JPS61156510A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To obtain a thin film head provided with both a high read-out performance and a high write performance under recording of a high density by providing an auxiliary magnetic pole so as to be adjacent to a main magnetic pole having an exciting coil layer. CONSTITUTION:The titled magnetic head has a substrate 21, an insulating layer 17 and 18, a lower main magnetic pole 11, an upper main magnetic pole 12, coil 15 and a recording and reproducing gap 16, and a lower auxiliary magnetic pole 13 and an upper auxiliary magnetic pole 14 are provided through the insulating layer 17 on the lower main magnetic pole 11 and the upper main magnetic pole 12, respectively. As for the thin film head, at the time of write, both the main magnetic pole 11 and 12, and the auxiliary magnetic pole 13 and 14 are excited by a powerful magnetic flux generated by a current flowing to the coil layer 15, and a powerful write magnetic field Hw can be generated. At the time of read-out,a magnetic field generated from a recording medium is small as <= about 1/3 of the write magnetic field, therefore, by a gap of the auxiliary magnetic pole and the main magnetic pole, the magnetic flux in the lower auxiliary magnetic pole 13 and the upper auxiliary magnetic pole 14 is cut off and does not reach the main magnetic pole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film magnetic head suitable for high-density magnetic recording and reproduction.

[Conventional technology]

Conventionally, this type of thin film head has a substrate 6 as shown in FIG.
1, two magnetic pole pieces 51 and 52 are placed above and below the coil layer 55.
and are disposed via an insulating layer 58i. Incidentally, the linear density in the recording track direction in this type of thin film head is closely related to the thickness pb of the magnetic pole piece 51, the thickness pt of the magnetic pole piece 52, and the length g of the recording/reproducing gap 56 between them. , these dimensions need to be reduced to improve linear density.

[Problem that the invention seeks to solve]

In the conventional thin film head described above, each of the above dimensions g,
When pb and pt are made small, the magnetic field strength generated during writing decreases, resulting in a disadvantage that desired writing performance cannot be obtained. In order to generate a strong magnetic field during writing, it is necessary to increase the dimensions of the three locations mentioned above, but this also deteriorates the high frequency characteristics during reading, making it unsuitable for high-density recording. As described above, conflicting requirements have arisen regarding the recording/reproducing gigang length and the thickness dimensions of the two magnetic pole pieces from the standpoint of writing and reading performance.

For the above reasons, in the conventional thin film head where the recording/reproducing gearing length and the thickness of the two magnetic pole pieces are narrowed,
The limit of high density change was about 700 bits.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional thin film head,
The object of the present invention is to provide a thin film head that has both high read performance and high write performance under high density recording.

[Failure to solve the problem]

The present invention is a thin film magnetic head characterized in that an auxiliary magnetic pole is attached adjacent to a main magnetic pole provided with an excitation coil layer.

〔Example〕

Hereinafter, the present invention will be explained with reference to the drawings.

Referring to FIG. 1, one embodiment of the invention includes a substrate 21;
It is composed of insulating layers 17 and 18, a lower main magnetic pole 11, an upper main magnetic pole 12, a coil 15, a recording/reproducing gap 16, a lower auxiliary magnetic pole 13, and an upper auxiliary magnetic pole 14.

The lower main magnetic pole 11 and the upper main magnetic pole 2 formed on the substrate 21 have a minute gap serving as a recording/reproducing gap 16 at the end facing the recording medium (not shown). are arranged in parallel so that they are in contact with each other at opposite ends. A coil layer 15 made of a conductor is formed between the lower main pole 11 and the upper main pole 120 with the entire insulating layer 18 interposed therebetween.

The above-mentioned lower main pole 1, upper main pole 12, and coil layer 15 are thin film layers formed by mesh or by slicing in a vacuum, and the material of the two main poles is Ni-Fe.
/9-Malloy, the coil layer is Cu. A thin film head element that performs electromagnetic conversion is constructed as described above. The feature of this embodiment is that a lower auxiliary magnetic pole 1 is provided below the lower main magnetic pole 11.
3) The upper auxiliary magnetic pole 14t is disposed on the upper auxiliary magnetic pole 12 with the entire insulating layer 17 interposed therebetween. As shown in FIG. 3, the lower auxiliary magnetic pole 13 and the upper auxiliary magnetic pole 14
The height mFi of the lower main magnetic pole 11 and the upper main magnetic pole 12 is set very short.

