JPH1139642A - Magnetic recording medium, its production and its use method - Google Patents

Magnetic recording medium, its production and its use method

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Publication number
JPH1139642A
JPH1139642A JP20740197A JP20740197A JPH1139642A JP H1139642 A JPH1139642 A JP H1139642A JP 20740197 A JP20740197 A JP 20740197A JP 20740197 A JP20740197 A JP 20740197A JP H1139642 A JPH1139642 A JP H1139642A
Authority
JP
Japan
Prior art keywords
magnetic
magnetic layer
layer
recording medium
signal
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.)
Pending
Application number
JP20740197A
Other languages
Japanese (ja)
Inventor
Haruyuki Takahashi
東幸 高橋
Etsushi Kanda
悦史 神田
Yasuo Toyofuku
康雄 豊福
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toppan Infomedia Co Ltd
Original Assignee
Tokyo Magnetic Printing Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Tokyo Magnetic Printing Co Ltd filed Critical Tokyo Magnetic Printing Co Ltd
Priority to JP20740197A priority Critical patent/JPH1139642A/en
Publication of JPH1139642A publication Critical patent/JPH1139642A/en
Pending legal-status Critical Current

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  • Magnetic Record Carriers (AREA)
  • Digital Magnetic Recording (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)

Abstract

PROBLEM TO BE SOLVED: To improve authentication judgement performance and visibility by recording fixed signals in at least two magnetic layers of magnetic layers in such manner that the fixed signals are formed by a magnetic field generated from signals recorded in order magnetic layers or by the magnetic field and he orientation magnetic field and that the fixed signals can not be rewritten, and recording different unrewritable fixed signals in an least two magnetic layers of the magnetic layers. SOLUTION: A first magnetic layer 2 capable of magnetic recording is formed by using magnetic powder such as γ-Fe2 O3 , Co-coated γ-Fe2 O3 , and Ba ferrite on a nonmagnetic substrate 1 and specified signals are magnetically recorded. Then a second magnetic recording layer 3 of a same component is formed on the first magnetic layer 2, and then a third magnetic layer 4 having different saturation magnetization characteristics is formed thereon. The coercive force of the magnetic powder in the first magnetic layer 2 is preferably controlled to three or more times of the coercive force of the magnetic powder in the second magnetic layer 4. The third magnetic layer 4 is subjected to DC orientation treatment in a magnetic field higher than the saturation magnetic field in the parallel direction to the coating direction so as to form a fixed pattern with a different saturation magnetization effect.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明はプリペイドカードに
使用するのに適した磁気カードに関するものであり、特
に磁気信号の改ざん、偽造による不正使用を困難にした
磁気カード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 card suitable for use in a prepaid card, and more particularly to a magnetic card which makes it difficult to tamper with a magnetic signal or to illegally use it by forgery.

【０００２】[0002]

【従来技術】最近の磁気カードにおいてはプリペイドカ
ードと呼ばれる前払い方式の磁気カードが広く普及して
きた。しかしこのプリペイドカードは市場において金券
同様に扱われるため、磁気信号の改ざん偽造による不正
使用を防止しなければならず、これまでに種々の考案が
なされている。例えば、実開昭５８−６５６４４号公報
に開示されたような磁性インキによる固定パターンを形
成する方法である。また、特開平６−２０３３６６号公
報、特開平７−２１０８５９号公報に開示されたような
磁気記録可能な第１の磁性層に磁気記録し、この上に第
１の磁性層に磁気記録した磁気パターンに対応した書換
不能な固定パターンを第２の磁性層に形成する方法であ
る。これらの方法は大別して磁気カードに真偽判定情報
として固定パターンを利用するものである。2. Description of the Related Art In recent magnetic cards, prepaid magnetic cards called prepaid cards have become widespread. However, since the prepaid card is treated like a cash voucher in the market, it is necessary to prevent unauthorized use due to falsification and forgery of a magnetic signal, and various ideas have been made so far. For example, there is a method of forming a fixed pattern using magnetic ink as disclosed in Japanese Utility Model Laid-Open No. 58-64464. Further, magnetic recording is performed on a magnetically recordable first magnetic layer as disclosed in JP-A-6-203366 and JP-A-7-210859, and magnetic recording is further performed on the first magnetic layer. This is a method of forming a non-rewritable fixed pattern corresponding to the pattern on the second magnetic layer. These methods roughly use a fixed pattern as magnetic discrimination information in a magnetic card.

