JPH10208009A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely judge a magnetic recording medium to be true or not to make alteration of the magnetic recording medium difficult by arranging plural minute projecting parts in a magnetic layer on a substrate in the scanning direction of a magnetic head and recording fixed magnetic information in the magnetic layer. SOLUTION: Fixed magnetic information consisting of plural minute recessed parts 5 arranged in the scanning direction (the direction of an arrow (a)) of the magnetic head is recorded in a recording part 4 of a magnetic layer 3 on a magnetic recording medium 1. These recessed parts 5 are sets of recessed parts 6 like dots formed by partially and physically removing the magnetic layer 3. These recessed parts 6 like dots are arranged approximately orthogonally to the scanning direction of the magnetic head, and one array of them constitutes one recessed part 5, and two or more kinds of recessed parts 5 different in densities of recessed parts 6 exist. Thus, fixed magnetic information consisting of minute recessed parts 5 is recorded in the recording part 4, and fixed magnetic information as an invariable record can be data particular to each magnetic recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium having a magnetic layer formed on a substrate for preventing forgery.

[0002]

2. Description of the Related Art Conventionally, in order to prevent forgery of a magnetic recording medium such as a prepaid card, information is written at a high recording density on a magnetic layer so that recorded information cannot be easily read from the outside.

However, since the recorded information can be freely rewritten and erased due to the characteristics of the magnetic layer, forgery and falsification are possible. In recent years, it has been highlighted as a major social problem. In particular, since magnetic stripes are now readily available, it is possible to manufacture similar magnetic recording media, and to read magnetic information from the magnetic layer exposed on the surface of the magnetic recording medium, There is also a problem that magnetic information can be easily transferred to another magnetic layer by the transfer technique.

In order to solve such a problem, a magnetic recording medium has been developed in which a magnetic layer is composed of a layer containing a magnetic material having a relatively high coercive force and a layer containing a magnetic material having a low coercive force. In this magnetic recording medium, information recorded on a magnetic layer containing a magnetic material having a relatively high coercive force is different from information recorded on a magnetic layer containing a magnetic material having a low coercive force. Cannot be read accurately.

However, the magnetic recording medium as described above can read magnetic information under a normal environment by using a commercially available magnetic recording device. Here, the normal environment means an environment in which temperature, humidity, and the like are not changed. Further, the magnetic layer containing a magnetic material having a relatively high coercive force can be erased and rewritten by a magnetic head under a normal environment by using a specific device. Even if magnetic information is recorded on a magnetic layer containing a material, there has been a problem that forgery and alteration cannot be effectively prevented.

Further, variable magnetic information such as balance information cannot be recorded on a layer made of a low coercivity magnetic material capable of ordinary magnetic recording from the viewpoint of forgery prevention. Although it is possible to store variable magnetic information,
The burden on the terminal is large and not practical.

Therefore, in order to prevent forgery of a magnetic recording medium such as a prepaid card, a predetermined magnetic pattern is formed on the magnetic recording medium in advance. This is to determine the authenticity of the magnetic recording medium by reading a pre-formed magnetic pattern at the time of use and determining whether a predetermined magnetic output signal is obtained.

For reading such a magnetic pattern,
Usually, a magnetic head wound with two coils is used. A constant current is applied to one of the coils of the magnetic head, and the induced current or voltage induced when the magnetic head scans the magnetic pattern is applied to the other coil. To detect. The induced current is generated according to a change in the magnetic flux of the magnetic head.

On the other hand, as a material constituting the magnetic pattern, for example, a ferromagnetic material is used, and various shapes of the magnetic pattern can be considered. A so-called bar code pattern is generally used. . This magnetic pattern is configured by arranging a plurality of magnetic bars, which are pattern elements, in the width direction thereof, and the width of each magnetic bar constituting the magnetic pattern is one type or two or more types. A magnetic output signal can be obtained by scanning the bar-code-shaped magnetic pattern at a constant speed with the above-described magnetic head in close contact.

As a method for forming the above magnetic pattern, a screen printing method, an offset printing method, a gravure printing method, or the like can be used. These printing methods are advantageous in terms of manufacturing costs.

[0011]

However, pattern formation by the printing method has the following problems due to the characteristics of the printing method.

For example, in the screen printing method, since the number of meshes and the diameter of the screen mesh cannot be ignored,
There is a physical limit to reducing the print line width itself, and there is a disadvantage that the recording density cannot be improved. In addition, as the recording density is increased, the transfer of the ink becomes more unstable, and the printing shape becomes non-uniform due to ink leveling and the like (in addition, the printing film thickness tends to increase as the width increases). There is a disadvantage that the magnetic output and the waveform are also unstable, and it is difficult to obtain accurate information. Therefore, the width of one bit of a general magnetic barcode is limited to about 100 μm, and there is a problem that the recording density must be lower than that of ordinary magnetic information. Also, in the method of printing, since the same pattern as the printing plate is duplicated, only a certain amount of information is given to the magnetic recording medium, and different information cannot be given to each magnetic recording medium. There is.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is possible to prevent forgery, improve the recording density, and improve the accuracy of the obtained information. It is an object of the present invention to provide a magnetic recording medium that can accurately perform the recording.

[0014]

In order to achieve the above object, the present invention provides a magnetic recording medium comprising at least a substrate and a magnetic layer formed on the substrate,
The magnetic layer has recorded thereon fixed magnetic information composed of a plurality of fine concave portions or convex portions arranged along the scanning direction of the magnetic head, and each of the concave portions is substantially orthogonal to the scanning direction of the magnetic head. As well as the collection of dot-shaped recesses formed in the magnetic layer, there are two or more types of recesses in the recesses having different densities of the dot-like recesses,
Each of the protrusions is a set of dot-like protrusions formed on the magnetic layer so as to be substantially orthogonal to the scanning direction of the magnetic head, and the protrusions have two different dot-like protrusion densities. The configuration was such that the above-mentioned convex portions existed.

In the magnetic recording medium of the present invention, the fixed magnetic information may include a plurality of concave portions having the same density of the dot-shaped concave portions or a plurality of concave portions having the same density of the dot-shaped convex portions of the convex portions. The structure was such that two or more types of regions consisting of the convex portions existed.

Further, the magnetic recording medium of the present invention has a multilayer structure in which the magnetic layer has at least two types of magnetic layers having different magnetic characteristics.
The structure was such that fixed magnetic information composed of a plurality of fine concave or convex portions was recorded in the layer.

Further, in the magnetic recording medium of the present invention, the dot-shaped concave portions are formed by physically removing a surface of the magnetic layer partially, and the dot-shaped convex portions are partially A structure such that the magnetic layer is formed by providing the magnetic layer on the substrate on which the dot-shaped minute concave portions are formed by removing the magnetic layer, or the magnetic layer in which the dot-shaped convex portions are provided on the substrate. The structure was such that it was formed by forming a dot-shaped minute concave portion by partially physically removing it and then providing a magnetic layer thereon.

