A JP6063081 A JP 6063081A JP H026121 B2 JPH026121 B2 JP H026121B2
- Authority
- JP
- Japan
- Prior art keywords
- magnetic field
- bias magnetic
- recording medium
- value
- bias
- 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
- 238000000034 method Methods 0.000 claims description 22
- 230000005415 magnetization Effects 0.000 claims description 6
- 230000007246 mechanism Effects 0.000 description 11
- 238000010586 diagram Methods 0.000 description 5
- 229910016629 MnBi Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000020169 heat generation Effects 0.000 description 2
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
- G11B11/1055—Disposition or mounting of transducers relative to record carriers
- G11B11/10556—Disposition or mounting of transducers relative to record carriers with provision for moving or switching or masking the transducers in or out of their operative position
- G11B11/1056—Switching or mechanically reversing the magnetic field generator
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
- G11B5/027—Analogue recording
- G11B5/03—Biasing
Landscapes
- Recording Or Reproducing By Magnetic Means (AREA)
- Adjustment Of The Magnetic Head Position Track Following On Tapes (AREA)
Description
【発明の詳細な説明】
本発明は垂直磁化式の光磁気記録方式におい
て、比較的簡単な構成で外部バイアス磁界を印加
することができるバイアス磁界印加方式に関する
ものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bias magnetic field application method that can apply an external bias magnetic field with a relatively simple configuration in a perpendicular magnetization type magneto-optical recording method.
従来、光磁気記録等に用いられる外部バイアス
磁界の印加方式としては、記録媒体がMnBi、
TbFe等の垂直磁化膜の場合膜面に対して垂直方
向の磁界成分が必要のため、第１図に示すように
ターンテーブル１上に載置した記録媒体すなわち
デイスク２の裏面にリングヘツド３を置きその漏
洩磁界をバイアス磁界として用いる方式、又は、
第２図に示すように空心コイル４をデイスク２の
外周にそつて設置しその磁界をバイアス磁界とし
て用いる方式が使用されていた。第１図の場合、
磁気回路的に閉磁路構造となつているため磁界発
生効率が良く、ギヤツプ中心部分の磁界の30％程
度が媒体面の記録部分（レーザ等により加熱され
る部分）の面に垂直な磁界として利用できること
が実験的に確かめられている。またこの方式によ
ると、必要なバイアス磁界の最大値である600Oe
程度の磁界強度は比較的容易に得られる。第３図
においては上述したヘツドの磁界分布を、横軸に
ギヤツプ中心部からの距離、たて軸に垂直及び水
平方向の相対磁界強度を用いて示している。ここ
で添え字ｘおよびｙはそれぞれデイスク２の膜面
に対して水平および垂直方向を表わしている。こ
のリングヘツド方式を垂直磁化膜に使用する場
合、記録部分とギヤツプ中心部をデイスク２の表
面と裏面の同位置に配置することになるため、記
録幅がヘツド面の幅以下のテープ状記録媒体を使
用する場合はこの方式は優れたバイアス磁界印加
方法であるが、デイスク状の記録媒体の場合には
記録スポツトの移動とともにヘツド３を半径方向
へ移動させなければならないので、移動機構の複
雑化、大型化等の問題が生ずる。一方、第２図に
示すような空心コイル４をデイスク２の外周にそ
つて設置しその磁界をバイアス磁界として用いる
方式の場合は、デイスク全面に磁界が一様に分布
しまた上述したような移動機構を必要としない
が、コイルの径が大きくなるため磁界の発生効率
が悪くコイルの発熱、電源の大型化等の問題が生
ずる。たとえば、直径20cmのデイスク状記録媒体
２を使用した場合、コイル４を実用的な大きさに
するために0.5mmφ以下の線材を使用し巻数を
1000ターン前後とするとコイル抵抗は40〜50Ωと
なり、200〜300Oe程度の磁界を発生させるため
には４〜5Aの電流を印加しなければならず、コ
イルの消費電力は100W以上となりコイルの発熱、
電源の大型化といつた問題が生ずる。 Conventionally, as a method of applying an external bias magnetic field used for magneto-optical recording, etc., the recording medium is MnBi,
In the case of a perpendicularly magnetized film such as TbFe, a magnetic field component perpendicular to the film surface is required, so as shown in FIG. A method that uses the leakage magnetic field as a bias magnetic field, or
As shown in FIG. 2, a method was used in which an air-core coil 4 was installed along the outer periphery of the disk 2 and its magnetic field was used as a bias magnetic field. In the case of Figure 1,
Since the magnetic circuit has a closed magnetic circuit structure, the magnetic field generation efficiency is high, and about 30% of the magnetic field at the center of the gap is used as a magnetic field perpendicular to the surface of the recording part of the medium surface (the part heated by a laser, etc.). It has been experimentally confirmed that this is possible. Also, according to this method, the maximum required bias magnetic field is 600Oe.