【０００３】[0003]

【発明が解決しようとする課題】しかしながら従来のこ
れらの方法は磁気信号の改ざん、偽造による不正使用を
防止するのに必ずしも十分とはいえない。例えば実開昭
５８−６５６４４号公報に開示されたような方法では、
磁性インキによる固定パターンをスクリーン印刷等の方
法で形成されるため、固定パターンの種類の数だけシル
ク版を準備する必要があり、一般に同一の固定パターン
をもつ大量の磁気カードが製造されてしまうという欠点
をもつ。これに対し特開平６−２０３３６６号公報、特
開平７−２１０８５９号公報に開示されたような方法で
は、磁気記録可能な第１の磁性層に磁気記録した磁気パ
ターンに対応した固定パターンが第２の磁性層に形成さ
れるため、個々の磁気カードで異なった真偽判定情報を
固定パターンとして形成できる。However, these conventional methods are not always sufficient to prevent tampering of the magnetic signal and unauthorized use by forgery. For example, in the method disclosed in Japanese Utility Model Application Laid-Open No. 58-65644,
Since the fixed pattern using magnetic ink is formed by a method such as screen printing, it is necessary to prepare silk plates for the number of types of the fixed pattern, and in general, a large number of magnetic cards having the same fixed pattern are manufactured. Has disadvantages. On the other hand, in the methods disclosed in JP-A-6-203366 and JP-A-7-210859, the fixed pattern corresponding to the magnetic pattern magnetically recorded on the magnetically recordable first magnetic layer is replaced with the second pattern. , Different authenticity determination information can be formed as a fixed pattern for each magnetic card.

【０００４】しかし特開平６−２０３３６６号公報に開
示されたような方法では、固定パターンは第１の磁性層
に磁気記録した磁気パターンの磁束反転部に磁性粒子が
集まって形成されるため、磁気パターンの１回の磁束反
転に対し固定パターンは２回の磁束反転を有し、この２
回の磁束反転による信号波長は第１の磁性層に磁気記録
した記録波長に関係なく一定である。このため記録密度
がある程度高くなると単一波長の固定信号に近づき、Ｆ
２Ｆ方式のような周波数変調方式には対応できなくなる
という欠点をもつ。また特開平７−２１０８５９号公報
に開示されたような方法では、第２の磁性層を形成する
ときの配向処理により第一の磁性層に磁気記録した磁気
パターンと等しい信号波長の固定パターンを形成でき
る。しかし固定パターンの形成は磁性粒子の粗密により
形成されるものであり、従来技術に共通の欠点として、
印刷等で形成した固定パターンと同様の手段で読み取り
可能であること、また固定パターンは凹凸として形成さ
れるため読み取り信号と同様のパターンが目視可能であ
るという欠点をもつ。本発明者らはかかる問題点を解決
し、固定信号の読取方法による真偽判定性および視認性
を改善したさらに安全性の高い磁気記録媒体を提供しよ
うとするものである。However, according to the method disclosed in Japanese Patent Application Laid-Open No. 6-203366, the fixed pattern is formed by gathering magnetic particles in a magnetic flux reversal portion of the magnetic pattern magnetically recorded on the first magnetic layer. The fixed pattern has two flux reversals for one flux reversal of the pattern.
The signal wavelength resulting from the first magnetic flux reversal is constant irrespective of the recording wavelength magnetically recorded on the first magnetic layer. Therefore, when the recording density is increased to some extent, the signal approaches a fixed signal of a single wavelength, and F
It has a drawback that it cannot support a frequency modulation system such as the 2F system. In the method disclosed in Japanese Patent Application Laid-Open No. 7-210859, a fixed pattern having the same signal wavelength as the magnetic pattern magnetically recorded on the first magnetic layer is formed by the orientation treatment when forming the second magnetic layer. it can. However, the formation of the fixed pattern is formed by the density of the magnetic particles.
It has the drawback that it can be read by the same means as a fixed pattern formed by printing or the like, and that the fixed pattern is formed as unevenness, so that the same pattern as the read signal can be viewed. The present inventors have attempted to solve such a problem and to provide a more secure magnetic recording medium with improved authenticity determination and visibility by a fixed signal reading method.

【０００５】[0005]

【課題を解決するための手段】本発明の磁気記録媒体
は、非磁性基体上に少なくとも１つの磁気記録可能な第
１の磁性層を有し、少なくとも２つの外部磁界に対して
飽和磁化特性の異なる第２、第３の磁性層を積層して成
る磁気記録媒体であり、前記第２、第３の磁性層は前記
第１の磁性層に記録された信号による磁界もしくは、同
磁界と配向磁界の影響により、形成された書換不能な固
定信号が形成され、前記第２、第３の磁性層には異なっ
た書換不能な固定信号が形成されている（図１）。The magnetic recording medium of the present invention has at least one magnetically recordable first magnetic layer on a non-magnetic substrate, and has a saturation magnetization characteristic with respect to at least two external magnetic fields. A magnetic recording medium comprising a stack of different second and third magnetic layers, wherein the second and third magnetic layers are a magnetic field based on a signal recorded on the first magnetic layer, or the same magnetic field and an orientation magnetic field As a result, a non-rewritable fixed signal is formed, and different non-rewritable fixed signals are formed in the second and third magnetic layers (FIG. 1).