Further, in the magnetic recording medium of the present invention, the opening width of the dot-shaped concave portion and the maximum width of the dot-shaped convex portion are 3
The configuration was such that the range was 0 to 1000 μm.

Further, the magnetic recording medium of the present invention is configured such that the formation pitch of the dot-shaped concave portions and the formation pitch of the dot-shaped convex portions are in the range of 1 μm to 5 mm.

Further, in the magnetic recording medium of the present invention, the depth of the dot-shaped concave portions and the height of the dot-shaped convex portions may be 2 to 3
The configuration was such that the range was 0 μm.

Further, the magnetic recording medium of the present invention has a configuration in which the pitch of the concave portions and the pitch of the convex portions are not less than 30 μm.

Further, the magnetic recording medium of the present invention has a configuration in which a concealing layer is formed on the magnetic layer.

In the present invention as described above, a plurality of fine concave portions which are a set of dot-shaped concave portions or a plurality of fine convex portions which are a set of dot-shaped convex portions are formed along the scanning direction of the magnetic head. The fixed magnetic information is recorded on the magnetic layer by being arranged in a row, and the above-mentioned concave portions and convex portions have two or more types of concave portions and convex portions having different densities of dot-shaped concave portions or dot-shaped convex portions. When a magnetic head is scanned over the magnetic layer, a magnetic output signal from the fixed magnetic information is obtained, and the magnetic output signal indicates an output corresponding to the density of the dot-shaped concave portion or the dot-shaped convex portion, Since the dot-shaped concave portions and the dot-shaped convex portions are formed by partially removing the magnetic layer or the substrate, various patterns can be formed, and the recording density can be improved.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a card-shaped magnetic recording medium for explaining an embodiment of the present invention. As shown in FIG. 1, a magnetic recording medium 1 according to the present invention includes a substrate 2 and a magnetic layer 3 formed on the substrate 2. The recording section 4 is set on the magnetic layer 3 along the scanning direction of the magnetic head (in the illustrated example, parallel to the long side of the substrate 2 (the direction of arrow a)).

FIG. 2 is a partially enlarged plan view of the recording portion 4 of the magnetic layer 3 in the magnetic recording medium 1 shown in FIG. 1, and FIG. FIG. 2 is a cross-sectional view taken along the line A, which is schematically and simply drawn by enlarging the cross-sectional state in order to facilitate understanding of the present invention. As shown in FIGS. 2 and 3, the recording section 4 of the magnetic layer 3 has a fixed magnetic field composed of a plurality of fine concave portions 5 arranged along the scanning direction of the magnetic head (the direction of arrow a in the drawing). Information is recorded. The recess 5 is formed by a dot-like recess 6 formed by partially physically removing the magnetic layer 3.
Is a set of The dot-shaped concave portions 6 are arranged so as to be substantially orthogonal to the scanning direction of the magnetic head, and one row thereof includes one concave portion 5 (in FIG. 2, one concave portion 5 is surrounded by a chain line). There are two or more types of concave portions 5 having different densities of dot-shaped concave portions 6. In the illustrated example, 6 is formed so as to be substantially orthogonal to the scanning direction of the magnetic head.
There is a concave portion 5a composed of three dot-shaped concave portions 6 and a concave portion 5b composed of three dot-shaped concave portions 6 similarly. Then, an area A1 having a plurality of (six in the illustrated example) continuous concave portions 5a is formed in the fixed magnetic information, and an area A2 having a plurality of (six in the illustrated example) continuous concave portions 5b is formed in the fixed magnetic information. Have been.

Substrate 2 constituting magnetic recording medium 1 described above
In consideration of heat resistance, strength, rigidity, etc. required as a substrate, resins such as nylon, cellulose diacetate, cellulose triacetate, vinyl chloride, polystyrene, polyethylene, polypropylene, polyester, polyimide, polycarbonate, etc., biodegradable resins , Copper, aluminum and other metals, paper, impregnated paper, and other suitable materials alone or in combination. The thickness of such a substrate 2 is 0.00
It can be about 5 mm to 5 mm.

The magnetic layer 3 can be usually a hard magnetic layer containing a hard magnetic powder and a resin binder, or a soft magnetic layer containing a soft magnetic powder and a resin binder. In this case, the thickness of the magnetic layer 3 is 3 to 50 μm, preferably 5 to 50 μm.
About 20 μm. Further, the magnetic layer 3 may be either non-oriented or oriented.

Examples of the hard magnetic powder used for forming such a magnetic layer 3 include γ-Fe ₂ O ₃ , Co-coated γ
_{-Fe 2 O 3, Fe 3 O} 4, Fe, Fe-Cr, Fe-
Co, Co-Cr, Co-Ni, Ba ferrite, Sr
Examples include magnetic fine particles such as ferrite and CrO ₂ . Examples of the soft magnetic powder include a magnetic alloy material made of Al, Si, Fe, etc., a metal having a high magnetic permeability such as Permalloy, Sendust, and Fe, and a ferrite such as Mn-Zn ferrite, Co-Zn ferrite, and Ni-Zn ferrite. And metal amorphous materials.

The resin binder (or ink vehicle) in which the above hard magnetic powder or soft magnetic powder is dispersed includes butyral resin, vinyl chloride / vinyl acetate copolymer resin, urethane resin, polyester resin, cellulose resin, and acrylic resin. A styrene / maleic acid copolymer resin or the like is used, and a rubber resin such as a nitrile rubber or a urethane elastomer is added as necessary. Further, in consideration of heat resistance, a resin having a high glass transition temperature (Tg) such as polyamide, polyimide, or polyethersulfone, or a system in which Tg increases by a curing reaction can be used. As necessary, a pigment such as a surfactant, a silane coupling agent, a plasticizer, a wax, a silicone oil, or carbon is added to the dispersion of the magnetic particles dispersed in the resin or the ink vehicle as described above. You may. Further, a radiation-curable or electron beam-curable resin binder can also be used. In this case, photopolymerizable oligomers such as epoxy acrylate, urethane acrylate, polyester acrylate, polyether acrylate, silicon acrylate, unsaturated polyester and polyene / thiol; photopolymerization such as monofunctional acrylate such as styrene and vinyl acetate, and polyfunctional acrylate Monomer (reactive diluent); benzoin-based, acetophenone-based, thioxanthone-based, peroxide-based photoinitiator; amine-based, quinone-based photoinitiator; other, if necessary, thermal polymerization inhibitor, inorganic Alternatively, a radiation-curable resin binder can be formed using an organic filler, an adhesion-imparting agent, a thixo-imparting agent, a non-reactive polymer, a pigment, and the like. Resin binder.

The magnetic layer 3 can be formed by using the above-mentioned hard magnetic material or soft magnetic material itself by a vacuum deposition method, a sputtering method, a plating method, or the like. In this case, the thickness of the magnetic layer 3 can be about 200 to 1000 °, preferably about 400 to 800 °.

