JPS6255202B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel structure for a magnetic head. Figure 1 shows a conventional ring-shaped magnetic head with a gap G.
A coil 2 is attached to a core 1 having a core 1, and when the magnetic recording medium 4 moves relatively in the direction of arrow A, information is recorded by applying a recording magnetic field to the magnetic recording medium 4 through a gap G. . Therefore, in the conventional magnetic head of FIG. 1, the effective component of the recorded magnetic field is in the direction of media movement. In order to perform high-density recording with this type of magnetic head, it is necessary to make the gap G of the read head extremely small.Currently, gap G of about 0.3 to 0.5μ is used, but this is approximately This is a mechanical limit.

Two new recording methods have been proposed to solve this problem. One of them has a magnetic gap almost perpendicular to the direction of relative movement with the recording medium and is disclosed in Japanese Patent Application Laid-open No. 50-81505 and U.S. Patent No. 3,984,874, and the other is a perpendicular magnetization method. It is called. The former method allows for a high recording density, but has the disadvantage that it is impossible to read out data using the same head because a large number of recorded signals are read out. On the other hand, the latter has a structure as shown in FIG. 2, for example, in which a recording magnetic field 6 is generated between a main magnetic pole 5 having a sharp edge and a main magnetic pole 5 having a sharp edge via a magnetic recording medium 4 by a coil 2 attached to a core 1. The effective component of the magnetic field is in the thickness direction of the magnetic recording medium. This method allows high-density recording, but since the magnetic path is an open magnetic path, it is difficult to read out recorded signals.

In order to solve this problem, the present applicant previously proposed in Japanese Patent Laid-Open No. 5417/1983 a new magnetic head structure which operates in the perpendicular magnetization system as shown in FIGS. 3A to 3C. In each figure, 10 is an approximately U-shaped core made of magnetic material that constitutes the main magnetic pole;
12 is a non-magnetic spacer inserted into the gap of the core 10; 13 is a magnetic tape; 14 is an auxiliary magnetic pole; 15 is a recording magnetic field;
indicates the direction of relative movement of the magnetic tape. core 10
is the side surface 10a that gently approaches the magnetic tape.
and a side surface 10b that is abruptly separated from the tape. As shown, the core 10 has an asymmetrical shape with respect to the tape traveling direction. Since the auxiliary magnetic pole 14 is provided opposite the core 10 via the tape, the recording magnetic field 15 becomes perpendicular to the film surface of the magnetic recording medium (in the thickness direction). Since the side surface 10b has a sharp cut surface, the linear recording density is equivalent to that of the perpendicular magnetization method shown in FIG. , the influence of external noise is reduced. Furthermore, since the magnetic path is a closed magnetic path even during recording, crosstalk between the heads is reduced even when a plurality of heads are arranged.

Since the core 10 includes a gentle side surface 10a and a sharp side surface 10b, during reproduction, the time of the magnetic flux applied to the portion 10a on the left side of the right end 10b of the head out of the recording magnetic field that exists over the entire width W of the head. The change in voltage is gradual, and therefore almost no voltage is induced to the coil 11 from this portion 10a. The recording magnetic field is located at the right end of the head.
At the moment when the magnetic flux passes through b, there is a large change in magnetic flux in the core 10, so a large induced voltage is generated in the coil 11. In other words, the reproduced signal is the rightmost 1 of the head.
Since it is applied only from the magnetic field passing through 0b, a high-density recording magnetic field can be reproduced even though the width W of the core 10 is wide.

The magnetic head shown in Fig. 3 is capable of high-density recording using the perpendicular magnetization method, but there is a mechanical limit to narrowing the track width, and the width D of the leg cannot be made small. It has the disadvantage that it is not suitable for magnetic heads.

Therefore, it is an object of the present invention to provide a magnetic head using a perpendicular magnetization method with a narrow track width, and its feature is that the longitudinal direction of the parallel legs of the substantially U-shaped ferromagnetic core is aligned with the moving direction of the magnetic recording medium. and that the core is composed of two thin plates and an upper base made of a ferromagnetic material that connects the two with one leg. This will be explained in detail below with reference to the drawings.

FIG. 4A is a diagram of each leg of the magnetic head according to the present invention, FIG. 4B is a perspective view of the magnetic head according to the present invention,
FIG. 5A shows a plan view of the magnetic head according to the present invention, FIG. 5B shows an operation explanatory view, and FIG. 5C shows a side view.

