JP2936533B2 - Magnetic recording medium and magnetic recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a magnetic recording medium.

[0002]

In a magnetic recording medium such as a magnetic tape or a magnetic disk, a coating type using a binder resin as a magnetic layer provided on a support is required due to a demand for high-density recording. In addition, a metal thin film type without using a binder resin has been proposed. That is, a magnetic recording medium in which a magnetic layer is formed by wet plating means such as electroless plating, or dry plating means such as vacuum deposition, sputtering, or ion plating has been proposed. This type of magnetic recording medium has a high filling density of a magnetic material and is suitable for high-density recording.

[0003] By the way, with the increase in recording density, the shortest recording wavelength of a signal used for recording has become shorter.
Also, the magnetic layer tends to be thin. However, there has been little research on how to design the thickness of the magnetic layer. That is, there has been little research on how to design the thickness of the magnetic layer so as to obtain a high reproduction output and efficiently erase a recorded signal.

Accordingly, an object of the present invention is to provide a technique which has a high reproduction output and a high demagnetization rate of a recording signal.

[0005]

An object of the present invention is to provide a magnetic tape in which recording is performed using a magnetic head having a gap length of g and using a signal having a minimum recording wavelength of λ.
The magnetic layer of the magnetic tape is a metal thin film type magnetic layer,
The thickness a of the magnetic layer is determined by the following conditions (1) , (2) and
(3) It is solved by a magnetic tape characterized by being set so as to satisfy.

A method for recording a signal on a magnetic tape having a metal thin-film type magnetic layer having a thickness a, wherein a gap length satisfying the following conditions (1) , (2) and (3) is satisfied: The problem is solved by a magnetic recording method characterized in that recording is performed using a magnetic head of g and a signal having a minimum recording wavelength of λ.

Condition (1) 0.8 (0.5 g + 0.06λ) ≦ a ≦ 1.1 (0.5
g + 0.06λ) Condition (2) g = 0.1-0.3 μm Condition (3) λ = 0.2-1.5 μm That is, the above conditions (1) , (2) and (3) should be satisfied. Magnetic tape with designed metal thin film type magnetic layer
It has been confirmed that even if the recording wavelength to be written on the tape is short, the already recorded signal can be efficiently erased and the reproduction output is high.

[0008]

Magnetic tape of the embodiment of the present invention uses a magnetic head gap length g, the magnetic tape recording shortest recording wavelength is used signal λ is is performed, the magnetic
The magnetic layer of the magnetic tape is a metal thin film type magnetic layer, and the thickness a of the magnetic layer is set so as to satisfy the following conditions (1), (2) and (3) . Is resolved.

[0009] The magnetic recording method of the present invention, the thickness of a gold
A method for recording a signal on a magnetic tape having a metal thin film type magnetic layer, comprising the following conditions (1), (2) and
The recording is performed using a magnetic head having a gap length g satisfying the condition (3) and using a signal having a minimum recording wavelength of λ. Condition (1) 0.8 (0.5 g + 0.06λ) ≦ a ≦ 1.1 (0.5
g + 0.06λ) Condition (2) g = 0.1-0.3 μm Condition (3) λ = 0.2-1.5 μm

Hereinafter, this will be described in more detail. FIG. 1 is a schematic sectional view of a magnetic recording medium according to the present invention. In FIG. 1, 1
Is a support. The support 1 may be magnetic or non-magnetic. Generally, it is non-magnetic. For example, polyethylene terephthalate (PET)
Flexible polymer materials such as olefin-based resins such as polyester, polyamide, polyimide, polysulfone, polycarbonate, and polypropylene, cellulose-based resins, and vinyl chloride-based resins are used.

