JP3456232B2 - Magnetic recording medium and reading method thereof - Google Patents

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 having a magnetic pattern composed of magnetic portions made of different magnetic materials, and more particularly to a magnetic recording medium having a magnetic pattern containing information data and authenticity determination data. And its reading method.

[0002]

2. Description of the Related Art Magnetic recording media that have become popular in recent years include credit cards, cash cards, prepaid cards, commuter passes, coupon tickets, admission tickets, etc. In addition to the magnetic data recording section for recording the information, a bar code type identification pattern is provided as another magnetic recording for identifying a regular magnetic recording medium and a specific magnetic recording medium. There is. An example of this identification pattern is a combination of only a magnetic part using magnetic ink, or one or more magnetic parts using magnetic ink and non-magnetic parts using non-magnetic ink in a predetermined arrangement. Therefore, the information data is formed by associating the magnetic portion with “1” and the non-magnetic portion with “0”. This is scanned by a magnetic sensor, the magnetic output is detected, and the data is read. In particular, in the latter, although it is impossible to identify the appearance, it is possible to prevent fraud by a third party because the information data can be obtained by reading the magnetic output. However, this method has a drawback that the safety is not so high because the magnetism can be easily read.

Therefore, as a magnetic bar code composed of a magnetic portion made of a special magnetic material for the purpose of preventing forgery, JP-A-4-318322 and JP-A-4-318323 are available.
As disclosed in Japanese Patent Application Laid-Open No. 4-321926, etc., there is one in which a magnetic portion made of a soft magnetic material of 60 Oe or less having two different magnetic saturation characteristics is provided in a predetermined pattern. The value of the magnetic part can be obtained according to the strength of the magnetic field. By changing the bias current applied to the magnetic head used for reading, even if the arrangement pattern of the magnetic part is the same, two types of output can be obtained. It has been proposed as a high-security system with a large amount of information that can obtain signals.

[0004]

However, a magnetic recording medium having a bar code provided with a magnetic portion made of a soft magnetic material having two different magnetic saturation characteristics as described above is a magnetic recording medium for reading attached to a reading device. Two different bias currents are applied to the magnetic head to obtain an output waveform, and this is measured.Therefore, the bias current value may vary depending on the reading device, and there is a problem that stability is poor and reading reliability is poor. In addition, since a large bias current needs to be passed through the magnetic head to increase the output difference, there is a problem that the reading device is burdened.

Therefore, according to the present invention, two data, for example, authenticity determination data and information data, can be easily read from the magnetic output difference between the magnetic parts made of two different magnetic materials, and the reading device can be simplified. An object of the present invention is to provide a magnetic recording medium and a method of reading the same.

[0006]

The present invention has been made to achieve the above object. The invention of claim 1 is a magnetic part made of a needle-shaped crystalline magnetic material, and a shape magnetic anisotropy other than the needle-shaped crystals. Has a weak coercive force and is as young as a needle-shaped crystalline magnetic material
Indicates a close value, but the magnetic output level with and without an external magnetic field
Is a magnetic recording medium characterized by comprising forming a magnetic portion made of different magnetic materials, the magnetic pattern composed on the substrate surface.

According to the second aspect of the invention, the coercive force of the magnetic material is 6
It is a magnetic recording medium characterized by being 0 Oe or more.

According to a third aspect of the present invention, there is provided a magnetic recording medium characterized in that the magnetic pattern has a bar code shape.

According to a fourth aspect of the invention, there is provided a magnetic recording medium comprising a magnetic recording layer provided between the magnetic pattern and the base material.

According to a fifth aspect of the present invention, there is provided a magnetic recording medium characterized in that a magnetic pattern is provided with a dummy portion from which a magnetic read output cannot be obtained.

A sixth aspect of the present invention is the magnetic recording medium, wherein the magnetic pattern is oriented in the card moving direction by an external magnetic field having a coercive force twice or more.

According to a seventh aspect of the invention, there is provided a magnetic recording medium characterized in that a concealing layer is provided on the magnetic pattern.

An eighth aspect of the present invention is a magnetic recording medium characterized in that a protective layer is provided on the magnetic pattern.

