JPH01208726A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To facilitate production and to improve security by providing a 1st magnetic pattern of the line width finer than 1mm and the 2nd magnetic pattern having >=1mm line width so that information can be recorded simply by changing the line width of the magnetic patterns. CONSTITUTION:A card 5 which has the 1st magnetic pattern 2b having the line width finer than 1mm and the 2nd magnetic pattern having >=1mm line width is carried. The magnetic flux changes when a magnetic head 6 passes above the magnetic ink patterns. The output voltage in a reverse direction is generated in the terminal of a detecting coil 62 at the beginning and terminating ends of the patterns. Whereas, this output voltage is much larger in the case of the pattern 2b finer than 1mm as compared to the case of the pattern 2a having >=1mm line width. The binary information of a low level is reproduced from the pattern 2a and of a high level from the pattern 2b by utilizing this phenomenon. The recording of the information is thus enabled simply by changing the line width and the production is facilitated. Since the thickness is uniform, the patterns are hardly visible and the security is improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic recording medium having a magnetic pattern.For example, the present invention can be applied to cards having a magnetic barcode, information recording carriers using magnetic bars, etc. .

[Conventional Technique #iJ Some securities, cards, etc. that are widely used today have magnetic patterns formed thereon for authenticity determination. By detecting this with a magnetic sensor, it is possible to determine whether it is genuine or not, thereby adding and improving security.

Not only in securities and cards but also in magnetic recording media in general, when a magnetic pattern is used to construct a code or to record some information, the information is stored at 0° or '.
It may be recorded as binary information of l°.

FIG. 5 is an explanatory diagram when binary information is constructed using a conventional magnetic recording medium.

As shown in the figure, in order to record binary information based on the magnitude of the detected voltage using the conventional method, it is necessary to change the thickness of the magnetic pattern 102 formed on the base material 101 according to the binary information. was there.

That is, a thick magnetic pattern 102b is formed to obtain a high level output, and a thin magnetic pattern 102a is formed to obtain a low level output.

By scanning such a magnetic pattern, a detection voltage corresponding to the thickness of the magnetic pattern is obtained from the detection coil 62 of the magnetic helad 6, and binarized information is reproduced.

[Problems to be Solved by the Invention] However, if binary information is constructed based on the magnitude of the detection voltage of the conventional magnetic pattern, the thickness of the magnetic pattern must be changed as described above. This poses a problem in that the magnetic pattern becomes more complicated and the magnetic pattern becomes easier to see, which is disadvantageous in terms of security.

The present invention aims to solve this problem, and it is possible to increase the detection voltage without changing the thickness of the magnetic pattern, record binary information, and easily detect information. The purpose is to provide magnetic recording media.

[Means for Solving the Problems] In order to achieve the above object, a magnetic recording medium according to the present invention has a first magnetic pattern having a line width smaller than 1 mm and a line width smaller than 1 mm.
and a second magnetic pattern having a line width greater than or equal to the line width.

[Function] When a magnetic pattern with a line width smaller than 1 mm is detected by a magnetic head, the detection voltage increases significantly compared to a case with a line width of 1 mm or more. In particular, when the line width is 0.5 mm or less, the detection voltage increases by 30% to 110%, resulting in a remarkable effect.

Therefore, with the above configuration, information can be recorded simply by changing the line width, making manufacturing easier, and since the thickness is uniform, it is difficult to see visually and security is improved.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIGS. 4(A) to 4(I)) are manufacturing process diagrams of an embodiment of a magnetic recording medium according to the present invention.

First, as shown in the same figure (A), the thickness is 188gm or 2mm.
A base material l of 507 parts m of polyethylene terephthalate film is provided.

Next, as shown in the same figure (B), magnetic ink patterns 2a and 2b were printed on the base material l. Pattern 2a is a magnetic bar with a line width of 1 mm or more, and pattern 2b is a magnetic bar with a line width of less than 1 mm. The arrays of patterns 2a and 2b correspond to the binarized information to be recorded.

Note that the lengths of both patterns were unified to lO, Omm.

The magnetic ink patterns 2a and 2b are printed by screen printing, and the screen mesh used in this case is Tetron 250 lines.

The stock solution of the magnetic ink contains 48 parts of carbonyl iron (parts by weight, the same applies hereinafter) and a modified polyester resin liquid (solid content of 5 parts).
0% by weight), 7 parts of isophorone, 7 parts of butyl cellosolve, 7 parts of cyclohexanone, and 10 parts of cyclohexanone.
0 and kneaded for 2 hours using a roll mill. Its viscosity was about 100 boids. Carbonyl iron has a Mito degree of 3.0 to 3.2 g/cm3 and a particle size of 1.
5 to 1.8 lm and a coercive force of about 10 (Oe) was used.

