JP2518620B2 - Magnetic recording / reproducing method and apparatus - Google Patents
Magnetic recording / reproducing method and apparatusInfo
- Publication number
- JP2518620B2 JP2518620B2 JP61178503A JP17850386A JP2518620B2 JP 2518620 B2 JP2518620 B2 JP 2518620B2 JP 61178503 A JP61178503 A JP 61178503A JP 17850386 A JP17850386 A JP 17850386A JP 2518620 B2 JP2518620 B2 JP 2518620B2
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- Japan
- Prior art keywords
- magnetic
- signal
- magnetic layer
- recording medium
- layer
- Prior art date
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Description
【発明の詳細な説明】 産業上の利用分野 本発明は、磁気記録媒体および磁気記録再生装置に関
するものであり、特に、金融、流通などの代金決済に用
いられるなど高い機密性を要する磁気カード等に適用す
る磁気記録媒体および磁気記録再生方法および装置に関
するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium and a magnetic recording / reproducing apparatus, and in particular, a magnetic card or the like which is required to have high confidentiality such as being used for settlement of payment for finance and distribution. The present invention relates to a magnetic recording medium and a magnetic recording / reproducing method and apparatus applied to.
従来の技術 従来、金融、流通などの代金決済には、広く磁気カー
ドが利用されており、最近では、ますます種類、量とも
増えてきている。ところが磁気カードは安価で、取り扱
い易く、データの書き換えが可能である、といった長所
の反面、記録・再生が容易であるため、比較的簡単な記
録再生装置で、記録内容が読めたり、書き換えたりする
ことができる。従って、磁気カードは、偽造・データ改
ざん・悪用などの危険にさらされており、特に代金決済
といった高い機密性を必要とする装置には、磁気カード
自体に、より高い機密性を有するものが要求されてい
る。これらを解決する手段として、特開昭55−93514号
公報に開示されたように、磁性層の上に高透磁率材料層
を設け、磁気出力を遮蔽し、通常状態での読み出しを不
能にする方法が提案されている。2. Description of the Related Art Conventionally, magnetic cards have been widely used for payments for finance, distribution, etc., and in recent years, types and amounts have been increasing more and more. However, magnetic cards are inexpensive, easy to handle, and data can be rewritten. On the other hand, since they are easy to record and reproduce, the contents can be read and rewritten with a relatively simple recording and reproducing device. be able to. Therefore, magnetic cards are exposed to risks such as forgery, data falsification, and misuse. Especially, for devices that require high confidentiality such as payment for payment, the magnetic cards themselves are required to have higher confidentiality. Has been done. As a means for solving these problems, as disclosed in Japanese Patent Laid-Open No. 55-93514, a high magnetic permeability material layer is provided on a magnetic layer to shield magnetic output and disable reading in a normal state. A method has been proposed.
発明が解決しようとする問題点 しかしながら、このような従来の方法では、次のよう
な問題があった。すなわち、磁気遮蔽材として好適な、
Ni−Fe合金などの高透磁率強磁性金属材料は、磁気カー
ドなどのプラスチック基体上に、箔状で接着された場合
には、基体の変形などにより磁性層に応力が発生すると
その磁気特性が悪化するし、粉粒体にして塗布される場
合には、各製造工程において材料が化学的変質を受けな
いよう特別な注意をはらう必要がある。しかも、この種
の高透磁率強磁性金属材料は、通常磁気テープや磁気カ
ードなどに用いる磁性材料であるγFe2O3やコバルト被
着型γFe2O3などに比べると、非常に高価である。Problems to be Solved by the Invention However, such a conventional method has the following problems. That is, suitable as a magnetic shielding material,
High-permeability ferromagnetic metal material, such as N i -F e alloy, on a plastic substrate such as a magnetic card, if it is bonded in a foil shape, a stress is generated in the magnetic layer due to the deformation of the substrate that magnetic If the characteristics deteriorate and they are applied in the form of powder or granules, special care must be taken to prevent the material from undergoing chemical alteration during each manufacturing process. Moreover, this kind of high magnetic permeability ferromagnetic metal material, when usually compared to such [gamma] F e2 O 3 or cobalt-coated [gamma] F e2 O 3 which is a magnetic material used for a magnetic tape or a magnetic card, it is very expensive .
本発明の目的は、前述したような従来技術の問題点に
かんがみて、安価な材料を用いしかも簡単な構成ながら
偽造・データ改ざん等を困難にした磁気記録媒体および
磁気記録再生方法および装置を提供することである。In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a magnetic recording medium, a magnetic recording medium, and a magnetic recording / reproducing method and device in which it is difficult to forge, falsify data, etc., using an inexpensive material and having a simple structure. It is to be.
問題点を解決するための手段 本発明のある特徴によれば、少なくとも所定の状態に
おいて保磁力の異なる少なくとも２つの磁性層を積層し
てなる磁気記録媒体の磁気記録再生方法において、先ず
一方の磁性層に信号を書き込み、次いで前記一方の磁性
層に書き込まれた信号を他方の磁性層に磁気転写するこ
とによって記録を行い、前記他方の磁気転写された信号
を直流消磁してから前記一方の磁性層に記録された信号
を読み取るようにする。According to one aspect of the present invention, in a magnetic recording / reproducing method for a magnetic recording medium, in which at least two magnetic layers having different coercive forces are laminated in at least a predetermined state, first one of the magnetic layers is Recording is performed by writing a signal in a layer, then magnetically transferring the signal written in the one magnetic layer to the other magnetic layer, and demagnetizing the other magnetically transferred signal by direct current, and then demagnetizing the one magnetic layer. Read the signal recorded on the layer.
本発明の別の特徴によれば、少なくとも所定の状態に
おいて保磁力の異なる少なくとも２つの磁性層を積層し
てなる磁気記録媒体に信号を書き込むための書込み装置
において、前記磁気記録媒体に対して所望の信号を記録
するための信号記録手段と、該信号記録手段による所望
の信号の記録後に、前記磁性層のうち保磁力の最も低い
磁気記録層に、保磁力の高い磁性層の残留磁化を、磁気
転写するための磁気転写手段とが備えられる。According to another feature of the present invention, in a writing device for writing a signal on a magnetic recording medium having at least two magnetic layers having different coercive forces laminated at least in a predetermined state, the writing device is desired for the magnetic recording medium. Signal recording means for recording the signal of, and after the desired signal is recorded by the signal recording means, the residual magnetization of the magnetic layer having a high coercive force is recorded in the magnetic recording layer having the lowest coercive force among the magnetic layers, And a magnetic transfer means for magnetically transferring.
本発明の更に別の特徴によれば、少なくとも所定の状
態において保磁力の異なる少なくとも２つの磁性層を積
層してなり、前記磁性層のうち保磁力の最も低い磁性層
には、保磁力の高い磁性層の残留磁化が磁気転写されて
いるような磁気記録媒体から所望の信号を読み取るため
の読取り装置において、前記磁気転写された低保磁力層
の残留磁化を消去するための残留磁化消去手段と、該残
留磁化消去手段による残留磁化の消去後、前記磁気記録
媒体の信号を再生するための信号再生手段とが備えられ
る。According to still another feature of the present invention, at least two magnetic layers having different coercive forces are laminated in at least a predetermined state, and the magnetic layer having the lowest coercive force has a high coercive force. In a reader for reading a desired signal from a magnetic recording medium in which the remanent magnetization of a magnetic layer is magnetically transferred, a remanent magnetization erasing means for erasing the remanent magnetization of the magnetically transferred low coercive force layer. Signal reproducing means for reproducing a signal of the magnetic recording medium after the residual magnetization is erased by the residual magnetization erasing means.