【０００６】本発明の磁気記録媒体は次のようにして形
成される。先ず非磁性基体上に磁気記録可能な磁性材料
から成る第１の磁性層を形成し、次いで前記第１の磁性
層に所定の信号を磁気記録し、その後第２の磁性層を形
成する磁性体から成る磁性塗料を塗布、乾燥、固化す
る。更に次ぎに前記第２の磁性層と飽和磁化特性の異な
る磁性体から成る磁性塗料を塗布、乾燥、固化すること
により第３の磁性層を形成する。[0006] The magnetic recording medium of the present invention is formed as follows. First, a first magnetic layer made of a magnetic material that can be magnetically recorded is formed on a non-magnetic substrate, then a predetermined signal is magnetically recorded on the first magnetic layer, and then a second magnetic layer is formed. Is applied, dried and solidified. Next, a third magnetic layer is formed by applying, drying, and solidifying a magnetic paint made of a magnetic material having a different saturation magnetization characteristic from the second magnetic layer.

【０００７】前記第２の磁性層を形成するとき、前記磁
性塗料が乾燥、固化する前に特に配向処理を行わなくて
もよいが、前記第１磁性層の保磁力以下の磁界強度で配
向処理を行ってもよい。配向処理を行わない場合、磁性
粒子は前記第１の磁性層に磁気記録した所定の信号の磁
束反転部に集中する。このとき第２の磁性層を形成する
磁性塗料の塗布時の乾燥前の厚み（ウェット厚）と前記
第１の磁性層の磁束反転部から発生する磁界分布の到達
距離の関係で、磁界分布の到達距離よりウェット厚が大
きいとき、小さいときで前記第１の磁性層に磁気記録し
た所定の信号に対し２倍、４倍の記録波長を有する固定
パターンが第２の磁性層に形成される。また塗布方向に
対し平行な直流配向処理を行うと前記第１の磁性層に記
録した所定の信号と同じ記録波長を有する固定パターン
が第２の磁性層に形成される。When forming the second magnetic layer, it is not necessary to perform an orientation treatment before the magnetic paint is dried and solidified. However, the orientation treatment is performed at a magnetic field strength equal to or lower than the coercive force of the first magnetic layer. May be performed. When the orientation treatment is not performed, the magnetic particles concentrate on the magnetic flux reversal part of the predetermined signal magnetically recorded on the first magnetic layer. At this time, the relationship between the thickness (wet thickness) before drying when applying the magnetic paint for forming the second magnetic layer and the reaching distance of the magnetic field distribution generated from the magnetic flux reversal portion of the first magnetic layer is represented by the following formula. When the wet thickness is larger or smaller than the reach distance, a fixed pattern having a recording wavelength twice or four times as large as a predetermined signal magnetically recorded on the first magnetic layer is formed in the second magnetic layer. Further, when a direct current orientation process is performed in parallel with the coating direction, a fixed pattern having the same recording wavelength as a predetermined signal recorded on the first magnetic layer is formed on the second magnetic layer.

【０００８】前記第３の磁性層を形成するとき、前記第
２の磁性層の飽和磁界強度以上の塗布方向に対して平行
な直流配向処理を行うことにより前記第２の固定パター
ンの影響がなくなり、第１の磁性層に記録した信号と同
じ固定信号が形成できる。また、前記第１の磁性層に記
録した所定の信号を、前記第２の磁性層に固定信号を形
成した後に別の信号に書き換えて、前記第３の磁性層に
固定信号を形成することもできる。このとき前記第２の
磁性層の飽和磁界強度以下、前記第３の磁性層の飽和磁
界強度以上の配向処理を行うと前記第１の磁性層に記録
した所定の信号と前記第２の磁性層に形成された固定信
号とが合成された固定信号として形成できる。[0008] When the third magnetic layer is formed, by performing a DC alignment process in parallel with a coating direction that is higher than the saturation magnetic field strength of the second magnetic layer, the influence of the second fixed pattern is eliminated. Thus, the same fixed signal as the signal recorded on the first magnetic layer can be formed. It is also possible to form a fixed signal on the third magnetic layer by rewriting a predetermined signal recorded on the first magnetic layer with another signal after forming a fixed signal on the second magnetic layer. it can. At this time, when the orientation process is performed at a saturation magnetic field intensity of the second magnetic layer or less and a saturation magnetic field intensity of the third magnetic layer or more, a predetermined signal recorded on the first magnetic layer and the second magnetic layer Can be formed as a fixed signal that is synthesized with the fixed signal formed in step (1).