It is relatively easy to obtain a magnetic field strength of approximately In FIG. 3, the above-described magnetic field distribution of the head is shown using the distance from the gap center on the horizontal axis and the relative magnetic field strength in the vertical and horizontal directions on the vertical axis. Here, the subscripts x and y represent the horizontal and vertical directions with respect to the film surface of the disk 2, respectively. When this ring head method is used for a perpendicularly magnetized film, the recording portion and the center of the gap are placed at the same position on the front and back surfaces of the disk 2, so a tape-shaped recording medium with a recording width less than the width of the head surface is used. When used, this method is an excellent method for applying a bias magnetic field, but in the case of a disk-shaped recording medium, the head 3 must be moved in the radial direction along with the movement of the recording spot, which complicates the movement mechanism. Problems such as increasing the size arise. On the other hand, in the case of a method in which an air-core coil 4 is installed along the outer periphery of the disk 2 and its magnetic field is used as a bias magnetic field as shown in FIG. Although no mechanism is required, since the diameter of the coil becomes large, the efficiency of generating a magnetic field is poor, causing problems such as heat generation in the coil and an increase in the size of the power supply. For example, when using a disk-shaped recording medium 2 with a diameter of 20 cm, in order to make the coil 4 a practical size, use a wire rod with a diameter of 0.5 mm or less and reduce the number of turns.
If the number of turns is around 1000, the coil resistance will be 40 to 50Ω, and in order to generate a magnetic field of about 200 to 300 Oe, a current of 4 to 5 A must be applied, and the power consumption of the coil will be over 100 W, which will cause the coil to generate heat.
Problems arise as the power supply becomes larger.
本発明の目的は上述した不具合を解決し、比較
的簡単な構成で外部バイアス磁界を印加すること
ができるバイアス磁界印加方式を提供するもので
ある。 An object of the present invention is to solve the above-mentioned problems and provide a bias magnetic field application method that can apply an external bias magnetic field with a relatively simple configuration.
本発明は、膜面に垂直な磁気異方性を有する磁
性記録媒体を使用した垂直磁化式光磁気記録に用
いられるバイアス磁界印加方式において、記録媒
体の下面又は上面に記録媒体の半径方向に延在
し、長手方向に沿つて着磁させた永久磁石を、前
記膜面に垂直に作用する磁界の大きさを変え得る
よう変位自在に配置し、その永久磁石の膜面に垂
直な磁界を記録部分に対応した場所に設けた磁気
感応素子で検出し、あらかじめ設定したバイアス
磁界の値と前記検出値を比較し、その比較値に応
じて駆動手段により設定値に応じた大きさのバイ
アス磁界を得るよう永久磁石を変位させることを
特徴とするものである。 The present invention provides a method for applying a bias magnetic field used in perpendicular magnetization type magneto-optical recording using a magnetic recording medium having magnetic anisotropy perpendicular to the film surface. Permanent magnets magnetized along the longitudinal direction are disposed movably so as to change the magnitude of the magnetic field acting perpendicular to the film surface, and the magnetic field perpendicular to the film surface of the permanent magnet is recorded. The detected value is detected by a magnetically sensitive element provided at a location corresponding to the part, and the detected value is compared with a preset bias magnetic field value, and according to the comparison value, a bias magnetic field of a magnitude corresponding to the set value is generated by the driving means. It is characterized by displacing the permanent magnet so as to obtain the desired result.