Here, carbonyl iron is a spherical iron powder with uniform particle size obtained by reducing iron carbonyl, and there are usually two types depending on the reduction method.

The first type contains carbon, nitrogen, and oxygen and has a high Vickers hardness of about 900, and the second type contains carbon, nitrogen, and oxygen.
It has low nitrogen and oxygen content and high purity, and has a Vickers hardness Hv of approximately 150.0 In this example, the particles do not deform and maintain a spherical shape when formed into ink, and there is almost no change in coercive force. A first type of carbonyl iron was used.

On the other hand, reduced iron powder obtained by reducing oxides and electrolytic iron powder obtained by iron electrorefining have an irregular shape, a wide particle size distribution, and a particle size of several + pm.
Because of the above, it is difficult to make ink. Furthermore, magnetic ink patterns using these materials have larger output fluctuations during detection than those using carbonyl iron.

When the magnetic ink stock solution using carbonyl iron was used as it was and printed with a screen mesh of 250 lines, the film thickness of pattern 2 was about 91 Lm. This sample is hereinafter referred to as sample A.

In addition, using a thinner consisting of 1 part isophorone, 1 part butyl cellosolve, LM cyclohexanone, and 1 part Turupez 100, dilute 10 parts of the above magnetic ink with 1 part thinner, and apply the diluted magnetic ink to a screen metre. When printed with 250 lines, the film thickness is approximately 7.5 JLm.
It became.

This is called sample B.

In addition, when screen printing was performed under the same conditions with 10 parts of the above magnetic ink diluted with 2 parts of the above thinner, the film thickness was 5.
．． It was 51 parts m. This is called sample C.

This magnetic ink pattern was measured using a sample vibrating magnetometer (V
When measuring the magnetic flux density and coercive force by applying a magnetic field up to 5000 (Oe) using SM), the results were approximately 4400 Gauss and 1 Gauss, respectively.
It was 0.1 (Oe).

Next, as shown in FIG. CG), a silver ink layer 3 is formed to hide the formed magnetic ink pattern 2.

The pigment of the silver ink is in the form of scales, and even if the thickness is about 1 to 2 JLm, sufficient hiding power can be obtained. The thickness of the silver ink layer 3 here is approximately 1 pm. Note that, as such a pigment, there is a scale-like aluminum pigment.

Next, as shown in FIG. 3D, an overcoat layer 4 is formed on the silver ink layer 3. The overcoat layer 4 is used for detecting the magnetic ink pattern 2! It is provided to withstand the friction of the i-air head, and is formed to have a thickness of about 21 Lm.

The thus formed product was processed into a commuter pass size of 5757-5mm x 85mm, and the sample card 5 of this example was
was created.

FIGS. 1A to 1C are explanatory diagrams showing the relationship between the magnitude of the output voltage and the line width of the magnetic ink pattern when scanning the present embodiment with a magnetic head.

In the same figure (A), the magnetic head 6 has a gap of 304
m, the track width is 1 mm, and the bias coil 61
and a detection coil 62.

First, a DC bias current of about 2'OmA is applied to the bias coil 61 to generate a leakage magnetic field of about 1000 (Oe). Then, the card 5 is conveyed in the direction of the arrow in the figure to detect the magnetic ink pattern. At this time, in order to prevent a decrease in the output level, the scanning direction of the gap of the magnetic heald 6 is set so as to be substantially perpendicular to the edges of the patterns 2a and 2b. Further, the conveyance speed of the card 5 was approximately 45 cm/sec.

When the card 5 is conveyed and the magnetic sludge passes over the magnetic ink pattern, magnetic coupling occurs and the magnetic flux changes, causing the detection coil 62 to be activated at the beginning and end of the pattern as shown in CB) in the same figure. Reverse output voltage is generated at the terminal.

However, this output voltage is significantly higher in the case of the pattern 2b having a line width of less than 1 mm than in the case of the pattern 2a having a line width of 1 mm or more. Using this phenomenon, the low level starts from pattern 2a.

High-level binarized information can be reproduced from pattern 2b.

Next, the phenomenon that the output voltage changes depending on the line width will be demonstrated using the above samples A, B, and C.

Sample A is printed with the above magnetic ink stock solution and has a thickness of 9g.
Sample B has a pattern of approximately 7.51 parts m thick printed with magnetic ink diluted 10:1, and Sample C is printed with magnetic ink diluted 10:2. The pattern has a thickness of approximately 5.5 lumens.