According to a ninth aspect of the present invention, there is provided a magnetic structure comprising a magnetic portion made of a needle-shaped crystalline magnetic material on a surface of a base material and a magnetic portion made of a magnetic material having a weak shape magnetic anisotropy other than needle-shaped crystals. Read the pattern while applying an external magnetic field of a predetermined intensity,
In addition, it is a method for reading an information recording medium, which is characterized by reading the residual magnetization without applying an external magnetic field.

[0015]

According to the present invention, a magnetic portion composed of a needle-shaped crystal magnetic material provided on a substrate and a magnetic portion made of a magnetic material other than needle-shaped crystals having a weak shape magnetic anisotropy is used. The output signal from the magnetic part by a magnetic sensor such as a magnetic head in the state where an external magnetic field is generated by applying a DC bias current to the pattern and the magnetic signal by the magnetic sensor such as a magnetic head in the absence of the external magnetic field. An output signal from the residual magnetic flux can be obtained, and two pieces of information recorded in the same pattern can be obtained separately.

The magnetic recording medium reading method of the present invention, as described above, detects the magnetic output of each magnetic portion depending on the presence or absence of the external magnetic field at the time of reading, and extracts each signal from the difference in the magnetic output, Two types of information can be obtained separately.

[0017]

The present invention will be described in detail below with reference to the drawings.
1 is a plan view of a magnetic recording medium of the present invention, FIG. 2 is a sectional view taken along line XX of the magnetic recording medium of FIG. 1, and FIG. 3 is a plan view of a magnetic recording medium of another embodiment. 4 is a cross-sectional view of the magnetic recording medium of FIG. 3 taken along line YY,
FIG. 5 is a sectional view of a magnetic recording medium of another embodiment.
8 is a hysteresis loop showing the electrostatic characteristic of the magnetic material used in the magnetic recording medium of the present invention, FIG. 7 is a hysteresis loop showing the relationship between the bias current and the reproduction output voltage of the magnetic recording medium of the present invention, and FIG. FIG. 9 is a schematic diagram showing a reading device for reading information on the magnetic recording medium of the present invention, and FIG. 9 is a waveform showing an output waveform when a DC bias current is applied to the magnetic recording medium of the present invention and an external magnetic field is applied. FIG. 10 is a waveform diagram showing a residual magnetic flux output waveform in a state in which an external magnetic field is not applied to the magnetic recording medium of the present invention.

As shown in FIG. 1, a magnetic pattern is formed on the base material of the magnetic recording medium 1, and this magnetic pattern is composed of a magnetic portion consisting of a rectangular bar. As shown in the cross-sectional view of the magnetic recording medium 1 of the present invention in FIG. 2, a magnetic recording layer 3 composed of a magnetic pattern 10 and a protective layer 4 are sequentially laminated on a base material 2, and the magnetic recording layer 3 is magnetically formed as necessary. The magnetic recording layer 3 is a concealment layer 6 that conceals the data recording layer 5 and the magnetic recording layer 3.
And the protective layer 4 can be provided.

The substrate 1 is made of polyvinyl chloride, polyester,
It is possible to use synthetic resins such as polycarbonate, polymethyl methacrylate, polystyrene, and polyethylene terephthalate, natural resins, paper, synthetic paper, metal, ceramics, etc., alone or in combination as a composite. Further, the shape can be selected according to the application such as a card shape or a sheet shape, a film shape, and further considering the physical properties required according to the application, such as strength, rigidity, hiding power, light opacity, etc., the above material Can be selected as appropriate.

The magnetic recording layer 3 has magnetic portions 7 and 8 made of two different magnetic materials as rectangular bars arranged so as to represent a preset signal.
0 is formed. In this embodiment, the magnetic parts 7 and 8 are in the form of a bar code composed of a rectangular bar, but the shape may be another pattern shape such as a round shape or a triangular shape, or a character or a mark. It is also possible to have different forms of magnetic patterns.

Here, the magnetic portion 7 is made of a needle-shaped crystal magnetic material, and the magnetic portion 8 is made of a magnetic material having a weak shape magnetic anisotropy other than needle-shaped crystals. That is, the basic principle of the present invention is, as shown in FIG. 6, the shape of the magnetic material A made of needle crystals and the magnetic material B other than the magnetic material B such as spherical or polyhedral, the strength of magnetic anisotropy, or By utilizing the difference in the magnetostatic characteristic BH curve caused by the difference in the squareness ratio δr / δs, even if the magnetic material has the same or close coercive force, the magnetic output level greatly differs depending on the presence or absence of the external magnetic field.
By reading this magnetic output, it is possible to identify and obtain each information.

