JPH0760514B2 - Magnetic recording medium and manufacturing method thereof - Google Patents
Magnetic recording medium and manufacturing method thereofInfo
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- JPH0760514B2 JPH0760514B2 JP1232715A JP23271589A JPH0760514B2 JP H0760514 B2 JPH0760514 B2 JP H0760514B2 JP 1232715 A JP1232715 A JP 1232715A JP 23271589 A JP23271589 A JP 23271589A JP H0760514 B2 JPH0760514 B2 JP H0760514B2
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- magnetic
- recording medium
- magnetic recording
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Description
【発明の詳細な説明】 ［発明の技術分野］ 本発明は磁気記録媒体及びその製造方法に関し、更に詳
しくは、高密度記録が可能な磁気記録媒体及びその製造
方法に関する。Description: TECHNICAL FIELD The present invention relates to a magnetic recording medium and a method for manufacturing the same, and more particularly to a magnetic recording medium capable of high density recording and a method for manufacturing the same.
［発明の技術的背景とその問題点］ 磁気記録媒体は、例えばポリエチレンテレフタレート
（PET）樹脂からなる支持基体の表面に、所定の磁性粉
がステアリン酸のような分散剤とともに例えば塩化ビニ
ル，酢酸ビニルのような樹脂結合剤に分散されて成る磁
気塗料を塗布して磁性粉の層を形成することによって製
造されている。[Technical Background of the Invention and Problems Thereof] A magnetic recording medium includes a support base made of, for example, polyethylene terephthalate (PET) resin, a predetermined magnetic powder and a dispersant such as stearic acid, for example, vinyl chloride or vinyl acetate. It is manufactured by applying a magnetic paint dispersed in a resin binder such as the above to form a layer of magnetic powder.
その際、従来は、磁気記録、再生にはγ−Fe2O3,CrO2な
どの針状結晶からなる磁性粉を記録媒体の面内長手方向
に配向させ、面内長手方向の残留磁化を利用する方式が
一般的である。しかしこの記録再生方式では、記録の高
密度化に伴って磁気記録媒体内の反磁界が増加する傾向
が大きくなり、特に短波長領域における記録再生が悪く
なるという欠点がある。この反磁界に打ち勝って高密度
記録を行うには記録媒体の保磁力を高める一方、磁気記
録層を薄くする必要がある。しかしながら、現状では磁
気記録層の高保磁力化は困難であり、また磁気記録層を
薄くすることは再生信号の特性低下を招くなどの問題が
あり好ましくない。結局、従来よりの針状磁性粉を面内
長手方向に配向させ該方向の残留磁化を利用する方式に
よっては、磁気記録の高密度化は困難である。At that time, conventionally, for magnetic recording and reproduction, magnetic powder consisting of needle crystals such as γ-Fe 2 O 3 and CrO 2 was oriented in the in-plane longitudinal direction of the recording medium, and the residual magnetization in the in-plane longitudinal direction was measured. The method used is general. However, this recording / reproducing system has a drawback that the demagnetizing field in the magnetic recording medium tends to increase as the recording density increases, and the recording / reproducing particularly in the short wavelength region deteriorates. In order to overcome this demagnetizing field and perform high density recording, it is necessary to increase the coercive force of the recording medium and thin the magnetic recording layer. However, at present, it is difficult to increase the coercive force of the magnetic recording layer, and thinning the magnetic recording layer causes problems such as deterioration of characteristics of a reproduction signal, which is not preferable. After all, it is difficult to increase the density of magnetic recording by a conventional method of orienting acicular magnetic powder in the longitudinal direction of the surface and utilizing the residual magnetization in that direction.
そこで、磁気記録媒体の面に対し垂直方向の残留磁化を
用いる方式が提案された。このような垂直磁化記録方式
においては、用いる磁性粉は記録媒体の表面に対して垂
直な方向に磁化容易軸を有していることが必要である。
現在のところ、次のような記録媒体が提案されている。Therefore, a method using residual magnetization in the direction perpendicular to the surface of the magnetic recording medium has been proposed. In such a perpendicular magnetization recording method, it is necessary that the magnetic powder used has an easy axis of magnetization in a direction perpendicular to the surface of the recording medium.
