JPS59188829A - Double-layered magnetic recording medium - Google Patents

Abstract

PURPOSE:To enable recording and reproducing at a high recording density and high track density by providing a buffer layer between two upper and lower magnetic layers, and decreasing the influence of the recording magnetic field on the lower magnetic layer during recording of a data signal on the upper magnetic layer. CONSTITUTION:A double-layered magnetic recording medium 1 is constituted by forming a lower magnetic layer 5 on a non-magnetic substrate 6, forming a buffer layer 4 consisting of a non-magnetic material having high conductivity thereon, forming further an upper magnetic layer 3 for recording data signal thereon, and forming a protective film 2 thereon in order to prevent the damage of the layer 3 by contact with a magnetic head, etc. A magnetic material consisting of, for example, Co, Ni, Mn and P formed by a plating method is used for the layer 5 formed on the substrate 6, and a material having high coercive force is selected. A non-magnetic material having high conductivity such as, for example, Cu and Ag, formed by a plating method is selected for the layer 4. A magnetic material consisting of, for example, Co, Ni and P, formed by a plating method is selected for the layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording device that accurately aligns a magnetic head to a desired data track and enables high recording density, high data track density, and more particularly, the present invention relates to a magnetic recording device that accurately aligns a magnetic head to a desired data track and enables high recording density and high track density. There is a data signal and a data tracker at position 4@ (hereinafter referred to as servo signal).
It pertains to a magnetic double layer recording medium in which

In a magnetic recording device that records data in concentric circles on the surface of a magnetic recording medium, it is necessary to constantly align the dots with the desired data tracks in the magnetic field for recording and reproduction. As a method for improving the accuracy of alignment between magnetic fields and desired data tracks, there is a method of using a magnetic double layer disk as a magnetic recording medium, as described in detail in Japanese Patent Publication No. 41-2586. . That is, I+
'In a magnetic double layer disk, two magnetic layers with different coercive forces are formed on a magnetic disk substrate so that the coercive force of the lower magnetic layer is higher than the coercive force of the upper magnetic layer. Recording is performed on the lower magnetic layer. The servo signal and the data signal recorded on the upper magnetic layer are simultaneously read out by the magnet, the two signals are separated from the read signal, and the obtained servo signal is transferred to the magnetic layer and the desired data is read out. This is a method that matches the top of the track.

However, with this method, when recording a 1-wheel signal using the servo controller of the lower magnetic layer, if the coercive force of the lower magnetic layer is too large, the servo signal may not be recorded. As a result, a magnetic material having a sufficiently large coercive force cannot be used. Therefore, when recording data signals on the upper magnetic layer, the magnetization is affected by the write magnetic field, which deteriorates the magnetization/<turn of the lower magnetic layer where the servo signals are recorded. Become.

In order to improve these above-mentioned drawbacks, magnetic recording with a simple structure in which the threatening magnetic field of the data signal does not reach the lower magnetic layer and in which it is easy to write and retrieve servo signals to and from the lower magnetic layer is required. It would be great if the medium could make it happen. In view of these points, it is an object of the present invention to provide a magnetic recording medium that enables high recording density, high density recording and reproduction.

According to the present invention, the magnetic layer consists of two upper and lower magnetic layers formed on a non-magnetic substrate, the upper magnetic layer is for recording data signals,
In a magnetic recording medium in which a servo signal for track positioning is recorded in a lower magnetic layer, a buffer layer made of a non-magnetic material having high conductivity is provided between the two upper and lower magnetic layers,
Datatra in the upper magnetic layer using the electromagnetic skin effect of the buffer layer.

When recording a data signal on the buffer layer, it is possible to eliminate the influence of the recording magnetic field on the lower magnetic layer where the servo signal is recorded. By being able to easily carry out this process without being affected by this, it is possible to obtain a magnetic double r@ recording medium that is capable of recording and reproducing with high recording density, high torque, and high accuracy.

The configuration and effects of the present invention will be explained below using the drawings.

FIG. 1 is a sectional view parallel to the recording direction of an embodiment of the magnetic double layer recording medium of the present invention.

The magnetic double layer recording medium 1 of this embodiment has a lower magnetic layer 5 formed on a non-magnetic substrate 6, and a wire tN#4 made of a non-magnetic material having high conductivity is formed on the lower magnetic layer 5 by, for example, plating. In this structure, an upper magnetic layer 3 for recording data signals is formed on top of the upper magnetic layer 3, and a protective film 2 is formed on top of the upper magnetic layer 3 to prevent damage to the lower magnetic layer 3 due to contact with magnetic fields. It has become.

Next, the principle of the present invention will be explained.

That is, since the recording magnetic field for data signals written into the upper magnetic layer 3 using the magnetic head can be regarded as a high frequency electromagnetic field,
Due to the magnetic skin effect of the highly conductive non-magnetic buffer layer 4, high frequency leakage flux to the magnetic layer #5 is partially blocked. As a result, it is difficult to consider changing the magnetization pattern of the lower magnetic layer 5 in which the servo signals are recorded. Further, since the coordinates of the leakage magnetic flux of the servo signal from the magnetization pattern of the simultaneous KT partial magnetic layer 5 are fixed to the magnetic recording medium 1, it can be regarded as a DC magnetic field when viewed from the buffer layer 4.

