JPS61194607A - magnetic head - Google Patents

Abstract

PURPOSE:To reduce a head resistance which is the main cause of a thermal noise and to reduce a head noise even when a head is made into multicoil by making the core width smaller. CONSTITUTION:The core width of a head coil window part in at least one head core part is set to a value range more than 0.05mm and less than 0.7mm, and the number of coils are more than 25. Thus the thermal noise due to the practical resistance of the head can be reduced, whereby a noise level can lie within the range of a conventional head even if the number of head coils is set to more than 25.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic head for high-density recording in floppy devices and the like, and particularly to a magnetic head with low head thermal noise.

[Background of the invention]

Conventionally, with regard to magnetic heads, improvements in playback output.

Studies have been conducted on reducing sliding noise, modulation noise, etc., and efforts have been made to improve the noise ratio. On the other hand, noise attributable to the head itself includes tape sliding noise and thermal noise.
pisa, published by Kyoritsu Shuppan. These are smaller than media noise, amplifier noise, etc., and have not been given much consideration in the past. However, in recent years, as recording density has improved, track width has become narrower, and in order to compensate for the lack of reproduction output, it has become necessary to increase the number of windings in the head. At this time, according to preliminary experiments conducted by the inventors, the thermal noise of the head increases with the number of windings, as shown in Figure 9, and there is a possibility that it may account for most of the noise of the head medium and amplifier system. It became clear. Therefore, it is very important to reduce this head thermal noise.

[Purpose of the invention]

An object of the present invention is to provide a magnetic head for high-density recording in which the head has low thermal noise.

[Summary of the invention]

The inventors investigated head thermal noise, head dimensions, head shape,
We investigated the relationship between the number of wires and the number of wires in detail, and found that head thermal noise can be significantly reduced by reducing the head core volume at the head winding section.

In other words, the core width around the first winding is 0.7 mm or less,
More preferably, it is 0.5 an or less. Here, in order to maintain the mechanical strength of the core.

The core width is desirably 0.0511111 or more, more preferably 0.1 m or more. Furthermore, the head gap depth is 20 μm or less and 1 μm or more.

More preferably, by setting the thickness to 10 μm or less and 2 μm or more, it is possible to reduce noise and improve recording and reproducing efficiency. Note that the lower limit for the gap depth is necessary here in order to maintain reliability with respect to sliding resistance.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

That is, M n -Z n ferrite single crystal is used as the magnetic core material, and the dimensions of each part C core side core width t, I core side core width U, core rear part core width V and gap depth g are shown in Table 1.
The values shown are as follows. Here, the core thickness T was set to four types: 50, 100, 150, 200° and 400 μm, and the head winding was set to five types: 25, 30°, 50.70, and 100°.

FIG. 2 shows another embodiment. That is, M n −Zn
This is a ring head in which a high saturation magnetic flux density magnetic alloy is formed on a ferrite substrate, and the dimensions of each part are as shown in Table 2.

Table 1 Table 2 Here, as a high saturation magnetic flux density magnetic alloy, the film thickness is 40 μm.
We used an amorphous magnetic alloy such as Co-Zr-Nb-based amorphous magnetic alloy of m, but Fe-Aρ-8i alloy, N
i-Fe alloy, Fe-5i-Ru alloy, or a laminated film of these may be used, and the substrate may also be AQ, 03-TiC, or non-magnetic Z.
A nonmagnetic substrate such as n-ferrite may also be used.

According to this embodiment, thermal noise based on the effective resistance of the head can be reduced, so even if the number of head windings is increased to 25 or more, the noise level can be suppressed to the level of a conventional head. Figure 3 shows the structure shown in Figure 1 with a head gap depth of 20 μm, u = 0.7 m, v = 0.6 mm, and T.
is 0.15m.

It can be seen that the head noise can be reduced by setting the core width t to 0.7 mm or less, more preferably 0.5 mm, which indicates the head noise when t is changed from 0.1 w to 2 -.

t=0.5mm, u=0.6rm+.

