JPS6171413A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent the satn. of magnetic flux during recording and to improve the head output during reproducing by providing plural low coercive force layers having the magnetic permeability different from the magnetic permeability of satd. magnetization between a substrate material and high coercive force layer. CONSTITUTION:The 1st and 2nd low coercive force layers 9, 10 are constituted between the high coercive force layer 12 and the substrate material 13 to form a magnetic recording medium 11. A material having large satd. magnetization Ms, for example, a material such as pure iron or an alloy of iron and Co (Fe70Co30) having 2,300-2,400 Gauss satd. magnetization is used for the layer 9. A material having large magnetic permeability mu, for example, an alloy of Ni and iron such as 'Permalloy(R)' (Ni78Fe22) or amorphous material (CoZr amorphous material) is used for the layer 10. The saturation of the magnetic flux is prevented by the layer 9 having the high satd. magnetization Ms even in the part of the high magnetic flux density owing to the focusing of the magnetic flux during writing by using the two-layered low coercive force in the above-mentioned manner. The magnetic flux from the layer 12 flows efficiently to the auxiliary magnetic pole even during reproducing and therefore the head output is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording medium for magnetically recording information.

Structures of conventional examples and their problems In recent years, with the improvement of magnetic recording density, perpendicular magnetization recording methods have been proposed that reduce the demagnetizing field in the magnetic recording layer and enable high-density recording (for example, Japanese Patent Laid-Open No. 52 -134706, 53-3209). Furthermore, as a magnetic recording medium suitable for this method, a medium consisting of two layers, a magnetization layer and a low coercive force layer, has been proposed (Japanese Patent Laid-Open No. 54-518
(See Publication No. 04).

FIG. 1 shows an example of a conventional magnetic recording medium. A magnetic recording medium 1 has a large coercive force and is composed of a magnetic layer 2 having an axis of easy magnetization in the perpendicular direction, a low coercive force layer 3, and a base material 4. The base material 4 is a polyester film or the like, and on top of this, R
With F sputtering method etc. (-Low coercive force material such as malloy 3
Further, a magnetized layer 2 made of a high coercive force material such as a CoCr alloy is formed on the low coercive force material 3. This magnetic recording medium performs recording and reproduction using a single magnetic pole head, for example, a head having the configuration shown in FIG. The main magnetic pole (single magnetic pole) 6 is composed of a thin film with high magnetic permeability, and an auxiliary magnetic pole 6 is arranged on the opposite side of the magnetic recording medium 1, and electrical signals are input and output from a coil 7 wound around the auxiliary magnetic pole 6. do. For writing, a current according to the signal is passed through the coil 7, and the magnetic flux 8 generated thereby is focused on the low coercive force layer 3 of the magnetic recording medium 1, and then focused on the magnetic layer 2 having high coercive force. The current flows to the main magnetic pole 5.

For this reason, the magnetic layer 2 of the magnetic recording medium 1 has a high coercive force.
Residual magnetization remains in the area where the magnetic flux is focused and is recorded.
By relatively moving the magnetic recording medium 1 and the head (main magnetic pole 5 and auxiliary magnetic pole 6), residual magnetization is sequentially recorded in accordance with signals.

Reproduction is the reverse process to the above-mentioned writing, and in the part of the magnetic recording medium 1 near the main magnetic pole 6, the magnetic flux 8 generated from the perpendicular residual magnetization left in the magnetic layer 2 with high coercive force is It flows from the coercive force layer 3 through the auxiliary magnetic coil 6, crosses the coil 7, and becomes the head output.

As mentioned above, during recording, the magnetic flux 8 generated from the auxiliary magnetic pole 6 is focused and passes through the low coercive force layer 3, so the magnetic flux is concentrated near the main magnetic pole 6, and the low coercive force layer 3 is not saturated. requires a high saturation magnetization Ms. Conversely, during reproduction, it is important for the magnetic flux to flow efficiently through the low coercive force layer 3 to the auxiliary magnetic pole 6 in order to increase the head output, and the magnetic permeability μ of the low coercive force layer 3 is high. is required. However, the conventional example has the drawback that it is difficult to simultaneously satisfy high saturation magnetization Ms and high magnetic permeability μ with a single material.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and aims to prevent saturation of magnetic flux during recording and improve head output during reproduction.