Therefore, the leakage magnetic flux of the servo signal is not affected by the buffer layer 4 at all and leaks to the surface of the magnetic double layer recording medium 10, so it is possible to detect this leakage magnetic flux with a magnetic head and obtain a low-frequency servo signal. can.

The lower magnetic layer 5 formed on the non-magnetic substrate 6 is made of Go, Ni, Mn, etc. formed by plating, for example.
A magnetic material made of P is used, and a material with high coercive force is selected.

The buffer layer 4 is made of Cu, A, formed by plating, for example.
A non-magnetic material with high conductivity, such as g, shall be selected. Due to the effect of this buffer layer 4, when a data signal is input into the upper magnetic layer m3Kff, the leakage magnetic flux is blocked from reaching the lower magnetic layer 5. Therefore, the coercive force of the lower magnetic layer 5 is made of a material that is not so high. There's no need to choose. In addition, the upper magnetic layer was formed by three companies, for example, Co, Nt,
Assume that a magnetic material made of P is selected.

In this way, providing the non-magnetic buffer N4 with high conductivity has the advantage that the coercive force of the partial magnetic layer 5 does not need to be selected to be very high, and that it is possible to reduce the magnetic force when recording data signals. There is also an advantage that the deterioration of the magnetization pattern of the lower magnetic layer 5, which generates the servo signal, is almost impossible due to the penetrating magnetic field.

FIG. 2 shows the effect of the buffer HM4 on the leakage magnetic flux of the magnetic head when the buffer layer 4 is made of a conductive non-magnetic material such as Cu in the magnetic double layer recording medium according to the embodiment of the present invention. This is a diagram.

That is, the thickness of the buffer layer 4 is plotted on the horizontal axis, and for each of the frequency 7 of the recording magnetic field for servo signals and the frequency r8 of the recording magnetic field for data signals, the strength of the magnetic field at a certain observation point is the thickness of the buffer layer 4. The effects of the electromagnetic skin effect,
It is normalized and shown by the intensity of the magnetic field when the buffer layer 4 is not present.

For example, the recording frequency 8 for data signals commonly used in floppy disk devices is several MHz,
Also, a frequency of about i7 to 100 KH2 is used for servo signals. Therefore, FIG. 2 shows a case where, for example, the recording frequency 8 for data signals is 5 MH, and the frequency 7 for servo signals is 100 KH2. As shown in the figure 5, due to the effect of the buffer layer 4, the magnetic field is hardly reduced in the case of the low frequency 7 for the servo signal, whereas in the case of the high frequency 8 for the data signal, the magnetic field is reduced by 111
1tili! When the film thickness of No. 4 is 5 μm, the strength of the magnetic field is attenuated by 20%, and when it is 10 μm, it is attenuated by 30%. Therefore, if the buffer layer 4 is made of a non-magnetic material with high conductivity and has a certain film thickness, for example, about 10 μm, the write magnetic field when recording data signals in the upper magnetic layer 3 will be lower than the lower magnetic layer. M
Since the influence on the servo signals can be completely eliminated, there is an advantage that deterioration of the magnetization pattern that generates the servo signal is almost impossible.

Further, leakage magnetic flux from the magnetization pattern that generates the servo signal of the lower magnetic layer 5 can be regarded as a DC magnetic field when viewed from the buffer layer 4 because the dust mark is fixed to the recording medium l. Therefore, the leakage magnetic flux from the magnetization pattern that generates the servo signal is not affected by the buffer M4 at all and leaks to the surface of the magnetic double layer recording medium 1. A frequency servo signal can be obtained.

According to the present invention, a non-magnetic buffer layer having high conductivity is provided between the upper and lower magnetic layers, and the electromagnetic skin effect of the buffer layer is used to In addition to recording the vc data signal, it is possible to reduce the influence of the recording magnetic field on the lower magnetic layer where the servo signal is recorded, while writing and reading the servo signal to the lower magnetic layer does not require the lI! Since a magnetic double layer recording medium is obtained that is not affected by the impact layer and can be easily used, the servo signal and the data signal can be read out simultaneously with the magnetic field and the magnetic field, and each can be separated to obtain the position error signal. By using a method of causing a magnetic head to follow a desired data track, high recording density and high track density recording and reproducing, which has been a problem for some time, can be achieved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view parallel to the recording direction of an embodiment of the magnetic double layer recording medium of the present invention, and FIG. 2 illustrates the effect of the highly conductive buffer layer 4 of the present invention on the strength of the magnetic field. This is a diagram shown for the purpose. l... Magnetic double layer recording medium, 2... Protective film, 3.5
...Magnetic layer, 4...Buffer layer having conductivity, 6...
・Non-magnetic basics, 7, 8...frequency. 145

Claims (1)

[Scope of Claims] Consisting of two magnetic layers, upper and lower, the upper magnetic layer is used for recording data signals, and the lower magnetic layer has a magnetic layer. In a magnetic recording medium in which a servo signal for positioning is recorded, a loose wIJ layer made of a highly conductive non-magnetic material is provided between the two upper and lower magnetic layers, and the upper magnetic layer is A magnetic double layer recording medium characterized in that even during data signal recording, the influence of the recording magnetic field on the lower magnetic layer on which servo signals are recorded is reduced.