本発明のもう１つの特徴によれば、少なくとも所定の
状態において保磁力の異なる少なくとも２つの磁性層を
積層してなる磁気記録媒体に信号を書き込みその信号を
読み取る磁気記録再生装置において、前記磁気記録媒体
に対して所望の信号を記録するための信号記録手段と、
該信号記録手段による所望の信号の記録後に、前記磁性
層のうち保磁力の最も低い磁性層に、保磁力の高い磁性
層の残留磁化を、磁気転写するための磁気転写手段と、
前記磁気転写された低保磁力層の残留磁化を消去するた
めの残留磁化消去手段と、該残留磁化消去手段による残
留磁化の消去後、前記磁気記録媒体の信号を再生するた
めの信号再生手段とが備えられる。According to another feature of the present invention, in a magnetic recording / reproducing apparatus for writing a signal to a magnetic recording medium having at least two magnetic layers different in coercive force at least in a predetermined state and reading the signal, the magnetic recording A signal recording means for recording a desired signal on the medium,
Magnetic recording means for magnetically transferring the remanent magnetization of the magnetic layer having a high coercive force to the magnetic layer having the lowest coercive force after the desired signal is recorded by the signal recording means,
A residual magnetization erasing means for erasing the residual magnetization of the magnetically transferred low coercive force layer, and a signal reproducing means for reproducing a signal of the magnetic recording medium after the residual magnetization is erased by the residual magnetization erasing means. Is provided.
本発明の更にまた別の特徴によれば、基体上に磁性層
を順次積層してなる磁気記録媒体において、上方の磁性
層を構成する磁性体のキュリー温度は、下方の磁性層を
構成する磁性体のキュリー温度より低いものとされてい
る。According to still another feature of the present invention, in a magnetic recording medium in which magnetic layers are sequentially laminated on a substrate, the Curie temperature of the magnetic material forming the upper magnetic layer is set to the magnetic property forming the lower magnetic layer. It is said to be lower than the Curie temperature of the body.
本発明の更にもう１つ別の特徴によれば、少なくとも
所定の状態において保磁力の異なる少なくとも２つの磁
性層を積層してなる磁気記録媒体の正当性判定方法にお
いて、先ず一方の磁性層に信号を書き込み、次いで前記
一方の磁性層に書き込まれた信号を他方の磁性層に磁気
転写した後に読み取った再生出力レベルと、前記他方の
磁性層に磁気転写された信号を直流消磁した後に読み取
った再生出力レベルとを比較する。According to still another feature of the present invention, in a method for determining the validity of a magnetic recording medium, which comprises stacking at least two magnetic layers having different coercive forces at least in a predetermined state, first, a signal is recorded on one magnetic layer. , And then the read output level read after magnetically transferring the signal written in the one magnetic layer to the other magnetic layer and the read output read after demagnetizing the signal magnetically transferred to the other magnetic layer by DC demagnetization. Compare with the output level.
実施例 次に、添付図面に基づいて本発明の実施例について本
発明をより詳細に説明する。Examples Next, the present invention will be described in more detail with reference to the accompanying drawings with reference to the examples of the present invention.
第１図は、本発明において使用する磁気記録媒体の部
分断面図である。第１図に示されるように、この磁気記
録媒体１は、例えば、ポリエチレンテレフタレート（PE
T）などのプラスチック基板４の上に、例えば、保磁力
が3000エルステッドの、バリウムフェライトなどから成
る高保磁力の第２の磁性層３と、例えば、保磁力が650
エルステッドの、コバルト被着型γFe2O3などから成る
低保磁力の第１の磁性層２とが、積層されて構成されて
いる。FIG. 1 is a partial sectional view of a magnetic recording medium used in the present invention. As shown in FIG. 1, the magnetic recording medium 1 is made of, for example, polyethylene terephthalate (PE
On the plastic substrate 4 such as T), a second magnetic layer 3 having a high coercive force, such as barium ferrite, having a coercive force of 3000 oersted, and a coercive force of, for example, 650
The first magnetic layer 2 having a low coercive force and made of cobalt-coated γF e2 O 3 or the like of Oersted is laminated.
ここで、本発明は、高保磁力磁性層（マスター）か
ら、低保磁力磁性層（スレーブ）に、信号を転写する接
触磁気転写方法を利用するものであり、このような接触
磁気転写方法においては、社団法人電気学会、社団法人
電子通信学会1978年２月24日発行「電子通信学会磁気記
録研究会信学技報MR77−35（1978−２）」における三村
升平・檜森 広明・栃原 重三（東京磁気印刷株式会
社）による「接触磁気転写に関する一考察」と題する論
文に開示されているように、マスターの保磁力は、スレ
ーブの保磁力の2.5倍以上必要であることが、従来より
知られている。従って、第１図の磁気記録媒体１におい
ても、第１の磁性層２の保磁力（HcI）と、第２の磁性
層３の保磁力（HcII）との間には、 HcII＞2.5HcIなる関係が成り立つように選定されている
ものとする。Here, the present invention utilizes a contact magnetic transfer method for transferring a signal from a high coercive force magnetic layer (master) to a low coercive force magnetic layer (slave). , The Institute of Electrical Engineers of Japan, The Institute of Electronics, Information and Communication Engineers, published on February 24, 1978, "Technical Bulletin of the Institute of Electronics and Communication Engineers, Magnetic Recording Research Group MR77-35 (1978-2)", Mitsuhei Mimura, Hiroaki Hinomori and Shigezo Tochihara ( It was previously known that the coercive force of the master needs to be 2.5 times or more that of the slave, as disclosed in a paper entitled "One Consideration on Contact Magnetic Transfer" by Tokyo Magnetic Printing Co., Ltd.). ing. Therefore, also in the magnetic recording medium 1 of FIG. 1, HcII> 2.5HcI between the coercive force (HcI) of the first magnetic layer 2 and the coercive force (HcII) of the second magnetic layer 3. It is assumed that the relationship is selected.
第２図は、第１図の磁気記録媒体に信号を書き込み本
発明の磁気記録媒体を与えるための本発明の一実施例と
しての書込み装置の動作を説明するための概略図であ
る。第２図において、参照番号５は、第１の磁性層２お
よび第２の磁性層３を、同時に記録するための記録ヘッ
ドを示し、参照番号６は、保磁力の低い（HcI）第１の
磁性層の残留磁化を消去すると同時に保磁力の高い第２
の磁性層の信号磁化を、磁気転写によって第１の磁性層
２に再度記録するための交流磁界を発生させる転写用ヘ
ッドを示している。FIG. 2 is a schematic diagram for explaining the operation of the writing device as one embodiment of the present invention for writing a signal on the magnetic recording medium of FIG. 1 to provide the magnetic recording medium of the present invention. In FIG. 2, reference numeral 5 indicates a recording head for simultaneously recording on the first magnetic layer 2 and the second magnetic layer 3, and reference numeral 6 indicates a first coercive force-lowering (HcI) first magnetic layer. A second coercive force that is high at the same time that the residual magnetization of the magnetic layer is erased
2 shows a transfer head that generates an AC magnetic field for re-recording the signal magnetization of the magnetic layer in the first magnetic layer 2 by magnetic transfer.