Structure of the Invention The present invention provides a magnetic recording medium characterized in that a plurality of low coercive force layers having different saturation magnetizations and magnetic permeabilities are provided between a base material and a high coercive force layer.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a cross-sectional view of a magnetic recording medium in one embodiment of the present invention, and the magnetic recording medium 11 of this embodiment has a high coercive force layer 1.
2 and the base material 14, first and second low coercive force layers 9
, 1o. The first low coercive force layer 9 has a saturation magnetization Ms
Materials with large values such as pure iron and alloys of iron and Co (Fe
-r. Saturation magnetization such as Co 3°) 23000-240
00 Gauss material is used.

The second low coercive force layer 1o is made of a material with a large magnetic permeability μ, for example, an alloy of Ni and iron such as permalloy (N1-r
aF e 22 ) and ammo/lz 77 materials (C
oZr-based amorphous material).

In this way, by forming the low coercive force layer into two layers, saturation of the magnetic flux can be prevented by the first low coercive force layer 9 having a high saturation magnetization Ms even in a portion of high magnetic flux density due to magnetic flux convergence during writing.

Also, during reproduction, since the second low coercive force layer 10 is made of a material with a large magnetic permeability μ, the magnetic flux from the high coercive force layer 12 efficiently flows to the auxiliary magnetic pole (not shown), so that the head output will improve.

FIG. 4 shows a sectional view of a magnetic recording medium in another embodiment of the present invention.

The magnetic recording medium 11 of this embodiment has first and second low coercive force layers 9°1o arranged between the high coercive force layer 12 and the base material 14 in the reverse order from that in FIG. That is, a first low coercive force layer 9 made of a material with a large saturation magnetization Ms is provided on the base material 14, a second low coercive force layer 1o made of a material with a large magnetic permeability μ is provided on top of the first low coercive force layer 9; A high coercive force layer 12 is provided thereon. In this case, the second low coercive force layer 10 with high magnetic permeability is close to the high coercive force layer 12, and a magnetic flux with high magnetic permeability flows easily during reproduction, which is advantageous during reproduction.

In the magnetic recording medium of the present invention, there may be not only one high saturation magnetization layer and one high permeability layer, but also two or more layers, and the head used for recording and reproduction may have a single magnetic pole. It goes without saying that any type of head other than the one illustrated in FIG. 2 may be used as long as it is a head.

Effects of the Invention In short, the present invention provides a magnetic recording medium in which two or more low coercive force layers having different saturation magnetizations and magnetic permeabilities are provided between a base material and a high coercive force layer. It is possible to prevent magnetic flux and improve reproduction output.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional magnetic recording medium, FIG. 2 is an overview of a recording/reproducing head using the conventional example, and FIG. 3 is a sectional view of a magnetic recording medium in an embodiment of the present invention. FIG. 4 is a sectional view of a magnetic recording medium in another embodiment of the present invention. 9...First low coercive force layer made of high saturation magnetization material, 1o...Second low coercive force layer made of high magnetic permeability material, 11...Magnetic Recording medium, 12...
...High coercive force layer, 13...Base material. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) A high coercive force layer having an axis of easy magnetization in the thickness direction is provided on at least one main surface of the base material, and two or more layers with different saturation magnetizations and magnetic permeabilities are provided between the base material and the high coercive force layer. A magnetic recording medium characterized by being provided with a coercive layer. (2) The low coercive force layer provided between the base material and the high coercive force layer is comprised of a high saturation magnetization material layer and a high permeability material layer. magnetic recording medium. (3) The magnetic recording medium according to claim 2, wherein the high magnetic permeability material layer is formed between the high coercive force layer and the high saturation magnetization material layer.