JPS5958619A - Vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To simplify the high-density vertical magnetic recording and to reduce the lowering of the SN ratio, by making the area of a high-permeability layer of a magnetic recording medium larger than that of a vertical magnetized layer. CONSTITUTION:A vertical magnetized layer 4' of a recording medium 7 is formed on a high-permeability layer 5 from one side in the lengthwise direction of this layer 5 except a slight part, and the area of the high-permeability layer 5 is wider than that of the vertical magnetized layer 4'. When a signal current is given to a recording/reproducing coil 3 wound around an auxiliary magnetic pole 2, a magnetic flux 8 is transmitted through a closed magnetic circuit formed with a main magnetic pole 1, the vertical magnetized layer 4', the high- permeability layer 5, the auxiliary magnetic pole 2, and the main magnetic pole 1 to perform the vertical magnetization recording on the vertical magnetized layer 4'. Since the complete closed magnetic circuit is formed easily, the high- density vertical magnetic recording is performed easily and the lowering of the SN ratio is reduced.

Description

[Detailed description of the invention] The present invention relates to a recording medium used for perpendicular magnetic recording.

The horizontal magnetic recording method, which magnetizes parallel to the surface of the recording medium, is generally used to record on magnetic recording media such as floppy disks and video tapes. , the output during reproduction becomes very small due to the influence of the demagnetizing field. On the other hand, a so-called perpendicular magnetic recording method has also been developed in which magnetization is performed directly on the surface of a magnetic recording medium. According to this method, the demagnetizing field becomes almost zero, and even when high-density recording is performed, an appropriate reproduction output can be obtained. A typical example of a perpendicular magnetic recording medium used in this perpendicular magnetic recording system is a high-permeability, high-permeability, vi-based thin film such as permalloy (Ni-Fe) on a non-magnetic support such as a plastic film. Perpendicular magnetization cans consisting of a magnetic layer and a ferromagnetic film such as Co-Cr (the crystal grains of the ferromagnetic material have the C-axis direction perpendicular to the support surface) are sequentially provided. There is (Special Publication No. 54-51804). There are two types of actual perpendicular magnetic recording systems using such recording media, as shown in Figures 1 (a) and (b).
), the magnetic head 9 has two magnetic poles from above and below the recording medium 7 (4 is a perpendicular magnetization 7 layer, 5 is a high permeability layer, 6 is a support body), that is, a main magnetic pole 1 and an auxiliary magnetic pole 2. (In the case of the bJO method, the head 9 records only from above the recording medium, similar to the ring head.

In either case, by passing a signal current through the recording/reproducing coil 3, the magnetic flux 8 forms a closed circuit as shown in this figure, but in the method (a), it is necessary to put the recording medium between the heads. However, the method itself has an inherent drawback in that the recording and reproducing efficiency of the head decreases for thick recording media.

On the other hand, method b) does not have these drawbacks, but does not form a complete closed circuit (the magnetic flux 8 emitted from the main pole 1 passes through the vertical magnetization layer 4 to the horizontal magnetization layer 5). After passing through the magnetic flux 8, it must pass through the perpendicular magnetic layer 4 before reaching the auxiliary magnetic pole 2. At this time, most of the magnetic flux 8 escapes into the air or toward the high permeability layer 5. (This does not result in a completely closed circuit.) As a result of increased magnetic resistance and decreased sensitivity of the head, there is a drawback in that the recording and reproducing efficiency of the head decreases, resulting in a decrease in the S/N ratio.

The first object of the present invention is to provide a recording medium that can easily perform high-density perpendicular magnetic recording.

The second object of the present invention is to create a magnetic recording medium that does not reduce the S/N ratio even when the perpendicular magnetic recording method shown in FIG. 1(b) is applied by forming a completely closed circuit during reproduction and recording. It is to provide.

That is, the perpendicular magnetic recording medium of the present invention is a 4M perpendicular magnetic recording medium in which a high magnetic permeability layer and a perpendicular magnetic layer are sequentially provided on at least one surface of a non-magnetic support, in which the high magnetic permeability layer is higher than the perpendicular magnetic layer. It is also characterized by having a large area.