As shown in FIG. 2, six small dots 5 formed substantially perpendicular to the scanning direction of the magnetic head are formed in the minute concave portions 5 constituting the fixed magnetic information recorded on the magnetic layer 3. There is a concave portion 5a composed of the concave portion 6 and a concave portion 5b composed of the same three dot-shaped concave portions 6. The pitch at which the concave portions 5 are formed can be set in consideration of the characteristics of the magnetic head, the relative scanning speed between the magnetic head and the magnetic recording medium, and can be set, for example, in a range of 30 μm or more.

The shape of the dot-shaped concave portion 6 constituting the concave portion 5 is not particularly limited, and may be any of an inverted conical shape, an inverted pyramid shape, a cylindrical shape, and the like. The opening width of the dot-shaped recess 6 is about 30 to 1000 μm, the pitch at which the dot-shaped recess 6 is formed in one recess 5 is about 1 μm to 5 mm, and the depth of the dot-shaped recess 6 is about 2 to 30 μm. Can be set in the range. Furthermore, the density of the dot-shaped concave portions 6 can be appropriately set according to the type of density of the concave portions 5 required (two types in the illustrated example). In the magnetic recording medium 1 of the present invention, the relative magnitude relation of the output of the fixed magnetic information is determined by the density of the dot-shaped concave portions 6 forming the concave portions 5.

By changing the number of the concave portions 5a and 5b constituting the concave portion 5 in the basic length along the scanning direction of the magnetic head, the read output waveform is made different.
Data can be discriminated into digital signal values of “0” and “1”. For example, as shown in FIG. 4, "1" is provided with two concave portions 5a in the basic length L (1 bit),
For "0", one concave portion 5a can be provided in the basic length L (one bit). In this case, the magnetic output signal waveform is as shown in the figure.

The formation of such a dot-shaped recess 6 can be performed by, for example, a method of irradiating a laser beam to a position corresponding to the formation of the dot-shaped recess 6, a method of irradiating an electron beam, a destruction by electric discharge,
It can be performed by routing (engraving) processing or the like.

When a laser beam is used, the type of laser to be used, the laser wavelength, the laser power, and the like may be appropriately set in consideration of the size of the dot-shaped concave portion to be formed.

As a gas laser, a He-Ne laser, a He-Cd laser, an argon laser (0.48
Rare gas ion laser such as 8 μm continuous oscillation, 0.1 to 20 W); carbon dioxide laser (10.6 μm continuous oscillation, 1
W to 10 kW); a metal vapor laser or the like can be used. As a solid laser, a ruby laser (0.6943 μm pulse oscillation, 10 to 1000 J),
Nd glass laser (1.06 μm pulse oscillation, 10 to 10
1000J), pulsed solid-state laser such as Nd: YAG laser; or ruby laser, Nd glass laser, Nd: YAG laser (continuous oscillation of 1.06 μm,
1 to 200 W), and a continuous excitation solid-state laser such as an Nd: YAlO ₃ laser can be used. As the liquid laser, a dye laser, a Raman laser, a chelate laser, an Nd ³⁺ liquid laser or the like can be used, and as the semiconductor laser, a GaAs diode laser or the like can be used.

Among them, a CO ₂ gas laser having a wavelength of 10.6 μm (output: 0.5 W to 20 W), an Ar gas laser having a wavelength of 0.488 μm (or 0.5145 μm) (output: 0.5 W to 20 W), a wavelength of 1.06 μm
Nd: YAG laser (output: 0.5 W to 20 W) is a preferred example.

In the formation of the dot-like concave portions 6 using the laser as described above, for example, the laser pulse frequency,
Alternatively, the formation density of the dot-shaped concave portions 6 constituting the concave portions 5 can be changed by controlling the frequency of opening and closing the shutter. For example, as shown in FIG.
When the dot-shaped concave portion 6 is formed by moving the pulse-excited solid-state laser at a constant speed as shown by an arrow, after the formation of the dot-shaped concave portion 6 in the area A1, the pulse frequency is reduced to half and the dot in the area A2 is reduced. By forming the concave portions 6, it is possible to form the concave portions 5 a and the concave portions 5 b having different densities of the dot-shaped concave portions 6 as illustrated.

If the output of the laser becomes too large, the magnetic layer 3 is damaged by the high temperature and the pattern of the concave portion 5 becomes inaccurate. On the other hand, if the output becomes too small, the desired dot-shaped concave portion 6 is formed. Therefore, it is necessary to appropriately set the laser output in consideration of the shape to be formed by removing the magnetic layer 3 and the like.

In the magnetic recording medium 1 of the present invention, fixed magnetic information comprising a plurality of fine concave portions 5 is recorded in the predetermined recording portion 4 of the magnetic layer 3 as described above. Since the fixed magnetic information is constituted by the dot-shaped concave portions 6 formed in the layer 3, the fixed magnetic information as the invariable recording can be individual data for each magnetic recording medium.

Next, an example of signal detection of the fixed magnetic information of the magnetic recording medium 1 will be described with reference to FIG. FIG.
(A) shows the fixed magnetic information shown in FIGS. 2 and 3, and a magnetic head for reading is indicated by an arrow in the drawing on a plurality of fine concave portions 5 constituting the fixed magnetic information. FIG. 6B shows a magnetic output signal waveform generated when scanning is performed at a constant speed from left to right. That is, FIG.
As shown (B), the recess in the region A1 of the concave portion 5a of six dot-like recesses 6, the output of the magnetic output signal waveform is P _1, then consisting of three dot-shaped recesses 6 in the region A2 of 5b, the output of the magnetic output signal waveform becomes P _2. Then, the ratio of the density of the dot-shaped recess 6 in the recess 5a to the density of the dot-shaped recess 6 in the recess 5b (2:
Approximately corresponds to 1), domain output P ₁ of the magnetic output signal waveform at the A1 output of the magnetic output signal waveform in the region A2 P ₂ also approximately 2: 1, and the size of the pattern is present in the output.

As described above, in the magnetic recording medium 1 of the present invention, when the magnetic head scans the magnetic layer 3, a magnetic output signal from the fixed magnetic information is obtained, and this magnetic output signal is It is characterized in that it shows an output corresponding to the density of the dot-shaped recess 6. Therefore, the authenticity of the magnetic recording medium can be reliably determined based on whether a magnetic output signal having a predetermined output pattern from the fixed magnetic information is obtained.

When the magnetic layer 3 is a soft magnetic layer,
The reading magnetic head is caused to scan in the direction of the arrow while applying a reproducing bias current.

In the above example, the output pattern of the magnetic output signal from the fixed magnetic information is an output pattern of output P ₁ : output P ₂ = 2: 1, but the present invention is not limited to this.
Next, another example of the output pattern of the magnetic output signal from the fixed magnetic information will be described with reference to FIGS.

