JPS61188709A - Magnetic head - Google Patents

Abstract

PURPOSE:To raise remarkably the saturation magnetic flux density, and also to eliminate the danger property which causes demagnetization due to seizure by a sliding friction, and an abnormal temperature rise, even in case when a magnetic head is slid with a recording medium, by attaching the magnetic head body to a cooling device which has been packed with a cooling medium. CONSTITUTION:As for a liquid nitrogen 2 being a cooling medium which has been packed completely in a closed space between the inside wall of a vacuum dewer 1 and a sealed wall 3, a liquid temperature is set to about 77 deg.K. A head body containing case 4 surrounded by the sealed wall 3 is fixed to a window part 5 provided on the center part, so that a magnetic head body 6 exposes the top surface having a magnetic gap. As for the magnetic head body 6, it is set to such a low temperature as about 77 deg.K, therefore, a saturation magnetic flux density Bs of a ferrite core rises by scores of %.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a magnetic head that performs magnetic recording, and particularly to a magnetic head that can be used in VTRs and the like that require high recording density.

Traditionally, magnetic heads used for magnetic recording in VTRs, computers, etc. have high magnetic permeability, high saturation magnetic flux density, low coercive force,
Further, characteristics such as high frequency characteristics and wear resistance against media are required. Therefore, the magnetic head is made of a magnetic material as is well known, and a typical example thereof is Mn-Zn.
There are single crystal ferrite, sendust alloy, and amorphous alloy. First, the Mn-Zn single crystal ferrite core (hereinafter simply referred to as ferrite core) has a recording medium made of
It has been praised because it is compatible with γ-Fe2O3 obtained from acicular goethite particles, which has been used for a long time.
It is considered difficult to further improve saturation in magnetic flux density characteristics. Next, Sendust alloy and amorphous alloy cores are definitely compatible with metal magnetic powder, where the medium has a main composition such as Fe-Go or Fe-Go-Nt, whereas ferrite cores are not compatible. Therefore, it is expected that it will be put into practical use in the future. Among them, Sendust alloy is
As is publicly known, it is an alloy whose main composition is Fe-51-Ml etc.
3) and Japanese Unexamined Patent Publication No. 18916/1983.

A comparison of the specific properties of the ferrite core and the sendust alloy core is shown in Table 1 below.

Table 1 Magnetic materials for video heads By the way, as can be seen from Table 1 above, the Sendust alloy core has a lower Vickers hardness than the ferrite core, and therefore has a wear resistance of 4'F11! It also has the disadvantage of low magnetic permeability in the high frequency band.In addition, Sendust alloy is more brittle than ferrite when processing core winding grooves and track grooves, making it somewhat difficult to use in terms of practicality. Despite these drawbacks, the reason why Sendust alloy has begun to be used in magnetic heads for metal tapes with high recording densities is that it has an overwhelmingly higher saturation magnetic flux density than ferrite.

Therefore, even if a ferrite core is used, it is sufficient to obtain a high saturation magnetic flux density, but it has been difficult to improve the material quality of the ferrite. Based on the above background, the present invention proposes a magnetic head in which the drawbacks of the ferrite core are corrected.

Mouth
This invention proposes that a magnetic head body formed using a ferrite core in a conventional manner be attached to a cooling device filled with a coolant. That is, the present invention is characterized in that the magnetic head body itself uses a ferrite core, which has been used in the past, and is attached to a cooling device to obtain high saturation magnetic flux density characteristics.

Production 1 - In this invention, the temperature of the magnetic hend body is set to an extremely low temperature by the cooling device, so that the saturation magnetic flux density increases significantly. Further, in this invention, since the magnetic head main body is constantly cooled, even when sliding with a recording medium, it is possible to eliminate the risk of burning due to sliding friction or demagnetization due to abnormal temperature rise.

FIG. 1 is a conceptual diagram of a magnetic head to be referred to in explaining an embodiment of the present invention. First, 1 is a vacuum dure of a cooling device that brings the temperature to an extremely low temperature. 2 is liquid nitrogen as a refrigerant that is completely filled in the sealed space between the inner wall of the vacuum dure 1 and the sealing wall 3, and the liquid temperature is set to about 77°K.

4 is a head body storage tape surrounded by a sealing wall 3;
A magnetic nod main body 6 is fixed to a window 5 provided in the center so as to expose the top surface having a magnetic gap. Now, the magnetic head main body 6 is made of Mn-Z similar to the conventional one.
It uses an n single-crystal ferrite core and has a structure as shown in FIG. That is, in FIG. 2, cores 7 and 8 are half-open, provided with a winding insertion window 9, a winding locking groove 10, 11, and bonded with low melting point glass 12 as an adhesive. Then, the curved polished top surface 13 of the magnetic head main body 6
A magnetic gap 14 is formed approximately in the upper center.

Further, 15 is a coil winding.

The magnetic head whose structure has been explained above is installed in a cooling device.
Since the magnetic head body 6 is set at a low temperature of about 776°C, the saturation magnetic flux density Bs of the ferrite core increases by several tens of percent. This point is important for Mn-Z, as shown in Figure 3.
Temperature-saturation magnetization characteristic curve 16 of n single crystal ferrite core
Comparing the saturation magnetization Ms at point A at normal temperature and point B at 1000 ℃ above, it is found that the saturation magnetization Ms increases by about 50% at point B compared to point A.

In the above embodiment, Mn-zn is used as the ferrite core.
Although single crystal ferrite and liquid nitrogen are used as the refrigerant, in this invention, hot pressed ferrite, ethylene glycol, etc. may also be used.

According to this invention, the low saturation magnetic flux density, which is a drawback of conventional ferrite cores, can be corrected, so it is fully compatible with recording media such as metal tapes, and it can be used with sendust alloy cores. A magnetic head capable of high-density recording can be obtained even without this. Further, according to the present invention, accidents such as demagnetization of the core due to abnormal temperature rise can be avoided, and a magnetic head that operates stably can be expected.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a magnetic head for explaining an embodiment of the present invention, FIG. 2 is a perspective view of the main body of the magnetic head, and FIG. 3 is a temperature-saturation diagram of Mn-Zn single crystal ferrite. It is a magnetization characteristic curve diagram. 1... Cooling device (vacuum dua), 2...
- Refrigerant (liquid nitrogen), 6...Magnetic head body.

Claims (1)

[Claims] A magnetic head characterized in that a magnetic head body using a ferrite core is attached to a cooling device filled with a refrigerant.