At present, the following recording media have been proposed.
一つは、支持基体の表面にスパッタ法によってCo−Cr合
金膜を形成したものである。しかし、この記録媒体の場
合、Co−Cr合金膜と磁気ヘッドとが摺動する際に記録媒
体と磁気ヘッド双方の損耗がはなはだしくなること、記
録媒体自体が可とう性に劣り取扱いが困難であること、
更には製造上の生産性が低いことなどの欠点があり、実
用には供し難いものであった。One is a Co-Cr alloy film formed on the surface of a supporting substrate by a sputtering method. However, in the case of this recording medium, when the Co-Cr alloy film and the magnetic head slide, the wear of both the recording medium and the magnetic head becomes remarkable, and the recording medium itself is inferior in flexibility and difficult to handle. thing,
Furthermore, it has drawbacks such as low productivity in manufacture, which makes it difficult to put it into practical use.
このようなことから、本発明者らは、六方晶系一軸結晶
磁気異方性を有する六方晶フェライト粉を用いた垂直磁
化方式の記録媒体を提案した（特開昭56−61101号参
照）。ここで用いる磁性粉は、ミクロに観察すると、平
面が六角面で、ある厚みを有する六角柱状体又は六角板
状体であり、該六角面と垂直な方向に磁化容易軸を有す
るものである。Under these circumstances, the present inventors have proposed a perpendicular magnetization type recording medium using hexagonal ferrite powder having hexagonal uniaxial crystal magnetic anisotropy (see JP-A-56-61101). When observed microscopically, the magnetic powder used here is a hexagonal columnar body or a hexagonal plate-like body having a flat surface with a hexagonal surface and a certain thickness, and having an easy axis of magnetization in a direction perpendicular to the hexagonal surface.
この磁性粉を用いた磁気記録媒体は従来のものに比べる
と大幅な高密度記録が可能である。A magnetic recording medium using this magnetic powder is capable of significantly higher density recording than conventional ones.
しかしながら、近時、情報量の増大に伴い、更に高密度
記録を可能にする磁気記録媒体の開発が強く望まれてい
る。However, recently, along with the increase in the amount of information, it has been strongly desired to develop a magnetic recording medium that enables higher density recording.
［発明の目的］ 本発明は、本発明者らが提案している上記磁気記録媒体
よりもその高密度記録が可能である、更に改良された磁
気記録媒体及びその製造方法の提供を目的とする。[Object of the Invention] It is an object of the present invention to provide a further improved magnetic recording medium capable of higher density recording than the magnetic recording medium proposed by the present inventors and a method for manufacturing the same. .
［発明の概要］ 本発明者らは、上記目的を達成すべく六方晶系一軸結晶
磁気異方性を有する磁性粉の形状に関し詳細に検討を加
えたところ、磁性粉を構成する六角柱状体又は六角板状
体が所定の寸法形状にあるとき、更に優れた高密度記録
が可能になるという事実を見出し、本発明の磁気記録媒
体を開発するに到った。[Summary of the Invention] The present inventors have made a detailed study on the shape of a magnetic powder having hexagonal uniaxial crystal magnetic anisotropy in order to achieve the above object. The present inventors have discovered the fact that when the hexagonal plate has a predetermined size and shape, higher density recording can be achieved, and the magnetic recording medium of the present invention has been developed.
すなわち、本発明の磁気記録媒体は、支持基体と、該基
体の表面に塗布された磁性層とからなる磁気記録媒体に
おいて、該磁性層に含有される磁性粉が粒径が0.01〜0.
09μｍであり粒径と厚みとの比が2.3〜５である一軸結
晶磁気異方性を有する六方晶系フェライトからなり、そ
の主たる配向方向が該磁性層の膜面に対して略垂直方向
にあることを特徴とし、またその製造方法は、粒径が0.