【０００９】前記磁気記録媒体の使用方法としては、ま
ず前記第１の磁性層に記録した信号を直流消去する。次
に所定のバイアス磁界を印加しながら前記磁気記録媒体
の固定信号を読み取る。さらに次に、これと異なったバ
イアス磁界を印加しながら前記磁気記録媒体の固定信号
を読み取る。このとき前記第２の磁性層と前記第３の磁
性層に飽和磁化特性の異なる、異なった固定信号が形成
してあるため、バイアス磁界の変化により異なった出力
波形が得られる（図４、図５）。As a method of using the magnetic recording medium, a signal recorded on the first magnetic layer is first DC-erased. Next, a fixed signal of the magnetic recording medium is read while applying a predetermined bias magnetic field. Next, the fixed signal of the magnetic recording medium is read while applying a different bias magnetic field. At this time, since different fixed signals having different saturation magnetization characteristics are formed in the second magnetic layer and the third magnetic layer, different output waveforms are obtained due to a change in the bias magnetic field (FIGS. 4 and 4). 5).

【００１０】本発明の効果としては、まず第２の磁性層
と第３の磁性層に、飽和磁化特性が異なった固定パター
ンが形成されている。このため２つ以上の異なったバイ
アス磁界強度で読み取ることにより、２つ以上の異なっ
た再生波形が得られる。この再生波形の変化は従来にな
い本発明の磁気記録媒体に特有のバイアス依存性であ
る。また固定信号を目視で確認しようとすると第３の磁
性層に形成された固定信号のパターンのみが確認され、
第２の磁性層の固定信号のパターンは確認できず、実質
的に目視での確認は不可能である。よって本発明の磁気
記録媒体は極めて偽造、変造しにくく、不正使用防止効
果が高い。As an effect of the present invention, first, fixed patterns having different saturation magnetization characteristics are formed in the second magnetic layer and the third magnetic layer. Therefore, by reading with two or more different bias magnetic field strengths, two or more different reproduced waveforms can be obtained. This change in the reproduction waveform is a bias dependency peculiar to the magnetic recording medium of the present invention, which has not existed conventionally. Further, when the fixed signal is visually checked, only the fixed signal pattern formed on the third magnetic layer is checked,
The pattern of the fixed signal of the second magnetic layer cannot be confirmed, and cannot be confirmed visually. Therefore, the magnetic recording medium of the present invention is extremely difficult to forge or falsify, and has a high effect of preventing unauthorized use.

【００１１】[0011]

【発明の実施の形態】次に本発明の磁気記録媒体を実施
例により説明する。図１は本発明の一実施例としての磁
気記録媒体の断面図である。同図において、磁気記録媒
体は、非磁性基体１上に磁気記録可能な第１の磁性層２
を有し、その上に第２の磁性層３を有する。磁性層３に
は外部磁界に対して第２の磁性層３とは飽和磁化特性の
異なる第３の磁性層４を積層してある。前記第２、第３
の磁性層は前記第１の磁性層に記録された信号による磁
界もしくは、同磁界と配向磁界の影響により、形成され
た書換不能な固定信号が形成されており、第２、第３の
磁性層には互いに異なった書換不能な固定信号が形成さ
れる。非磁性基体１にはプラスチック、紙、または非磁
性金属板であっても良いが、特にプラスチックを用いる
場合にはポリエチレンテレフタレートが好ましい。第１
の磁性層２はγ−Ｆｅ2 Ｏ3 、Ｃｏ被着γ−Ｆｅ2 Ｏ
3 、Ｂａフェライトなどの磁性粉と適当な結合剤、添加
剤よりなる通常用いられる磁気記録層であって良い。た
だし、第１の磁性層２に用いられる磁性粉は第２の磁性
層３に用いられる磁性粉の保磁力より大きく、好ましく
は３倍以上大きいことが好ましい。第２の磁性層３は第
１の磁性層２と同様の通常の磁気記録層であって良く、
またはカルボニル鉄粉、Ｆｅ−Ａｌ合金、Ｆｅ−Ｎｉ合
金、Ｆｅ−Ａｌ−Ｓｉ合金、Ｍｎ−Ｚｎフェライト、Ｎ
ｉ−Ｚｎフェライトなどの軟磁性粉と適当な結合剤、添
加剤よりなる磁性層であっても良い。第３の磁性層４は
第２の磁性層３と同様であって良い。ただし、第２の磁
性層３とは飽和磁化特性が異なることが好ましい。Next, the magnetic recording medium of the present invention will be described with reference to examples. FIG. 1 is a sectional view of a magnetic recording medium according to one embodiment of the present invention. In FIG. 1, a magnetic recording medium includes a first magnetic layer 2 that can be magnetically recorded on a non-magnetic substrate 1.
And a second magnetic layer 3 thereon. A third magnetic layer 4 having a different saturation magnetization characteristic from the second magnetic layer 3 with respect to an external magnetic field is laminated on the magnetic layer 3. The second and third
In the magnetic layer, a non-rewritable fixed signal formed by the magnetic field of the signal recorded in the first magnetic layer or the influence of the magnetic field and the orientation magnetic field is formed, and the second and third magnetic layers are formed. , Different non-rewritable fixed signals are formed. The non-magnetic substrate 1 may be plastic, paper, or a non-magnetic metal plate, but when plastic is used, polyethylene terephthalate is preferred. First
The magnetic layer 2 of γ-Fe 2 O 3 and γ-Fe 2 O coated with Co
3. A commonly used magnetic recording layer comprising a magnetic powder such as Ba ferrite and a suitable binder and additive may be used. However, the magnetic powder used for the first magnetic layer 2 is preferably larger than the coercive force of the magnetic powder used for the second magnetic layer 3, and more preferably three times or more. The second magnetic layer 3 may be a normal magnetic recording layer similar to the first magnetic layer 2,
Or carbonyl iron powder, Fe-Al alloy, Fe-Ni alloy, Fe-Al-Si alloy, Mn-Zn ferrite, N
A magnetic layer composed of soft magnetic powder such as i-Zn ferrite and a suitable binder or additive may be used. The third magnetic layer 4 may be similar to the second magnetic layer 3. However, the second magnetic layer 3 preferably has a different saturation magnetization characteristic.