An example in which the recording medium of the present invention is applied in the form of a tape to the perpendicular magnetic recording method shown in FIG. 1(b) is shown in FIGS. 2(,) and (b).
, and shown in FIG. Note that FIG. 2(a) is a perspective view of the example, and FIG. 2(bl is a side view of FIG. 2(a). Third
The figure is a side view of another example. In the case of FIG. 2, the perpendicular magnetization 1 so 4' in the recording medium 7 of the present invention leaves a small portion (for example, 2 to 4 wn in the case of a tape with a width of 8 to 10 mm) from one longitudinal side of the high magnetic permeability WJ5. High permeability RJ
The high permeability N5 jut formed on the magnetic layer S is therefore wider than the perpendicular magnetization layer 4'. In the case of FIG. 3, the perpendicular magnetization M4' is formed on the high magnetic permeability layer 5, leaving the central part in the longitudinal direction of the high magnetic permeability layer 5 (for example, 2 to 4 brains in the case of a tape with a width of 8 to 105 W). Therefore, in this case as well, the area of the high magnetic permeability layer 50 is wider than that of the perpendicular magnetization layer 4'. In either case, when a signal current corresponding to the information to be recorded is applied to the recording/reproducing coil 3 wound around the auxiliary magnetic pole 2, the magnetic flux 8 is changed from the main magnetic pole l→perpendicular magnetic layer 4'→high permeability rib 5→ It passes through the closed magnetic circuit formed by the sleeve auxiliary magnetic pole 2 → main magnetic pole. As a result, information corresponding to the current is magnetically recorded in the recording medium 70 directly magnetized layer 4' facing the tip of the main magnetic pole 1 in a direction perpendicular to the narrow surface of the recording medium 7.

Note that in these figures there is a step between the perpendicular magnetization layer 4' and the high permeability Jso 5, but in reality this step is so small that it can be said that there is almost no difference, so it is shown in Fig. 4. Such head movements can be performed smoothly without any interference.

To make the perpendicular magnetic recording medium of the present invention, a high permeability magnetic material is deposited on at least one surface of a non-magnetic support by a method such as vapor deposition or sputtering to form a high permeability layer, and then a high permeability layer is formed on the layer. a) Masking is performed to obtain a perpendicular magnetization layer of a desired size, and then the perpendicular magnetization layer is deposited by a method such as vapor deposition or sputtering, and then the mask y/ is removed, or b) the perpendicular magnetization layer is formed. A perpendicular magnetization layer of a desired size may be provided on the high magnetic permeability layer by depositing the perpendicular magnetization layer on the entire surface and then etching this surface so as to obtain a perpendicular magnetization layer of a desired size. The quotient magnetic permeability magnetic materials used here are permalloy (N1-Fe), M
a-Per-z Roy, Cu-Mo-Permalloy, Co
-Zr-Nb, etc. can be exemplified. Examples of the material for forming perpendicular magnetization Iψ include Co-Cr, Co-Ru, Ba-ferrite, Co-Ni-P, and the like. Further, as the non-magnetic support, a plastic film (for example, a film of polyester or polyimide), a glass plate, or a non-magnetic support (for example, a plate of Al, Cu, etc.) can be used.

In the magnetic recording medium of the present invention, since the area of the high magnetic permeability layer is larger than the area of the perpendicular magnetic layer, a complete closed circuit is formed during recording and reproduction as shown in FIGS. 2 and 3. Therefore, high density recording with a low S/N ratio is possible.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are explanatory diagrams of the perpendicular air recording method, FIGS. 2(a) and (b), and FIG. 3 are respectively illustrations of the state in which recording is performed on the magnetic recording medium of the present invention. They are a perspective view of one example, a side view thereof, and a side view of another example. l... Main magnetic pole 2... Auxiliary magnetic pole 3... Coil 4, 4'... Directly magnetized layer 5... High permeability layer 6... Reluctant support 7... Perpendicular loss recording medium 8...Magnetic flux 9...Magnetic head procedural amendment November 18, 1980 Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office ■, Indication of the case Relationship to the case of Patent Application No. 170020 of 1982 Patent Applicant Ricoh Co., Ltd. 1-3-6 Nakamagome, Ota-ku, Tokyo (674) Representative Takeshi Oue 4, Agent 5, "Detailed Description of the Invention" column of the specification to be amended and drawings Contents of the amendment 1) Add “(lift-off method)” after “etching” on page 6, line m4 of the specification. 2) Replace Figure 2(b) and rJt5@3 with the attached drawings. 7 List of attached documents

Claims (1)

[Claims] 1. In a perpendicular magnetic recording medium in which a high magnetic permeability layer and a perpendicular magnetization layer are sequentially provided on at least one surface of a nonmagnetic support,
A perpendicular magnetic recording medium characterized in that the high magnetic permeability 1- has a larger area than the perpendicular magnetization stirrup.