If T=0.2mm and V is changed, or t=
0.4+m, v=0.8+m, T=0.13m
Similar results were obtained when U was changed as o and in the case of the structure shown in FIG. However, when each width of t g u @ V was set to 0.1 mm or less, the mechanical strength of the core decreased significantly, which was not preferred in practice.

In Figure 4, t=0.4III, u=o, 4mm
, v = 0, 7 mm, T = 0, 14
The thermal noise of the head having the structure shown in FIG. 2 with the gap depth changed from 1 μm to 100 μm and the reproduction output when recording and reproduction is performed using a video tape are shown. From this, it can be seen that when the gap depth is set to 20 μm or less, the noise is significantly reduced, and when the gap depth is set to 10 μm or less, the reproduction output is also significantly increased. However, if the gap depth is less than 1 to 2 μm, the life of the head will be shortened due to wear, which is not preferred in practice.

The above results were the same for the head having the structure shown in FIG.

On the other hand, in Fig. 5, u=0.6mm+, t=0.4mm
.

The noise of the head having the structure shown in FIG. 2 is shown when v=0.6m++ and T is varied from 50 to 1000 μm. It can be seen that noise can be reduced when the core thickness is 400 μm or less. However, if the thickness is less than 30 μm, the strength will decrease, which is not very desirable.

FIG. 6 and FIG. 7 respectively show the first diagram of the present invention.

An embodiment of a head for a magnetic disk or floppy disk device in which a head chip having the structure shown in FIG. 2 is embedded in a non-magnetic slider is shown. In both cases, the noise was lower than that of conventional large heads, but due to the relationship with amplifier noise and media noise, the S/N of the device was particularly high when the number of windings was set to 25.
The ratio has improved significantly. As the head chip in Figure 7,
Each core width dimension, gap depth and core thickness are the values shown in Table 2.

The core may have a structure shown in FIG. 8.

〔Effect of the invention〕

As described above, according to the present invention in which the core width is reduced, the head resistance, which is the biggest cause of thermal noise, can be reduced, so that even when the head has multiple windings, the head noise can be reduced. In particular, the effects of the present invention are remarkable when the number of windings is set to 25 or more in consideration of amplifier noise and medium noise.

[Brief explanation of the drawing]

1 and 2 are top and side views of a magnetic head as an embodiment of the present invention, respectively. FIGS. 6 and 7 are bird track diagrams of a magnetic head as another embodiment of the present invention, respectively. Figure, 4th
5 is a diagram showing the relationship between head noise and core width, gap depth, and core thickness. FIG. 8 is a diagram showing a head core shape according to an embodiment of the present invention. FIG. A diagram showing the relationship between noise and the number of windings. 1... Magnetic core, 2... Winding window, 3... Glass,
4... Substrate, 5... High saturation magnetic flux density material, 6... Magnetic head, 7... Nonmagnetic slider, 8... Head,
9...Non-magnetic slot 3 Solid i 'f14 Illustration 71 Rejection 3ty Akira Vl 5 Eye open Figure 7

Claims (1)

[Claims] 1. A magnetic head characterized in that the core width of the head winding window in at least one head core part is 0.7 mm or less and 0.05 mm or more, and the number of windings is 25 or more. . 2. The magnetic head according to claim 1, wherein the core width is 0.5 mm or less and 0.1 mm or more. 3. Both sides of the head core and rear core width are 0.
．． The magnetic head according to claim 1, wherein the magnetic head is 5 mm or less and 0.1 mm or more. 4. The magnetic head according to claim 1, claim 2, or claim 3, characterized in that the gap depth is 20 μm or less and 1 μm or more. 5. The magnetic head according to claim 1, claim 2, or claim 3, wherein the gap depth is 10 μm or less and 2 μm or more. 6. A magnetic head according to claims 1 to 5, characterized in that the core thickness is 400 μm or less. 7. The magnetic head according to claim 1, wherein the magnetic head is embedded in a slider made of a non-magnetic material.