More specifically, in the examples of the present invention, the coercive force is a magnetic material having a coercive force of 60 Oe or more, and the acicular crystal magnetic material has a squareness ratio δr / δs of 0 due to shape anisotropy even if it is unoriented. Approximately 0.4, a hard magnetic material having poor shape anisotropy, such as a spherical or polyhedron other than acicular crystals, or an amorphous shape, has a squareness ratio δr / δs of 0.1.
It is about 0.2. The magnetic material A in FIG. 6 has a coercive force of 250.
Oe acicular crystal magnetic substance γ-hematite, magnetic material B
Is a spherical crystal magnet magnetite with a coercive force of 250 Oe. The magnetic materials A and B have almost the same coercive force, and when the saturation magnetic flux densities Bm are made equal, the initial magnetization curves are also almost equal, but the magnetic field is gradually weakened.
The value of the magnetic flux density, that is, the residual magnetic flux density is greatly different, and the magnetic material A is larger than the magnetic material B.

This difference in the magnetostatic characteristics also appears in the hysteresis of the magnetic output when a DC bias current is applied and the external magnetic field is not applied, as shown in FIG. Therefore, the reproduction output voltage of the magnetic material A is higher than that of the magnetic material B especially when no external magnetic field is applied, so that the magnetic material having two different magnetic characteristics depending on the presence or absence of the external magnetic field is used. The magnetic part is different in magnetic output.

The magnetic recording medium of the present invention is arranged on the base material based on the information recorded by using the magnetic material having the magnetic output difference in each magnetic portion. The magnetic portion 7 on the magnetic recording layer 3 is made of the magnetic material A, and the magnetic portion 8 is made of the magnetic material B.

Specifically, the magnetic material A is 60 Oe or more.
The needle-shaped hard magnetic material is γ-hematite (γ-Fe).
₂O₃), Cobalt deposition-γ-hematite (Co-γ-
Fe ₂O₃), Various hard ferrites, magnetite, etc.
(Fe₃O_Four), Chromium dioxide (CrO₂) And Fe,
Metals or alloys such as Co and Fe-Co can be used.
It is more preferable that the form ratio δr / δs> 0.4. Well
In addition, spherical or polyhedron other than acicular crystals, or amorphous
For hard magnetic materials with poor shape anisotropy such as
Cubic magnetite (Fe ₃O_Four),
It is possible to use the above-mentioned various acicular crystalline materials that have been pulverized.
it can.

These magnetic materials are mixed with a binder to form a magnetic ink, and the magnetic ink is applied or printed on a forming surface such as a base material. The binder is a resin solution such as butyral resin, vinyl resin, vinyl chloride / vinyl acetate copolymer resin, urethane resin, polyester resin, cellulose resin, acrylic resin, styrene / maleic acid copolymer resin alkyd resin, alone or in a mixture. Consists of. In addition, a surfactant, a colorant, a stabilizer and the like are added to the magnetic ink as needed. The magnetic portions 7 and 8 are formed by appropriately selecting from the printing methods such as the offset printing method, the gravure printing method and the screen printing method using the above magnetic ink.

The protective layer 4 protects the magnetic portions 7 and 8 constituting the magnetic recording layer 3 against external rubbing and scratches. For example, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, starch, styrene- Maleic acid copolymers, homopolymers or copolymers of methacrylic resins such as polymethylmethacrylate / polyethylmethacrylate, polystyrene, acrylic-styrene copolymers, acrylic resins, polyester resins, chroman resins, ABS resins, nitrocellulose, etc. Resin or fluorine resin, resin mixed with silicon resin as it is or dissolved or dispersed in a solvent such as toluene or xylene, spin coating method, roll coating method, knife edge method, offset printing method, gravure Printing method, screen printing method, etc. And printing method using a thickness 1-5
The protective layer 4 is formed to a thickness of about μm. In addition, a thermosetting resin, an ultraviolet curable resin, a curable resin such as an electron beam curable resin,
Alternatively, it is possible to use an ink.