The above-mentioned condition [0.8 (0.5 g + 0.06λ) ≦ a ≦ 1.1 (0 .0) is applied to the support 1 by dry plating means such as vapor deposition or sputtering, in particular, oblique vapor deposition means.
5g + 0.06λ)] is provided. For example, the magnetic film 2 having a thickness a is provided by using the oblique deposition apparatus shown in FIG. In FIG. 2, 1 is a support, 10 is a cooling can roll, 11 is a crucible, 12 is a magnetic metal filled in the crucible 11, 13 is a shielding plate, 14 is an oxygen gas supply nozzle, and 15 is an electron gun. Then, the inside of the vacuum chamber 16 is, for example, 10 ^-4 to 10 ^-6 T
The magnetic film 2 is provided by evacuating to about orr, irradiating the magnetic metal 12 with an electron beam from the electron gun 15 to evaporate, and depositing (oblique deposition) metal magnetic particles.
The coercive force Hc of the magnetic film 2 set to the thickness a is 1200 to 1200
It is 1700 Oe. The saturation magnetic flux density Bs is 5000 to 8
000G. The squareness ratio Sq is 0.85 to 0.99. Examples of the material of the magnetic metal 12 include Fe, Co,
In addition to metals such as Ni, Co-Ni alloy, Co-Pt alloy, Co-Ni-Pt alloy, Fe-Co alloy, Fe-N
i alloy, Fe-Co-Ni alloy, Fe-Co-B alloy,
A Co-Ni-Fe-B alloy, a Co-Cr alloy, or an alloy containing these different metals is used.
Examples of the metal thin film type magnetic film include nitrides (for example, Fe-N, Fe-NO) and carbides (for example, Fe-C, Fe-CO) of the above materials.

A protective film 3 made of diamond-like carbon or the like having a thickness of 10 to 500.degree. The protective film is, for example, EC
A film can be formed using an R microwave plasma CVD apparatus.
If necessary, a fluorine-based lubricant film 4 is provided to a thickness of about 10 to 70 ° by means such as immersion or ultrasonic spraying.

[0013]

[Embodiment 1] Using an oblique deposition apparatus shown in FIG.
Co metal magnetic film 2 of thickness a on PET film 1 of thickness m
Was provided. The conditions for forming the Co metal magnetic film 2 are as follows. The traveling speed of the PET film 1; 1 m / min; the output of the electron gun 15; 10 kw, the minimum incident angle during oblique deposition; 60 °, the supply amount of oxygen gas from the nozzle 14; 20 sccm, and the thickness a of the obtained Co metal magnetic film 2 is: According to Tally Step manufactured by Rank Taylor Hobson, it is 1300 °, and according to measurement by VSM, its coercive force Hc is 13 °.
00Oe, saturation magnetic flux density Bs is 6400G, squareness ratio Sq
Was 0.94.

The ECR is formed on the Co metal magnetic film 2.
Using a CVD apparatus, a diamond-like carbon film (protective film) 3 having a thickness of 100 mm was provided, and a film 4 of a perfluoropolyether-based lubricant was further provided thereon with a thickness of 15 mm. Further, a paint containing carbon black and a binder resin was applied to the opposite surface so that the thickness after drying was 0.5 μm, and a back coat film 5 was provided.

Thereafter, a magnetic tape was manufactured through a predetermined process. Recording was performed on the magnetic tape thus obtained by using a ring-type magnetic head having a gap length g of 0.22 μm and a signal having a minimum recording wavelength λ of 0.5 μm.

[0016]

Example 2 A magnetic tape was obtained in the same manner as in Example 1.
The thickness a of the Co metal magnetic film 2 of the obtained magnetic tape is 90
0 °, coercive force Hc was 1240 Oe, saturation magnetic flux density Bs was 6900 G, and squareness ratio Sq was 0.96. With respect to the magnetic tape thus obtained, the gap length g was 0.1
Recording was performed using a ring-type magnetic head of 6 μm and a signal having a minimum recording wavelength λ of 0.3 μm.

[0017]

Example 3 A magnetic tape was obtained in the same manner as in Example 1.
The thickness a of the Co metal magnetic film 2 of the obtained magnetic tape is 21
00 °, coercive force Hc is 1420 Oe, saturation magnetic flux density Bs
Was 5700 G and the squareness ratio Sq was 0.90. With respect to the magnetic tape obtained in this manner, the gap length g is set to be equal to 0.
Recording was performed using a ring-type magnetic head of 30 μm and a signal having a shortest recording wavelength λ of 1.5 μm.

