JP2544646B2 - Magnetic card - Google Patents
Magnetic cardInfo
- Publication number
- JP2544646B2 JP2544646B2 JP63043973A JP4397388A JP2544646B2 JP 2544646 B2 JP2544646 B2 JP 2544646B2 JP 63043973 A JP63043973 A JP 63043973A JP 4397388 A JP4397388 A JP 4397388A JP 2544646 B2 JP2544646 B2 JP 2544646B2
- Authority
- JP
- Japan
- Prior art keywords
- magnetic
- magnetic recording
- recording layer
- coercive force
- layer
- 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 - Fee Related
Links
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、IDカード，プリペイドカード等として用い
るのに適した磁気カードに関するものである。Description: TECHNICAL FIELD The present invention relates to a magnetic card suitable for use as an ID card, a prepaid card, or the like.
（従来の技術） 一般に磁気カードは短いために磁気ヘッドとの相対運
動が安定しないことから、記録再生のための同期信号を
磁気カードを搬送するモータあるいは磁気カードが移動
することによって回転するタッチローラから得ても線記
録密度を向上させることができず、210BPI程度と磁気テ
ープやフレキシブルディスクに比べて非常に低密度で記
録される。このため、従来の磁気カードの記録容量は非
常に小さいと言う欠点があった。また、磁気カードと磁
気ヘッドとの相対運動を安定にするにはカードリーダラ
イタが高価になり過ぎることから、記憶容量に大ならし
める試みは放棄されていた。また、情報が一つの磁気記
録層に記録されたこれまでの磁気カードでは、既に大量
に使用されているリング形磁気ヘッドで記録再生ができ
るため、容量に磁気ヘッドが入手されて記録情報が改ざ
んされる欠点があった。したがって、IDカード，プリペ
イドカード等として用いるには、記憶容量の増大ととも
に記録情報の改ざんが防止できる磁気カードが待望され
ていた。(Prior Art) Generally, since a magnetic card is short, the relative movement with the magnetic head is not stable. Therefore, a touch roller that rotates when a motor for carrying a magnetic card or a magnetic card moves a synchronous signal for recording and reproduction. The linear recording density cannot be improved even when obtained from the above, and it is recorded at a very low density of about 210 BPI, which is much lower than that of a magnetic tape or a flexible disk. Therefore, the conventional magnetic card has a disadvantage that the recording capacity is very small. Further, since the card reader / writer is too expensive to stabilize the relative movement between the magnetic card and the magnetic head, attempts to increase the storage capacity have been abandoned. In addition, in the conventional magnetic cards in which information is recorded on one magnetic recording layer, recording and reproduction can be performed with the ring-shaped magnetic head which is already used in large quantities, so the magnetic head is available in the capacity and the recorded information is tampered with. There was a drawback. Therefore, for use as an ID card, a prepaid card, or the like, there has been a long-felt demand for a magnetic card capable of preventing alteration of recorded information as the storage capacity increases.
また、第５図は従来の二つの磁気記録層を有する磁気
カードの実施例である。第５図（イ）の構成について見
ると、磁気カード１は、基板２上に保磁力が大きい磁気
記録層３と、前記保磁力より小さい磁気記録層４から構
成されていた。このような磁気カードにおいては、磁気
記録層３の磁気記録層４とにそれぞれ異なる情報を記録
すると、第５図（ロ）の破線で示すように、情報を記録
したことから生ずる磁化による磁束が磁気カードの表面
に漏れるため、いずれか一方の磁気記録層の線記録密度
を極端に小さくして記録し、情報の再生では周波数で弁
別するフィルターを使用する必要があった。しかし、こ
の場合には記憶容量の増加は非常に僅かのものであっ
た。FIG. 5 shows an example of a conventional magnetic card having two magnetic recording layers. As for the structure of FIG. 5 (a), the magnetic card 1 is composed of a magnetic recording layer 3 having a large coercive force on the substrate 2 and a magnetic recording layer 4 having a smaller coercive force. In such a magnetic card, when different information is recorded on the magnetic recording layer 3 and the magnetic recording layer 4, respectively, as shown by a broken line in FIG. Since it leaks to the surface of the magnetic card, the linear recording density of either one of the magnetic recording layers must be extremely reduced for recording, and it is necessary to use a filter for discriminating on the basis of frequency when reproducing information. However, in this case, the increase in storage capacity was very slight.