01〜0.09μｍであり粒径と厚みとの比が2.3〜５である
一軸結晶磁気異方性を有する六方晶系フェライトからな
る磁性粉を溶剤と共に樹脂結合材と混合し、これを該支
持基体上に塗布した後、垂直磁場配向装置中で該磁性粉
の主たる配向方向が該磁性層の膜面に対して略垂直方向
を成すように配向を行いながら乾燥することを特徴とす
る。That is, the magnetic recording medium of the present invention is a magnetic recording medium comprising a supporting base and a magnetic layer coated on the surface of the base, and the magnetic powder contained in the magnetic layer has a particle size of 0.01 to 0.
It is made of hexagonal ferrite having a uniaxial crystal magnetic anisotropy of 09 μm and a grain size to thickness ratio of 2.3 to 5, and the main orientation direction is substantially perpendicular to the film surface of the magnetic layer. In addition, its manufacturing method has a particle size of 0.
Magnetic powder consisting of hexagonal ferrite having a uniaxial crystal magnetic anisotropy of 01 to 0.09 μm and a particle size to thickness ratio of 2.3 to 5 is mixed with a solvent together with a resin binder, and this is mixed with the supporting substrate. After the coating, the magnetic powder is dried while being oriented in a vertical magnetic field orientation device so that the main orientation direction of the magnetic powder is substantially perpendicular to the film surface of the magnetic layer.
本発明の磁気記録媒体で用いる支持基体の材料として
は、従来から用いられているものであれば何であっても
よい。各種の樹脂シートである。The material of the supporting substrate used in the magnetic recording medium of the present invention may be any conventionally used material. These are various resin sheets.
用いる磁性粉は六方晶系一軸結晶磁気異方性を有するも
ので、例えばCo若しくはFe,Ni含有のco合金;MnBi合金;M
nAl合金；各種の希土類（Ｒ）とCoとの合金であるRCo5,
R2Co17;Ba,Sr,Pb,Caなどを含有する六方晶フェライト；
又は、該六方晶フェライトのFeの一部をCo,Ti,Ni,Mn,C
u,Zn,In,Ga,Nb,Zr,V,Alの群から選ばれる少なくとも１
種の元素で置換した置換型六方晶フェライトである。The magnetic powder used has a hexagonal uniaxial crystal magnetic anisotropy, for example Co or Fe, Ni containing co alloy; MnBi alloy; M
nAl alloy; RCo 5 , which is an alloy of various rare earth (R) and Co,
R 2 Co 17 ; Hexagonal ferrite containing Ba, Sr, Pb, Ca etc .;
Or, a part of Fe of the hexagonal ferrite is Co, Ti, Ni, Mn, C
at least 1 selected from the group of u, Zn, In, Ga, Nb, Zr, V, Al
It is a substitutional hexagonal ferrite substituted with certain elements.
また、保持力が200〜2000Oeの範囲内にある磁性粉は高
密度記録にとって有用である。Further, the magnetic powder having a coercive force within the range of 200 to 2000 Oe is useful for high density recording.
ここで粒径とは、六角柱状体又は六角板状体の六角面に
おける角頂点間の距離の最大値を表わし、厚みとは該柱
状体又は板状体の高さ又は厚みを表わすものである。Here, the particle size represents the maximum value of the distance between the corner vertices on the hexagonal surface of the hexagonal columnar body or the hexagonal plate-shaped body, and the thickness represents the height or thickness of the columnar body or the plate-shaped body. .
粒径が0.01μｍ未満の場合には飽和磁化（σg:emu/g）
が十分に大きくなく、逆に0.09μｍを越えると高密度記
録が達成されないばかりではなく記録再生時に発生ノイ
ズが大きくなって不適である。Saturation magnetization (σg: emu / g) when the particle size is less than 0.01 μm
Is not sufficiently large, and on the contrary, if it exceeds 0.09 μm, not only high density recording cannot be achieved, but also noise generated during recording and reproduction becomes large, which is not suitable.
粒径の厚みの比が2.3より小さい場合には、記録再生時
の出力が低くなり、高密度記録が達成できたとはいいが
たく、特に2.3〜５の磁性粉を用いることにより充填率
を高めることができる。When the ratio of particle size to thickness is less than 2.3, it is difficult to say that high-density recording was achieved because the output during recording and reproduction was low. Especially, the filling rate was increased by using magnetic powder of 2.3 to 5. be able to.
