JPH02260102A - magnetic recording device - Google Patents

Abstract

PURPOSE:To execute a recording cleanly even to a deep part by using a magnetic head and confining the ratio of the recording current to the wavelength of twice the effective gap length of this head and the recording current to the wavelength of thrice the effective gap length of the magnetic head to the value within + or -6dB. CONSTITUTION:A magnetic layer 8 is formed by vapor deposition of a metallic thin film consisting of a Co-Ni-O system (20wt.% Ni in this embodiment) on a high-polymer film. The magnetic layer 8 has the directivity occurring in a column structure when the vapor deposition is started from a connection direction along a cylindrical can and is executed to 0.2mum thickness at 30 deg. min. incident angle in an O2 atmosphere. High recorded and reproduced outputs are obtd. when a tape 8 and the magnetic head 6 travel in an arrow direction shown in figure. The good reproduced output and noise level are obtd. by confining the recording current when the ratio lambda/l of the recording wavelength lambdaand the effective gap length l is lambda/l=2 to the value within + or -6dB with respect to the current when lambda/l=3. The recording to not only the surface layer part of the magnetic layer 8 but also down to the deep part in the short wavelength recording is cleanly executed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording device that performs high-density magnetic recording using a thin film magnetic tape.

BACKGROUND OF THE INVENTION In recent years, various magnetic recording methods have been developed to achieve higher density recording, depending on the purpose.

Among these, analog image recording using magnetic tape is widely used for consumer and business purposes because it is low cost, has high image quality, and can record for a long time. Due to the large amount of information in magnetic recording, it is necessary to increase the density in order to make the equipment smaller and achieve higher image quality. In order to achieve higher density, research is being conducted not only on recording methods but also on improving the performance of magnetic tapes and magnetic heads.

An example of the above-mentioned conventional magnetic recording system will be described below with reference to the drawings.

FIG. 4 is a conceptual diagram of a conventional magnetic recording system interface, FIG. 5 is a diagram showing recording current characteristics, and FIG. 6 is a block diagram of a recording signal. In FIG. 4, 1 is a magnetic head;
2 is a head gap, 3 is a magnetic layer, 4 is an area where short wavelengths are recorded neatly, and 5 is an area where short wavelengths are recorded in a disordered manner.

In FIG. 5, the horizontal axis represents recording wavelength/effective cap length (hereinafter abbreviated as λ/e), and the vertical axis represents recording current. The recording current is the recording current to the magnetic head when a voltage intermediate to the dynamic range of the input signal is selected and a single frequency signal of each frequency corresponding to the horizontal axis is input to the input signal to the magnetic recording device. It is. However, frequencies affected by carrier waves when FM modulated are excluded.

If it is necessary to evaluate the recording current for a frequency affected by a carrier wave when FM modulated, the following method can be used for evaluation. That is, in the block diagram shown in FIG. 6, the frequency characteristics of the pre-emphasis before FM modulation and the frequency characteristics of the recording equalizer and recording amplifier after FM modulation are investigated, and the correspondence relationship between the input signal frequency and the recording current frequency is determined. It can be evaluated by considering the

Regarding the conventional magnetic recording device configured as described above,
The operation will be explained below.

In Figure 5, when λ/2 is 2, the recording current is 3
It is -11d,B compared to the time of . This is based on the recording characteristics of conventional magnetic tapes, and is a problem that occurs when the recording wavelength λ approaches the effective gap length e due to high-density recording. The playback output output is also quite small. The cause of this phenomenon is thought to be as follows. In Figure 4, the effective gap length of the magnetic head conventionally used for magnetic recording is 0.28.
~0.5 μm, the shortest recording wavelength is optimal recording current μm, and the magnetic layer thickness is approximately 2.5 to 6 μm.