FIG. 7 is a plan view corresponding to FIG. 2, showing another embodiment of the magnetic recording medium of the present invention. In the magnetic recording medium 1 ′ shown in FIG. 7, a fixed magnetic field composed of a plurality of minute concave portions 5 arranged in the recording section 4 of the magnetic layer 3 along the scanning direction of the magnetic head (the direction of arrow a in the drawing). Information is recorded, and the fixed magnetic information includes an area A1 in which a plurality of (four in the illustrated example) continuous concave parts 5a, an area A2 in which a plurality of (four in the illustrated example) continuous concave parts 5b are provided, and a concave part. An area A3 in which a plurality of (five in the illustrated example) 5c are continuous is provided. The concave portions 5a, 5b, 5c are a group of dot-shaped concave portions 6 formed by partially physically removing the magnetic layer 3, and have different densities of the dot-shaped concave portions 6. That is, the concave portion 5a is composed of six dot-shaped concave portions 6 formed substantially orthogonal to the scanning direction of the magnetic head, and the concave portion 5b is also composed of four dot-shaped concave portions 6;
The concave portion 5c is also composed of two dot-shaped concave portions 6. Therefore, the density of the dot-shaped concave portions 6 of the concave portions 5a, 5b, 5c is 3: 2: 1.

An example of the detection of the signal of the fixed magnetic information of the magnetic recording medium 1 'will be described with reference to FIG. FIG.
(A) shows BB of the recording portion 4 of the magnetic layer 3 shown in FIG.
FIG. 3 is a cross-sectional view taken along a line, when a magnetic head for reading scans a plurality of minute concave portions 5 constituting fixed magnetic information at a constant speed from left to right as indicated by arrows in the drawing. The resulting magnetic output signal waveform is as shown in FIG.
That is, in the area A1 of the concave portion 5a of six dot-like recesses 6, the output of the magnetic output signal waveform is P _1, then in the area A2 of the concave portion 5b of four dot-shaped recesses 6, The output of the magnetic output signal waveform becomes P ₂ , and the area A of the concave portion 5 c including two dot-shaped concave portions 6 is formed.
In No. 3, the output of the magnetic output signal waveform is P ₃ .
Then, the dot-shaped concave portions 6 of the concave portions 5a, 5b, 5c described above.
Almost correspond to the density ratio (3: 2: 1) of the area A1,
Outputs P ₁ and P of the magnetic output signal waveforms at A2 and A3
The ratio of ₂ and P ₃ is also approximately 3: 2: 1, and there is a pattern in the output.

FIG. 9 is a plan view corresponding to FIG. 2, showing another embodiment of the magnetic recording medium of the present invention. In the magnetic recording medium 1 ″ shown in FIG. 9, the fixed portion composed of a plurality of fine concave portions 5 arranged in the recording portion 4 of the magnetic layer 3 along the scanning direction of the magnetic head (the direction of arrow a in the drawing). Information is recorded, and the fixed magnetic information alternately includes an area A1 in which a plurality of (four in the illustrated example) continuous recesses 5a and an area A2 in which a plurality of (four in the illustrated example) continuous recesses 5b are provided. The recesses 5 a and 5 b are provided in the magnetic layer 3.
Is a set of dot-shaped concave portions 6 formed by partially physically removing the dot-shaped concave portions 6, each having a different density of the dot-shaped concave portions 6. That is, the concave portions 5a are formed of six dot-shaped concave portions 6 formed so as to be substantially orthogonal to the scanning direction of the magnetic head.
And the concave portion 5b is also composed of three dot-shaped concave portions 6. Therefore, the density of the dot-shaped concave portions 6 of the concave portions 5a and 5b is 2: 1.

An example of signal detection of fixed magnetic information of such a magnetic recording medium 1 "will be described with reference to FIG.
(A) shows CC of the recording section 4 of the magnetic layer 3 shown in FIG.
FIG. 3 is a cross-sectional view taken along a line, when a magnetic head for reading scans a plurality of minute concave portions 5 constituting fixed magnetic information at a constant speed from left to right as indicated by arrows in the drawing. The resulting magnetic output signal waveform is as shown in FIG. That is, a concave portion 5a composed of six dot-shaped concave portions 6
In the area A1, the output of the magnetic output signal waveform is P ₁
And then a recess 5 composed of three dot-like recesses 6
In the region A2 of b, the output of the magnetic output signal waveform is P
_2, and then the magnetic output signal waveform of the area A1 in the output P ₁ is repeated to obtain, in the region A2 the output P
₂ magnetic output signal waveforms are obtained. The ratio between the outputs P ₁ and P ₂ of the magnetic output signal waveforms in the repetitive regions A1 and A2 is also substantially equal to the ratio (2: 1) of the density of the dot-shaped concave portions 6 of the concave portions 5a and 5b. : 1 and a pattern exists in the output.

The magnetic recording media 1, 1 of the present invention as described above
There is no particular limitation on the arrangement pattern of the dot-shaped recesses 6 formed in the magnetic layer 3 and forming the above-described recesses 5 in “1” and “1”, for example, as shown in FIG. It may be arranged at regular or different intervals so as to be substantially perpendicular to the direction (the direction of arrow a in the drawing). Further, as shown in FIG. The arrangement of the dot-shaped recesses 6 as shown in Fig. 11 (B) is usually such that the density of the dot-shaped recesses 6 is the highest. 5 is used.

The above-mentioned magnetic recording medium has a concealing layer for making it difficult to recognize the pattern of the plurality of minute recesses 5 constituting the fixed magnetic information, and a protective layer for improving the protection / decoration effect. ) May be provided on the magnetic layer 3. Such a concealing layer and a protective layer may be formed of a cellulose derivative such as ethyl cellulose, cellulose nitrate, ethyl hydroxyethyl cellulose, cellulose acetate propionate, or cellulose acetate; polystyrene, poly-α.
A styrene resin such as methylstyrene or a styrene copolymer resin; an acrylic resin or a methacrylic resin such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; or rosin and rosin Rosin ester resins such as modified maleic acid resin, rosin-modified phenol resin, and polymerized rosin; should be colored on binders such as polyvinyl acetate resin, cumarone resin, vinyl toluene resin, vinyl chloride resin, polyester resin, polyurethane resin, and butyral resin. Various pigments are added according to the color, and if necessary, titanium oxide, alumina powder, microsilica, etc., which have a magnetic head cleaning effect, are added.If necessary, a plasticizer, a stabilizer, and a wax are added. , Grease,
After adding a drying agent, a drying aid, a curing agent, a thickening agent, and a dispersing agent, knead well with a solvent or diluent, and then use a coloring paint or ink. It can be formed by a coating method such as a method or an offset method or a printing method.