なお、第２図において、矢印16は、記録ヘッド５およ
び転写用ヘッド６と、磁気記録媒体１との相対的移動方
向を示している。In FIG. 2, the arrow 16 indicates the relative movement direction of the recording head 5, the transfer head 6, and the magnetic recording medium 1.
第２図の書込み装置において、磁気記録媒体１に所望
の信号を書き込むための動作について以下説明する。先
ず、記録ヘッド５により、高保磁力の第２の磁性層３を
充分磁化できる強いヘッド磁界を発生させる。記録ヘッ
ド５のギャップ部が通過した後の磁気記録媒体１には、
第２の磁性層３の残留磁化７と、第１の磁性層２の残留
磁化８とが、矢印で示すように、それぞれ同じ方向に発
生する。この状態において、それぞれの磁性層の残留磁
化から発生した磁束９は、互いに加算されて、磁気記録
媒体１の表面にあらわれているので、再生ヘッドをその
磁気記録媒体１の表面に近接させれば、その磁気記録媒
体１の記録内容を大きな出力で取り出し再生することが
できる。しかるに、本発明の書込み装置によれば、前述
の記録動作の直後に、記録済の磁気記録媒体１を、第１
の磁性層２を消去するには充分であり且つ第２の磁性層
３の残留磁化には影響を与えない程度の強さの交流磁界
を発生させる転写用ヘッド６に接近させると、第１の磁
性層２の残留磁化８は、転写用ヘッド６のギャップ部分
が近づき、交流磁界が強まるにつれ、徐々に減衰する。
そして、ギャップ部分の直下にきた時に、残留磁化８は
完全に消失し、更に転写用ヘッド６のギャップ部から遠
ざかり、交流磁界が徐々に減衰していく過程で、第１の
磁性層２には、第２の磁性層３の残留磁化が磁気転写さ
れる。この時、第１の磁性層２に形成される残留磁化
８′は、第２の磁性層３の残留磁化により磁気転写され
たものなので、磁化の向きは、記録ヘッド５によって記
録された残留磁化８とは逆向きになる。従って、第２の
磁性層３の残留磁化７と、第１の磁性層２の残留磁化
８′から発生した磁束は、互いに向きが逆なため打ち消
し合い、双方の磁束の差だけが磁気記録媒体１の表面に
あらわれることになる。この状態で、この磁気記録媒体
１に記録された所望の信号を通常の磁気記録再生装置で
再生しようとしても、僅かな再生出力しか得られず、こ
の磁気記録媒体１の所望の記録内容を正常に読み出すこ
とはできない。The operation for writing a desired signal on the magnetic recording medium 1 in the writing apparatus of FIG. 2 will be described below. First, the recording head 5 generates a strong head magnetic field capable of sufficiently magnetizing the second magnetic layer 3 having a high coercive force. In the magnetic recording medium 1 after the gap of the recording head 5 has passed,
The remanent magnetization 7 of the second magnetic layer 3 and the remanent magnetization 8 of the first magnetic layer 2 are generated in the same direction as indicated by arrows. In this state, the magnetic fluxes 9 generated from the residual magnetization of the respective magnetic layers are added to each other and appear on the surface of the magnetic recording medium 1. Therefore, if the reproducing head is brought close to the surface of the magnetic recording medium 1. The recorded contents of the magnetic recording medium 1 can be taken out and reproduced with a large output. However, according to the writing device of the present invention, immediately after the above-mentioned recording operation, the recorded magnetic recording medium 1 is first recorded.
Of the first magnetic layer 2 is erased, and when the transfer head 6 that generates an alternating magnetic field of a strength that is sufficient to erase the remanent magnetization of the second magnetic layer 3 is removed, The remanent magnetization 8 of the magnetic layer 2 is gradually attenuated as the gap portion of the transfer head 6 approaches and the alternating magnetic field intensifies.
Then, when it comes directly below the gap portion, the remanent magnetization 8 completely disappears, and further away from the gap portion of the transfer head 6, the AC magnetic field gradually attenuates. , The residual magnetization of the second magnetic layer 3 is magnetically transferred. At this time, since the remanent magnetization 8'formed in the first magnetic layer 2 is magnetically transferred by the remanent magnetization of the second magnetic layer 3, the direction of the magnetization is the remanent magnetization recorded by the recording head 5. It is the opposite of 8. Therefore, the remanent magnetization 7 of the second magnetic layer 3 and the remanent magnetization 8'of the first magnetic layer 2 cancel each other because their directions are opposite to each other, and only the difference between the two magnetic fluxes is present. It will appear on the surface of 1. In this state, even if the desired signal recorded on the magnetic recording medium 1 is reproduced by a normal magnetic recording / reproducing apparatus, only a small reproduction output is obtained, and the desired recorded content of the magnetic recording medium 1 is normally obtained. Can not be read.
第３図は、第２図の書込み装置によって情報信号を記
録された磁気記録媒体１からその情報信号を読み出すた
めの本発明の一実施例としての読取り装置の動作を説明
するための概略図である。第３図において、参照番号10
は、第２の磁性層３の残留磁化によって磁気転写された
第１の磁性層２の残留磁化を、直流消磁するための消磁
ヘッドを示し、参照番号11は、第２の磁性層３の残留磁
化を読み取るための再生ヘッドを示している。なお、矢
印17は、消去ヘッド10及び再生ヘッド11と磁気記録媒体
１との間の相対移動方向を示している。FIG. 3 is a schematic diagram for explaining the operation of the reading device as an embodiment of the present invention for reading the information signal from the magnetic recording medium 1 on which the information signal is recorded by the writing device of FIG. is there. In FIG. 3, reference numeral 10
Indicates a degaussing head for degaussing the remanent magnetization of the first magnetic layer 2 magnetically transferred by the remanent magnetization of the second magnetic layer 3, and reference numeral 11 indicates the remanent magnetization of the second magnetic layer 3. The read head for reading the magnetization is shown. An arrow 17 indicates the relative movement direction between the erasing head 10 and the reproducing head 11 and the magnetic recording medium 1.
第２図において説明した記録状態の磁気記録媒体１か
ら信号を読み出すには、先ず、消去ヘッド10に第１の磁
性層２の残留磁化を反転させるに充分であり且つ第２の
磁性層３の残留磁化には影響を与えない程度の強さの直
流磁界を発生させたうえで、磁気記録媒体１を通過させ
ると、第１の磁性層２の残留磁化８′は完全に消失し、
第２の磁性層３の残留磁化７のみが残る。この状態で磁
気記録媒体１の表面には、第２の磁性層の残留磁化７に
よる磁束12があらわれるので、再生ヘッド11により第２
の磁性層３に記録された内容を正常に読み出すことがで
きる。In order to read a signal from the magnetic recording medium 1 in the recording state described in FIG. 2, first, the erasing head 10 is sufficient to reverse the residual magnetization of the first magnetic layer 2 and the second magnetic layer 3 When a DC magnetic field having a strength that does not affect the remanent magnetization is generated and then passed through the magnetic recording medium 1, the remanent magnetization 8'of the first magnetic layer 2 disappears completely,
Only the remanent magnetization 7 of the second magnetic layer 3 remains. In this state, since the magnetic flux 12 due to the residual magnetization 7 of the second magnetic layer appears on the surface of the magnetic recording medium 1, the second magnetic field is generated by the reproducing head 11.
The contents recorded in the magnetic layer 3 can be read normally.