Problems to be Solved by the Invention However, in the above structure, although the thickness of the magnetic layer is quite thick in FIG. 4, short wavelengths are actually recorded only in the surface layer parts of regions 4 and 5. Furthermore, the region 4 where short wavelengths are recorded neatly contributes to the reproduction output, but the region 5 where the short wavelengths are recorded in a disordered manner reduces the reproduction output and increases noise. Therefore, in short wavelength recording, the reproduction output is determined by the balance between the thicknesses of the layers in regions 4 and 5, so that the optimum recording current is a low recording current that does not increase the thickness of region 5. The problem with the ratio of the thicknesses of regions 4 and 5 is the magnetization process in which the magnetic tape is magnetized by the magnetic field created by the magnetic head, and this can be treated as a parameter of recording wavelength/effective cap length (λ/2). That's a problem. Experimentally, when λ/2 becomes 3 or less, the thickness of region 5 becomes a big problem, and as shown in Figure 5, when λ/2 becomes 3 or less,
The optimum condition is a recording current setting that is 11 dB lower than when 2 is 3. In a magnetic recording device configured in this way, the potential of Br and He, which magnetic tape originally has, cannot be fully utilized in the short wavelength region, and the reproduction output and C/N are lower than the original ability of magnetic tape. It had the problem of becoming.

In view of the above-mentioned problems, the present invention provides a magnetic recording device that can fully utilize the original capabilities of the magnetic tape by improving the orientation of the magnetic tape and the recording current characteristics of the magnetic recording device. be.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a ratio of a recording current to a wavelength that is twice the effective gap length of the magnetic head and a recording current to a wavelength that is three times the effective gap length of the magnetic head. is within ±6 dB.

Effects The present invention, with the above-described configuration, enables deep and clear magnetic recording in the thickness direction even when λ/2 is 3 or less, thereby making full use of the inherent ability of the magnetic tape. will be possible.

EXAMPLE Hereinafter, a magnetic recording device according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram of an interface of a magnetic recording system according to a first embodiment of the present invention, and FIG. 2 is a diagram showing recording current characteristics. In FIG. 1, 6 is a magnetic head, 7 is a head gap, and 8 is a magnetic layer of a C0-0 series or Co-Ni-0 series metal thin film magnetic tape. FIG. 2 is a diagram similar to FIG. 5, and shows the relationship between λ/2 and recording current.

The operation of the magnetic recording device for recording FM modulated images configured as described above will be described below with reference to FIGS. 1 and 2.

First, FIG. 1 is a conceptual diagram of a magnetic recording system interface. The magnetic layer in this example is manufactured by depositing CoCo-N1 (20%) on a polymer film. Vapor deposition was started from the connecting direction along the cylindrical can, and was deposited to a thickness of 0.20 μm at a minimum incident angle of 30” in an 02 atmosphere. The magnetic layer of the magnetic tape manufactured in this way is shown in Figure 1. It has a column structure as shown in Figure 1, and has a directionality due to the column structure.The recording and playback output is higher when the tape and head run in the direction of the arrow shown in Figure 1. It turns out that this is a problem during recording, not during reproduction.The direction of easy magnetization of the magnetic layer is not in the in-plane direction (the direction tilted from the in-plane is the easy magnetization direction. Because of the structure of the magnetic layer, the magnetization process is thought to be slightly different from that of a normal magnetic layer.Using an amorphous magnetic head with an effective Rad gap length of 0.2 μm,
Magnetic recording and reproduction were performed using a magnetic recording device having recording current characteristics as shown in FIG. The results are shown in Table 1.

In Table 1, A and B are conventional examples using a magnetic recording device with the conventional recording current characteristics shown in Figure 5, and C and D are magnetic recording devices with the recording current characteristics shown in Figure 2. These are a reference example and an example using a recording device. A and C use a metal powder coated magnetic tape, and B and D use a Co-Ni-0 metal thin film magnetic tape. For the recording current and reproduction output, the optimum conditions for the Co-Ni-0 metal thin film type magnetic layer when λ/e-3 are OdB, and the conditions for the metal powder coated type are shown for the optimum recording current of -1 dB. . As is clear from Table 1, according to this example, λ/e-2
High playback output can be obtained even when