[0018]

Comparative Examples 2 to 4 A ring-type magnetic head having a gap length g of 0.22 μm was used for the magnetic tape of Example 1.
The shortest recording wavelength λ is 1.2 μm, 1.5 μm, 2.
Recording was performed using a 0 μm signal.

[0019]

Comparative Examples 6 to 9 A ring-type magnetic head having a gap length g of 0.16 μm was used for the magnetic tape of Example 2.
The shortest recording wavelength λ is 0.8 μm, 1.2 μm, 1..
Recording was performed using signals of 5 μm and 2.0 μm.

[0020]

[Comparative Examples 10 and 11 ] With respect to the magnetic tape of Example 3,
Recording was performed using a ring-type magnetic head having a gap length g of 0.30 μm and signals having a minimum recording wavelength λ of 0.3 μm and 0.5 μm.

[0021]

Comparative Examples 13 to 15 A magnetic tape was obtained in the same manner as in Example 1. The thickness a of the Co metal magnetic film 2 of the obtained magnetic tape was 1850 °, the coercive force Hc was 1500 Oe, the saturation magnetic flux density Bs was 5800 G, and the squareness ratio Sq was 0.88. A ring-type magnetic head having a gap length g of 0.22 μm was used for the magnetic tape thus obtained, and the shortest recording wavelength λ was 0.3 μm, 0.5 μm, 0.8 μm.
Recording was performed using the signal of m.

[0022]

[Characteristics] The recorded magnetic tape was reproduced using the same head, and its output is shown in Tables 1 to 3. Table 1 Magnetic film thickness a Gap length g Shortest recording wavelength λ Reproduction output Example 1 1300Å 0.22 μm 0.5 μm + 3.1 dB Comparative example 2 1300Å 0.22 μm 1.2 μm + 0.8 dB Comparative example 3 1300Å 22 μm 1.5 μm 0.0 dB Comparative Example 4 1300Å 0.22 μm 2.0 μm -0.8 dB Comparative Example 6 900Å 0.16 μm 0.8 μm +0.9 dB Comparative Example 7 900Å 0.16 μm 1.2 μm -1.5 dB Comparative Example 8 900Å 0.16 μm 1.5 μm-1.8 dB Comparative Example 9 900Å 0.16 μm 2.0 μm-2.4 dB Comparative Example 10 2100Å 0.30 μm 0.3 μm + 0.9 dB Comparative Example 11 2100Å 0.30 μm 0.5 μm + 0 0.9 dB Comparative Example 13 1850Å 0.22 μm 0.3 μm 0 * Reproduction output is based on Comparative Example 13. Thickness a gap length g shortest recording wavelength λ reproduction output Example 2 900Å 0.16 μm 0.3 μm +3.7 dB Comparative Example 2 1300Å 0.22 μm 1.2 μm +1.1 dB Comparative Example 3 1300Å 0.22 μm 1.5 μm − 0.3 dB Comparative Example 4 1300Å 0.22 μm 2.0 μm-1.4 dB Comparative Example 6 900Å 0.16 μm 0.8 μm + 0.7 dB Comparative Example 7 900Å 0.16 μm 1.2 μm-0.7 dB Comparative Example 8 900Å 0. 16 μm 1.5 μm-1.8 dB Comparative Example 9 900Å 0.16 μm 2.0 μm-2.2 dB Comparative Example 11 2100Å 0.30 μm 0.5 μm + 0.8 dB Comparative Example 14 1850Å 0.22 μm 0.5 μm 0 * Reproduction output Table 3 Magnetic film thickness a Gap length g Shortest recording wavelength λ Reproduction output Example 3 2100 ° .30 μm 1.5 μm +2.4 dB Comparative Example 2 1300Å 0.22 μm 1.2 μm +0.9 dB Comparative Example 3 1300Å 0.22 μm 1.5 μm -0.3 dB Comparative Example 4 1300Å 0.22 μm 2.0 μm -1.2 dB Compare Example 6 900Å 0.16 μm 0.8 μm + 0.4 dB Comparative Example 7 900Å 0.16 μm 1.2 μm-1.4 dB Comparative Example 8 900Å 0.16 μm 1.5 μm-2.1 dB Comparative Example 9 900Å 0.16 μm 2.0 μm -2.9 dB Comparative Example 11 2100 ° 0.30 μm 0.5 μm +0.9 dB Comparative Example 15 1850 ° 0.22 μm 0.8 μm 0 * The reproduction output is based on Comparative Example 15. The thickness a of the magnetic film should be designed so that the relationship between the thickness a, the gap length g of the magnetic head, and the shortest recording wavelength λ satisfies the conditions of the present invention. Accordingly, it can be seen that the magnetic recording medium having high reproduction output can be obtained. A magnetic recording medium having a high reproduction output is recorded on a magnetic recording medium having a magnetic film thickness a so that the gap length g and the shortest recording wavelength λ of the magnetic head satisfy the conditions of the present invention. Is obtained.