【００１２】図１の実施例により具体的に説明する。 （実施例１）まず、厚さ１８８μｍの白色ポリエチレン
テレフタレートの非磁性基体１上に保磁力２７５０ Ｏ
ｅのＢａフェライト粉と樹脂、分散剤、硬化剤、その他
添加剤とを溶剤中で均一に混合した磁性塗料をグラビア
塗布し、厚さ５μｍの第１の磁性層２を形成した。第１
の磁性層２の所定の領域に３００ ＦＣＩの信号を飽和
記録し、この状態でカードサイズに打ち抜き、第１の磁
性層２に飽和記録できるライトヘッドとバイアスコイル
付きリードヘッドを装着したリーダーライターでバイア
ス電流を流さずに再生出力を読み取ったところ、図２に
示すように再生波形が得られた。次に第１の磁性層２上
に保磁力が２０ Ｏｅのカルボニル鉄粉と樹脂、分散
剤、硬化剤、その他添加剤とを溶剤中で均一に混合した
磁性塗料をナイフ塗布し、厚さ３μｍの第２の磁性層３
を形成した。このとき特に配向処理は行わなかった。こ
の状態でカードサイズに打ち抜き、前記リーダーライタ
ーで第１の磁性層２に記録された信号を直流消去し、２
０ｍＡのバイアス電流を流しながら再生出力を読み取っ
たところ、図３に示すように第１の磁性層２に記録した
信号周波数の２倍の再生波形が得られた。さらに次に第
２の磁性層３上に保磁力が２０ ＯｅのＦｅ−Ｓｉ系軟
磁性合金の鱗片粉と樹脂、分散剤、硬化剤、その他添加
剤とを溶剤中で均一に混合した磁性塗料をナイフ塗布
し、厚さ８μｍの第３の磁性層４を形成した。このとき
磁性塗料が乾燥固化するまえにソレノイドコイル配向装
置を用い磁界強度６００ Ｏｅで、第２の磁性層３を形
成し、これをカードサイズに打ち抜いた。This will be described more specifically with reference to the embodiment shown in FIG. Example 1 First, a coercive force of 2750 O was applied on a non-magnetic substrate 1 of white polyethylene terephthalate having a thickness of 188 μm.
The magnetic paint obtained by uniformly mixing the Ba ferrite powder of (e) with a resin, a dispersant, a curing agent, and other additives in a solvent was gravure coated to form a first magnetic layer 2 having a thickness of 5 μm. First
Saturation recording of a 300 FCI signal is performed in a predetermined area of the magnetic layer 2 of this embodiment, and a card size is punched out in this state. When the reproduction output was read without flowing a bias current, a reproduction waveform was obtained as shown in FIG. Next, a magnetic paint in which carbonyl iron powder having a coercive force of 20 Oe and a resin, a dispersant, a curing agent, and other additives are uniformly mixed in a solvent is knife-coated on the first magnetic layer 2 to have a thickness of 3 μm. Second magnetic layer 3
Was formed. At this time, no alignment treatment was particularly performed. In this state, the card was punched into a card size, and the signal recorded on the first magnetic layer 2 was DC-erased by the reader / writer.
When the reproduction output was read while applying a bias current of 0 mA, a reproduction waveform twice as high as the signal frequency recorded on the first magnetic layer 2 was obtained as shown in FIG. Next, on the second magnetic layer 3, a magnetic paint in which flake powder of a Fe-Si soft magnetic alloy having a coercive force of 20 Oe, a resin, a dispersant, a hardener, and other additives are uniformly mixed in a solvent. Was applied by knife to form a third magnetic layer 4 having a thickness of 8 μm. At this time, before the magnetic paint was dried and solidified, the second magnetic layer 3 was formed at a magnetic field strength of 600 Oe using a solenoid coil orientation device, and this was punched into a card size.