以下図面を参照して本発明を詳細に説明する。 The present invention will be described in detail below with reference to the drawings.
第４図は本発明によるバイアス磁界印加方式の
一例の構成を示している。第４図において、ター
ンテーブル８に取り付けられたTbFe、DyFe、
MnBi等より成るデイスク状記録媒体７上に、記
録または再生のためフオーカシング、トラツキン
グ機構を備えたピツクアツプ９より射出され記録
媒体上にスポツトを結ぶ光ビーム１０を照射す
る。このスポツトにより照射される部分にバイア
ス磁界を印加し後述のような方法でデータを記録
するため、デイスク７をはさんでピツクアツプ９
の反対側にデイスク７の半径方向に延在し、両端
面長手方向にそつて着磁された永久磁石１１を設
置する。永久磁石１１からのバイアス磁界をピツ
クアツプ９の先端部に置かれたホール素子等の磁
気感応素子１２で検出し、その出力を増幅器１４
で増幅し、比較増幅器１６へ供給する。このと
き、記録媒体面でのバイアス磁界の値と磁気感応
素子１２の部分との値は素子１２が記録媒体７か
らわずかに離れているため若干相異しているが、
素子１２と記録媒体７の相対的距離はほとんど一
定であるため、素子１２の出力に適当な係数を乗
じておけば記録媒体面上の値に換算できる。一
方、記録時に必要なバイアス磁界の値はバイアス
磁界設定回路１５から比較増幅器１６へ供給し、
その値と前記増幅器からの値とのレベルを合わせ
た後両者の差分を誤差信号として永久磁石駆動機
構駆動回路１７に供給し、永久磁石駆動機構１３
を駆動する。この駆動機構としては、たとえばス
テツピングモータ等が利用でき駆動回路１７の出
力に応じてモータの軸を回転し、設定値と実際の
バイアス磁界強度が等しくなれば誤差信号はゼロ
となるためモータの回転は停止し、設定値に応じ
たバイアス磁界が得られることになる。 FIG. 4 shows the configuration of an example of the bias magnetic field application method according to the present invention. In Fig. 4, TbFe, DyFe,
A light beam 10 is emitted from a pickup 9 equipped with a focusing and tracking mechanism and connects a spot on the recording medium for recording or reproduction onto a disk-shaped recording medium 7 made of MnBi or the like. In order to apply a bias magnetic field to the area irradiated by this spot and record data using the method described later, a pick-up 9 is placed between the disks 7 and 9.
A permanent magnet 11 is installed on the opposite side of the disk 7, extending in the radial direction of the disk 7 and magnetized along the longitudinal direction of both end faces. The bias magnetic field from the permanent magnet 11 is detected by a magnetic sensing element 12 such as a Hall element placed at the tip of the pickup 9, and its output is sent to an amplifier 14.
and supplies it to the comparison amplifier 16. At this time, the value of the bias magnetic field at the surface of the recording medium and the value at the magnetically sensitive element 12 are slightly different because the element 12 is slightly away from the recording medium 7.
Since the relative distance between the element 12 and the recording medium 7 is almost constant, by multiplying the output of the element 12 by an appropriate coefficient, it can be converted into a value on the surface of the recording medium. On the other hand, the value of the bias magnetic field required during recording is supplied from the bias magnetic field setting circuit 15 to the comparison amplifier 16,
After matching the levels of that value and the value from the amplifier, the difference between the two is supplied as an error signal to the permanent magnet drive mechanism drive circuit 17, and the permanent magnet drive mechanism 13
to drive. As this drive mechanism, for example, a stepping motor or the like can be used, and the shaft of the motor is rotated according to the output of the drive circuit 17. If the set value and the actual bias magnetic field strength become equal, the error signal becomes zero, so the motor Rotation stops and a bias magnetic field corresponding to the set value is obtained.
