JPH0283821A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain a read-only medium suitable for mass fast duplication, with records contained therein being free from damages by external magnetic field, and its production method by providing magnetic recording films not on the whole surface of a sheet but only on such places required for recording. CONSTITUTION:The recording dots 3 are printed with a magnetic ink by high- accuracy printing technique such as gravure along with virtual tracks 2 on a substrate 1. After applying a coating material on the medium, DC magnetic field is applied to magnetize the magnetic ink. By this method, even if the magnetic ink is demagnetized by external disturbance magnetic field, normal reproduction of records can be performed by applying normal magnetization prior to reproduction. Therefore, mass duplication of the medium can be realized without damaging records.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium and a method for manufacturing the same, and more particularly to a magnetic recording medium that can be reproduced in large quantities at high speed and a method for manufacturing the same.

[Conventional technology]

Conventional read-only magnetic recording media, such as floppy disks, use a magnetic head to magnetize the required areas on a magnetic thin film that is applied to the entire surface of the disk or sheet by means such as coating or vapor deposition. This is used to record information.

[Problem to be solved by the invention]

In conventional magnetic recording media, when copying recorded contents, information written on the entire surface cannot be transferred all at once, and it is necessary to read and write each time using a head. For this reason, it takes a long time to copy a large amount of the same information, and it has been impossible to make tens of thousands of copies within a few hours, for example. Furthermore, in the above-mentioned prior art, there is a problem in that the recording is destroyed if, for example, a permanent magnet is brought into contact with a recorded disk or sheet.

SUMMARY OF THE INVENTION An object of the present invention is to provide a read-only magnetic recording medium that is suitable for high-volume high-speed duplication and whose records are not destroyed by external magnetic fields, and a method for manufacturing the same.

[Means to solve the problem]

The above object is achieved by not providing the magnetic recording film over the entire surface of the sheet, but by providing it only at the locations necessary for recording.

[For production]

If we assume that "1" in binary information corresponds to a magnetized part and 'O' to a non-magnetized part, the magnetic film is needed only in the part corresponding to "1", so from the beginning ○
If a magnetic film is not attached to the `` portion, the information will be destroyed by the influence of an external magnetic field.Word = 4 = No, and ``1'' Create a pattern that represents only the tp portion, and print this on the disk or sheet with magnetic ink. By printing a pattern, you can make large numbers of copies in a short amount of time.

〔Example〕

The present invention will be explained below with reference to Examples. FIG. 1 shows an embodiment of a disk in which magnetic recording information is printed on a substrate 1. The substrate 1 uses paper or a plastic sheet. In the case of paper, surface smoothness is an issue, so coated paper whose surface has been treated with powder such as calcium carbonate is suitable.

Furthermore, in the case of plastic sheets, surface treatment is required to improve ink wettability to enable high-precision printing.

In any case, it needs to have little elongation or deformation due to heat and moisture absorption, but in particular there should be no significant difference in elongation rate between the paper making direction or the stretching direction when making a plastic sheet and the direction perpendicular to it. is desirable, but plastic sheets are more suitable in this respect because their elongation rate is one order of magnitude lower than that of paper.

Further, as the substrate 1, in addition to plastic, glass or non-magnetic metal may be used in the form of a disk.

In these cases, the printability and thermal properties are the same as in the case of the sheet described above. Recording dots are printed with magnetic ink using high-precision printing technology along tracks 2 virtually provided on the substrate 1. Print 3. Magnetic ink has the property of becoming magnetized when a strong magnetic field is applied to it, but is not magnetic at the printing stage.

The most common printing method today is offset printing.

Since the printing original plate is created using a photographic method, the accuracy of the original plate can be sufficiently expressed down to several μm. The pattern of this original plate is printed on a photoresist film coated on an aluminum plate, and developed to create minute irregularities (called a printing plate). Apply ink and transfer the ink to paper via a rubber roller. In such a process, accuracy is reduced because a rubber roller is used as an intermediary for transfer, and currently only a resolution of about 30 μm or more can be obtained.

However, other methods such as gravure printing can print with higher precision, and the most accurate method has a resolution of 5 μm.
is obtained. Therefore, if the size of the recording dots 3 in FIG. 1 is made, for example, 10 .mu.m square, 2 to 3 MB can be recorded on a 3.5 inch disk.

FIG. 2 is an enlarged view of a cross section along track 2 of FIG. There are recording dots 3 printed with magnetic ink on a disk substrate 1, and a coating 4 is applied to fill in the unprinted portions between the dots and make the entire surface flat. When the length of dot 3 corresponds to 1 bit, it is the minimum length determined by printing accuracy, for example, 10 μm, which is 61".
rr is 20 μm if two consecutive
1 The length is an integral multiple of the number of consecutive rrs. Similarly, the unprinted portion between the dots, that is, the ``O'' information portion, is left with a length corresponding to the number of consecutive 0''s.