なお、再生ヘッド11の直後に、第２図で説明した転写
用ヘッドを設け、第１の磁性層２に再び第２の磁性層３
の残留磁化を磁気転写すれば、通常の磁気記録再生装置
では再生不能な状態にできることは明らかである。ここ
で、再生ヘッド11による出力信号レベルについて説明す
る。第３図の消去ヘッド10にて第１の磁性層２の残留磁
化８′のみを消去した後に磁気記録媒体１の表面にあら
われている磁束12（Φｃ）と、第２図で説明した記録ヘ
ッド５にて記録した後の磁気記録媒体１の表面にあらわ
れている磁束９（Φａ）とは明らかに異なり、Φａ＞Φ
ｃの関係が成り立つ。さらに、第２図において、転写用
ヘッド６で、第１の磁性層２の残留磁化８′を第２の磁
性層３の残留磁化７と逆向きに形成した後の、磁気記録
媒体１の表面にあらわれる磁束（Φｂ−図示せず）と
は、Φｃ≫Φｂの関係が成り立つのも明白である。再生
ヘッド11の出力信号は、磁気記録媒体１の表面にあらわ
れる磁束の変化に比例するのでΦｃの磁束変化による出
力信号Ecと、前記Φａ、Φｂの磁束変化による出力信号
Ea、Ebとは、Ea＞Ec≫Ebなる関係が成り立つことも明ら
かである。第４図は、前述した本実施例の磁気記録媒体
の再生特性を示す図である。第４図において、曲線13
は、磁気記録媒体１に記録ヘッド５で信号を記録した
後、転写用ヘッド６により交流磁界を印加した時の、そ
の転写用交流磁界の強さと、その時の再生レベルの関係
を示している。なお、再生出力レベルは、記録ヘッド５
で磁気記録媒体１に記録した時の再生出力レベルを100
％として表してある。曲線14は、曲線13で示した転写後
の磁気記録媒体１に、消去ヘッド10により800エルステ
ッドの直流磁界を印加して、第１の磁性層２のみを消去
した時の再生出力レベルを示している。すなわち、曲線
13は、記録ヘッド５で磁気記録媒体１に信号を記録した
後、転写用ヘッド６にて1000エルステッド以上の交流磁
界を印加することにより、再生出力レベルは、記録ヘッ
ド５で記録した時の出力の約10％に低下することを示し
ており、また曲線14は、その後消去ヘッド６にて800エ
ルステッドの直流磁界を印加することにより、記録ヘッ
ド５による記録後の再生出力レベルの約65％まで回復す
ることを示している。第４図の斜線部15は、第１の磁性
層２による、第２の磁性層３の再生出力の遮蔽効果を示
している。なお、曲線13において交流磁界が０エルステ
ッド付近の平坦な部分の出力がEaに、1000エルステッド
以上の平坦な部分の出力がEbに、曲線14の平坦な部分が
Ecに相当することは説明するまでもない。Immediately after the reproducing head 11, the transfer head described with reference to FIG. 2 is provided, and the second magnetic layer 3 is formed on the first magnetic layer 2 again.
It is clear that if the residual magnetization of 1 is magnetically transferred, it cannot be reproduced by a normal magnetic recording / reproducing apparatus. Here, the output signal level of the reproducing head 11 will be described. The magnetic flux 12 (Φc) appearing on the surface of the magnetic recording medium 1 after erasing only the residual magnetization 8'of the first magnetic layer 2 by the erasing head 10 in FIG. 3 and the recording head described in FIG. Clearly different from the magnetic flux 9 (Φa) appearing on the surface of the magnetic recording medium 1 after recording at 5, Φa> Φ
The relationship of c holds. Further, in FIG. 2, the surface of the magnetic recording medium 1 after the remanent magnetization 8 ′ of the first magnetic layer 2 is formed in the transfer head 6 in the opposite direction to the remanent magnetization 7 of the second magnetic layer 3. It is also clear that the relationship of Φc >> Φb is established with the magnetic flux (Φb-not shown) that appears. Since the output signal of the reproducing head 11 is proportional to the change of the magnetic flux appearing on the surface of the magnetic recording medium 1, the output signal Ec due to the change of the magnetic flux of Φc and the output signal due to the change of the magnetic flux of Φa and Φb.
It is also clear that the relationship Ea> Ec >> Eb holds true with Ea and Eb. FIG. 4 is a diagram showing the reproducing characteristics of the magnetic recording medium of this embodiment described above. In FIG. 4, the curve 13
Shows the relationship between the strength of the AC magnetic field for transfer and the reproduction level at that time when an AC magnetic field is applied by the transfer head 6 after recording a signal on the magnetic recording medium 1 by the recording head 5. The reproduction output level is the same as that of the recording head 5.
Playback output level when recorded on magnetic recording medium 1 with 100
Expressed as a percentage. A curve 14 represents a reproduction output level when only the first magnetic layer 2 is erased by applying a DC magnetic field of 800 Oersted to the magnetic recording medium 1 after transfer shown in the curve 13 by the erasing head 10. There is. Ie the curve
The recording head 5 records a signal on the magnetic recording medium 1 and then the transfer head 6 applies an AC magnetic field of 1000 Oersted or more, so that the reproduction output level is the output when the recording head 5 records. Curve 14 and then applying a DC magnetic field of 800 oersted by the erasing head 6 to about 65% of the reproduction output level after recording by the recording head 5. It shows that it will recover. The hatched portion 15 in FIG. 4 shows the effect of shielding the reproduction output of the second magnetic layer 3 by the first magnetic layer 2. In the curve 13, the output of the flat part near the AC magnetic field of 0 oersted is Ea, the output of the flat part of 1000 oersted or more is Eb, and the flat part of the curve 14 is
It goes without saying that it corresponds to Ec.
第２図に関して説明した書込み装置と、第３図に関し
て説明した読取り装置とを組み合わせることにより、本
発明の磁気記録再生装置を構成することができるのであ
るが、この場合において、記録ヘッド５と、転写用ヘッ
ド６と、消去ヘッド10とは、ヘッドに流す電流値と電流
波形を制御する手段を用意すれば、前記３者のうちの２
者のいずれの組合せにおいても共通化でき、また３者す
べてでも共通化することができる。The magnetic recording / reproducing apparatus of the present invention can be configured by combining the writing device described with reference to FIG. 2 and the reading device described with reference to FIG. 3. In this case, the recording head 5 and If the transfer head 6 and the erasing head 10 are provided with means for controlling the current value and the current waveform to flow through the head, two of the three can be used.
It can be shared by any combination of persons, and can be shared by all three persons.
また記録ヘッド５と再生ヘッド11とを共通化してもよ
いし、さらに前記２者と消去ヘッド10とを共通化するこ
とも可能である。Further, the recording head 5 and the reproducing head 11 may be commonly used, or the two and the erasing head 10 may be commonly used.
さらに、再生ヘッド11と、消去ヘッド10とを、同一の
ヘッドコア上に構成して、第１の磁性層の直流消磁と同
時に、第２の磁性層の残留磁化を再生することもあり得
る。Further, the reproducing head 11 and the erasing head 10 may be formed on the same head core to reproduce the residual magnetization of the second magnetic layer at the same time as the DC demagnetization of the first magnetic layer.
さらに消去ヘッド10は第１の磁性層を消去できる直流
磁界を発生する永久磁石、例えばバリウムフェライト磁
石であってもよい。また転写用ヘッド６は交流減衰磁界
を発生するものであればよく、例えばソレノイドコイル
であってもよいし、Ｎ極とＳ極とが多数配置された永久
磁石であってもよい。Further, the erasing head 10 may be a permanent magnet, such as a barium ferrite magnet, which generates a DC magnetic field capable of erasing the first magnetic layer. Further, the transfer head 6 may be any one that can generate an AC damping magnetic field, and may be, for example, a solenoid coil or a permanent magnet having a large number of N poles and S poles.