第５図は第４図に示すバイアス磁界印加機構の
部分を抜き出した斜視図であり、図中第４図と同
一の符号を付すことにより説明は省略する。 FIG. 5 is a perspective view of a portion of the bias magnetic field applying mechanism shown in FIG. 4, in which the same reference numerals as in FIG. 4 are given, and the explanation thereof will be omitted.
第６図は本発明のバイアス磁界印加方式を説明
する説明図である。図中、横軸は永久磁石の中心
軸からの距離、たて軸は記録媒体面７に対して垂
直及び水平方向の磁界成分を示している。第６図
ａにおいて、両端面長手方向にそつて着磁された
永久磁石１１の着磁された面を光ビームが結ばれ
る位置の下に記録媒体に対して直角に置くと、媒
体面では媒体面に垂直な磁界成分Hyが最大とな
り一方媒体面に平行な磁界成分Hxはゼロとなる。
垂直磁化式の光磁気記録において必要なバイアス
磁界の最大値は600Oe程度であるため、永久磁石
１１の形状、種類、記録媒体７と永久磁石１１の
距離を適当に選べば、必要な最大磁界強度は容易
に得られる。また、バイアス磁界の大きさを最小
値と最大値との間で任意に変化させる場合には永
久磁石１１を回転させれば良く、たとえば永久磁
石１１を記録媒体７に平行とすれば記録スポツト
位置の磁界成分は第６図ｂに示すように媒体面内
成分であるHx成分のみとなり、記録媒体として
垂直磁化膜を使用した場合バイアス磁界として有
効なHy成分はゼロとなる。バイアス磁界の極性
を反転させる場合には永久磁石１１を180゜回転さ
せれば良く、このようにして永久磁石１１を垂直
方向の磁界成分の最大値をHymとして０〜360゜
の間で回転させれば、Hym〜−Hymの間で任意
に設定できることになる。また、平行方向の磁界
成分もその最大値をHxmとすれば同様にHxm〜
−Hxmの間で任意に設定できる。ここで、垂直
方向の磁界成分をバイアス磁界として使用すると
き第６図ｂの場合Hy＝０の状態でHxが最大とな
り、記録媒体面上の残留磁化の方向を面内方向に
向けるなど悪影響を与えることも考えられるが、
TbFe等の垂直異方性エネルギーの大きな記録媒
体を使用すればこの影響は無視してさしつかえな
い。 FIG. 6 is an explanatory diagram illustrating the bias magnetic field application method of the present invention. In the figure, the horizontal axis represents the distance from the central axis of the permanent magnet, and the vertical axis represents the magnetic field components in the vertical and horizontal directions with respect to the recording medium surface 7. In FIG. 6a, when the magnetized surface of the permanent magnet 11, which is magnetized along the longitudinal direction of both end faces, is placed perpendicular to the recording medium below the position where the light beam is focused, the medium surface is The magnetic field component Hy perpendicular to the surface becomes maximum, while the magnetic field component Hx parallel to the medium surface becomes zero.
The maximum value of the bias magnetic field required for perpendicular magnetization type magneto-optical recording is approximately 600 Oe, so if the shape and type of the permanent magnet 11 and the distance between the recording medium 7 and the permanent magnet 11 are appropriately selected, the required maximum magnetic field strength can be adjusted. is easily obtained. Furthermore, when the magnitude of the bias magnetic field is arbitrarily changed between the minimum value and the maximum value, it is sufficient to rotate the permanent magnet 11. For example, if the permanent magnet 11 is made parallel to the recording medium 7, the recording spot position can be adjusted. As shown in FIG. 6b, the magnetic field component is only the Hx component which is an in-plane component of the medium, and when a perpendicular magnetization film is used as the recording medium, the Hy component effective as a bias magnetic field is zero. When reversing the polarity of the bias magnetic field, it is sufficient to rotate the permanent magnet 11 by 180 degrees, and in this way, the permanent magnet 11 is rotated between 0 and 360 degrees with the maximum value of the vertical magnetic field component as Hym. If so, it can be set arbitrarily between Hym and -Hym. Similarly, if the maximum value of the magnetic field component in the parallel direction is Hxm, Hxm ~
-Hxm can be set arbitrarily. When the vertical magnetic field component is used as a bias magnetic field, Hx becomes maximum when Hy = 0 in the case of Figure 6b, causing negative effects such as directing the direction of residual magnetization on the surface of the recording medium in the in-plane direction. Although it is possible to give
This effect can be ignored if a recording medium with high vertical anisotropy energy such as TbFe is used.