FIG. 12 is a sectional view corresponding to FIG. 3, showing another embodiment of the magnetic recording medium of the present invention. In FIG. 12, a magnetic recording medium 11 of the present invention includes a substrate 12 and a magnetic layer 13 formed on the substrate 12.
In the magnetic recording medium 11, a plurality of minute dot-shaped recesses 12a are formed in the substrate 12 by partially removing the substrate 12 physically. On the side of the boundary surface between the magnetic layer 13 formed on the substrate 12 and the substrate 12, dot-shaped convex portions 18 are formed corresponding to the minute dot-shaped concave portions 12a. The dot-shaped projections 18 are arranged so as to be substantially perpendicular to the scanning direction of the magnetic head (the direction of arrow a), and each arrangement constitutes one projection 17. Therefore, a plurality of protrusions 17 are arranged on the magnetic layer 13 along the scanning direction of the magnetic head (the direction of arrow a), and fixed magnetic information formed by the protrusions 17 is recorded. The projections 17 include two or more types in which the density of the dot-shaped projections 18 is different. (For example, a high-density area A1 and a low-density area A2 can be provided as shown in the figure.) In such a magnetic recording medium 11 of the present invention, a plurality of fine lines formed as described above are formed. Since the fixed magnetic information including the convex portions 17 is recorded on the magnetic layer 13, and each of the convex portions 17 is constituted by the dot-shaped convex portions 18 formed on the magnetic layer 13, the fixed magnetic information as invariable recording is provided. Can be individual data for each magnetic recording medium.

When the magnetic head for reading scans the magnetic layer 13 in the direction of the arrow a in FIG.
The magnetic output signal waveform of the output corresponding to the density of the dot-like convex portions 18 constituting the above is obtained. When the magnetic layer 13 is a soft magnetic layer, the read magnetic head is scanned while applying a reproducing bias current.

Small dot-shaped concave portion 12a on substrate 12
Can be formed in the same manner as the formation of the dot-shaped concave portions 6 in the magnetic layer 3 of the magnetic recording medium 1 described above, and can be formed using, for example, a pulse-excited solid laser. The shape, size, formation density, and the like of the minute dot-shaped recesses 12a formed on the substrate 12 are appropriately set in the same manner as the dot-shaped recesses 6 formed on the magnetic layer 3 of the magnetic recording medium 1 described above. Can be. Therefore, the magnetic layer 1
The 3 dot-shaped convex portions 18 have a maximum width of about 30 to 1000 μm, a formation pitch of about 1 to 5 mm, and a height of 2 to 30 μm.
The density of the dot-shaped convex portions 18 can be appropriately set according to the type of the density of the required convex portions 17. The magnetic recording medium 11
The substrate 12 used in the above can be the one exemplified as the substrate 2 constituting the magnetic recording medium 1 described above, and the description is omitted here.

The magnetic layer 13 constituting the magnetic recording medium 11 may be either a hard magnetic layer or a soft magnetic layer, and the presence or absence of the magnetic orientation treatment is not limited. Such a magnetic layer 13 can be formed in the same manner as the above-described magnetic layer 3. However, when the magnetic layer 13 is formed by a coating method, the magnetic layer 13 is coated with a magnetic coating material in consideration of the surface smoothness of the magnetic layer 13. It is preferable to use an electron beam-curable resin binder as the resin binder.

As in the case of the above-described magnetic recording medium 1, such a magnetic recording medium 11 has a concealing layer and a protective layer for making it difficult to recognize the pattern of a plurality of fine projections 17 constituting the fixed magnetic information. A protective layer (including a pattern) for improving the decorative effect may be provided on the magnetic layer 13.

FIG. 13 is a sectional view corresponding to FIG. 3, showing another embodiment of the magnetic recording medium of the present invention. In FIG. 13, the magnetic recording medium 21 of the present invention includes a substrate 22 and a magnetic layer 23 formed on the substrate 22.
In this magnetic recording medium 21, the magnetic layer 23 has a structure in which a magnetic layer 23a and a magnetic layer 23b having different magnetic characteristics are stacked. In the magnetic layer 23a, fixed magnetic information composed of a plurality of fine concave portions 25 arranged along the scanning direction of the magnetic head (the direction of arrow a) is recorded. The concave portion 25 is a set of dot-shaped concave portions 26 formed by physically removing the magnetic layer 23a partially, and the dot-shaped concave portions 26 are arranged in the scanning direction of the magnetic head (the direction of arrow a).
Are arranged so as to be substantially orthogonal to each other, and one row thereof constitutes one concave portion 25. In the concave portion 25, there are two or more kinds of concave portions having different densities of dot-like concave portions 26 (for example, as shown in the drawing). A high-density region A1 and a low-density region A2 can be provided in the same region). Therefore, the fixed magnetic information as the constant recording can be individual data for each magnetic recording medium.

The magnetic layer 23 constituting the magnetic recording medium 21
The magnetic layer 23a and the magnetic layer 23b may both be hard magnetic layers, or both may be soft magnetic layers, or may be a combination of a hard magnetic layer and a soft magnetic layer. However, when the magnetic layer 23a is a soft magnetic layer and the magnetic layer 23b is a hard magnetic layer, the coercive force of the soft magnetic layer 23a is
b is smaller than the coercive force. This is for the following reason. That is, the magnetization direction of the soft magnetic layer is reversed by the magnetic field generated in the read magnetic head to which the reproducing bias current is applied, and the magnetization direction of the hard magnetic layer is not reversed by the generated magnetic field. Things. Generally, in order to reverse the magnetization direction of the magnetic layer,
It is necessary to apply an external magnetic field about three times the coercive force (coercive force) of the magnetic layer. Therefore, for example, for a magnetic head that generates a magnetic field of a strength of 30 [Oe] as a bias magnetic field, a soft magnetic layer having a coercive force of 10 [Oe] or less as the magnetic layer 23a and a coercive force of 100 [Oe] as the magnetic layer 23b. Oe] or more is preferably formed.

The magnetic layer 23 is formed of the above-described magnetic layer 3
After the formation of the magnetic layer 23b in the same manner as
3b, a magnetic layer 23a is formed on the
6 and the presence or absence of the magnetic alignment treatment is not limited. The magnetic layer 23a and the magnetic layer 2
When forming 3b, the thickness of each magnetic layer is 3 to 50 μm,
It can be preferably about 5 to 20 μm,
When the magnetic layer is formed by a vacuum deposition method, a sputtering method, a plating method, or the like, the thickness of each magnetic layer can be about 200 to 1000 °, preferably about 400 to 800 °.

Further, the dot-shaped concave portions 26 are formed in the magnetic layer 23a.
Can be formed in the same manner as the formation of the dot-shaped concave portions 6 in the magnetic layer 3 of the magnetic recording medium 1 described above, and can be formed using, for example, a pulse-excited solid laser. In addition, the shape, size, formation density, and the like of the dot-shaped concave portions 26 can be appropriately set in the same manner as the dot-shaped concave portions 6 formed in the magnetic layer 3 of the magnetic recording medium 1 described above.

Like the above-described magnetic recording medium 1, such a magnetic recording medium 21 has a concealing layer or a protective layer for making it difficult to recognize a pattern of a plurality of minute concave portions 25 constituting fixed magnetic information. A protective layer (including a pattern) for improving the decorative effect may be provided on the magnetic layer 23.
Note that the substrate 22 forming the magnetic recording medium 21 can be the same as the substrate 2 forming the above-described magnetic recording medium 1, and thus the description thereof is omitted here.