第５図は、本発明の別の実施例において使用する磁気
記録媒体の部分断面図である。第５図に示されるよう
に、この磁気記録媒体101は、プラスチック基体104の上
に、室温25℃における保磁力が3000エルステッド、キュ
リー点が450℃のバリウムフェライトなどから成る高保
磁力の第２の磁性層103と、室温における保磁力が550エ
ルステッド、キュリー点が130℃の二酸化クロム（Cr
O2）などから成る低保磁力の第１の磁性層102とが積層
して構成されている。ここで、第１の磁性層102と第２
の磁性層103とは、それぞれ温度に対して第６図に示す
ような保磁力Hcおよび飽和磁化Isの変化を示す。第６図
において、曲線118は、第１の磁性層102に使われている
CrO2のHc温度特性を示し、曲線119は、第１の磁性層102
に使われているCrO2のIsの温度特性を示し、曲線120
は、第２の磁性層103に使われているバリウムフェライ
トのHcの温度特性を示し、曲線122は、第２の磁性層103
に使われているバリウムフェライトのIsの温度特性を示
している。この第６図から明らかなように、CrO2は、そ
のキュリー点130℃付近でHc、Isともに零に近づき、小
さな外部磁界で同媒体への記録が可能になる。しかる
に、バリウムフェライトは、130℃付近の温度ではCrO2
に比較して十分大きなHcとIsの値を示している。FIG. 5 is a partial sectional view of a magnetic recording medium used in another embodiment of the present invention. As shown in FIG. 5, this magnetic recording medium 101 comprises a plastic substrate 104, a second coercive force of 3000 oersted at room temperature of 25 ° C., and a high coercive force of barium ferrite having a Curie point of 450 ° C. Magnetic layer 103 and chromium dioxide (CrO2) with a coercive force of 550 oersteds at room temperature and a Curie point of 130 ° C.
The first magnetic layer 102 having a low coercive force such as O 2 ) is laminated. Here, the first magnetic layer 102 and the second magnetic layer
The magnetic layer 103 has a change in coercive force Hc and saturation magnetization Is as shown in FIG. 6 with respect to temperature. In FIG. 6, curve 118 is used for the first magnetic layer 102.
The Hc temperature characteristic of CrO 2 is shown, and the curve 119 shows the first magnetic layer 102.
The temperature characteristics of Is of CrO 2 used in
Indicates the temperature characteristic of Hc of barium ferrite used for the second magnetic layer 103, and the curve 122 indicates the second magnetic layer 103.
Shows the temperature characteristics of Is of barium ferrite used in. As is clear from FIG. 6, both Hc and Is of CrO 2 approach zero near the Curie point of 130 ° C., and recording on the same medium becomes possible with a small external magnetic field. However, barium ferrite has a CrO 2 content at temperatures near 130 ° C.
The values of Hc and Is are much larger than those of.
第７図は、第５図の磁気記録媒体に信号を書き込み本
発明の磁気記録媒体を与えるための本発明の別の実施例
としての書込み装置の動作を説明するための概略図であ
る。第７図において、参照番号５は、第２図の書込み装
置の場合と同様に、第１の磁性層102および第２の磁性
層103を、同時に記録するための記録ヘッドを示し、参
照番号106は、第１の磁性層102をそのキュリー点である
130℃付近まで加熱するための熱ロールを示している。
矢印116は、記録ヘッド５および熱ロール106と、磁気記
録媒体101との相対的移動方向を示している。FIG. 7 is a schematic diagram for explaining the operation of a writing device as another embodiment of the present invention for writing a signal on the magnetic recording medium of FIG. 5 to provide the magnetic recording medium of the present invention. In FIG. 7, reference numeral 5 indicates a recording head for simultaneously recording the first magnetic layer 102 and the second magnetic layer 103, as in the writing device of FIG. 2, and reference numeral 106. Is the Curie point of the first magnetic layer 102.
A hot roll for heating up to around 130 ° C is shown.
An arrow 116 indicates the relative movement direction of the recording head 5, the heat roll 106, and the magnetic recording medium 101.
磁気記録媒体101に信号を書き込む時は、記録ヘッド
５により、高保磁力の第２の磁性層103を十分磁化でき
る強いヘッド磁界を発生させ、磁気記録媒体101に第２
の磁性層103の残留磁化７および第１の磁性層102の残留
磁化８とをそれぞれ同じ方向に残す。この状態では、第
２図と同様に、それぞれの磁性層の残留磁化から発生し
た磁束は、互いに加算されて磁気記録媒体101の表面に
もれ磁束９としてあらわれる。次に、このようにして記
録済の磁気記録媒体101の第１の磁性層102を熱ロール10
6によって、そのキュリー点である130℃付近の温度状態
にすると、この第１の磁性層102の保磁力および残留磁
化は、殆ど零になる。磁気記録媒体101が熱ロール106を
通過した後は、徐々に冷却され、それに従って第１の磁
性層102のHcおよびIsが増加する過程で、第１の磁性層1
02は、第２の磁性層103の信号磁化７により磁化され
る。そして、室温まで冷却されると、第１の磁性層の保
磁力は、約550エルステッドに回復し、記録ヘッドで飽
和記録したのと同様な大きな残留磁化が得られる。この
時、第１の磁性層102に形成される残留磁化８′は、第
２の磁性層103の残留磁化７により熱磁気転写されたも
のなので、磁化の向きは、記録ヘッド５によって記録さ
れた残留磁化８とは逆向きになる。そのため、第２の磁
性層103の残留磁化７と第１の磁性層102の残留磁化８′
は、互いに打ち消し合い、両者の差だけが磁気記録媒体
の表面にあらわれることになる。この状態で、磁気記録
媒体を通常の磁気記録再生装置で再生しても、僅かな再
生出力しか得られず、記録内容を正常に読み出すことは
できない。When writing a signal to the magnetic recording medium 101, the recording head 5 generates a strong head magnetic field capable of sufficiently magnetizing the second magnetic layer 103 having a high coercive force, and the second magnetic layer 101 is generated on the magnetic recording medium 101.
The remanent magnetization 7 of the magnetic layer 103 and the remanent magnetization 8 of the first magnetic layer 102 are left in the same direction. In this state, as in FIG. 2, the magnetic fluxes generated from the residual magnetization of the respective magnetic layers are added to each other and appear as leakage magnetic flux 9 on the surface of the magnetic recording medium 101. Next, the first magnetic layer 102 of the magnetic recording medium 101 which has been recorded in this way is formed on the heat roll 10.
When the temperature is set to about 130 ° C., which is the Curie point, by 6, the coercive force and the residual magnetization of the first magnetic layer 102 become almost zero. After the magnetic recording medium 101 passes through the heat roll 106, the magnetic recording medium 101 is gradually cooled, and Hc and Is of the first magnetic layer 102 increase accordingly.
