JPH04188410A - Magnetic head - Google Patents

Abstract

PURPOSE:To improve core efficiency, and to increase a reproducing output by mounting a piezoelectric element at the lower end of a magnetic gap while using a material, magnetic characteristics of which are changed by pressure, as a magnetic material for a core. CONSTITUTION:A ferroelectric (a piezoelectric element) 4 displaying a piezoelectric effect is set up at the lower end (the depth direction) of a gap 2. Pressure is applied to a core 1 by applying voltage to the piezoelectric element 4. A magnetic substance used as the core 1 is selected in its material, composition and crystal orientation such that permeability mu is reduced by applying pressure, thus decreasing effective gap depth, then improving the core effect. Accordingly, the core efficiency of a magnetic head can be enhanced, and the reproducing output of the magnetic head can be increased without shallowing gap depth directly related to the lifetime of the magnetic head.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head used in a magnetic recording/reproducing device.

[Conventional technology]

Figure 17 is a schematic diagram of a conventional magnetic head shown in, for example, "Introduction to Home VTR" (Published by Corona Publishing Co., Ltd., co-authored by Katsuya Yokoyama, Akira Kuzuta, and Atsumi Watabe), and Figure 18 is a schematic diagram of a conventional magnetic head shown in "Introduction to Home VTR" (Published by Corona Publishing Co., Ltd., co-authored by Katsuya Yokoyama, Akira Kuzuta, and Atsumi Watanabe). This is an enlarged view of the 1st air gap, showing the gap depth in detail. In the figure! 2 is the gap, 3 is the gap depth, 6 is the reinforcing glass, and 7 is the coil.

In magnetic heads used in video tape recorders (hereinafter referred to as VTR) and audio tape recorders (hereinafter referred to as MUTR), generally speaking, when the gap depth is made shallower (smaller), the efficiency of the core increases and the playback output increases. known to grow large.

FIG. 19 shows a schematic diagram of the regeneration process. - The total magnetic flux Φ picked up by the magnetic field 7 and 8 from the recording medium 9 is divided into ΦI passing through the magnetic path M and Φ passing through the magnetic path B. This is shown in an equivalent circuit in Figure 5. Unless the magnetic resistance RA of magnetic path 0 is made smaller than the magnetic resistance RI+ of magnetic path B, the magnetic flux passing through magnetic path M will contribute to the reproduction efficiency. It can be seen that decreases.

That is, by reducing the gap depth, Rβ can be increased.

In actual VTR magnetic heads, the gap depth is often determined from the wear characteristics of the core material, and is usually 50 μm.
It is as follows.

[Problem a that the invention seeks to solve]

In conventional magnetic heads, what is the efficiency of the core? However, in order to obtain a magnetic head with a high reproduction output), it was necessary to create a magnetic head with a shallow gap depth.
Since recording and reproducing are performed while the magnetic head and the recording medium are in contact with each other at the TIL, the life of the magnetic head is determined by wear. Therefore, in order to increase core efficiency, it is advantageous to have a shallow gap depth, but from the standpoint of the life of the magnetic head, a deep gap depth is advantageous.
The reality is that they are contradictory to each other.

This invention was made to solve the above-mentioned problems, and by installing the pressure IT element at the lower end of the gap (in the depth direction) to reduce the effective gap depth,
The objective is to obtain a magnetic head that has the same lifespan as conventional magnetic heads, has a higher core efficiency than conventional magnetic heads, and has a larger reproduction output.

[Second method to solve the problem]

In the magnetic head according to the present invention, a pressure IE element is provided at the lower end of the gap (in the depth direction) to apply pressure to the core and reduce the magnetic permeability of the core, thereby reducing the effective gap depth. Decrease the core efficiency of magnetic heads? It was designed to raise the level.

[Effect]

It is known that the magnetic permeability μ of gJ magnetic material changes significantly under pressure. In the case of magnetic materials with magnetic anisotropy, the convexity generally differs greatly depending on the crystal orientation. For example, as shown in Fig. 21, Mn- < of Zn ferrite
111>Change in magnetic permeability when pressure is applied in the axial direction P is shown.The present invention utilizes the above-mentioned property that pressure affects the magnetic permeability of a ferromagnetic material to reduce the effective gap depth of the core. The aim is to increase core efficiency.

〔Example〕

Embodiments of the present invention will be described below. In FIG. In the magnetic head device IIGx according to the present invention, which is a coil, a ferroelectric material (piezoelectric element) exhibiting a piezoelectric effect is provided at the lower end of the gap (in the depth direction). By applying a voltage to the piezoelectric element 4, pressure is applied to the core. The material, composition, and crystal orientation of the magnetic material used for the core are selected so that the magnetic permeability μ decreases when pressure is applied, thereby reducing the effective gap depth and increasing the core effectiveness by $3. You can do it ^
Also, II! ! The method is also suitable for mass production, as the manufacturing process for conventional magnetic heads using ferrite 2 can be used in many parts.