When the magnetic head for reading scans the magnetic layer 23 in the direction of the arrow a in the figure, the magnetic recording medium 21 has dots forming the recesses 25 in the same manner as the magnetic recording medium 1 described above. A magnetic output signal waveform having an output corresponding to the density of the concave portions 26 is obtained. When the magnetic layer 23a is a soft magnetic layer, the read magnetic head is scanned while applying a reproducing bias current.

FIG. 14 is a sectional view corresponding to FIG. 3, showing another embodiment of the magnetic recording medium of the present invention. 14, a magnetic recording medium 31 according to the present invention includes a substrate 32 and a magnetic layer 33 formed on the substrate 32.
In this magnetic recording medium 31, the magnetic layer 33 has a structure in which a magnetic layer 33a and a magnetic layer 33b having different magnetic characteristics are laminated via a non-magnetic material layer 39. The scanning direction of the magnetic head (the direction of arrow a) is provided on the magnetic layer 33b.
Fixed magnetic information comprising a plurality of fine concave portions 35 arranged along the line is recorded. The concave portion 35 is a set of dot-shaped concave portions 36 formed by physically removing the magnetic layer 33b partially, and the dot-shaped concave portions 36 are arranged so as to be substantially orthogonal to the scanning direction of the magnetic head (the direction of arrow a). Are arranged, one row of which constitutes one recess 35,
5 includes two or more kinds of dot-shaped concave portions 36 having different densities (for example, a high-density region A1 and a low-density region A2 can be provided as shown). Therefore, the fixed magnetic information as the constant recording can be individual data for each magnetic recording medium.

Magnetic Layer 33 Constituting Magnetic Recording Medium 31
The magnetic layer 33a and the magnetic layer 33b may be both hard magnetic layers, or both soft magnetic layers, or a combination of a hard magnetic layer and a soft magnetic layer. However, when the magnetic layer 33b is a soft magnetic layer and the magnetic layer 33a is a hard magnetic layer, the coercive force of the soft magnetic layer 33b is
It is assumed to be smaller than the coercive force of a. This is for the same reason as the relationship between the soft magnetic layer 23a and the hard magnetic layer 23b described above.

Such a magnetic layer 33 is formed of the above-described magnetic layer 3.
After forming the magnetic layer 33b and forming the dot-shaped concave portions 36 in the same manner as described above, the non-magnetic material layer 39 is formed on the magnetic layer 33b, and then the magnetic layer 33a is formed. Further, the presence or absence of the magnetic orientation treatment of the magnetic layers 33a and 33b is not limited. When the magnetic layers 33a and 33b are formed by a coating method, the thickness of each magnetic layer is 3 to 5
0 μm, preferably about 5 to 20 μm, and when formed by vacuum evaporation, sputtering, plating, or the like, the thickness of each magnetic layer is 200 to 10 μm.
00 °, preferably about 400 to 800 °. The non-magnetic material layer 39 can be formed by a method of applying a coating material obtained by removing a magnetic powder from the above-described coating material for forming a magnetic layer and drying the coating material, and has a thickness of 1 to 30 μm, preferably about 2 to 10 μm. is there.

Further, the dot-shaped concave portions 36 are formed in the magnetic layer 33b.
Can be formed in the same manner as the formation of the dot-shaped concave portions 6 in the magnetic layer 3 of the magnetic recording medium 1 described above, and can be formed using, for example, a pulse-excited solid laser. In addition, the shape, size, formation density, and the like of the dot-shaped concave portion 36 can be appropriately set in the same manner as the dot-shaped concave portion 6 formed in the magnetic layer 3 of the magnetic recording medium 1 described above.

The magnetic recording medium 31 has a concealing layer and a protective layer for making it difficult to recognize the pattern of the plurality of minute concave portions 35 constituting the fixed magnetic information, similarly to the magnetic recording medium 1 described above. A protective layer (including a pattern) for improving the decorative effect may be provided on the magnetic layer 33.
Note that the substrate 32 forming the magnetic recording medium 31 can be the same as the substrate 2 forming the magnetic recording medium 1 described above, and thus the description thereof is omitted.

When the magnetic head for reading scans the magnetic layer 33 at a constant speed in the direction of arrow a in FIG.
A magnetic output signal waveform of an output corresponding to the density of the dot-shaped concave portions 36 constituting the fifth concave portion 5 is obtained. When the magnetic layer 33b is a soft magnetic layer, the read magnetic head is scanned while applying a reproducing bias current.

[0069]

Next, the present invention will be described in more detail with reference to specific examples. Example 1 First, a magnetic coating material A for a hard magnetic layer having the following composition was prepared.

Composition of magnetic paint A : Ba ferrite powder: 41 parts by weight Polyurethane resin: 7 parts by weight Methyl ethyl ketone: 25 parts by weight Toluene: 25 parts by weight Isocyanate curing agent: 2 parts by weight A card substrate made of polyethylene terephthalate having a thickness of 250 μm was prepared, and the above magnetic paint A was applied to the card substrate by gravure coating to form a hard magnetic layer having a thickness of 10 μm. In the formation of the hard magnetic layer, a magnetic orientation treatment was performed along the long side direction of the card substrate using a counter magnet or a solenoid.

Next, using a Nd: YAG laser beam, a dot-shaped concave portion was formed in the hard magnetic layer by a laser pulse under the following conditions as shown in FIG.

Conditions for forming dot-shaped concave portions Laser output: 20 W Laser spot diameter: 60 μm (circular) Pulse frequency: 20 kHz, 10 kHz The formed dot-shaped concave portions have an average depth of 6 μm. Are formed of two types, a high-density concave portion having a dot-shaped concave portion forming pitch of 120 μm and a low-density concave portion having a dot-shaped concave portion forming pitch of 240 μm. By arranging a plurality of concave portions in the scanning direction of the magnetic head (longer side direction of the card substrate) above, a region A1 composed of concave portions having a high density of dot-shaped concave portions and an area A2 composed of concave portions having a low density of the dot-shaped concave portions are formed. Fixed magnetic information (recording density about 210b
pi) was recorded to produce a magnetic recording medium as shown in FIGS.

Further, a coating for a concealing layer having the following composition was applied by gravure coating on the magnetic layer having the concave portions to form a concealing layer having a thickness of 5 μm.

Composition of coating material for concealing layer : micro silica: 10.5 parts by weight; titanium oxide powder: 10.5 parts by weight; polyurethane resin: 4 parts by weight; methyl ethyl ketone: 50 parts by weight; toluene: 25 parts by weight As a result of reading the fixed magnetic information of the magnetic recording medium manufactured as described above using a card reader, a magnetic output waveform as shown in FIG. 6 was obtained, and the magnetic output in the area A1 was 4 V (pp). And the magnetic output in the region A2 was 2 V (pp). This fixed magnetic information can be used as magnetic information that cannot be magnetically erased, like a conventional magnetic barcode or the like. (Example 2) First, a hard magnetic layer having a thickness of 10 µm was formed on a card substrate in the same manner as in Example 1. In the formation of the hard magnetic layer, a magnetic orientation treatment was performed along the long side direction of the card substrate using a counter magnet or a solenoid.