02 is magnetized by the signal magnetization 7 of the second magnetic layer 103. Then, when cooled to room temperature, the coercive force of the first magnetic layer is restored to about 550 oersted, and a large residual magnetization similar to that of saturation recording with the recording head is obtained. At this time, since the remanent magnetization 8'formed in the first magnetic layer 102 was thermomagnetically transferred by the remanent magnetization 7 of the second magnetic layer 103, the direction of magnetization was recorded by the recording head 5. It is opposite to the remanent magnetization 8. Therefore, the remanent magnetization 7 of the second magnetic layer 103 and the remanent magnetization 8'of the first magnetic layer 102 are
Cancel each other out, and only the difference between the two appears on the surface of the magnetic recording medium. In this state, even if the magnetic recording medium is reproduced by an ordinary magnetic recording / reproducing apparatus, only a small reproduction output is obtained and the recorded contents cannot be read normally.
なお、第７図の書込み装置によって記録された磁気記
録媒体101から記録信号を読み出すための読取り装置
は、第３図に関して説明したものと同じでよいが、第８
図に概略的に示す構成の読取り装置によって記録信号の
読み出しを行うこともできる。すなわち、第８図の読取
り装置の実施例においては、消去ヘッド10の直前に、第
１の磁性層102をそのキュリー点付近まで加熱するため
の第２の熱ロール121を設け、第１の磁性層102の残留磁
化８′を、第２の熱ロール121にて消去し、その直後
に、第１の磁性層102の温度がやや低下して、HcおよびI
sが増加する時点で、消去ヘッド10から第２の磁性層103
の残留磁化７による信号磁界より強く、且つ第２の磁性
層103の残留磁化の向きを反転させない程度の直流磁界
を与えるようにすることにより、第１の磁性層のみを消
去することも可能である。この場合、第２の磁性層の保
磁力（HcII）と第１の磁性層の保磁力（HcI）との関係
は、第１の磁性層のキュリー点付近において、第２の磁
性層の保磁力が、第１の磁性層より高ければよく、室温
において、HcII＞HcIである必要はない。The reading device for reading the recording signal from the magnetic recording medium 101 recorded by the writing device of FIG. 7 may be the same as that described with reference to FIG.
It is also possible to read a recording signal with a reading device having a configuration schematically shown in the figure. That is, in the embodiment of the reading apparatus shown in FIG. 8, the second magnetic roll 121 for heating the first magnetic layer 102 to near the Curie point is provided immediately before the erasing head 10, and the first magnetic layer 121 is provided. The residual magnetization 8'of the layer 102 is erased by the second thermo roll 121, and immediately after that, the temperature of the first magnetic layer 102 is slightly lowered, and Hc and I
When s increases, the erase head 10 moves to the second magnetic layer 103.
It is also possible to erase only the first magnetic layer by applying a DC magnetic field that is stronger than the signal magnetic field due to the remanent magnetization 7 and does not reverse the direction of the remanent magnetization of the second magnetic layer 103. is there. In this case, the relationship between the coercive force (HcII) of the second magnetic layer and the coercive force (HcI) of the first magnetic layer is that the coercive force of the second magnetic layer near the Curie point of the first magnetic layer. However, it is not necessary that HcII> HcI at room temperature as long as it is higher than that of the first magnetic layer.
なお、矢印117は、第２の熱ロール121、消去ヘッド10
及び再生ヘッド11と磁気記録媒体101との間の相対移動
方向を示している。The arrow 117 indicates the second thermo roll 121 and the erasing head 10.
3 shows the relative movement direction between the reproducing head 11 and the magnetic recording medium 101.
発明の効果 以上説明したように、本発明では、記録時に、磁気記
録媒体を構成している２層構造の磁性体の保磁力の差を
利用して磁気転写により、低保磁力磁性層の信号磁化
を、高保磁力磁性層の信号磁化と逆向きに発生させ、そ
れぞれの信号磁化同志が互いに打ち消し合って、外部に
信号磁界が漏れないようにしてあるので、通常の磁気記
録再生装置では、記録再生が不可能であるばかりでな
く、磁気記録媒体に対する記録および再生過程の３つの
段階、すなわち、記録ヘッドにて磁気記録媒体の両磁性
層を同時に記録した時と、その記録済の磁気記録媒体転
写用手段にて磁気転写を行った時と、その転写済の磁気
記録媒体の低保磁力磁性層のみを消去ヘッドにて直流消
磁を行った時とにおいて、それぞれ異なった再生出力レ
ベルが得られるので、前述の各段階における再生出力レ
ベルを比較することによりその磁気記録媒体の偽造・悪
用や信号データの改ざんなどに対して防御性が高いもの
とすることができる。すなわち、本発明によれば、磁気
記録媒体は、通常の磁気テープや磁気カードなどに用い
られる安価な磁性材料で構成されていながら、通常の磁
気記録再生装置では、磁気記録媒体に記録されている信
号の読み取りや書き込みができないため、偽造・データ
改ざんなどに対して、機密性の高い磁気記録再生システ
ムを提供することができる。As described above, according to the present invention, during recording, the signal of the low coercive force magnetic layer is obtained by magnetic transfer utilizing the difference in coercive force of the magnetic substance of the two-layer structure that constitutes the magnetic recording medium. Since the magnetization is generated in the direction opposite to the signal magnetization of the high coercive force magnetic layer, and the respective signal magnetizations cancel each other out to prevent the signal magnetic field from leaking to the outside, a normal magnetic recording / reproducing apparatus is used. Not only is reproduction impossible, but three stages of the recording and reproducing processes for the magnetic recording medium, that is, when both magnetic layers of the magnetic recording medium are simultaneously recorded by the recording head, and the recorded magnetic recording medium. Different reproduction output levels are obtained when magnetic transfer is performed by the transfer means and when only the low coercive force magnetic layer of the transferred magnetic recording medium is DC demagnetized by the erasing head. Therefore, by comparing the reproduction output levels in each of the above-mentioned steps, it is possible to obtain high protection against forgery / abuse of the magnetic recording medium and falsification of signal data. That is, according to the present invention, the magnetic recording medium is made of an inexpensive magnetic material used for an ordinary magnetic tape or a magnetic card, but is recorded on the magnetic recording medium in an ordinary magnetic recording / reproducing apparatus. Since a signal cannot be read or written, it is possible to provide a magnetic recording / reproducing system with high confidentiality against forgery / data tampering.