After recording the signal having the wavelength of 0.98 μm, the signal having the shortest recording wavelength λ is overwritten, the signal recorded at the wavelength of 0.98 μm recorded first is read, and the remaining signal is measured. The erasure rate was examined, and the results are shown in Table-4. From Table 4, the overwrite characteristics can be improved by designing the thickness a of the magnetic film so that the relationship between the thickness a of the magnetic film, the gap length g of the magnetic head, and the shortest recording wavelength λ satisfies the condition of the present invention. It can be seen that an excellent (high demagnetization) magnetic recording medium can be obtained. Further, by recording on a magnetic recording medium having a magnetic film thickness of a so that the gap length g and the shortest recording wavelength λ of the magnetic head satisfy the conditions of the present invention, the recording medium has excellent overwrite characteristics. It turns out that it becomes.

[0024]

According to the present invention, 0.8 (0.5 g + 0.06λ) ≦ a ≦
1.1 (0.5 g + 0.06λ) , g = 0.1 to 0.3
[mu] m, the metal thin film so as to satisfy the lambda = 0.2 and 1.5 .mu.m
High output can be obtained in the case of short-wavelength recording because the type of magnetic layer is set, and the signal spreads to the lower part of the magnetic layer during overwriting, and the signal recorded in the lower part can be erased. , High demagnetization rate.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a magnetic recording medium.

FIG. 2 is a schematic view of an oblique vapor deposition apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support body 2 Magnetic film 3 Protective film 4 Lubricant film 5 Back coat film

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-109061 (JP, A) JP-A-6-111266 (JP, A) JP-A-60-45932 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G11B 5 / 02,5 / 66

Claims (4)

(57) [Claims] 1. A magnetic head in which recording is performed using a magnetic head having a gap length of g and a signal having a minimum recording wavelength of λ.
In the tape , the magnetic layer of the magnetic tape is a metal thin film type magnetic layer, and the thickness a of the magnetic layer is set to the following conditions (1), (2) and
(3) A magnetic tape, which is set so as to satisfy the condition. Condition (1) 0.8 (0.5 g + 0.06λ) ≦ a ≦ 1.1 (0.5
g + 0.06λ) Condition (2) g = 0.1-0.3 μm Condition (3) λ = 0.2-1.5 μm 2. The coercive force of a magnetic layer is 1200 to 1700O.
e. The magnetic tape according to claim 1, wherein the squareness ratio is 0.85 to 0.99. 3. The saturation magnetic flux density of the magnetic layer is 5,000 to 80.
Magnetic tape according to claim 1 or claim 2 characterized in that it is a 00G. 4. A method for recording signals on a magnetic tape having a metal thin film type magnetic layer having a thickness a, wherein a gap length satisfying the following conditions (1), (2) and (3) is satisfied. A magnetic recording method using a magnetic head of g and recording using a signal having a minimum recording wavelength of λ. Condition (1) 0.8 (0.5 g + 0.06λ) ≦ a ≦ 1.1 (0.5
g + 0.06λ) Condition (2) g = 0.1-0.3 μm Condition (3) λ = 0.2-1.5 μm