Then, using a Nd: YAG laser beam, a dot-like concave portion was formed in the hard magnetic layer by a laser pulse under the following conditions as shown in FIG.

Conditions for forming dot-shaped concave portions Laser output: 20 W Laser spot diameter: 60 μm (circular) Pulse frequency: 30 kHz, 20 kHz, 10 kHz The formed dot-shaped concave portions have an average depth of 6 μm. The concave portion composed of a group of the concave portions is a high-density concave portion having a dot pitch of 80 μm.
There are three types of concave portions having a dot-shaped concave portion forming pitch of 240 μm and low density, and a concave portion having a dot-shaped concave portion forming pitch of 160 μm and medium density. Such concave portions are formed on the magnetic layer in the scanning direction of the magnetic head ( By arranging a plurality of dots in the direction of the long side of the card substrate), the area A1 composed of concaves having a high density of dot-shaped concaves, the area A2 composed of concaves having a medium density of the dot-shaped concaves, and the density of the dot-shaped concaves Fixed magnetic information (recording density: about 210 bpi) having an area A3 having a low concave portion was recorded to produce a magnetic recording medium as shown in FIG.

Further, a concealing layer having a thickness of 5 μm was formed on the formed hard magnetic layer in the same manner as in Example 1.

As a result of reading the fixed magnetic information of the magnetic recording medium manufactured as described above using the same card reader as in the first embodiment, a magnetic output waveform as shown in FIG. The magnetic output is 6V (p-
p), the magnetic output in the region A2 was 4 V (pp), and the magnetic output in the region A3 was 2 V (pp). This fixed magnetic information can be used as magnetic information that cannot be magnetically erased, like a conventional magnetic barcode or the like. Example 3 A card substrate made of polyethylene terephthalate having a thickness of 250 μm was prepared as a substrate, and Nd: YAG
As shown in FIG. 5, dot-shaped minute concave portions were formed by a laser pulse using a laser beam under the following conditions. The dot-shaped minute concave portions formed in a direction orthogonal to the long side direction of the card substrate have a row having an average depth of 10 μm and a formation pitch of 120 μm, and an average depth of 10 μm and a formation pitch of 2 μm.
40 μm rows.

Conditions for forming dot-shaped concave portions Laser output: 20 W Laser spot diameter: 60 μm (circular) Pulse frequency: 20 kHz, 10 kHz Next, the same magnetic coating material A for the hard magnetic layer as used in Example 1 A hard magnetic layer having a thickness of 10 μm was formed by gravure coating on the card substrate on which the dot-shaped minute concave portions were formed. As a result, on the card substrate side of the hard magnetic layer, dot-shaped protrusions corresponding to the above-mentioned dot-shaped minute recesses are formed. Part formation pitch is 120
There were two types of protrusions: a high-density convex portion having a thickness of μm, and a low-density convex portion having a dot pitch of 240 μm. And
By arranging a plurality of such protrusions in the scanning direction of the magnetic head (the long side direction of the card substrate), an area A1 composed of high-density dot-shaped depressions and a low-density dot-shaped depression are formed. The fixed magnetic information having the area A2 (recording density: about 210 bpi) was recorded to produce a magnetic recording medium as shown in FIGS. In the formation of the hard magnetic layer, a magnetic orientation treatment was performed along the long side direction of the card substrate using a counter magnet or a solenoid.

Further, a concealing layer having a thickness of 5 μm was formed on the formed hard magnetic layer in the same manner as in Example 1.

As a result of reading the fixed magnetic information of the magnetic recording medium manufactured as described above using the same card reader as in the first embodiment, a magnetic output waveform as shown in FIG. The magnetic output is 3.6V (p-
p), the magnetic output in the region A2 is 1.8 V (pp)
Met. This fixed magnetic information can be used as magnetic information that cannot be magnetically erased, like a conventional magnetic barcode or the like. Example 4 First, a hard magnetic layer having a thickness of 15 μm was formed on a card substrate in the same manner as in Example 1. In the formation of the hard magnetic layer, a magnetic orientation treatment was performed along the long side direction of the card substrate using a counter magnet or a solenoid.

Next, a magnetic coating material B for a soft magnetic layer having the following composition was applied onto the hard magnetic layer by gravure coating to give a thickness of 1%.
A 0 μm soft magnetic layer was formed. In the formation of this soft magnetic layer, no magnetic orientation treatment was performed.

Composition of magnetic paint B : Permalloy powder: 41 parts by weight Polyurethane resin: 7 parts by weight Methyl ethyl ketone: 25 parts by weight Toluene: 25 parts by weight Isocyanate-based curing agent: 2 parts by weight Next, an Nd: YAG laser Using light, a dot-shaped concave portion was formed in the soft magnetic layer by a laser pulse under the following conditions as shown in FIG.

Conditions for forming dot-shaped concave portions Laser output: 20 W Laser spot diameter: 60 μm (circular) Pulse frequency: 20 kHz, 10 kHz The formed dot-shaped concave portions have an average depth of 5 μm. The two types of recesses were composed of a high-density recess having a dot-shaped recess forming pitch of 120 μm and a low-density recess having a dot-forming recess forming pitch of 240 μm. By arranging a plurality of such recesses on the soft magnetic layer in the scanning direction of the magnetic head (longer side direction of the card substrate), an area A1 consisting of a high density of dot-like recesses and a dot-like recess are formed. Fixed magnetic information (recording density: about 210 bpi) having an area A2 composed of a low-density concave portion was recorded to produce a magnetic recording medium as shown in FIGS.

Further, a concealing layer having a thickness of 5 μm was formed on the formed soft magnetic layer in the same manner as in Example 1.

As a result of reading the fixed magnetic information of the magnetic recording medium manufactured as described above using a card reader (reproduction bias current = 100 mA DC), a magnetic output waveform as shown in FIG. 6 was obtained. The magnetic output in A1 was 5 V (pp), and the magnetic output in region A2 was 2.5 V (pp). This fixed magnetic information can be used as magnetic information that cannot be magnetically erased, like a conventional magnetic barcode or the like. Example 5 First, a hard magnetic layer having a thickness of 15 μm was formed on a card substrate in the same manner as in Example 1. In the formation of the hard magnetic layer, a magnetic orientation treatment was performed along the long side direction of the card substrate using a counter magnet or a solenoid.

Next, dot-shaped concave portions were formed in the hard magnetic layer in the same manner as in Example 1 using Nd: YAG laser light.

Next, a paint for a nonmagnetic material layer having the following composition was prepared.

Composition of paint for nonmagnetic material layer Polyurethane resin: 16 parts by weight Methyl ethyl ketone: 40 parts by weight Toluene: 40 parts by weight Isocyanate-based curing agent: 4 parts by weight A non-magnetic material layer having a thickness of 5 μm was formed on the magnetic layer by gravure coating.