第１図は、本発明において使用する磁気記録媒体の部分
断面図、第２図は、第１図の磁気記録媒体に信号を書き
込み本発明の磁気記録媒体を与えるための本発明の一実
施例としての書込み装置の動作を説明するための概略
図、第３図は、第２図の書込み装置によって情報信号を
記録された磁気記録媒体からその情報信号を読み出すた
めの本発明の一実施例としての読取り装置の動作を説明
するための概略図、第４図は、第１図の記録済の磁気記
録媒体の再生特性を示す図、第５図は、本発明の別の実
施例において使用する磁気記録媒体の部分断面図、第６
図は、第５図の磁気記録媒体の各磁性層に使われている
材料の保磁力温度特性および飽和磁化温度特性を示す
図、第７図は、第５図の磁気記録媒体に信号を書き込み
本発明の磁気記録媒体を与えるための本発明の別の実施
例としての書込み装置の動作を説明するための概略図、
第８図は、第７図の書込み装置によって情報信号を記録
された磁気記録媒体からその情報信号を読み出すための
本発明の別の実施例としての読取り装置の動作を説明す
るための概略図である。 １、101……磁気記録媒体、２、102……第１の磁性層、
３、103……第２の磁性層、４、104……プラスチック基
体、５……記録ヘッド、６……転写用ヘッド、10……消
去ヘッド、11……再生ヘッド、106……第１の熱ロー
ル、121……第２の熱ロール。FIG. 1 is a partial sectional view of a magnetic recording medium used in the present invention, and FIG. 2 is an embodiment of the present invention for writing a signal on the magnetic recording medium of FIG. 1 to provide the magnetic recording medium of the present invention. 3 is a schematic view for explaining the operation of the writing device as an example, and FIG. 3 is an embodiment of the present invention for reading the information signal from the magnetic recording medium on which the information signal is recorded by the writing device of FIG. 4 is a schematic diagram for explaining the operation of the reading device of FIG. 4, FIG. 4 is a diagram showing the reproduction characteristics of the recorded magnetic recording medium of FIG. 1, and FIG. 5 is used in another embodiment of the present invention. Partial sectional view of magnetic recording medium, sixth
5 is a diagram showing the coercive force temperature characteristic and the saturation magnetization temperature characteristic of the material used for each magnetic layer of the magnetic recording medium of FIG. 5, and FIG. 7 is for writing signals to the magnetic recording medium of FIG. Schematic diagram for explaining the operation of a writing device as another embodiment of the present invention for providing the magnetic recording medium of the present invention,
FIG. 8 is a schematic diagram for explaining the operation of a reading device as another embodiment of the present invention for reading the information signal from the magnetic recording medium recorded with the information signal by the writing device of FIG. is there. 1, 101 ... Magnetic recording medium, 2, 102 ... First magnetic layer,
3, 103 ... second magnetic layer, 4, 104 ... plastic substrate, 5 ... recording head, 6 ... transfer head, 10 ... erasing head, 11 ... reproducing head, 106 ... first Heat roll, 121 …… Second heat roll.
Claims (19)
なる少なくとも２つの磁性層を積層してなる磁気記録媒
体の磁気記録再生方法において、先ず一方の磁性層に信
号を書き込み、次いで前記一方の磁性層に書き込まれた
信号を他方の磁性層に磁気転写することによって記録を
行い、前記他方の磁気転写された信号を直流消磁してか
ら前記一方の磁性層に記録された信号を読み取ることを
特徴とする磁気記録媒体の磁気記録再生方法。1. A magnetic recording / reproducing method for a magnetic recording medium comprising at least two magnetic layers having different coercive forces laminated at least in a predetermined state. First, a signal is written in one magnetic layer, and then the one magnetic layer. Recording is performed by magnetically transferring the signal written in the other magnetic layer to the other magnetic layer, and the signal recorded in the one magnetic layer is read after the other magnetically transferred signal is degaussed by direct current. Magnetic recording / reproducing method for magnetic recording medium.
力は、少なくとも常温において前記他方の磁性層を構成
する磁性体の保磁力よりも大きく、且つ前記他方の磁性
層への磁気転写は、所定の強さの減衰交流磁界を印加す
ることにより行う特許請求の範囲第（１）項記載の磁気
記録媒体の磁気記録再生方法。2. The coercive force of the magnetic substance forming the one magnetic layer is larger than the coercive force of the magnetic substance forming the other magnetic layer at least at room temperature, and the magnetic transfer to the other magnetic layer is performed. Is a magnetic recording / reproducing method for a magnetic recording medium according to claim 1, which is performed by applying a damping AC magnetic field having a predetermined strength.
リー温度は、前記一方の磁性層を構成する磁性体のキュ
リー温度より低く、且つ前記他方の磁性層への磁気転写
は、先ず前記一方の磁性層に信号を書き込み、しかる後
に前記他方の磁性層をキュリー温度近傍まで加温してか
ら冷却することにより行う特許請求の範囲第（１）項記
載の磁気記録媒体の磁気記録再生方法。3. The Curie temperature of the magnetic substance forming the other magnetic layer is lower than the Curie temperature of the magnetic substance forming the one magnetic layer, and the magnetic transfer to the other magnetic layer is performed first by the above-mentioned method. A magnetic recording / reproducing method for a magnetic recording medium according to claim 1, wherein a signal is written in one of the magnetic layers, and then the other magnetic layer is heated to near the Curie temperature and then cooled. .
力は、少なくとも常温において前記他方の磁性層を構成
する磁性体の保磁力よりも高い特許請求の範囲第（３）
項記載の磁気記録媒体の磁気記録再生方法。4. The coercive force of the magnetic substance forming the one magnetic layer is higher than the coercive force of the magnetic substance forming the other magnetic layer at least at room temperature.
A magnetic recording / reproducing method for a magnetic recording medium according to the item.
を、前記他方の磁性層が前記一方の磁性層の保磁力以下
になる温度状態において所定の強さの直流磁界で消去す
る特許請求の範囲第（３）項記載の磁気記録媒体の磁気
記録再生方法。5. A signal magnetically transferred to the other magnetic layer is erased by a DC magnetic field having a predetermined strength in a temperature state in which the other magnetic layer becomes equal to or lower than the coercive force of the one magnetic layer. A method of magnetic recording / reproducing of a magnetic recording medium according to item (3).
なる少なくとも２つの磁性層を積層してなる磁気記録媒
体に信号を書き込むための書込み装置において、前記磁
気記録媒体に対して所望の信号を記録するための信号記
録手段と、該信号記録手段による所望の信号の記録後
に、前記磁性層のうち保磁力の最も低い磁気記録層に、
保磁力の高い磁性層の残留磁化を、磁気転写するための
磁気転写手段とを備えることを特徴とする書込み装置。6. A writing device for writing a signal on a magnetic recording medium comprising at least two magnetic layers having different coercive forces laminated at least in a predetermined state, for recording a desired signal on the magnetic recording medium. For recording a desired signal by the signal recording means and a magnetic recording layer having the lowest coercive force among the magnetic layers,
A writing device comprising: a magnetic transfer means for magnetically transferring the residual magnetization of a magnetic layer having a high coercive force.
転写を行う特許請求の範囲第（６）項記載の書込み装
置。7. A writing apparatus according to claim 6, wherein said magnetic transfer means performs magnetic transfer by an alternating magnetic field.
加熱されるとき、互いに保磁力が異なるようになるもの
であり、前記磁気転写手段は、前記所定の温度への加熱
による熱磁気転写を行う特許請求の範囲第（６）項記載
の書込み装置。8. The magnetic layers have different coercive forces when heated to at least a predetermined temperature, and the magnetic transfer means performs thermomagnetic transfer by heating to the predetermined temperature. A writing device according to claim (6).
なる少なくとも２つの磁性層を積層してなり、前記磁性
層のうち保磁力の最も低い磁性層には、保磁力の高い磁
性層の残留磁化が磁気転写されているような磁気記録媒
体から所望の信号を読み取るための読取り装置におい
て、前記磁気転写された低保磁力層の残留磁化を消去す
るための残留磁化消去手段と、該残留磁化消去手段によ
る残留磁化の消去後、前記磁気記録媒体の信号を再生す
るための信号再生手段とを備えることを特徴とする読取
り装置。9. At least two magnetic layers having different coercive forces are laminated in at least a predetermined state, and the magnetic layer having the lowest coercive force among the magnetic layers has a residual magnetization of the magnetic layer having a high coercive force. In a reading device for reading a desired signal from a magnetic recording medium which is magnetically transferred, a residual magnetization erasing means for erasing the residual magnetization of the magnetically transferred low coercive force layer, and the residual magnetization erasing means. And a signal reproducing means for reproducing a signal of the magnetic recording medium after the residual magnetization is erased by the reading device.
る消去を行う特許請求の範囲第（９）項記載の読取り装
置。10. A reader according to claim 9, wherein said residual magnetization erasing means erases by a DC magnetic field.