【００１３】実施例１の本発明をその使用方法により詳
細に説明する。まず前記リーダーライターで第１の磁性
層２に記録された信号を直流消去した。次に５ｍＡのバ
イアス電流を流しながら再生出力を読み取ったところ、
図４に示すように第１の磁性層２に記録した信号と等し
い再生波形が得られた。さらに次に５０ｍＡのバイアス
電流を流しながら再生出力を読み取ったところ、図５に
示すように図３に類似の第２の磁性層３と第３の磁性層
４の混合波形が得られた。これは図６に示すように第２
の磁性層３と第３の磁性層４に形成した固定信号のバイ
アス特性の差によるものであり、これにより本発明の磁
気記録媒体に特有のバイアス依存性が得られた。また、
固定信号を目視で確認した第３の磁性層４に形成された
固定信号のパターンのみが確認され、第２の磁性層３の
固定信号のパターンは確認できず、実質的に目視での確
認は不可能であった。The first embodiment of the present invention will be described in detail according to the method of use. First, the signal recorded on the first magnetic layer 2 was DC-erased by the reader / writer. Next, when the reproduction output was read while applying a bias current of 5 mA,
As shown in FIG. 4, a reproduced waveform equal to the signal recorded on the first magnetic layer 2 was obtained. Next, when the reproduction output was read while applying a bias current of 50 mA, a mixed waveform of the second magnetic layer 3 and the third magnetic layer 4 similar to FIG. 3 was obtained as shown in FIG. This is the second, as shown in FIG.
This is due to the difference in the bias characteristics of the fixed signals formed in the magnetic layer 3 and the third magnetic layer 4 of the first embodiment, thereby obtaining the bias dependency peculiar to the magnetic recording medium of the present invention. Also,
Only the fixed signal pattern formed on the third magnetic layer 4 in which the fixed signal was visually confirmed was confirmed, and the fixed signal pattern in the second magnetic layer 3 could not be confirmed. It was impossible.

【００１４】（実施例２）実施例１の第１の磁性層２の
所定の領域に１５０ ＢＰＩの信号を飽和記録し、第１
の磁性層２上に保磁力が９５０ ＯｅのＢａフェライト
粉と樹脂、分散剤、硬化剤、その他添加剤とを溶剤中で
均一に混合した磁性塗料をナイフ塗布し、厚さ５μｍの
第２の磁性層３を形成した。このとき塗布方向に対して
平行な６００ Ｏｅの直流配向処理は行った。次に第１
の磁性層２に記録された信号上に別のＦＭ信号をオーバ
ーライトした。更に次に第２の磁性層３上に保磁力が２
０ Ｏｅのカルボニル鉄粉と樹脂、分散剤、硬化剤、そ
の他添加剤とを溶剤中で均一に混合した磁性塗料をナイ
フ塗布し、厚さ３μｍの第３の磁性層４を形成した。こ
のとき磁性塗料が乾燥固化する前にソレノイドコイル配
向装置を用い第２の磁性層３の飽和磁界以上、第１の磁
性層の飽和磁界以下である磁界強度１２００ Ｏｅで、
第２の磁性層３を形成し、これをカードサイズに打ち抜
いた。(Embodiment 2) A signal of 150 BPI is saturatedly recorded in a predetermined area of the first magnetic layer 2 of Embodiment 1,
A magnetic paint obtained by uniformly mixing a Ba ferrite powder having a coercive force of 950 Oe with a resin, a dispersant, a curing agent, and other additives in a solvent is knife-coated on the magnetic layer 2 of No. 2, and a second 5 μm-thick The magnetic layer 3 was formed. At this time, a DC orientation treatment of 600 Oe parallel to the coating direction was performed. Then the first
And another FM signal was overwritten on the signal recorded on the magnetic layer 2 of FIG. Next, a coercive force of 2 is formed on the second magnetic layer 3.
A magnetic paint in which carbonyl iron powder of 0 Oe and a resin, a dispersant, a curing agent, and other additives were uniformly mixed in a solvent was knife-coated to form a third magnetic layer 4 having a thickness of 3 μm. At this time, before the magnetic paint is dried and solidified, a magnetic field strength of 1200 Oe, which is equal to or higher than the saturation magnetic field of the second magnetic layer 3 and equal to or lower than the saturation magnetic field of the first magnetic layer, using a solenoid coil orientation device,
A second magnetic layer 3 was formed, and was punched into a card size.