上述したように本発明によれば、バイアス磁界
発生手段として永久磁石を用い、その磁界を磁気
感応素子で検出し、あらかじめ設定した値に応じ
てこの永久磁石を変位させることにより最大磁界
強度の範囲内でその大きさ極性を任意に設定でき
るため、リングヘツドを使用した場合のようにピ
ツクアツプの移動に伴つてヘツドを移動させる等
の複雑な機構も必要でなく、空心コイルを使用し
た場合のように必要な磁界強度を得るための発熱
の問題はないため、比較的簡単な構成で極性を変
化できその大きさも任意に変化できる優れたバイ
アス磁界印加方式を提供できる。 As described above, according to the present invention, a permanent magnet is used as a bias magnetic field generating means, the magnetic field is detected by a magnetic sensing element, and the range of maximum magnetic field strength is determined by displacing this permanent magnet according to a preset value. Since the size and polarity can be set arbitrarily within the ring head, there is no need for complicated mechanisms such as moving the head as the pickup moves, unlike when using a ring head, and unlike when using an air-core coil. Since there is no problem of heat generation in order to obtain the necessary magnetic field strength, it is possible to provide an excellent bias magnetic field application method in which the polarity can be changed and the magnitude can be arbitrarily changed with a relatively simple configuration.
第１図は従来のリングヘツドによるバイアス磁
界印加方式を実施する装置の一例を示す線図、第
２図は空心コイルによるバイアス磁界印加方式を
実施する装置の一例を示す線図、第３図は第１図
におけるリングヘツドの磁界分布を示す図、第４
図は本発明のバイアス磁界印加方式の構成を示す
ブロツク図、第５図は第４図中のバイアス磁界印
加機構の部分を示す斜視図、第６図は本発明のバ
イアス磁界印加方式を説明する説明図である。
１……ターンテーブル、２……記録媒体、３…
…リングヘツド、４……バイアスコイル、７……
デイスク状記録媒体、８……ターンテーブル、９
……ピツクアツプ、１０……光ビーム、１１……
永久磁石、１２……磁気感応素子、１３……永久
磁石駆動機構、１４……増幅器、１５……バイア
ス磁界設定回路、１６……比較増幅器、１７……
永久磁石駆動機構駆動回路。
Fig. 1 is a diagram showing an example of a device that implements a bias magnetic field application method using a conventional ring head, Fig. 2 is a diagram showing an example of a device that implements a bias magnetic field application method using an air-core coil, and Fig. Figure 4 shows the magnetic field distribution of the ring head in Figure 1.
The figure is a block diagram showing the configuration of the bias magnetic field application method of the present invention, FIG. 5 is a perspective view showing a portion of the bias magnetic field application mechanism in FIG. 4, and FIG. 6 explains the bias magnetic field application method of the present invention. It is an explanatory diagram. 1...turntable, 2...recording medium, 3...
...Ring head, 4...Bias coil, 7...
Disk-shaped recording medium, 8...Turntable, 9
...Pickup, 10...Light beam, 11...
Permanent magnet, 12...Magnetic sensing element, 13...Permanent magnet drive mechanism, 14...Amplifier, 15...Bias magnetic field setting circuit, 16...Comparison amplifier, 17...