Next, an example of the manufacturing process shown in FIGS. 2 to 16□□□ will be explained.

■Process of obtaining a pair of head blocks 10'E from bulk material. FIG. 2 shows the hend block 10e.

Step of providing a groove U for embedding a piezoelectric element in the gap forming surface 18 of the head block 10 obtained in step ■■ (
(See FIG. 9), l. A step of embedding a ferroelectric material 4 exhibiting a piezoelectric effect in the block 10 that has completed step (■) (see FIG. 9).

II■ Head block 10.16 trunk machining groove hidden?
Welding process (see Figures 5 and 6), process of creating welding grooves 13 for integrating a pair of hend blocks 10 and 10 with reinforced glass (see Figures 7 and 8) ).

Step (2) Step of forming the conductive film 5 that will become the electrode of the piezoelectric element by a method such as sloping battering or steaming (see No. 9).

Step 2: Filling the trunk processing grooves and welding grooves with a non-magnetic material 6 such as glass for bonding (see Fig. 10).

Step (2) Thickening unnecessary portions of the non-magnetic material 6 to expose a gap surface where the core magnetic material portion has a predetermined trunk width (see FIGS. 11 and 12).

Prepare a pair of hend blocks that have completed process ■Process ■,
Step of forming @15 for coil winding aX on the gap forming surface of at least one head block IO (18th
(Refer to figure) Step 0 [Co., Ltd.] After completing Step ①, the non-magnetic gap material 16 is temporarily attached to the gear forming surface of the 7111 pair of head blocks to a predetermined thickness by using a steaming process such as sputtering. (See Figure 14).

Process 〇 A pair of head pro “7ri 1O116 Fig. 15,
As shown in FIG. 16, a step of joining each other and integrating under pressure and heat.

Step 2: Cut the joined head blocks lO/SlO at predetermined positions, and attach at least one type of magnetic head l'
ft: Obtaining process.

The magnetic head of the present invention can be easily obtained by the steps ① to ＠.

In step (2), the material used for the core is a bulk material such as Zn-Zn ferrite, Ni-Zn ferrite, sendust, or permalloy. 1! ! It is assumed that the crystal orientation of the block whose magnetic permeability changes with pressure is selected for the desired surface of the magnetic head. The film forming technique used in step (2) may be physical vapor deposition such as sputtering or vacuum evaporation, but other methods may be used instead depending on the case.

In addition, in the cutting in step ○, the required azimuth angle can be obtained by cutting obliquely to the bonding surface, as is conventional. In addition, the magnetic head of the present invention and its #reading method follow the prior art in matters not described in this specification.

In the above embodiment, the magnetic head's ! Conventionally, the ferrite head type was used for the R structure, but it can also be applied to the Metal In Gap type if the magnetic material used for the core of Camping satisfies the condition that the magnetic permeability decreases due to pressure.

〔Effect of the invention〕

As described above, according to the present invention, the effective gap depth can be reduced by applying pressure to the core and lowering the magnetic permeability by providing the pressure II element at the lower end (in the depth direction) of the gap of the magnetic head. Since it is possible, it is possible to increase the core efficiency of the magnetic head by 3.

Therefore, the reproduction output of the magnetic head can be increased without making the gap depth, which is directly related to the life of the magnetic head, shallower than before.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the main parts of an embodiment of the present invention;
16 are diagrams for explaining the method of aligning a magnetic head of the present invention, FIG. 17 is a perspective view showing a conventional magnetic head, and FIG. 18 is a partially enlarged perspective view of a conventional magnetic head. Figure 19 is a diagram of the regeneration process, Figure 20 is the equivalent circuit diagram of Figure 4, and Figure 21 is the Mill-Zn ferrite node 111.
The figure below shows the change in magnetic permeability when pressure is applied in the > direction. In the figure, 1 is the core, 2 is the gap, 3G = gap depth,
4 is a piezoelectric element, 5 is a conductive film, 6 is a reinforcing glass, and 7 is a coil.

Claims (1)

[Claims] In a magnetic head having a magnetic gap formed by abutting two magnetic core halves used for magnetic recording and reproduction, a piezoelectric element is provided at the lower end (depth direction) of the magnetic gap, and a piezoelectric element is provided as the magnetic material used for the core. A magnetic head characterized by using a material whose magnetic properties change depending on the temperature.