Although the attachment of the magnetic material by printing has been described in detail above, another method is to form a film of the magnetic material on the entire substrate 1 in advance, and then etch the parts other than those that should be left corresponding to the information. It is also possible to remove it.

When a DC magnetic field is applied to a printed and coated recording sheet, the magnetic ink becomes magnetized. The direction of magnetization may be parallel to the sheet surface as shown in FIG. 3, or perpendicular to the sheet surface as shown in FIG.

FIG. 3 is an enlarged cross-sectional view in the radial direction of FIG. 1, and the track pitch is P. By tracing the track with the magnetic head 5, an induced voltage is generated in the coil 6,
Play the signal. This method uses the same recording format as conventional magnetic recording such as floppy disks, and conventional magnetic heads can be used as is.

It has the advantage that relatively large output can be obtained.

FIG. 4 is also an enlarged radial cross-sectional view of FIG. 1.

Because magnetic ink becomes magnetized in the thickness direction.

The perpendicular magnetic head 7 must be used for reading.

However, since perpendicular magnetic heads can handle smaller magnetism, they have the advantage of being able to record and reproduce at a higher density if printing technology becomes more precise.

The perpendicular magnetic head 1 shown in FIG. 4 is of the MR type as an example. In the MR type, the magnetoresistive element 8 is placed opposite the recording dot, and the resistance value changes depending on the magnetic field received from the element, so that signal detection is performed based on the amount of voltage drop caused by the current flowing from the electrode 9.

To magnetize as shown in FIG. 3, a magnetization device shown in FIG. 5 is used. The yoke 10 has a pot-shaped core, and has a structure in which only the upper part is covered with thin iron. An excitation coil 12 is wound around the central core portion 1■.

When direct current is passed through the excitation coil 12, a magnetic flux is generated in the central core, and when it passes through the upper thin wall, it passes outside the surface due to saturation. Generates a radial magnetic field.

Therefore, if the magnetic sheet 1 is placed on top of this with its center aligned, it will be magnetized as shown in FIG.

To magnetize it as shown in Figure 4, it is sufficient to simply sandwich the top and bottom with large magnetic poles.

Next, the manufacturing process and reproduction process of the magnetic disk shown in FIG. 1 will be explained with reference to FIG. 6. The position of the digital information 600 to be written on the disk is determined by the patterning program (step 600), and the laser writing device is used to print it on the photographic plate (step 601).
). A large amount of magnetic ink is printed on a disk substrate using this printing original plate (step 602). This is magnetized using a magnetization device such as that shown in Fig. 5, and then reproduced. It is desirable to perform magnetization (step 603) after transportation from the printer to the reproducer and, if possible, immediately before reproduction (step 604). . This is because there is no need to worry about being affected by contact with a magnet or the like. Therefore.

It is most preferable to provide a reproducing device with a built-in magnetizing device, and this embodiment will be described below.

FIG. 7 shows its configuration, in which the disk substrate 1 is placed on a turntable (not shown) and rotated. The magnetic head is a composite head in which a read-only head 13 and a magnetization-only head 14 are integrated. This composite head is controlled to track with respect to the track 2 described above, and is always lined up and facing the same track. The magnetization head 14 uses a current from the magnetization circuit 15 to move the recording dot 3 into the third position.
Magnetize as shown. The output of the read-only head 13 is shaped by a signal processing circuit 16, and a digital output is taken out. According to this method, since it is magnetized immediately before reproduction, it is not only not affected by external disturbance magnetic fields, but also the fifth
There is no need for a large-scale magnetization device as shown in the figure, and the magnetization device-integrated regenerator can be made small and lightweight.

FIG. 8 shows another embodiment of a reproduction method that takes advantage of the features of a book-based magnetic disk. The difference from FIG. 3 is that the magnetic head 5 has two coils: coil 61 is a reading coil, and coil 62 is a magnetizing coil. In this case, it is not necessary to magnetize the recording dots 3 in advance.

When the coil 62 is energized, the magnetic permeability is high when the recording dot 3 is directly below the magnetic head 5, so the reading coil 6
If the number of magnetic fluxes interlinking with the magnetic head 1 increases and there is no recording dot 3 directly under the magnetic head 5, the magnetic permeability is low and the reading coil 6
The magnetic flux interlinked with 1 is reduced. In this way, the number of interlinked magnetic fluxes changes depending on the presence or absence of recording dots, and a voltage is induced in the reading coil 61, thereby reproducing the signal.

Therefore, according to the method of this embodiment, magnetization and reproduction can be performed with one magnetic head 5, and the method is simpler and more compact than the method shown in FIG.

In the case of this method, the magnetic material of the recording dots 3 only needs to have a high magnetic permeability, and does not need to have a high coercivity, so that it is even cheaper.