Next, a soft magnetic layer having a thickness of 10 μm was formed on the nonmagnetic material layer by gravure coating using the magnetic paint B for a soft magnetic layer used in Example 4. As a result, two types of recesses are formed on the non-magnetic material layer side of the hard magnetic layer, that is, a recess having a high density with a dot pitch of 120 μm and a recess having a low density with a dot pitch of 240 μm. By arranging a plurality of such two types of recesses in the scanning direction of the magnetic head (the long side direction of the card substrate), the area A1 composed of the recesses having a high density of dot-like recesses and the density of the dot-like recesses are formed. A composed of a concave part having a low height
2 (fixed magnetic information having a recording density of about 210 bpi)
Was recorded to produce a magnetic recording medium as shown in FIGS.

Further, a concealing layer having a thickness of 5 μm was formed on the formed soft magnetic layer in the same manner as in Example 1.

As a result of reading the fixed magnetic information of the magnetic recording medium manufactured as described above using the same card reader as in the first embodiment, a magnetic output waveform as shown in FIG. The magnetic output is 2.8V (p-
p), the magnetic output in the region A2 is 1.4 V (pp)
Met. This fixed magnetic information can be used as magnetic information that cannot be magnetically erased, like a conventional magnetic barcode or the like.

[0093]

As described above in detail, in the magnetic recording medium of the present invention, the magnetic layer formed on the substrate is provided with a plurality of fine concave portions or dot-shaped convex portions which are a set of dot-shaped concave portions. A plurality of fine projections as a set are arranged along the scanning direction of the magnetic head, and the above-mentioned depressions and projections have two or more types of depressions having different densities of dot-like depressions or dot-like projections. Since the fixed magnetic information is recorded on the magnetic layer so that the convex portions exist, a magnetic output signal is obtained from the fixed magnetic information when the magnetic head is scanned over the magnetic layer, and
Since this magnetic output signal indicates an output corresponding to the density of the dot-shaped concave portion or the dot-shaped convex portion, the magnetic output signal of the magnetic recording medium depends on whether a magnetic output signal having a predetermined output pattern from the fixed magnetic information is obtained. The authenticity can be reliably determined, the alteration of the magnetic recording medium is made extremely difficult, and the above-mentioned dot-shaped concave portions and dot-shaped convex portions are obtained by physically removing the magnetic layer or the substrate partially. By forming the magnetic recording medium, it is easy to control the magnetic output waveform by changing the shape, density, etc. of the dot-shaped concave portions and the dot-shaped convex portions. Fixed magnetic information can be recorded, and even if the recording density is increased, a stable magnetic output waveform can be obtained, and the recording density can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a card-shaped magnetic recording medium for describing an embodiment of the present invention.

FIG. 2 is a partially enlarged plan view of a recording portion of a magnetic layer in the magnetic recording medium shown in FIG.

FIG. 3 is an enlarged cross-sectional view taken along line AA of a recording portion of the magnetic layer shown in FIG. 2;

FIG. 4 is a diagram illustrating a format example of a digital signal of 1, 0;

FIG. 5 is a diagram showing an example of forming dot-shaped concave portions using a pulse laser.

FIG. 6 is a diagram specifically illustrating an example for detecting a signal.

FIG. 7 is a partially enlarged plan view of a recording portion of a magnetic layer in a magnetic recording medium according to another embodiment of the present invention.

FIG. 8 is a diagram for explaining specific signal detection in the embodiment shown in FIG. 7;

FIG. 9 is a partially enlarged plan view of a recording portion of a magnetic layer in a magnetic recording medium according to another embodiment of the present invention.

FIG. 10 is a view for explaining specific signal detection in the embodiment shown in FIG. 9;

FIG. 11 is a plan view showing an example of the arrangement of dot-shaped recesses constituting the magnetic recording medium of the present invention.

FIG. 12 is a diagram for explaining another embodiment of the present invention.

FIG. 13 is a diagram for explaining another embodiment of the present invention.

FIG. 14 is a diagram for explaining another embodiment of the present invention.

[Explanation of symbols]

 1, 11, 21, 31 ... magnetic recording medium 2, 12, 22, 32 ... substrate 3, 13, 23, 33 ... magnetic layer 5 (5a, 5b, 5c), 25, 35 ... concave portion 6, 26, 36 ... Dot-shaped concave portion 17: convex portion 18: dot-shaped convex portion

Claims (10)

[Claims] 1. A magnetic recording medium comprising at least a substrate and a magnetic layer formed on the substrate, wherein the magnetic layer comprises a plurality of fine magnetic layers arranged along a scanning direction of a magnetic head. Fixed magnetic information consisting of a concave portion or a convex portion is recorded, and each of the concave portions is a set of dot-shaped concave portions formed in the magnetic layer so as to be substantially orthogonal to the scanning direction of the magnetic head. Has two or more types of concave portions having different densities of the dot-shaped concave portions,
Each of the protrusions is a set of dot-like protrusions formed on the magnetic layer so as to be substantially orthogonal to the scanning direction of the magnetic head, and the protrusions have two different dot-like protrusion densities. A magnetic recording medium characterized by having the above-mentioned projections. 2. The fixed magnetic information includes a region formed by a plurality of concave portions having the same density of the dot-shaped concave portions or a plurality of convex portions having the same density of the dot-shaped convex portions of the convex portions. 2. The magnetic recording medium according to claim 1, wherein two or more types are present. 3. The magnetic layer has a multilayer structure including at least two types of magnetic layers having different magnetic characteristics, and one of the layers constituting the magnetic layer includes a plurality of fine concaves or convexes. The magnetic recording medium according to claim 1, wherein fixed magnetic information is recorded. 4. The dot-shaped concave portions are formed by partially physically removing the surface of the magnetic layer, and the dot-shaped convex portions are partially physically removed in advance to form dot-shaped minute portions. 2. The semiconductor device according to claim 1, wherein said magnetic layer is formed on said substrate having a concave portion.
The magnetic recording medium according to claim 3. 5. The dot-shaped convex portion is formed by partially physically removing a magnetic layer provided on the substrate to form a dot-shaped minute concave portion, and further providing a magnetic layer thereon. 4. The magnetic recording medium according to claim 3, wherein: 6. The magnetic recording medium according to claim 1, wherein an opening width of the dot-shaped concave portion and a maximum width of the dot-shaped convex portion are in a range of 30 to 1000 μm. . 7. The magnetic recording medium according to claim 1, wherein a formation pitch of the dot-shaped concave portions and a formation pitch of the dot-shaped convex portions are in a range of 1 μm to 5 mm. . 8. The magnetic recording medium according to claim 1, wherein the depth of the dot-shaped concave portions and the height of the dot-shaped convex portions are in a range of 2 to 30 μm. . 9. The magnetic recording medium according to claim 1, wherein a pitch at which the concave portions are formed and a pitch at which the convex portions are formed are 30 μm or more. 10. The magnetic recording medium according to claim 1, wherein a concealing layer is formed on the magnetic layer.