Permanent magnet drive mechanism drive circuit.
Claims (1)
体を使用した垂直磁化式光磁気記録に用いられる
バイアス磁界印加方式において、記録媒体の下面
又は上面に記録媒体の半径方向に延在し、長手方
向に沿つて着磁させた永久磁石を、前記膜面に垂
直に作用する磁界の大きさを変え得るよう変位自
在に配置し、その永久磁石の膜面に垂直な磁界を
記録部分に対応した場所に設けた磁気感応素子で
検出し、あらかじめ設定したバイアス磁界の値と
前記検出値を比較し、その比較値に応じて駆動手
段により設定値に応じた大きさのバイアス磁界を
得るよう永久磁石を変位させることを特徴とする
バイアス磁界印加方式。1. In a bias magnetic field application method used in perpendicular magnetization type magneto-optical recording using a magnetic recording medium having magnetic anisotropy perpendicular to the film surface, a magnetic field that extends in the radial direction of the recording medium on the bottom or top surface of the recording medium, Permanent magnets magnetized along the longitudinal direction are arranged so as to be freely displaceable so as to change the magnitude of the magnetic field acting perpendicularly to the film surface, and the magnetic field perpendicular to the film surface of the permanent magnet corresponds to the recording area. The detected value is detected by a magnetic sensing element installed at a location where the bias magnetic field is set in advance, and the detected value is compared with a preset bias magnetic field value, and according to the comparison value, the driving means is permanently set to obtain a bias magnetic field of a magnitude corresponding to the set value. A bias magnetic field application method characterized by displacing a magnet.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6063081A JPS57176505A (en) | 1981-04-23 | 1981-04-23 | Bias magnetic field applying system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6063081A JPS57176505A (en) | 1981-04-23 | 1981-04-23 | Bias magnetic field applying system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57176505A JPS57176505A (en) | 1982-10-29 |
| JPH026121B2 true JPH026121B2 (en) | 1990-02-07 |
Family
ID=13147812
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6063081A Granted JPS57176505A (en) | 1981-04-23 | 1981-04-23 | Bias magnetic field applying system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57176505A (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5938951A (en) * | 1982-08-27 | 1984-03-03 | Matsushita Electric Ind Co Ltd | Photomagnetic recording and reproducing device |
| JPS5992406A (en) * | 1982-11-17 | 1984-05-28 | Matsushita Electric Ind Co Ltd | Photo-magnetic recorder |
| JPS59117703A (en) * | 1982-12-25 | 1984-07-07 | Fujitsu Ltd | Photomagnetic disc device |
| JPS6324704U (en) * | 1986-07-31 | 1988-02-18 | ||
| JPS6397259U (en) * | 1986-12-15 | 1988-06-23 | ||
| JP2619373B2 (en) * | 1986-12-24 | 1997-06-11 | 株式会社日立製作所 | Magneto-optical disk drive |
| US5022017A (en) * | 1988-04-29 | 1991-06-04 | Laser Magnetic Storage International Company | Magneto optic data recording system with variable field strength, actuator therefor and method of providing |
| JPH04232602A (en) * | 1990-09-21 | 1992-08-20 | Sundstrand Data Control Inc | Magnetic bias device which is sealed in airtight pattern for magnetooptic-disk driving apparatus |
| JP2889427B2 (en) * | 1992-04-03 | 1999-05-10 | シャープ株式会社 | Thermomagnetic recording device |
| CN1695189A (en) * | 2002-11-29 | 2005-11-09 | 富士通株式会社 | Magneto-optical storage medium reproduction method and magneto-optical storage apparatus using the method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57133503A (en) * | 1981-02-10 | 1982-08-18 | Sharp Corp | Optical and magnetic recorder and reproducer |
-
1981
- 1981-04-23 JP JP6063081A patent/JPS57176505A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57133503A (en) * | 1981-02-10 | 1982-08-18 | Sharp Corp | Optical and magnetic recorder and reproducer |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57176505A (en) | 1982-10-29 |
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