（発明が解決しようとする課題） 本発明は上記の欠点を改善するために提案されたもの
でその目的は、線記録密度を向上させず、したがって、
カードリーダライタを高価ならしめずに記憶容量を２倍
にでき、かつ、あたかも一つの磁気記録層のみが存在す
る一般の磁気カードに見せ掛けて、重要な情報を隠蔽で
き、すなわち、記憶容量の増大とともに重要な記録情報
の改ざんが防止できる磁気カードを提供することにあ
る。(Problems to be Solved by the Invention) The present invention has been proposed in order to improve the above-mentioned drawbacks, and an object thereof is not to improve linear recording density.
The storage capacity can be doubled without making the card reader / writer expensive, and important information can be hidden by making it look like a general magnetic card having only one magnetic recording layer, that is, the storage capacity is increased. Another object is to provide a magnetic card that can prevent tampering with important recorded information.
（課題を解決するための手段） 本発明による磁気カードは、保磁力が異なる二つの磁
気記録層と、常温では前記磁気記録層の少なくとも一方
の磁気記録層の保磁力より大きい保磁力を有し、かつ、
前記磁気記録層の何れのキュリー点より低いキュリー点
の熱磁気転写層とが基板上に積層されたことを特徴とす
るもので、保磁力が大きい方の磁気記録層に記録された
重要な情報を熱磁気転写層に熱磁気転写することによっ
て情報を記録したことにより生ずる磁化による磁束が磁
気カードの表面にも漏れなくなり、したがって、磁性材
料の保磁力が最も小さい他方の磁気記録層には全く別の
情報の記録再生が容易になるとともに一般の磁気ヘッド
で前者の磁気記録層の重要な記録情報の改ざんが防止で
きるものである。(Means for Solving the Problem) A magnetic card according to the present invention has two magnetic recording layers having different coercive forces and a coercive force larger than that of at least one of the magnetic recording layers at room temperature. ,And,
The thermomagnetic transfer layer having a Curie point lower than any Curie point of the magnetic recording layer is laminated on the substrate, and important information recorded in the magnetic recording layer having the larger coercive force. Magnetic flux generated by recording information by thermomagnetic transfer to the thermomagnetic transfer layer does not leak to the surface of the magnetic card, so that the magnetic recording layer with the smallest coercive force of the magnetic material does not exist at all. It is possible to easily record and reproduce other information and prevent tampering of important recorded information in the former magnetic recording layer with a general magnetic head.
（作用） 本発明の磁気カードにおいては、保磁力が大きい方の
磁気記録層に記録された重要な情報を熱磁気転写層に熱
磁気転写すると、情報を記録したことにより生ずる該磁
気記録層の磁化による磁束は熱磁気転写されたことによ
る熱磁気転写層の磁化と閉ループを形成し、前記磁束は
磁気カードの表面にも漏れなくなる。したがって、保磁
力が小さい方の磁気記録層には全く別の情報の記録再生
が可能となる。ここで、保磁力が大きい方の磁気記録層
に最初に記録された重要な情報の再生は、一般の技術で
は不可能である。この再生を可能とするには、保磁力が
大きい方の磁気記録層，熱磁気転写層，これら２層のう
ちの保磁力の小さい方の層と、保磁力が最も小さい磁気
記録層とにおける情報による磁化を直流消去しなければ
ならない。(Operation) In the magnetic card of the present invention, when important information recorded in the magnetic recording layer having the larger coercive force is thermomagnetically transferred to the thermomagnetic transfer layer, the magnetic recording layer of the magnetic recording layer is generated by recording the information. The magnetic flux due to the magnetization forms a closed loop with the magnetization of the thermomagnetic transfer layer due to the thermomagnetic transfer, and the magnetic flux does not leak to the surface of the magnetic card. Therefore, it is possible to record and reproduce completely different information on the magnetic recording layer having the smaller coercive force. Here, it is impossible to reproduce the important information first recorded on the magnetic recording layer having the larger coercive force by a general technique. In order to enable this reproduction, information is recorded in the magnetic recording layer having the larger coercive force, the thermomagnetic transfer layer, the layer having the smaller coercive force of these two layers and the magnetic recording layer having the smallest coercive force. The magnetization due to must be DC erased.