As described above, according to this embodiment, a C0-N1-0 metal thin film magnetic tape and a magnetic head are used, and the recording current for a wavelength twice the effective gap length of the magnetic head is controlled by the effective gap length of the magnetic head. By setting the recording current to be 2 dB lower than the recording current for a wavelength three times the length, a high reproduction output could be obtained even at λ/e-2, and the true potential of the magnetic tape could be brought out.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 shows the characteristics of the reproduction output and noise level with respect to the recording current of the FM modulation image recording method according to the second embodiment of the present invention. In Figure 3, the horizontal axis is λ/
This is a recording current of λ/e-2 based on the recording current at e-3. The magnetic layer was a 0.16 .mu.m thick co-metal thin film prepared in the same manner as in Example 1, and a Sendust head with an effective Rad gap of 0.15 .mu.m was used. As is clear from FIG. 2, the reproduction output is almost saturated when the recording current difference is about 12 dB. First, the output saturation point is 12 dB, which is more than 4 dB higher than when other conventional media are used, and this point will be explained. In the conventional magnetic recording system, when λ/e-2, this is exactly λ-0,3
In μm, the thickness of the well-recorded layer shown in FIG. 4 is theoretically and experimentally λ/4=0.075 μm.

On the other hand, in this example, it is considered that the total magnetic layer thickness of 0.15 μm is magnetized neatly, so the optimum recording current is approximately doubled. The reason why it is considered that almost the total magnetic layer thickness is recorded is that the optimum recording current does not change at -2 dBL from when λ/e-3. Furthermore, regarding the output when the optimum recording current is exceeded, it is common knowledge that in the conventional example, the output decreases rapidly due to an increase in disturbed recording, but in this embodiment, there is almost no decrease in the output. This is considered to be because the Co-based metal thin film has extremely strong directionality in one direction. The noise level problem in FIG. 3 indicates the occurrence of cross-modulation in multi-frequency recording, and another problem will occur if the recording current at λ/e-2 is made too high.

As mentioned above, the recording current when λ/e-2 is λ/e-3
A good reproduction output noise level can be obtained by keeping the noise level within ±6 dB with respect to the case of .

In this example, the thickness of the magnetic layer is not particularly limited, but is preferably about 0.05 to 0.3 μm. Although amorphous and sendust were used as magnetic head materials, other materials such as ferrite may also be used. Further, as described in the second embodiment, the effect of the present invention is exhibited as the magnetic layer thickness becomes larger than λ/4, but at present, even when the magnetic layer thickness is ξλ, It has been confirmed that almost the entire magnetic layer is clearly magnetized.

In addition, a magnetic layer with a thickness of 0.16 to 0.20 μm has good electromagnetic conversion characteristics over the entire range from long wavelengths to short wavelengths, but
/λ-0.18 μm, the effect of the present invention is large in the region of λ0.72 μm or less. In other words, λ-0.72
Since λ/e-3 in μm, the effect of the present invention is large in the region where e is 0.24 μm or less. Note that although this embodiment has been described for FM modulation image recording, the purpose is not particularly limited.

Effects of the Invention As described above, according to the present invention, in short-wavelength recording, recording is performed not only in the surface layer of the magnetic layer (not only in the deep part), but also in the deep part, and the original electromagnetic conversion characteristics of the magnetic tape can be fully utilized. This excellent effect can be obtained.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of the magnetic recording system of the first embodiment of the present invention, FIG. 2 is a recording current characteristic diagram of the first embodiment of the present invention, and FIG. 3 is a diagram of the second embodiment of the present invention. Figure 4 is a conceptual diagram of the conventional magnetic recording system, Figure 5 is a conventional recording current characteristic diagram, and Figure 6 is a diagram showing the relationship between reproduction output and noise with respect to the recording current difference.
The figure is a block diagram of a recording signal. 6...Magnetic head, 7...Head gap, 8...Magnetic layer of Co-0-based or co-Ni-○-based metal thin film magnetic tape.

Claims (1)

[Claims] A magnetic recording device using a magnetic head, characterized in that the ratio of the recording current for a wavelength twice the effective gap length of the magnetic head to the recording current for a wavelength three times the effective cap length of the magnetic head is within ±6 dB. .