A concealing layer 6 may be provided on the magnetic recording layer 3 for concealing the magnetic recording layer 3 so that it cannot be seen, and it is usually formed between the magnetic recording layer 3 and the protective layer 4.
The hiding layer 6 is made of an ink having a high hiding property, such as Ag, Cr,
An ink in which a non-magnetic metal powder such as Al, Zn, Sn, Pb, Cu, Bi, Ge and In is dispersed in a binder solution,
Alternatively, spin coating method, roll coating method, knife edge method, offset printing method, gravure printing method, screen printing method, etc. are applied to a predetermined film thickness using an ink made of black or white inorganic pigment such as carbon black or titanium dioxide. -It is formed by the printing method.

As shown in FIGS. 3 and 4, the magnetic recording layer 3 of the magnetic recording medium 1 of the present invention can be provided at an arbitrary position and size such as a part or the whole surface of the substrate 2. It is possible to appropriately set the arrangement position and size according to the intended use.

Further, the magnetic recording medium of the present invention can be provided with a magnetic data recording layer 5 for information recording as shown in FIG. This is normally used for magnetic recording media such as magnetic cards and magnetic recording sheets.
o, Ni, γ-Fe ₂ O ₃ , Co deposited γ-Fe ₂ O ₃ ,
_{Fe 3 O 4, Fe-Cr} , Fe-Co, CrO 2, Co
-Cr, Co-Ni, MnAl, Ba ferrite, Sr
Fine particles made of known magnetic material such as ferrite are appropriately used, for example, butyral resin, vinyl chloride / vinyl acetate copolymer resin, urethane resin, polyester resin, cellulose resin, acrylic resin, styrene / maleic acid copolymer resin, etc. A resin or a mixture prepared by dispersing and mixing in an ink vehicle is formed as a magnetic ink on the base material 2 by a well-known roll coating method, knife edge method, gravure printing method, screen printing method or the like. The magnetic data recording layer 5 can be provided at an arbitrary position and size such as a part or the entire surface of the base material 2.

Further, in the information recording method of the magnetic recording medium of the present invention, the first information which is readable by applying a bias current and applying an external magnetic field and the second information which is readable by residual magnetization without applying an external magnetic field. There are two pieces of information, and the magnetic material forming the magnetic part 7 and the magnetic part 8 is 60 Oe, respectively.
A needle-shaped crystal magnetic material having the above coercive force and a spherical or polyhedral body other than the needle-shaped crystals having a coercive force of 60 Oe or more;
Alternatively, a magnetic material having a poor shape anisotropy such as an amorphous shape is used, and the first information is composed of the magnetic parts 7 and 8, and the second information is arranged so as to be composed of the magnetic part 8. The magnetic pattern 10 is formed.

Further, in the magnetic recording layer 3, a dummy part 9 made of a non-magnetic material may be provided at the same position as the magnetic parts 7 and 8. According to this, since the dummy part 9 has no magnetic output, the magnetic pattern 10 including the magnetic part 7 and the magnetic part 8 is formed.
It is possible to make it difficult to visually identify the magnetic pattern 10 without affecting the reading of information from the
Anti-counterfeiting effect can be obtained.

Next, a method of reading the magnetic recording medium of the present invention will be described. To read information from the magnetic recording layer 3,
As shown in FIG. 8, a magnetic sensor 11 such as a magnetic head, a Hall element, a magnetoresistive element or the like is brought into contact with the magnetic pattern 10 formed in a bar code shape as described above, and the magnetic recording layer 3
While sliding up, the magnetic output is obtained from the magnetic recording medium as an electrical output. That is, it is also a conversion element that converts a magnetic output into an electric output. A bias DC current circuit 12 for applying a DC external magnetic field to the magnetic recording layer 3 is connected to the magnetic sensor 11, and a bias current is applied when the magnetic recording layer 3 is read to apply the external magnetic field. It is possible to obtain the data I and the data II when the bias current is not applied and the external magnetic field is not applied. FIG. 9 shows data I in a state in which a DC bias current is applied and an external magnetic field is applied.
The output waveform of the data II is shown in FIG. 10, and the output waveform of the data II is shown in FIG. The waveform of the portion corresponding to the magnetic portion 8 in the state in which the external magnetic field is not applied is smaller than the waveform in the state in which the external magnetic field is applied. In this embodiment, as shown in data I, the magnetic portions 7 and 8 are adjusted so that the magnetic portions 7 and 8 have substantially the same magnetic output in the state where a bias current is applied and an external magnetic field is applied. Therefore, it is also possible to match the data II so that they have almost the same magnetic output.
In the data I and data II, a portion where no magnetic output exists is the dummy portion 9 made of a nonmagnetic material. Further, the magnetic field in the case of applying an external magnetic field to the magnetic recording layer 3 may be a value equal to or higher than the coercive force of the magnetic material, but preferably an external magnetic field of twice the coercive force or more is applied to perform stable magnetic reading. be able to.