（実施例） 次に本発明の実施例について説明する。なお、実施例
は一つの例示であって、本発明の精神を逸脱しない範囲
で、種々の変更あるいは改良を行いうることは言うまで
もない。(Example) Next, the Example of this invention is described. Needless to say, the embodiment is merely an example, and various modifications and improvements can be made without departing from the spirit of the present invention.
第１図は本発明による磁気カードのじ実施例の一部破
断断面図であって、図において、５は磁気カード、６は
基板、７はBaフェライト粒子を結合剤中に分散して形成
した第１の磁気記録層、８はCrO2粒子を結合剤中に分散
して形成した熱磁気転写層、９はγ−Fe2O3粒子を結合
剤中に分散して形成した第２の磁気記録層である。ここ
で、Baフェライト粒子の常温での保磁力は約2000oe,キ
ュリー点は約450℃で、CrO2粒子の常温での保磁力は約7
50oe,キュリー点は約130℃で、γ−Fe2O3粒子の常温で
の保磁力は約250oe,キュリー点は約590℃である。FIG. 1 is a partially cutaway sectional view of the same embodiment of a magnetic card according to the present invention, in which 5 is a magnetic card, 6 is a substrate, and 7 is Ba ferrite particles dispersed in a binder. The first magnetic recording layer, 8 is a thermomagnetic transfer layer formed by dispersing CrO 2 particles in a binder, and 9 is the second magnetic recording layer formed by dispersing γ-Fe 2 O 3 particles in the binder. It is a recording layer. Here, the coercive force of Ba ferrite particles at room temperature is about 2000oe, the Curie point is about 450 ° C, and the coercive force of CrO 2 particles at room temperature is about 7
The 50 oe, Curie point is about 130 ° C, the coercive force of γ-Fe 2 O 3 particles at room temperature is about 250 oe, and the Curie point is about 590 ° C.
次に、第１図に示した本発明による磁気カードの実施
例における情報の記録再生について図面を用いて説明す
る。第２図は第１図の磁気カードにおける情報の記録再
生について説明するための図である。まず、第２図
（イ）は、リング形磁気ヘッド（図では略）によって第
１の磁気記録層７に重要な情報を記録する。このときの
磁気カードの各層の磁化状態は第２図（イ）となる。第
１の磁気記録層７の保磁力が、熱磁気転写層８の保磁
力，第２の磁気記録層９の保磁力のいずれよりも大きい
ので、少なくとも第２の磁気記録層９の磁化をリング形
磁気ヘッドで直流消去することができ、このときの磁気
カードの各層の磁化状態は第２図（イ）から第２図
（ロ）に変わる。次に、加熱ヘッド（図では略）の下
を、磁気カード５の加熱ヘッドとの接触部において、第
１の磁気記録層7,第２の磁気記録層９がそれぞれ450℃,
590℃程度にはならないように、熱磁気転写層８がキュ
リー点の130℃以上になるように加熱して、磁気カード
５を通過させると、第１の磁気記録層７の記録情報は熱
磁気転写層８に熱磁気転写する。このときの磁化状態は
第２図（ハ）となり、熱磁気転写層８の厚さを適当に選
べば、これらの磁化による磁束は閉ループを形成し、磁
気カード５の表面には勿論第２の磁気記録層９にも漏れ
ない。第２の磁気記録層９の保磁力が最も小さいので、
リング形磁気ヘッドに流す電流を制限することによっ
て、第１の磁気記録層７に記録した重要な情報とは全く
別の情報を第２図（ニ）のように第２の磁気記録層９に
記録再生することができる。すなわち、ここではあたか
も第２の磁気記録層９のみが存在する一般の磁気カード
に見せ掛けて重要な情報を隠蔽できる。前に記録した重
要な情報は、以下のように再生できる。第１の磁気記録
層７の保磁力が最も大きいので、この磁気記録層７の磁
化だけを残し、熱磁気転写層８と第２の磁気記録層９の
磁化をリング形磁気ヘッドで直流消去でき、このときの
磁化状態は第２図（ホ）のようになり、第１の磁気記録
層７の磁化による磁束が磁気カードの表面に漏れる。し
たがって、リング形磁気ヘッドで重要な情報も再生が可
能となる。なお、実線矢印は磁化、破線は磁束が閉ルー
プを形成することを示す。Next, recording / reproducing of information in the embodiment of the magnetic card according to the present invention shown in FIG. 1 will be described with reference to the drawings. FIG. 2 is a diagram for explaining recording / reproduction of information on the magnetic card of FIG. First, in FIG. 2A, important information is recorded on the first magnetic recording layer 7 by a ring-shaped magnetic head (not shown). The magnetization state of each layer of the magnetic card at this time is shown in FIG. Since the coercive force of the first magnetic recording layer 7 is larger than both the coercive force of the thermomagnetic transfer layer 8 and the coercive force of the second magnetic recording layer 9, at least the magnetization of the second magnetic recording layer 9 is ringed. Direct current can be erased by the magnetic head of FIG. 2 and the magnetization state of each layer of the magnetic card at this time changes from FIG. 2 (a) to FIG. 2 (b). Next, under the heating head (not shown), at the contact portion of the magnetic card 5 with the heating head, the first magnetic recording layer 7 and the second magnetic recording layer 9 are heated to 450 ° C., respectively.