FIG. 9 shows an example in which the present invention is applied to a magnetic card. A part of the magnetic card 17 includes a magnetic tape section 18, on which recording dots 3 are provided using magnetic ink. For example, 20 rows of tracks each having a width of 300 μm are provided, and elongated dots measuring 100 μm×300 μm are lined up. Dots of this size can be drawn using a printer, so a special printer is used for writing, and a unique code is written on each card. - Once written, the data will never be erased even if a strong magnetic field is applied from the outside, so people who work in strong magnetic fields, such as superconducting magnetic levitation train crews and nuclear magnetic resonance medical diagnostic equipment operators, This can be a good card to use.

A thin film magnetic radar array 19 is suitable for playing this card. FIG. 10 is a conceptual diagram of a thin film magnetic field array. A plurality of thin film magnetic heads made of coils 21 and permalloy 22 formed on a silicon substrate 20 are lined up. For example, assume that 20 pieces of permalloy with a tip width of 150 μm and a coil width of 350 μm are lined up at a pitch of 400 μm. Opposed to this is the magnetic tape section 18 of the magnetic card 17 described above, which has a recording track 25 on which recording dots are printed with magnetic ink. The signal is guided through the signal processing board 24, where it is binarized and serially converted to become an output.

According to this embodiment, since the recording driver l~ is written using a printer, the data is not destroyed by an external magnetic field, and the data cannot be tampered with, making the magnetic card effective in terms of security.

〔Effect of the invention〕

According to the present invention, digital information “1” or it O
Since magnetic ink is applied only to the area corresponding to n, no matter how the magnetic ink is magnetized or demagnetized by external disturbance magnetic fields, normal reproduction can be performed if proper magnetization is performed immediately before reproduction. Therefore, it has the excellent effect that there is no risk of data being destroyed even if a permanent magnet etc. is brought close to it, and at the same time, it can be reproduced in large quantities at high speed, so it can be used as a medium for the latest information in place of weekly newspapers, etc., and can be used at low cost for mass users. It has the characteristics that can be supplied.

[Brief explanation of the drawing]

1 is an explanatory diagram of one embodiment of the magnetic disk according to the present invention, FIG. 2 is a diagram showing a cross section along a track of the magnetic disk of FIG. 1, and FIGS. 3 and 4 are illustrations of the magnetic disk of FIG. An explanatory diagram of the magnetization state of the disk, FIG. 5 is a configuration diagram showing an example of a magnetization device for magnetizing the magnetic disk of FIG. 1, and FIG. 6 is a manufacturing process and process of the magnetic disk of FIG. 1 up to playback. FIG. 7 is a block diagram showing an example of the magnetic disk reproducing apparatus of FIG. 1, FIG. 8 is a diagram showing an example of the reproducing head of FIG. 7, and FIGS. It is another example figure of. 1... Disc substrate, 3... Recording dot, 5...
Magnetic head, 7... Perpendicular magnetic head, 13... Read-only head, 14... Magnetization-only head. Representative Patent Attorney Tadashi Akimoto Actual Figure 10--Ichiyūdrink 11-m-Chu・Shokof vomit 12--Isshuki Kirikoi+l/

Claims (1)

[Claims] 1. A magnetic material is attached along a track on a non-magnetic substrate only at a position where the information to be recorded is either "1" or "0". magnetic recording medium. 2. The magnetic recording medium according to claim 1, wherein the substrate is a flexible paper or plastic sheet. 3. The magnetic recording medium according to claim 1, wherein the substrate is a disk made of plastic, glass, or non-magnetic metal. 4. Claim 1, wherein the magnetic body has a next coercive force of a predetermined value or more, and is reproduced by magnetizing the magnetic body and then detecting a magnetic field coerced by the magnetization. The magnetic recording medium described. 5. The magnetic recording medium according to claim 4, wherein the magnetization of the magnetic material is parallel to the substrate. 6. The magnetic recording medium according to claim 4, wherein the magnetization of the magnetic material is perpendicular to the substrate. 7. The magnetic recording medium according to claim 1, wherein a magnetic field is applied whose path includes an information recording position on the substrate, and the recorded information is reproduced depending on the presence or absence of a magnetic material at the position. 8. Generate a pattern that distinguishes between a small area on the substrate where only one of "1" or "0" of the digital recording information is recorded and a portion other than the small area, and use this pattern to record the information on the substrate. A method for manufacturing a magnetic recording medium, characterized in that the recording medium for the above-mentioned recorded information is manufactured by attaching a magnetic material only to the above-mentioned small region. 9. The method for manufacturing a magnetic recording medium according to claim 8, wherein the attachment of the magnetic material is performed by creating a printing master having the pattern and printing magnetic ink using the master. . 10. The method of manufacturing a magnetic recording medium according to claim 8, wherein the attachment of the magnetic material is performed by forming a magnetic thin film on the entire surface of the substrate and then etching using the pattern.