The main pole 20 of the magnetic head according to the present invention includes a core assembly consisting of a first core 21, a second core 22, an upper base 23 connecting both cores, and a coil 25 wound around the core through a window F. have The upper bottom portion 23 of the core is made of a ferromagnetic material, and is preferably made of the same material as both cores. The bottom portion 24 is a highly conductive non-magnetic spacer inserted into the gap of the core 20. The first core and the second core are plate-shaped, and each has a pair of substantially parallel legs l ₁ and l ₂ and a connecting piece l ₃ that connects them.
has. The shape of one of the legs includes a curved side 20a that gently approaches and touches the medium 26 in the traveling direction A of the magnetic recording medium 26, and a straight side 20b that intersects the curved side 20a. The angle that the straight side 20b makes with the traveling direction A of the medium is
90° or more. On the other hand, auxiliary magnetic pole 2
7 faces the main magnetic pole with the magnetic recording medium 26 in between as shown.

In the above structure, the loop of magnetic flux during recording or reproduction is the upper base 23 - the first core 21 - the medium 26.
- A closed loop consisting of the auxiliary magnetic pole 27 - the medium 26 - the second core 22 - the upper base 23. As the medium 26 moves, the magnetic flux in the main pole changes, and a voltage proportional to the rate of change (dφ/dt) is generated in the coil 25. The influence of the medium 26 on the rate of change of magnetic flux in the core is extremely small in the curve 20a because the sides of the curve gently approach the tape. However, the rate of change of the magnetic flux in the core at the moment when the medium directly passes through the side 20b is very large because the straight side 20b is suddenly separated from the medium, and as a result,
Most of the rate of change in magnetic flux is obtained at the moment the medium passes through the straight side 20b, and an induced voltage proportional to the rate of change is generated in the coil 25. The effect of the straight side 20b is further improved when the angle θ formed by the straight side with the medium is 90° or more. That is, by increasing the angle .theta., the straight side 20b is more rapidly separated from the medium, and therefore the rate of change of magnetic flux on the straight side 20b is increased, and the induced voltage in the head is increased. In the present invention, since the core and spacer are made of thin plate materials, the overall thickness d can be reduced.
It is possible to reduce the width of the recording track and obtain a magnetic head suitable for multi-channel systems.

As an example of the head size of the present invention, the thickness of both cores of the head 20 is 5 to 20 μm, the thickness of the upper and lower parts is 5 to 10 μm, and the width W of the head is 100 μm.
That's about it. The members used permalloy for both cores and the upper base, and copper for the lower base. Furthermore, the head structure is simple and a narrow head can be easily manufactured. Therefore, a recording track with a narrow width can be obtained, and in the case of a multi-channel system in which a recording medium has a plurality of tracks, it is possible to have a larger number of tracks than in the past.

As explained in detail in the embodiments above, the magnetic head according to the present invention has the advantage of being able to perform high-density recording using the perpendicular magnetization method with a simple structure and a large number of tracks by employing two cores, an upper bottom portion, and a spacer. .

[Brief explanation of the drawing]

1, 2, and 3A to 3C are structural examples of a magnetic head according to the prior art, FIG. 4A is a structure example of a magnetic head according to the present invention, and FIG. 4B is a structure example of a magnetic head according to the present invention. FIGS. 5A, 5B, and 5C are a plan view, an operation explanatory view, and a side view, respectively, of the magnetic head according to the present invention. 21; first core, 22; second core, 23; upper bottom portion, 24; lower bottom portion, 25; coil, 26; magnetic recording medium, 27: auxiliary magnetic pole, 28; recording magnetic field, 2
0: Main magnetic pole, 20a: Curved side, 20b: Direct side.

Claims (1)

[Claims] 1. In a perpendicular magnetization type magnetic head in which a magnetic recording medium is sandwiched between a main magnetic pole and an auxiliary magnetic pole and magnetic recording and reproduction are performed in the thickness direction of the medium, the main magnetic pole is
It has a pair of thin plate ferromagnetic cores shaped into a substantially U-shape, and the core has a pair of substantially parallel legs and a connecting piece that connects them. A pair of cores are stacked one on top of the other so that they are oriented in opposite directions and have a window in the center, and the upper base of a thin plate made of ferromagnetic material is held between one leg of each core, and the other leg of each core. a lower bottom part into which a thin plate made of a highly conductive non-magnetic material is inserted as a spacer, and a coil is wound around the core through the window, and the other leg of the core is connected to the leg part. Opposing a magnetic recording medium moving in the longitudinal direction, the legs have curved sides that gently approach the medium along the traveling direction of the magnetic recording medium, and intersect with the curved sides at the point where the curved sides contact the medium. the auxiliary magnetic pole is made of a ferromagnetic material that faces the main magnetic pole with the magnetic recording medium in between, and the angle between the linear side and the traveling direction of the magnetic recording medium is not less than 90°; A perpendicular magnetization type magnetic head characterized by the following.