Further, an arithmetic circuit 13 is connected to the magnetic sensor 11, and the obtained magnetic output is input to the arithmetic circuit 13. The arithmetic circuit 13 displays the read data 14 or the magnetic process before and after the data II by the arithmetic processing. The difference between the outputs may be taken to determine the type of the magnetic portion, and the data I may be calculated to extract only the necessary information 15. Still other recorded information means, such as OCR information, optical bar code information,
Two-dimensional code information such as Carla code, hologram information,
The authenticity determination 16 may be performed by reading collation data from magnetic recording information or the recording information recorded in a reading device (not shown) and comparing and collating the data.

When the magnetic recording layer 3 of the magnetic recording medium 1 is preliminarily applied with an external magnetic field at least twice the coercive force of the magnetic substance at the time of printing to orient it in the running direction of the magnetic medium 1, that is, the reading direction, it remains. Since the magnetic flux density becomes high, it is possible to easily obtain the magnetic output difference in reading when no bias current is applied.

Further, the magnetic parts 7, 8 of the magnetic recording medium of the present invention.
Has set the magnetic part so that the read output is matched when there is a bias current, but the magnetic part may be matched to the read output when there is no bias current as in the third embodiment. In that case, When a bias current is applied, the output value of the magnetic part made of a magnetic material with a weak shape anisotropy, such as a spherical or polyhedron other than the needle-shaped crystal, or an amorphous shape, is greater than the output value of the magnetic part made of the needle-shaped crystal magnetic material. Also grows.

Specific examples of the present invention will be given below.
The details will be described.

<Example 1> On a synthetic paper (Yupo manufactured by Oji Yuka Co., Ltd.) having a thickness of 200 μm, a magnetic ink A having the following composition was applied by a screen printing method using a Tetoron 250 line plate to give a thickness of 0.5 mm. The magnetic part 7 is 5μ as a width magnetic bar.
Printed to a thickness of m. Magnetic ink A 350 Oe γ-Fe ₂ O ₃ MX450 50 parts by weight (δr / δs = 0.46 manufactured by Toda Kogyo Co., Ltd.) Polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.) 30 parts by weight Cyclohexanone 40 parts by weight Butylcellsolve 20 parts by weight

Next, a magnetic ink B having the following composition was printed by a screen printing method using a Tetoron 250 line plate to form a magnetic portion 8 as a magnetic bar having a width of 0.5 mm in a thickness of 5 μm. Magnetic ink B 350 Oe Cubic type Fe ₃ O ₄ TMB300 50 parts by weight (Toda Kogyo δr / δs = 0.26) Polyester resin (Toyobo Co., Ltd. Byron 200) 30 parts by weight Cyclohexanone 40 parts butyl cellosolve 20 parts by weight In addition, UV STP ink (T & K
TOKA) and UV L Carton OP varnish (manufactured by T & K TOKA) as a protective layer ink were sequentially subjected to offset printing to provide a concealing layer 6 and a protective layer 4 to prepare the magnetic recording medium 1 of FIG.

Example 2 The magnetic part 7 of Example 1 was oriented in the running direction of the magnetic recording medium with an external magnetic field of 1000 gauss before printing and drying. Thereafter, as in Example 1, the magnetic part 8 and the concealing layer were formed. 6, the protective layer 4 was provided, and the magnetic recording medium was produced.