【００１５】実施例２の本発明をその使用方法により詳
細に説明する。まず前記リーダーライターで第１の磁性
層２に記録された信号を直流消去した。この状態でバイ
アス電流を流さずに再生波形を読み取ったところ、第２
の磁性層３に形成された固定信号の再生波形が得られ
た。次に５０ｍＡのバイアス電流を流しながら再生出力
を読み取ったところ、第２の磁性層３と第３の磁性層４
に形成された固定信号の混合波形が得られ、実施例１と
同様の本発明の磁気記録媒体に特有のバイアス依存性が
得られた。また、固定信号を目視で確認した第３の磁性
層４に形成された固定信号のパターンのみが確認され、
第２の磁性層３の固定信号のパターンは確認できず、実
質的に目視での確認は不可能であった。[0015] The present invention in Example 2 will be described in detail by its use. First, the signal recorded on the first magnetic layer 2 was DC-erased by the reader / writer. In this state, the reproduced waveform was read without flowing the bias current.
The reproduced waveform of the fixed signal formed on the magnetic layer 3 was obtained. Next, when the reproduction output was read while a bias current of 50 mA was passed, the second magnetic layer 3 and the third magnetic layer 4 were read.
Thus, a mixed waveform of the fixed signal formed as described above was obtained, and a bias dependence unique to the magnetic recording medium of the present invention similar to that of the first embodiment was obtained. Further, only the fixed signal pattern formed on the third magnetic layer 4 where the fixed signal was visually confirmed was confirmed,
The pattern of the fixed signal of the second magnetic layer 3 could not be confirmed, and it could not be confirmed visually.

【００１６】（比較例１）実施例１と同様の製造方法で
第２磁性層の製造工程を省略し、第１の磁性層上に第３
の磁性層による固定信号のみを形成し、同様の方法で固
定信号のバイアス依存性を確認したところ、バイアス磁
界の変化による出力波形の変化はみられなかった。(Comparative Example 1) The manufacturing method of the second magnetic layer was omitted in the same manufacturing method as in Example 1, and the third magnetic layer was formed on the first magnetic layer.
When only the fixed signal by the magnetic layer was formed and the bias dependency of the fixed signal was confirmed by the same method, no change in the output waveform due to the change in the bias magnetic field was observed.

【００１７】[0017]

【発明の効果】本発明によれば、非磁性基体上の異なっ
た固定信号を形成した２つ以上の飽和磁化特性の異なる
磁性層が積層して形成されているため、本発明の磁気記
録媒体に特有のバイアス依存性をもつ。また目視での固
定パターンの確認が実質的に困難である。このため、形
成された固定信号とあわせて、バイアス依存性を利用す
ることにより媒体を特定するための識別情報として使用
すれば、偽造や変造に対し極めて安全性の高い磁気記録
媒体を提供できる。According to the present invention, the magnetic recording medium of the present invention is formed by laminating two or more magnetic layers having different saturation magnetization characteristics on the non-magnetic substrate and forming different fixed signals. Has a bias dependence peculiar to. Further, it is substantially difficult to visually confirm the fixed pattern. For this reason, if it is used as identification information for specifying the medium by utilizing the bias dependency together with the formed fixed signal, it is possible to provide a magnetic recording medium with extremely high security against forgery and alteration.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明の一実施例としての磁気記録媒体の断面
図である。FIG. 1 is a sectional view of a magnetic recording medium according to one embodiment of the present invention.

【図２】実施例１の磁気記録媒体の第１の磁性層に記録
した信号の再生波形を示す。FIG. 2 shows a reproduced waveform of a signal recorded on a first magnetic layer of the magnetic recording medium of Example 1.

【図３】実施例１の磁気記録媒体の第２の磁性層に形成
された固定信号の再生波形を示す。FIG. 3 shows a reproduction waveform of a fixed signal formed on a second magnetic layer of the magnetic recording medium of Example 1.

【図４】実施例１の磁気記録媒体のバイアス電流５ｍＡ
での再生波形を示す。FIG. 4 shows a bias current of 5 mA for the magnetic recording medium of Example 1.
3 shows a reproduced waveform at the time of the second embodiment.

【図５】実施例１の磁気記録媒体のバイアス電流５０ｍ
Ａでの再生波形を示す。FIG. 5 shows a bias current of 50 m of the magnetic recording medium of Example 1.
3A shows a reproduced waveform at A.

【図６】実施例１の第２の磁性層と第３の磁性層に形成
された固定信号のバイアス特性を示す。FIG. 6 shows a bias characteristic of a fixed signal formed on the second magnetic layer and the third magnetic layer in Example 1.

