JPS58220233A - Magnetic head - Google Patents

Abstract

PURPOSE:To improve the maximum output level characteristics and to reduce the level fluctuation due to change of a bias current, by applying the treatment to give a low level permeability to a magnetic core half which is provided at the downstream side of the traveling direction of a magnetic recording medium. CONSTITUTION:Magnetic core halves 1 and 2 use the same material, and the treatment is applied to give a low level permeability to the half 2 which is situated at the downstream side of the traveling direction of a magnetic tape 5. For an example of the treatment to give a low level of permeability to the core half, an internal strain is produced by the half 2 by applying previously the physical external force to the half 2. This internal strain lowers the level of permeability. Otherwise a heat treatment is applied to the half 2 or the degree of magnetic strain is increased, to lower the permeability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head that uses a magnetic core with a lower magnetic permeability on the downstream side in the direction of movement of a magnetic recording medium.

Conventionally, the lower magnetic properties required for a magnetic head include high maximum saturation magnetic flux density and high magnetic permeability, and low coercive force.

In recent years, the development of magnetic materials has progressed rapidly, and several materials that satisfy the above-mentioned properties have appeared on the market. However, the maximum permeability is very large and the angular ratio of the hysteresis loop is very large*<,'L.

Materials with a high saturation 'fB magnetic field are generally used in low magnetic fields (50
・~100・). Therefore, when the bias current is increased, MOL (Maximu
There was a drawback that the maximum output level became small, and the maximum output level also fluctuated due to changes in the bias current (as shown by the broken line 1 in Figure 6).
0)゛. Therefore, in the present invention, a magnetic core body whose magnetic permeability is lowered by subjecting the magnetic core body provided on the downstream side in the traveling direction of the magnetic recording medium to a low magnetic permeability treatment is used. In short, □ Decrease the maximum magnetic permeability, increase the change in magnetic permeability of the magnetic material (that is, the derivative of magnetic permeability) in the vicinity of 5 to 100 (Oersted) as a DC magnetic property, and increase the bias current value. The objective is to improve the maximum output level (MOL) under the following conditions.

The present invention will be explained below using figures.

FIG. 1 is a plan view showing the magnetic head and magnetic recording medium of the present invention.

In Figure 1, 1 and 2 are, for example, ferrite, 78%
Perm 9i, high hardness permalloy ()・-dovermalloy)
, Sendust, amorphous, etc., a magnetic core half-hole made of a high permeability material, 6 a magnetic gap formed by butting the magnetic core halves 1 and 2 against each other, 4 a magnetic core. A coil is wound around the body 1.2, and 5 is a magnetic tape (magnetic recording medium) having a magnetic material 5b attached to a base 5a.

In the figure, the magnetic tape 5 is driven in the direction of an arrow 6 by a drive means (not shown).

Here, the magnetic core 1.2 is made of the same magnetic material,
The magnetic core body 2 located on the downstream side in the traveling direction of the magnetic tape 5 is subjected to a low magnetic permeability treatment.

As an example of the magnetic permeability reduction process, a physical external force is applied to the magnetic core body 2 in advance to generate internal strain, thereby reducing the magnetic permeability.

Further, as another example, it can be realized by subjecting the magnetic core body 2 to heat treatment to lower the magnetic permeability, or by increasing magnetostriction.

Figure 2 (=3 and (b) shows the B-H characteristics of high-hardness permalloy. The vertical axis shows the magnetic flux density B (Gauss), and the horizontal axis shows the coercive force H (00 or Oersted). As shown in the graphs of the magnetic properties, FIG. 2 (&) shows the case where the magnetic permeability reduction process is not performed, and FIG. 2 (b) shows the case where the magnetic permeability reduction process is performed.

That is, FIG. 2(1) shows the magnetic properties of the magnetic core and half body 1 in FIG. 1, and FIG. 2(b) shows the magnetic properties of the magnetic core body 2 in FIG. Solid line 7 & in the figure.

8& is the magnetic property in a high magnetic field using the scale 0 to 5 to 10 on the horizontal axis υ, and the broken line 7b and Bb are the scale 0 to (0,5
) to (1) in a low magnetic field. In FIG. 2 Tb), the magnetic permeability is reduced by applying a physical external force to the half of the magnetic core. (However, if B becomes small or H becomes large in magnetic permeability, the magnetic permeability becomes low).

Furthermore, a similar reduction in magnetic permeability can be achieved by heat treatment.

In this way, if the magnetic core half 2 located downstream in the direction of movement of the magnetic tube 5 is constructed of a magnetic material with low magnetic permeability, the bias current versus maximum output level (MOL) shown in FIG.
(hereinafter referred to as MOL characteristics) is obtained. Here, the horizontal axis is the frequency f3 with 800 mA as QaB.
D Represents the bias current value of KHz, and the vertical axis is 250
It represents the maximum output level of a signal with a frequency of 315Ha, where nwb/m is OaB. In FIG. 6, the solid line 9 shows the MOL characteristics obtained by the magnetic head of the present invention, and when compared with the MOL characteristics of the conventional magnetic head shown by the broken line 10, the maximum output level (MOL) at a bias current value i aB or more is has been improved.

In region 11 of the pick, the magnetic head of the present invention has little variation in MOL level with respect to changes in bias current, and
It can be seen that the characteristics have been improved.

As described above, the magnetic head of the present invention improves the MOL characteristics with an extremely simple configuration in which the magnetic permeability of the magnetic body located on the downstream side in the direction of movement of the magnetic recording medium is reduced. Level fluctuations can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the magnetic head and magnetic recording medium of the present invention. FIG. 2(&)t(b) is a graph showing the magnetic properties of the magnetic material used for the magnetic core body of the magnetic head of the present invention. Figure 6 shows the patent applicant Canon Electronics Co., Ltd. Kinsha using the magnetic head of the present invention and the conventional example.

Claims (1)

[Claims] (1) In a magnetic head in which a magnetic circuit is formed by abutting multiple magnetic core bodies against each other, the magnetic core half located on the downstream side in the direction of movement of the magnetic recording medium is subjected to a low magnetic permeability treatment to lower the magnetic permeability. A magnetic head characterized by using a magnetic core body. (2. A magnetic head according to claim (1), characterized in that the magnetic permeability reduction treatment includes application of an external force or heat treatment.