Example 3 White PE having a thickness of 188 μm
A magnetic coating material having the following composition was provided on T (U2W manufactured by Teijin Ltd.) by a gravure method so as to have a film thickness after drying of 10 μm, thereby forming a magnetic data recording layer 5. Magnetic coating 1750 Oe BaO · 6Fe ₂ O ₃ H-1000 (manufactured by Dowa Mining Co., Ltd.) 100 parts by weight Vinyl chloride-vinyl acetate copolymer VAGF (manufactured by UCC) 15 parts by weight Polyurethane resin Nipporan 2301 (manufactured by Nippon Polyurethane Co., Ltd.) 30 Parts by weight toluene 40 parts by weight methyl ethyl ketone 40 parts by weight methyl isobutyl ketone 10 parts by weight

A magnetic ink A having the following composition was formed on the magnetic data recording layer 5 by a screen printing method using a plate of Tetron 250 lines to form a magnetic bar having a width of 0.5 mm and a magnetic portion 7 having a thickness of 5 μm. It was printed and formed. Magnetic ink A 260 Oe γ-Fe ₂ O ₃ HR280 50 parts by weight (Magnox Co., Ltd. δr / δs = 0.54) Polyester resin (Toyobo Co., Ltd. Byron 200) 30 parts by weight Cyclohexanone 40 parts by weight Butylcellsolve 20 parts by weight

Next, magnetic ink B having the following composition was printed by a screen printing method using a Tetoron 250 line plate to form a magnetic portion 8 as a magnetic bar having a width of 0.5 mm in a thickness of 5 μm. Magnetic ink B 230 Oe Spherical Fe ₃ O ₄ MAT222 100 parts by weight (δr / δs = 0.22 manufactured by Toda Kogyo Co., Ltd.) Polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.) 30 parts by weight Cyclohexanone 40 parts by weight Butylcellsolve 20 parts by weight

Next, as an ink for the dummy bar made of a non-magnetic material, SS6K mat 911 black was screen-printed using a Tetoron 250 line plate to a thickness of 5 μm.
The dummy portions 9 are provided in the same line as the magnetic portions 7 and 8 so as to have the same thickness, so that it is difficult to discriminate them from the ink amount and the surface shape. Further, a silver ink having the following composition as a hiding layer ink was printed on the upper surface of the hiding layer 6 to a thickness of 3 μm by a screen printing method using a 350-line plate, and UV L carton O was used as a hiding layer ink.
Offset printing of P varnish (made by T & K TOKA),
By providing the protective layer 4, the magnetic recording medium of FIG. 5 was manufactured.

Table 1 shows the results of the magnetic outputs and the output ratios of the magnetic recording media of Examples 1 to 3 when a DC bias current was applied and an external magnetic field was applied and an external magnetic field was not applied. .

[0046]

[Table 1]

The magnetic recording medium of Example 1 had an output ratio of 2. when the residual magnetic flux was read without a bias current.
Since it is 16, there is a sufficient output difference, and it is possible to determine the type of the magnetic part. In the magnetic recording medium of Example 2, the magnetic part made of the acicular crystalline magnetic material has a coercive force of 2 to
By orienting by applying a magnetic field for orientation of about 3 times, a larger output difference can be obtained. The output ratio is 3.56, and it is easy to determine the type of magnetic part.

The magnetic recording medium of Example 3 has a combined magnetic output when the residual magnetic flux is read without a bias current. In this case, a bias current is applied and an external magnetic field is applied. Magnetic portion 7 made of a magnetic material having a weak shape anisotropy other than needle crystals, which causes a difference in magnetic output.
The output of becomes larger. The output ratio in this embodiment is 1.
95, which is sufficient to identify the magnetic part.

[0049]

The magnetic recording medium and the method for reading the magnetic recording medium according to the present invention include a magnetic portion made of a needle-shaped crystalline magnetic material provided on a substrate, and a magnetic material having a shape magnetic anisotropy other than the needle-shaped crystals. When an external magnetic field is generated by applying a DC bias current to a magnetic pattern composed of a magnetic part made of a material, the output signal from the magnetic part by a magnetic sensor such as a magnetic head and the state without an external magnetic field An output signal from the residual magnetic flux of the magnetic part by a magnetic sensor such as a magnetic head is obtained, and two data recorded in the same pattern from the magnetic output difference of the magnetic part, for example, authenticity determination data and information data. Can be easily discriminated and read, and it is difficult to discriminate these two data even if a normal magnetic sensor is used. Furthermore, since it is not necessary to apply an external magnetic field due to multiple bias currents,
The reading device can be simplified.