【符号の説明】[Explanation of symbols]

１ 非磁性基体 ２ 第１の磁性層 ３ 第２の磁性層 ４ 第３の磁性層 ５ 第２の磁性層のバイアス特性 ６ 第３の磁性層のバイアス特性 DESCRIPTION OF SYMBOLS 1 Nonmagnetic substrate 2 1st magnetic layer 3 2nd magnetic layer 4 3rd magnetic layer 5 Bias characteristic of 2nd magnetic layer 6 Bias characteristic of 3rd magnetic layer

Claims (6)

【特許請求の範囲】[Claims] 【請求項１】 非磁性基体上の全体または一部に３層以
上の磁性層を積層して成る磁気記録媒体において、前記
磁性層のうち少なくとも２つの磁性層は他の磁性層に記
録された信号による磁界もしくは、同磁界と配向磁界の
影響により形成された書換不能な固定信号が記録され、
前記磁性層のうち前記少なくとも２つの磁性層に異なっ
た書換不能な固定信号が記録されていることを特徴とす
る磁気記録媒体。1. A magnetic recording medium comprising three or more magnetic layers laminated on the whole or a part of a non-magnetic substrate, wherein at least two of the magnetic layers are recorded on another magnetic layer. A magnetic field by a signal or a non-rewritable fixed signal formed by the influence of the magnetic field and the orientation magnetic field is recorded,
A different non-rewritable fixed signal is recorded on the at least two magnetic layers of the magnetic layer. 【請求項２】 前記磁性層のうち少なくとも２つの磁性
層は外部磁界に対し異なった飽和磁化特性を有すること
を特徴とした請求項１の磁気記録媒体。2. The magnetic recording medium according to claim 1, wherein at least two of the magnetic layers have different saturation magnetization characteristics with respect to an external magnetic field. 【請求項３】 前記磁気記録媒体の製造方法であって、
先ず非磁性基体上に磁気記録可能な磁性材料から成る第
１の磁性層を形成し、次いで前記第１の磁性層に所定の
信号を磁気記録し、次いで第２の磁性層を形成する磁性
塗料を塗布、乾燥、固化して第２の磁性層を形成し、次
いで前記第２の磁性層とは異なった飽和磁化特性を有す
る磁性塗料を塗布、乾燥、固化することにより第３の磁
性層を形成することを特徴とする磁気記録媒体の製造方
法。3. The method of manufacturing a magnetic recording medium, comprising:
First, a first magnetic layer made of a magnetic material that can be magnetically recorded is formed on a non-magnetic substrate, then a predetermined signal is magnetically recorded on the first magnetic layer, and then a second magnetic layer is formed. Is applied, dried and solidified to form a second magnetic layer, and then a magnetic paint having a saturation magnetization characteristic different from that of the second magnetic layer is applied, dried and solidified to form a third magnetic layer. Forming a magnetic recording medium. 【請求項４】 前記第２の磁性層および前記第３の磁性
層の少なくとも一方の形成方法であって、前記磁性塗料
が乾燥固化する前に前記第１磁性層の保磁力以下の磁界
強度で、塗布方向に対し平行な直流配向処理することを
特徴とする請求項３の製造方法。4. A method for forming at least one of the second magnetic layer and the third magnetic layer, wherein the magnetic coating material has a magnetic field strength equal to or less than a coercive force of the first magnetic layer before the magnetic paint is dried and solidified. 4. The method according to claim 3, wherein a DC orientation treatment is performed in parallel with the coating direction. 【請求項５】 前記第３の磁性層の形成方法であって、
前記第１の磁性層に磁気記録した所定の信号を書き換え
た後、前記第３の磁性層を形成する請求項３および請求
項４の製造方法。5. The method for forming a third magnetic layer, comprising:
5. The method according to claim 3, wherein the third magnetic layer is formed after a predetermined signal magnetically recorded on the first magnetic layer is rewritten. 【請求項６】 請求項１の磁気記録媒体の使用方法であ
って、磁気ヘッドで所定のバイアス磁界を印加しながら
前記磁気記録媒体を読み取ったときの読み取り信号と、
これと異なったバイアス磁界を印加しながら前記磁気記
録媒体を読み取ったときの読み取り信号との相違を認識
することを特徴とする使用方法。6. A method for using a magnetic recording medium according to claim 1, wherein: a read signal when reading the magnetic recording medium while applying a predetermined bias magnetic field with a magnetic head;
A use method characterized by recognizing a difference from a read signal when reading the magnetic recording medium while applying a different bias magnetic field.
JP20740197A 1997-07-17 1997-07-17 Magnetic recording medium, its production and its use method Pending JPH1139642A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP20740197A JPH1139642A (en) 1997-07-17 1997-07-17 Magnetic recording medium, its production and its use method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP20740197A JPH1139642A (en) 1997-07-17 1997-07-17 Magnetic recording medium, its production and its use method

Publications (1)

Publication Number Publication Date
JPH1139642A true JPH1139642A (en) 1999-02-12

Family

ID=16539142

Family Applications (1)

Application Number Title Priority Date Filing Date
JP20740197A Pending JPH1139642A (en) 1997-07-17 1997-07-17 Magnetic recording medium, its production and its use method

Country Status (1)

Country Link
JP (1) JPH1139642A (en)

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