The thermo-magnetic transfer layer 8 is heated to 130 ° C. or higher of the Curie point so that the temperature does not reach 590 ° C.
After passing 5 , the recorded information in the first magnetic recording layer 7 is thermomagnetically transferred to the thermomagnetic transfer layer 8. The magnetization state at this time is as shown in FIG. 2C, and if the thickness of the thermomagnetic transfer layer 8 is properly selected, the magnetic flux due to these magnetizations forms a closed loop, and of course the surface of the magnetic card 5 is in the second state. It does not leak to the magnetic recording layer 9. Since the coercive force of the second magnetic recording layer 9 is the smallest,
By limiting the current flowing through the ring-shaped magnetic head, information that is completely different from the important information recorded in the first magnetic recording layer 7 is recorded in the second magnetic recording layer 9 as shown in FIG. It can be recorded and played back. That is, here, it is possible to conceal important information by disguising it as a general magnetic card in which only the second magnetic recording layer 9 exists. The important information previously recorded can be reproduced as follows. Since the coercive force of the first magnetic recording layer 7 is the largest, only the magnetization of the magnetic recording layer 7 is left, and the magnetizations of the thermomagnetic transfer layer 8 and the second magnetic recording layer 9 can be DC erased by the ring type magnetic head. The magnetization state at this time is as shown in FIG. 2E, and the magnetic flux due to the magnetization of the first magnetic recording layer 7 leaks to the surface of the magnetic card. Therefore, important information can be reproduced by the ring-shaped magnetic head. The solid arrows indicate magnetization, and the broken lines indicate that magnetic flux forms a closed loop.
第３図は本発明による磁気カードの他の実施例の一部
破断断面図であって、図において、６は基板、10はCoが
被着されたγ−Fe2O3粒子を結合剤中に分散して形成し
た第１の磁気記録層、11はNdFeB合金粒子を結合剤中に
分散して形成した熱磁気転写層である。なお、９は第１
図と同じくγ−Fe2O3粒子を結合剤中に分散して形成し
た第２の磁気記録層である。Coが被着されたγ−Fe2O3
粒子の常温での保磁力は約750oe,キュリー点は約520℃
である。NdFeB合金粒子の常温での保磁力は約12koe,キ
ュリー点は310℃である。第３図に示した本発明による
磁気カードの実施例における情報の記録再生について
は、第１図に示した本発明による磁気カードの実施例に
おける情報の記録再生とほぼ同様に行うことができる
が、リング形磁気ヘッドによって第１の磁気記録層10に
重要な情報を記録したとき、第４図（イ′）に示すよう
に第２の磁気記録層９にも記録されるが、熱磁気転写層
11の保磁力が非常に大きいので熱磁気転写層11には記録
されないことと、重要な情報を再生するとき、熱磁気転
写層11の磁化だけを残し、第４図（ホ′）に示すように
第１の磁気記録層10と第２の磁気記録層９の磁化をリン
グ形磁気ヘッドで直流消去して、熱磁気転写層11の磁化
による時速のみを磁気カードの表面に漏れさせることが
異なる。第３図に示した本発明による磁気カードの実施
例の特徴は、重要な情報が熱磁気転写される熱磁気転写
層11の保磁力が非常に大きくてもよく、実施例程度の保
磁力の場合には通常の磁石を接触させても重要な情報が
消えずに安定に保持されることである。FIG. 3 is a partially cutaway sectional view of another embodiment of the magnetic card according to the present invention, in which 6 is a substrate and 10 is Co-coated γ-Fe 2 O 3 particles in a binder. The first magnetic recording layer 11 is formed by dispersing NdFeB alloy particles in a binder, and the thermomagnetic transfer layer 11 is formed by dispersing NdFeB alloy particles in a binder. Note that 9 is the first
As in the figure, the second magnetic recording layer is formed by dispersing γ-Fe 2 O 3 particles in a binder. Γ-Fe 2 O 3 coated with Co
The coercive force of the particles at room temperature is about 750oe, and the Curie point is about 520 ° C.