In the thin film head of the present invention constructed as described above, as shown in FIG. 3, during writing, both the main magnetic poles 11 and 12 and the auxiliary magnetic poles 13 and 14 are is excited and can generate a strong write magnetic field HW f. During reading, the magnetic field generated by the recording medium (not shown) is as small as about 173 or less than the write magnetic field, so the magnetic flux in the lower auxiliary magnetic pole 13o and the upper auxiliary magnetic pole 14 is blocked by the gap between the auxiliary magnetic pole and the main magnetic pole, and the magnetic flux is It does not reach the magnetic pole. Therefore, only the main magnetic pole acts during reading, and only the thickness pb of the lower main magnetic pole 11, the thickness pt of the upper main magnetic pole 12, and the length g of the recording/reproducing gap 16 are the frequency characteristics of the thin film head during reading. (See Figure 2). FIG. 4 shows the recording density D5 (3 (bit a, /Hg) and the write density for the total dimension g + pt + pb of the recording/reproducing gap length, upper main magnetic pole thickness, and lower main magnetic pole thickness of the thin film head according to the present invention. It shows the change in the magnetic field (A/rn).D5o means the total recording density when the output voltage is 1/2 of the solitary wave output voltage when read using one parameter representing the recording density. As shown in the figure, when g+pt+pb f is decreased, D5o increases, but Hy tends to decrease.Hw usually needs to be more than twice the coercive force Hc of the recording medium, so for example, it has a coercive force of 30XIOA7m. The thin film head of the present invention has a capacity of 700 bits for the recording medium.
It can be seen that the recording/reproducing gap is greater than sA@. In contrast, the conventional thin film head has HW' (dashed line) in Figure 4.
The generated write magnetic field is low as shown in . For this reason, the recording medium has a recording/reproducing capacity of at most 600 bits/I for the above-mentioned recording medium having a holding power of 30 x 10 A/m. Note that since the recording density 'kDso' of the conventional thin film head almost coincides with D5o, it is not particularly shown in FIG.

As described above, the thin film head of the present invention can generate a strong write magnetic field under high density conditions.

Further, the strength of the write magnetic field is related to the thickness p bi of the lower auxiliary magnetic pole 13 and the thickness p t / of the upper auxiliary magnetic pole 14 (see FIG. 2). Therefore, by changing pb' and pt't, it is possible to generate a write magnetic field suitable for the recording density and recording medium used. Furthermore, in this embodiment, a thin film head having two auxiliary magnetic poles, one at the bottom and the other at the top, has been described.
Even if you leave, the effect will be diminished, but it still exists. Therefore, a thin film head having only a lower auxiliary magnetic pole or an upper auxiliary magnetic pole does not depart from the present invention.

〔Effect of the invention〕

As explained above, by arranging the auxiliary magnetic pole adjacent to the main magnetic pole, the writing magnetic field can be strengthened without impairing the high frequency characteristics during reading, and high-density recording and reproduction can be performed. It is effective.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional perspective view showing a thin film head of the present invention, FIG. 2 is a plan view of the thin film head of the present invention viewed from the recording medium side, FIG. 3 is a cross-sectional view of a thin film head 9 of the present invention, and FIG. The figure shows the recording density and write magnetic field strength of the thin film head of the present invention and the conventional thin film head, and FIG. 5 is a perspective view of a cross section of the conventional thin film head. 11...Lower main magnetic pole, 12...Upper main magnetic pole, 13.
...Lower auxiliary magnetic pole, 14...Top auxiliary magnetic pole, 15...
- Coil layer, 16...recording/reproducing gap.

Claims (1)

[Claims] (1) A thin film magnetic head characterized in that an auxiliary magnetic pole is attached adjacent to a main magnetic pole provided with an excitation coil layer.