FIG. 2 is a graph showing the relationship between the line width of the magnetic bar and the detected voltage. Note that the vertical axis of the graph represents the maximum value of the output voltage on each pattern of the magnetic head as a relative value. Further, the magnetic head, the transport speed of the card 5, etc. are the same as the conditions described above.

As shown in the same graph, in all samples A, B, and C, the output voltage hardly changes when the line width is between io, omm and 1.0 mm, but when the line width is in.
It increases significantly as the line width becomes thinner, and reaches a maximum value around 0.3 mm.
Compared to the average output at 0 mmcy), sample A has an increase of about 30%, sample B has an increase of about 85%, and sample C has an increase of about 110%.

Note that the output decreases when the m width is 0.2 mm, but this line width is close to the limit of silk screen printing, and this phenomenon may be due to its influence. Therefore, the line @0.
It cannot be said that it has become clear that the maximum value is reached around 3 mm.

However, it was confirmed that the output voltage increased by narrowing the line width, and it was clearly demonstrated that in Sample C, an output voltage increased by at least 110% was obtained.

Therefore, this change in output is expressed as l Q l of the binarized information.
and '1° can be made to correspond.

For example, in sample B, the relative output level is 120 when the line width is 0.3 mm, and it is 6 when the line width is 1.0 mm.
1, so permanent magnetic recording can be performed by arranging the lines +1@lO, 3 mm and 1.0 mm according to the binary information.

Furthermore, by taking advantage of the fact that the output voltage hardly changes between line widths of 1.0 mm to 10.0 mm, information is added to the line width itself and the output voltage caused by the line width, and both can be formed in a single printing process. It is also a turn.

For example, for wire 11@1 mm and 2 mm,
Although the line widths differ by a factor of two, the output voltages are similar.

Therefore, information can be placed on the line width itself. Conversely, in the case of line widths of 0.5 mm and 1 mm, the line width is also twice as different, but the output is MAfKAo, 5
mm is significantly higher. Therefore, information can be placed on the level of the output voltage.

FIG. 3 is an explanatory diagram showing the configuration of a magnetic pattern in another embodiment of the present invention.

As shown in the figure, in this example, the line 111i 1 m
A dummy pattern 2C made of a non-magnetic material is mixed with the magnetic pattern 2a having a line width of m or more and the magnetic pattern 2b having a line width of less than 1 mm.

On the dummy pattern 2C, no output voltage appears because the magnetic flux of the magnetic heald 6 does not change. Therefore, recorded information cannot be read from the apparent pattern, improving security.

Regarding security, this embodiment has advantages as described below.

When detecting a magnetic pattern with the magnetic helad 6 shown in FIG. 1(A), residual magnetization occurs in a magnetic ink pattern with a coercive force exceeding 30 (Oe).

For this reason, in the past, the magnetic ink pattern was easily visible on reprinted Magnetic Pure, etc.
To prevent this, it would be necessary to demagnetize each time, which would complicate the system.

However, the carbonyl iron powder used in this example has a coercive force of about 10 (Oe) and no residual magnetization occurs, making visual inspection using the magnetic pure or the like described above difficult. This is important for security.

It should be noted that the present invention is not limited to the above embodiments, but can be applied to magnetic recording media having magnetic patterns in general.

[Effects of the Invention] As described above in detail, the magnetic recording medium according to the present invention can record information simply by changing the line width of the magnetic pattern, and is easy to manufacture.

Furthermore, since the H is uniform, security is also improved.

[Brief explanation of the drawing]

FIGS. 1A to 1C are explanatory diagrams showing the relationship between the magnitude of the output voltage and the line width of the magnetic ink pattern when an embodiment of the magnetic recording medium according to the present invention is scanned by a magnetic head. FIG. 2 is an explanatory diagram showing the structure of the relationship turn between the line width of the magnetic bar and the detected voltage. It is an explanatory diagram when information is constituted. 1...Base material 2a, 2b+1...Magnetic ink pattern 2c@6 tatami dummy pattern 3...Silver ink layer 4-...Overcoat layer 5...Card 6...Magnetic head 61...Bias Coil 62 - Fist/Detection Coil Agent Patent Attorney Seki Yamashita Child 1 Figure 2 0, + 0.2 03 0.50.7 I0 1.5 2.5 5.0 +0
．． 0 No meeting, anxious ↑ fingers (mm) Fig. 3 Fig. 4 (A) (Cn (D) Fig. 5

Claims (3)

[Claims] (1) First magnetic pattern with line width thinner than 1 mm and 1 m
a second magnetic pattern having a line width of m or more. (2) The magnetic recording medium according to claim 1, wherein binary information is recorded by the first and second magnetic patterns. (3) The magnetic recording medium according to claim 1 or 2, characterized in that dummy patterns of non-magnetic material are mixed therein.