で加熱されるとき、互いに保磁力が異なるようになるも
のであり、前記残留磁化消去手段は、前記所定の温度へ
の加熱を行う加熱手段と、直流磁界印加手段との組合せ
からなる特許請求の範囲第（９）項記載の読取り装置。11. The magnetic layers have different coercive forces from each other when heated to at least a predetermined temperature, and the residual magnetization erasing means heats to the predetermined temperature. And a DC magnetic field applying means in combination, the reading device according to claim (9).
異なる少なくとも２つの磁性層を積層してなる磁気記録
媒体に信号を書き込みその信号を読み取る磁気記録再生
装置において、前記磁気記録媒体に対して所望の信号を
記録するための信号記録手段と、該信号記録手段による
所望の信号の記録後に、前記磁性層のうち保磁力の最も
低い磁性層に、保磁力の高い磁性層の残留磁化を、磁気
転写するための磁気転写手段と、前記磁気転写された低
保磁力層の残留磁化を消去するための残留磁化消去手段
と、該残留磁化消去手段による残留磁化の消去後、前記
磁気記録媒体の信号を再生するための信号再生手段とを
備えることを特徴とする磁気記録再生装置。12. A magnetic recording / reproducing apparatus for writing a signal on a magnetic recording medium having at least two magnetic layers having different coercive forces laminated at least in a predetermined state and reading the signal, which is desired for the magnetic recording medium. A signal recording unit for recording a signal, and after recording a desired signal by the signal recording unit, the residual magnetization of the magnetic layer having a high coercive force is magnetically transferred to the magnetic layer having the lowest coercive force among the magnetic layers. Magnetic retransfer means for erasing, remanent magnetization erasing means for erasing remanent magnetization of the magnetically transferred low coercive force layer, and a signal of the magnetic recording medium after erasing remanent magnetization by the remanent magnetization erasing means. A magnetic recording / reproducing apparatus comprising: a signal reproducing unit for reproducing.
気転写を行う特許請求の範囲第（12）記載の磁気記録再
生装置。13. A magnetic recording / reproducing apparatus according to claim 12, wherein said magnetic transfer means performs magnetic transfer by an alternating magnetic field.
で加熱されるとき、互いに保磁力が異なるようになるも
のであり、前記磁気転写手段は、前記所定の温度への加
熱による熱磁気転写を行う特許請求の範囲第（12）項記
載の磁気記録再生装置。14. The magnetic layers have different coercive forces when heated to at least a predetermined temperature, and the magnetic transfer means performs thermomagnetic transfer by heating to the predetermined temperature. A magnetic recording / reproducing apparatus according to claim (12).
る消去を行う特許請求の範囲第（12）項または第（13）
項記載の磁気記録再生装置。15. The remanent magnetization erasing means performs erasing by a DC magnetic field, according to claim (12) or (13).
Item 6. The magnetic recording / reproducing device according to Item 1.
で加熱されるとき、互いに保磁力が異なるようになるも
のであり、前記残留磁化消去手段は、前記所定の温度へ
の加熱を行う加熱手段と、直流磁界印加手段との組合せ
からなる特許請求の範囲第（12）項または第（14）項記
載の磁気記録再生装置。16. The magnetic layers have different coercive forces when they are heated to at least a predetermined temperature, and the residual magnetization erasing means heats to the predetermined temperature. The magnetic recording / reproducing apparatus according to claim (12) or (14), which comprises a combination of a magnetic field and a DC magnetic field applying means.
異なる少なくとも２つの磁性層を積層してなる磁気記録
媒体の正当性判定方法において、先ず一方の磁性層に信
号を書き込み、次いで前記一方の磁性層に書き込まれた
信号を他方の磁性層に磁気転写した後に読み取った再生
出力レベルと、前記他方の磁性層に磁気転写された信号
を直流消磁した後に読み取った再生出力レベルとを比較
することを特徴とする磁気記録媒体の正当性判定方法。17. A method for determining the validity of a magnetic recording medium comprising at least two magnetic layers having different coercive forces laminated at least in a predetermined state, wherein a signal is first written in one magnetic layer and then the one magnetic layer. The reproduction output level read after magnetically transferring the signal written in the other magnetic layer to the other magnetic layer is compared with the reproduction output level read after the DC demagnetization of the signal magnetically transferred to the other magnetic layer. And a method for determining the validity of a magnetic recording medium.
磁力は、少なくとも常温において前記他方の磁性層を構
成する磁性体の保磁力よりも大きく、且つ前記他方の磁
性層への磁気転写は、所定の強さの減衰交流磁界を印加
することにより行う特許請求の範囲第（17）項記載の磁
気記録媒体の正当性判定方法。18. The coercive force of the magnetic substance forming the one magnetic layer is larger than the coercive force of the magnetic substance forming the other magnetic layer at least at room temperature, and the magnetic transfer to the other magnetic layer is performed. Is a method for determining the validity of a magnetic recording medium according to claim (17), which is performed by applying a damping AC magnetic field having a predetermined strength.
ュリー温度は、前記一方の磁性層を構成する磁性体のキ
ュリー温度より低く、且つ前記他方の磁性層への磁気転
写は、先ず前記一方の磁性層に信号を書き込み、しかる
後に前記他方の磁性層をキュリー温度近傍まで加温して
から冷却することにより行う特許請求の範囲第（17）項
記載の磁気記録媒体の正当性判定方法。19. The Curie temperature of the magnetic substance forming the other magnetic layer is lower than the Curie temperature of the magnetic substance forming the one magnetic layer, and the magnetic transfer to the other magnetic layer is performed first by the above-mentioned method. The method for determining the validity of a magnetic recording medium according to claim (17), wherein a signal is written in one magnetic layer, and then the other magnetic layer is heated to near the Curie temperature and then cooled. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61178503A JP2518620B2 (en) | 1986-07-29 | 1986-07-29 | Magnetic recording / reproducing method and apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61178503A JP2518620B2 (en) | 1986-07-29 | 1986-07-29 | Magnetic recording / reproducing method and apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6334727A JPS6334727A (en) | 1988-02-15 |
| JP2518620B2 true JP2518620B2 (en) | 1996-07-24 |
Family
ID=16049602
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61178503A Expired - Fee Related JP2518620B2 (en) | 1986-07-29 | 1986-07-29 | Magnetic recording / reproducing method and apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2518620B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102004049999A1 (en) * | 2004-10-14 | 2006-04-20 | Giesecke & Devrient Gmbh | security element |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57164429A (en) * | 1981-04-01 | 1982-10-09 | Tokyo Jiki Insatsu Kk | Magnetic recording body |
| JPS5827881A (en) * | 1981-08-11 | 1983-02-18 | Mitsubishi Electric Corp | Fuel control valve |
| JPS6048807A (en) * | 1983-03-29 | 1985-03-16 | シユテイ−ヴア−フエルテイグングステヒニ−ク・シユテイヒト・ゲゼルシヤフト・ミツト・ベシユレンクテル・ハフツング | Conveyor for work or work holder |
| JPH0512838Y2 (en) * | 1984-10-29 | 1993-04-05 | ||
| JPS61145727A (en) * | 1984-12-19 | 1986-07-03 | Dainippon Printing Co Ltd | Cards having magnetic recording medium and its recording method |
-
1986
- 1986-07-29 JP JP61178503A patent/JP2518620B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6334727A (en) | 1988-02-15 |
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