次に、本発明の磁気記録媒体の製造方法を説明する。Next, a method for manufacturing the magnetic recording medium of the present invention will be described.
本発明にかかる磁性粉は、例えば特開昭56−67904号に
開示されているガラス結晶化法又は特開昭56−160328号
に開示されている共沈法などの手法を用いて調製するこ
とができる。The magnetic powder according to the present invention may be prepared by a method such as the glass crystallization method disclosed in JP-A-56-67904 or the coprecipitation method disclosed in JP-A-56-160328. You can
本発明の製造方法は、まず、前記磁性粉を公知の樹脂結
合剤に分散剤とともに分散せしめて磁気塗料とし、これ
を支持基体の表面に塗布する。In the manufacturing method of the present invention, first, the magnetic powder is dispersed in a known resin binder together with a dispersant to prepare a magnetic paint, and the magnetic paint is applied to the surface of the supporting substrate.
磁性塗料を支持基体の表面に塗布する方法としては、公
知の塗布方法を好適に採用することができ、例えばリバ
ースロールコーター、グラビアコーター等を用いた方法
を挙げることができる。As a method of applying the magnetic coating material to the surface of the support substrate, a known application method can be preferably adopted, and examples thereof include a method using a reverse roll coater, a gravure coater and the like.
次に、このように磁気塗料を塗布した後、これを垂直磁
場配向装置中で配向を行いながら乾燥する。Next, after applying the magnetic coating material in this way, it is dried while performing orientation in a vertical magnetic field orientation apparatus.
垂直磁場配向装置としては、垂直磁界を発生することの
できるものであれば特に制限はなく、例えば、永久磁
石、電磁石等を採用した公知の垂直磁場配向装置を挙げ
ることができる。The vertical magnetic field aligning device is not particularly limited as long as it can generate a vertical magnetic field, and examples thereof include a known vertical magnetic field aligning device employing a permanent magnet, an electromagnet, or the like.
このような装置中で配向を行いながら乾燥する方法とし
ては、該装置中で塗布面に対して垂直方向に磁界を作用
させつつ乾燥することができれば特に制限はなく、例え
ば、常温で乾燥してもよいし、加熱下に乾燥してもよ
い。The method for drying while performing orientation in such an apparatus is not particularly limited as long as it can be dried while applying a magnetic field in a direction perpendicular to the coated surface in the apparatus, and for example, drying at room temperature. Or may be dried with heating.
本発明の磁気記録媒体は、このようにして乾燥させたの
ちに、カレンダー処理をして得ることができる。The magnetic recording medium of the present invention can be obtained by calendering after being dried in this manner.
［発明の実施例］ 表に示した仕様のCo−Ti置換Baフェライト粉を９種類
と、参考例として１種類を用意した。[Examples of the Invention] Nine kinds of Co-Ti substituted Ba ferrite powders having the specifications shown in the table and one kind as a reference example were prepared.
これらを用いて下記する組成の磁気塗料を調製し、１μ
ｍフィルタで過した後、PETフィルム上に塗布した。 A magnetic paint having the following composition was prepared using these and
After passing through the m filter, it was coated on a PET film.
磁性粉100重量部，塩化ビニル酢酸ビニル共重合体10重
量部，ポリウレタン10重量部，レシチン４重量部，メチ
ルイソブチルケトン93重量部，トルエン93重量部，コロ
ネートＬ（商品名，日本ポリウレタン社製、ポリイソシ
アネート化合物）３重量部。Magnetic powder 100 parts by weight, vinyl chloride vinyl acetate copolymer 10 parts by weight, polyurethane 10 parts by weight, lecithin 4 parts by weight, methyl isobutyl ketone 93 parts by weight, toluene 93 parts by weight, Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd., Polyisocyanate compound) 3 parts by weight.
つぎに、PETフィルム表面の垂直方向に4000Oeの磁界を
作用させて磁性粉を磁場配向させつつ乾燥し、カレンダ
ー処理を施して表面平滑にした。これを1/2インチ幅に
切断して試片とした。Next, a magnetic field of 4000 Oe was applied in the direction perpendicular to the surface of the PET film to dry the magnetic powder while orienting the magnetic field, and calendering was applied to smooth the surface. This was cut into a 1/2 inch width to prepare a test piece.
これら試片に磁気記録を行なった後、再生出力を測定し
てそのテープ特性を調べた。このとき使用した磁気ヘッ
ドはリング型のフェライトヘッドでギャップ幅0.3μm,
トラック幅35μｍであり、ヘッドとテープの相対速度は
3.75m/sec,記周波数は4MHzであった。充填率の測定は、
磁気記録媒体の飽和磁化／磁性粉の飽和磁化とした。ま
た、ノイズの測定は０〜6MHzの範囲での積分ノイズとし
た。After magnetic recording was performed on these test pieces, the reproduction output was measured to examine the tape characteristics. The magnetic head used at this time was a ring type ferrite head with a gap width of 0.3 μm,
The track width is 35 μm, and the relative speed between the head and tape is
The frequency was 3.75 m / sec and the frequency was 4 MHz. The filling rate is measured by
The saturation magnetization of the magnetic recording medium / the saturation magnetization of the magnetic powder was used. Moreover, the noise was measured as integrated noise in the range of 0 to 6 MHz.
結果を図１および表１に示した。図１および表１から明
らかなように、粒径と厚みの比が2.3よりも小さい場合
には再生出力が小さくかつ急激に変化して不安定である
が、2.3より大きくなると再生出力はより大きくなりか
つ変化が小さくなって安定化する。しかし、５を超える
と磁性粉の充填率が低下しはじめ、ノイズが悪化する。The results are shown in FIG. 1 and Table 1. As is clear from FIG. 1 and Table 1, when the ratio of particle size to thickness is smaller than 2.3, the reproduction output is small and changes rapidly and is unstable, but when it is larger than 2.3, the reproduction output becomes larger. And the change becomes small and stabilizes. However, when it exceeds 5, the filling rate of the magnetic powder starts to decrease and the noise becomes worse.
更に、粒径と厚みの比が2.3〜５の範囲内であっても粒
径が0.09μｍを超えるとノイズが大きくなってしまう。Further, even if the ratio of particle diameter to thickness is within the range of 2.3 to 5, noise increases when the particle diameter exceeds 0.09 μm.
［発明の効果］ 本発明の磁気記録媒体は高密度記録が可能で、再生出力
も大きく、しかもその製造方法は従来の塗布方式をその
まま適用できるので工業的に有用である。[Effects of the Invention] The magnetic recording medium of the present invention is industrially useful because it enables high-density recording, has a large reproduction output, and can be applied to the conventional coating method as it is.
第１図は実施例で作製した磁気テープ試片における磁性
粉の粒径／厚みと再生出力との関係図である。FIG. 1 is a diagram showing the relationship between the particle size / thickness of the magnetic powder and the reproduction output in the magnetic tape samples produced in the examples.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 前田 辰巳 神奈川県川崎市幸区小向東芝町１番地 東 京芝浦電気株式会社総合研究所内 (72)発明者 深沢 昌広 神奈川県川崎市幸区小向東芝町１番地 東 京芝浦電気株式会社総合研究所内 (72)発明者 野村 力 神奈川県川崎市幸区小向東芝町１番地 東 京芝浦電気株式会社総合研究所内 (56)参考文献 特開 昭58−6526（ＪＰ，Ａ) 特開 昭55−86103（ＪＰ，Ａ) 特開 昭55−163633（ＪＰ，Ａ) 特開 昭57−150110（ＪＰ，Ａ) ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsumi Maeda 1 Komukai-shi Toshiba-cho, Kouki-ku, Kawasaki-shi, Kanagawa Higashi-Kishibaura Electric Co., Ltd. Research Institute (72) Masahiro Fukasawa Komukai-ku, Kawasaki-shi, Kanagawa 1st location, Toshiba Koshibaura Electric Co., Ltd. (72) Inventor, Riki Nomura 1st location, Komukai Toshibacho, Komukai-ku, Kawasaki City, Kanagawa Higashi Koshibaura Electric Co., Ltd. (56) Reference JP-A-58 -6526 (JP, A) JP-A-55-86103 (JP, A) JP-A-55-163633 (JP, A) JP-A-57-150110 (JP, A)
Claims (4)
とからなる磁気記録体において、 該磁性層に含有される磁性粉が粒径が0.01〜0.09μｍで
あり粒径と厚みとの比が2.3〜５である一軸結晶磁気異
方性を有する六方晶系フェライトからなり、その主たる
配向方向が該磁性層の膜面に対して略垂直方向にあるこ
とを特徴とする磁気記録媒体。1. A magnetic recording medium comprising a supporting substrate and a magnetic layer coated on the substrate, wherein the magnetic powder contained in the magnetic layer has a particle size of 0.01 to 0.09 μm and a particle size and a thickness. Recording medium comprising a hexagonal ferrite having uniaxial crystal magnetic anisotropy having a ratio of 2.3 to 5 and having a main orientation direction substantially perpendicular to the film surface of the magnetic layer. .
エールステッドである特許請求の範囲第１項記載の磁気
記録媒体。2. The coercive force of hexagonal ferrite is 200 to 2000.
The magnetic recording medium according to claim 1, which is Oersted.
気記録媒体の製造方法において、 粒径が0.01〜0.09μｍであり粒径と厚みとの比が2.3〜
５である一軸結晶磁気異方性を有する六方晶系フェライ
トからなる磁性粉を溶剤と共に樹脂結合材と混合し、こ
れを該支持基体上に塗布した後、垂直磁場配向装置中で
該磁性粉の主たる配向方向が該磁性層の膜面に対して略
垂直方向を成すように配向を行いながら乾燥することを
特徴とする磁気記録媒体の製造方法。3. A method of manufacturing a magnetic recording medium having a magnetic layer coated on a supporting substrate, wherein the particle size is 0.01 to 0.09 μm and the ratio of particle size to thickness is 2.3 to.
5, a magnetic powder made of hexagonal ferrite having uniaxial crystal magnetic anisotropy was mixed with a solvent together with a resin binder, and this was coated on the supporting substrate, and then the magnetic powder A method for producing a magnetic recording medium, which comprises drying while performing orientation so that a main orientation direction is substantially perpendicular to a film surface of the magnetic layer.
エールステッドである特許請求の範囲第３項記載の磁気
記録媒体の製造方法。4. The coercive force of hexagonal ferrite is 200 to 2000.
The method of manufacturing a magnetic recording medium according to claim 3, which is Oersted.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1232715A JPH0760514B2 (en) | 1989-09-11 | 1989-09-11 | Magnetic recording medium and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1232715A JPH0760514B2 (en) | 1989-09-11 | 1989-09-11 | Magnetic recording medium and manufacturing method thereof |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58150157A Division JPS6069822A (en) | 1983-08-19 | 1983-08-19 | Magnetic recording medium |
Related Child Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5237601A Division JPH06208917A (en) | 1993-09-01 | 1993-09-24 | Magnetic recording powder and magnetic recording medium employing the same |
| JP5237600A Division JPH06208916A (en) | 1993-09-01 | 1993-09-24 | Magnetic recording powder and magnetic recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0362313A JPH0362313A (en) | 1991-03-18 |
| JPH0760514B2 true JPH0760514B2 (en) | 1995-06-28 |
Family
ID=16943651
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1232715A Expired - Lifetime JPH0760514B2 (en) | 1989-09-11 | 1989-09-11 | Magnetic recording medium and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0760514B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4880275B2 (en) | 2005-10-03 | 2012-02-22 | オリンパスメディカルシステムズ株式会社 | Capacitive ultrasonic transducer |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6050323B2 (en) * | 1978-12-22 | 1985-11-08 | 株式会社東芝 | High density recording medium |
| JPS55163633A (en) * | 1979-06-08 | 1980-12-19 | Toshiba Corp | Manufacture of magnetic recording medium |
| JPS57150110A (en) * | 1981-03-12 | 1982-09-16 | Toshiba Corp | Magnetic reocrding system |
| JPS586526A (en) * | 1981-07-02 | 1983-01-14 | Toshiba Corp | Magnetic recording medium |
-
1989
- 1989-09-11 JP JP1232715A patent/JPH0760514B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0362313A (en) | 1991-03-18 |
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