Is. The coercive force of NdFeB alloy particles at room temperature is about 12 koe and the Curie point is 310 ° C. Recording and reproduction of information in the embodiment of the magnetic card according to the present invention shown in FIG. 3 can be performed in substantially the same manner as recording and reproduction of information in the embodiment of the magnetic card according to the present invention shown in FIG. When important information is recorded on the first magnetic recording layer 10 by the ring type magnetic head, it is also recorded on the second magnetic recording layer 9 as shown in FIG. layer
Since the coercive force of 11 is so large that it is not recorded in the thermomagnetic transfer layer 11, and only the magnetization of the thermomagnetic transfer layer 11 is left when reproducing important information, as shown in FIG. In addition, the magnetizations of the first magnetic recording layer 10 and the second magnetic recording layer 9 are DC-erased by a ring-shaped magnetic head, and only the velocity per hour due to the magnetization of the thermomagnetic transfer layer 11 is leaked to the surface of the magnetic card. . The feature of the embodiment of the magnetic card according to the present invention shown in FIG. 3 is that the coercive force of the thermomagnetic transfer layer 11 on which important information is thermomagnetically transferred may be very large. In some cases, important information cannot be erased even when a normal magnet is brought into contact with it, so that it can be held stably.
なお、第１の磁気記録層，第２の磁気記録層，熱磁気
転写層、これらの積層の順序は任意でよいことは明らか
であるが、磁気記録再生および熱磁気転写の効率からは
図示した実施例の順序が望ましい。また、磁気カードの
表層には化学的物理的な保護層を形成してもなんら差し
支えない。Although it is clear that the order of the first magnetic recording layer, the second magnetic recording layer, the thermomagnetic transfer layer, and these layers may be arbitrary, it is shown from the viewpoint of the efficiency of magnetic recording / reproducing and thermomagnetic transfer. The order of the examples is preferred. Further, a chemical / physical protective layer may be formed on the surface of the magnetic card.
（発明の効果） 以上説明したように、本発明によれば、磁気カードに
おいて保磁力が異なる二つの磁気記録層と、常温では前
記磁気記録層の少なくとも一方の磁気記録層の保磁力よ
り大きい保磁力を有し、かつ、前記磁気記録層の何れの
キュリー点より低いキュリー点の熱磁気転写層とが基板
上に積層することによって、線記録密度を向上させず、
したがって、カードリーダライタを高価ならしめずに記
憶容量を２倍にでき、かつ、あたかも一つの磁気記録層
のみが存在する一般の磁気カードに見せ掛けて重要な情
報を隠蔽でき、すなわち、記憶容量の増大とともに記録
情報の改ざんが防止できる磁気カードを提供できる。(Effects of the Invention) As described above, according to the present invention, a magnetic card having a coercive force larger than the coercive force of two magnetic recording layers having different coercive forces and at least one of the magnetic recording layers at room temperature is used. By having a magnetic force and a thermomagnetic transfer layer having a Curie point lower than any Curie point of the magnetic recording layer laminated on the substrate, the linear recording density is not improved,
Therefore, the storage capacity can be doubled without making the card reader / writer expensive, and important information can be hidden as if it were a general magnetic card having only one magnetic recording layer. It is possible to provide a magnetic card capable of preventing tampering with recorded information as the number increases.
第１図は本発明による磁気カードの実施例の一部破断断
面図、第２図は第１図の本発明による磁気カードの実施
例における情報の記録再生について説明するための図、
第３図は本発明による磁気カードの他の実施例の一部破
断断面図、第４図は第１図の実施例と第３図の実施例で
の情報の記録再生において異なるところを説明するため
の図、第５図は従来の二つの磁気記録層を有する磁気カ
ードの一部破断断面図を示す。 ５……磁気カード ６……基板 7,10……第１の磁気記録層 8,11……熱磁気転写層 ９……第２の磁気記録層FIG. 1 is a partially cutaway sectional view of an embodiment of a magnetic card according to the present invention, and FIG. 2 is a diagram for explaining recording and reproduction of information in the embodiment of the magnetic card according to the present invention of FIG.