Further, by preliminarily orienting the magnetic recording medium in the running direction with an external magnetic field larger than the coercive force, a larger magnetic output difference can be obtained.

Further, by providing the concealing layer, the presence of the magnetic portion is not notified, and by providing the dummy portion, it is possible to make it difficult to read from the appearance of the magnetic portion.

[Brief description of drawings]

FIG. 1 is a plan view of a magnetic recording medium of the present invention.

2 is a cross-sectional view of the magnetic recording medium of FIG. 1 taken along line XX.

FIG. 3 is a plan view of a magnetic recording medium according to another embodiment of the present invention.

4 is a cross-sectional view taken along line YY of the magnetic recording medium of FIG.

FIG. 5 is a cross-sectional view of a magnetic recording medium of another example.

FIG. 6 is a hysteresis loop showing the electrostatic characteristics of the magnetic material used in the magnetic recording medium of the present invention.

FIG. 7 is a hysteresis loop showing the relationship between the bias current and the reproduction output voltage according to the magnetic recording medium of the present invention.

FIG. 8 is a schematic diagram showing a reading device for reading information from the magnetic recording medium of the present invention.

FIG. 9 is a waveform diagram showing an output waveform when a DC bias current is applied to the magnetic recording medium of the present invention and an external magnetic field is applied.

FIG. 10 is a waveform diagram showing a residual magnetic flux output waveform when an external magnetic field is not applied to the magnetic recording medium of the present invention.

[Explanation of symbols]

1 Magnetic recording medium 2 base materials 3 Magnetic recording layer 4 protective layer 5 Magnetic data recording layer 6 Hiding layer 7 Magnetic part 8 Magnetic part 9 Dummy part 10 magnetic patterns 11 Magnetic sensor 12 DC current circuit for bias 13 Operation circuit 14 data display 15 Data extraction 16 True / False Judgment

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI G06K 19/00 A (56) References JP 61-139498 (JP, A) JP 62-65238 (JP, A) JP-A-63-69706 (JP, A) JP-A-3-22214 (JP, A) JP-A-4-318322 (JP, A) JP-A-4-318323 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G06K 19/06-19/10 G06K 17/00 B42D 15/10 G11B 5/00-5/024 G11B 5/62-5/82

Claims (9)

(57) [Claims] 1. A magnetic portion made of a needle-like crystal magnetic material, a shape magnetic anisotropy other than needle-like crystals having weak magnetic coercive force, and a needle having a coercive force.
The same value as or close to that of a crystalline magnetic material, but an external magnetic field
A magnetic recording medium comprising a magnetic pattern made of a magnetic material having a different magnetic output level depending on the presence or absence of the magnetic material , and a magnetic pattern formed on the surface of the base material. 2. The magnetic recording medium according to claim 1, wherein the magnetic material has a coercive force of 60 Oe or more. 3. The magnetic recording medium according to claim 1, wherein the magnetic pattern has a bar code shape. 4. The magnetic recording medium according to claim 1, wherein a magnetic recording layer is provided between the magnetic pattern and the base material. 5. The magnetic recording medium according to claim 1, wherein the magnetic pattern is provided with a dummy portion from which a magnetic read output cannot be obtained. 6. The magnetic recording medium according to claim 1, wherein the magnetic pattern is oriented in a card moving direction by an external magnetic field having a coercive force twice or more. 7. The magnetic recording medium according to claim 1, wherein a concealing layer is provided on the magnetic pattern. 8. The magnetic recording medium according to claim 1, wherein a protective layer is provided on the magnetic pattern. 9. A magnetic pattern composed of a magnetic portion made of a needle-shaped crystalline magnetic material and a magnetic portion made of a magnetic material having a weak shape magnetic anisotropy other than the needle-shaped crystals on the surface of the base material and having a predetermined strength. A method for reading a magnetic recording medium, characterized by reading while applying an external magnetic field and reading the residual magnetization without applying an external magnetic field.