FIG. 3 is a partially cutaway sectional view of another embodiment of the magnetic card according to the present invention, and FIG. 4 explains the difference between the embodiment of FIG. 1 and the embodiment of FIG. 3 in recording and reproducing information. FIG. 5 is a partially cutaway sectional view of a conventional magnetic card having two magnetic recording layers. 5 ... Magnetic card 6 ... Substrate 7,10 ... First magnetic recording layer 8, 11 ... Thermomagnetic transfer layer 9 ... Second magnetic recording layer
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｇ１１Ｂ 11/10 ５０６ Ｇ０６Ｋ 19/00 Ｂ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI technical display location G11B 11/10 506 G06K 19/00 B
Claims (2)
では前記磁気記録層の少なくとも一方の磁気記録層の保
磁力より大きい保磁力を有し、かつ、前記磁気記録層の
何れのキュリー点より低いキュリー点の熱磁気転写層と
が基板上に積層されたことを特徴とする磁気カード。1. Two magnetic recording layers having different coercive forces, and a coercive force larger than the coercive force of at least one of the magnetic recording layers at room temperature, and any Curie of the magnetic recording layers. A magnetic card characterized in that a thermomagnetic transfer layer having a Curie point lower than the point is laminated on a substrate.
方の磁気記録層を深層とし、次に熱磁気転写層、保磁力
の小さい方の磁気記録層の順で基板上に積層されたこと
を特徴とする請求項１記載の磁気カード。2. A magnetic recording layer having a larger coercive force of the two magnetic recording layers is a deep layer, and a thermomagnetic transfer layer and a magnetic recording layer having a smaller coercive force are laminated on the substrate in this order. The magnetic card according to claim 1, wherein
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63043973A JP2544646B2 (en) | 1988-02-26 | 1988-02-26 | Magnetic card |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63043973A JP2544646B2 (en) | 1988-02-26 | 1988-02-26 | Magnetic card |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01216891A JPH01216891A (en) | 1989-08-30 |
| JP2544646B2 true JP2544646B2 (en) | 1996-10-16 |
Family
ID=12678659
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63043973A Expired - Fee Related JP2544646B2 (en) | 1988-02-26 | 1988-02-26 | Magnetic card |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2544646B2 (en) |
-
1988
- 1988-02-26 JP JP63043973A patent/JP2544646B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01216891A (en) | 1989-08-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1079514A (en) | Polymodal magnetic recording media process for making and verifying the same and compositions useful therein | |
| US4281043A (en) | Polymodal magnetic recording media and compositions useful therein | |
| US3986206A (en) | Magnetic recording medium with highly anisotropic particles | |
| JP2544646B2 (en) | Magnetic card | |
| JP2837737B2 (en) | Magnetic recording media | |
| JP3121977B2 (en) | Magnetic recording medium and manufacturing method thereof | |
| JP3051644B2 (en) | Manufacturing method of magnetic recording medium | |
| JPH01216892A (en) | Magnetic card | |
| JP3384695B2 (en) | Magnetic recording media | |
| JP3019140B2 (en) | Perpendicular magnetic recording media | |
| Sugaya | Magnetic tapes for contact duplication by anhysteretic and thermal transfer methods | |
| JP2613854B2 (en) | Composite magnetic recording media | |
| JP2518620B2 (en) | Magnetic recording / reproducing method and apparatus | |
| JPH01216890A (en) | Multilayer magnetic card | |
| JP2908535B2 (en) | Signal reading method of magnetic recording type ticket | |
| JPS6353605B2 (en) | ||
| JP2597328B2 (en) | Recording / reproducing method for three magnetic layer magnetic card | |
| JP2990259B2 (en) | Magnetic recording head using ferromagnetic semiconductor | |
| JP3139301B2 (en) | Magnetic recording / reproducing device | |
| JPH01204216A (en) | Magnetic recording medium | |
| JPH02156416A (en) | Magnetic card | |
| JPH09180167A (en) | Magnetic recording medium and its production | |
| JP2856780B2 (en) | Magnetic recording medium and recording method thereof | |
| JPH05143959A (en) | Recording medium for magnetic card | |
| JPH09134519A (en) | Multi-layer magnetic recording medium and method for recording/reproducing the recording medium |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |