JPS592087B2 - Jikihed - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head for recording and reproducing information on magnetic tapes, magnetic disks, magnetic drums, etc., and particularly relates to the structure of a magnetic head that combines an inductive thin film magnetic head and a magnetoresistive head. It is something.

Traditionally, magnetic heads for magnetic recording devices have mainly been made of single-core induction magnetic heads made of processed ferrite.However, for reasons such as ease of processing and good uniformity, most of the magnetic head components Thin-film magnetic heads made of thin films are attracting attention.

This head is an inductive head like conventional heads, but compared to conventional ferrite heads, it is extremely difficult to manufacture by winding the excitation coil many times, and therefore the output value during playback is extremely small. I have it. In order to overcome these drawbacks, attempts have recently been made to use magnetoresistive elements as magnetic heads for reproduction. In the case of a magnetoresistive element, it is not an inductive type but a magnetic flux response type, so it does not depend on changes in magnetic flux over time, and there is no need to wind a coil many times.
A sufficiently large output can be obtained.

The disadvantage of magnetoresistive elements is that they do not have a recording function, so when used as a magnetic head, a separate recording head is required.

How the recording head and reproducing head are combined depends on the application. For example, in the case of analog applications such as tape recorders, the recording head and the reproducing head may be placed separately on the tape, but in the case of magnetic desks, etc., where the information string is constructed by a combination of binary information. Since pulse timing is very important, it is desirable to integrate the recording head and the reproducing head to eliminate timing discrepancies between recording and reproduction. The present invention relates to the latter type, that is, a head that integrates a recording head and a reproducing head, and provides a magnetic head that uses an inductive thin film magnetic head as the recording head and a magnetoresistive element as the reproducing head. In particular, the present invention provides a magnetic head having a structure in which the width of the reproducing head in the track direction is smaller than the width of the recording head in the track direction.

Conventional heads perform recording and playback using a single head, and as a result, the writing width and reading width are generally the same, but methods of writing in a wide area and reproducing the output from a narrow area are also considered. ing. For example, as summarized in the Industrial Technology Seminar sponsored by the Japan Industrial Technology Center, "Recent Progress and Future Trends in Component Technology for Magnetic Recording," pages 1110-112, the signal-to-noise ratio is degraded mainly due to track deviation. As a way to prevent the bottom, W, E.N.R.
/W method and tunnel erase method have been proposed. The former uses an erase head with a large track width to erase old information.
Records whose track width is smaller than the erasing area provided separately.
This is a method in which recording and playback are performed using a playback head, and the latter uses a recording/playback head with a specified track width to record and then
In this method, certain areas at both ends of the track width are erased using two erasing heads with narrow track widths, and information in the remaining recording area is reproduced by the first recording/reproducing head. These are the same in that they reproduce information in a narrow area, but the recording head
The playback head is a single head with the same track width and has a separate erase head. The purpose of these methods is to prevent noise from unerased information due to track misalignment, or to prevent noise from adjacent tracks by effectively widening the distance between adjacent tracks, aiming at high-density recording. This shows that the above-mentioned noise can be a major hindrance in some cases. The head according to the present invention is intended to achieve the above-mentioned effects by changing the track widths of the recording head and the reproducing head and reproducing information from a wide written area only in a narrow area. Most of the head is formed of a thin film, and the head is integrated with both.

The present invention will be explained below using the drawings.

The figure shows the configuration of an embodiment of the present invention, and shows the surface facing the medium.

In the figure, 1 is a substrate, 2 and 9 are high permeability magnetic materials,
3, 6 and 8 are insulating films, 5 and 7 are good metal conductors, and 4 is a magnetoresistive element. The conductor 5 and the magnetoresistive element 4 are electrically continuous with each other.

When recording with the head shown in the figure, a current is passed through the conductor 7 to magnetize the high permeability magnetic bodies 2 and 9, and information is recorded on the medium using the leakage magnetic field. During reproduction, a small current is passed between the conductor 5 and the magnetoresistive element 4, and the change in electrical resistance when the magnetization state of the magnetoresistive element 4 changes due to the leakage magnetic field from the medium is calculated by the conductor 5. Detected as a voltage change from both ends. A feature of the present invention is that recording is performed using an inductive head and reproduction is performed using a magnetoresistive element, and in a head that is formed by integrating both with a thin film for the most part, the width WW of the recording head is wider than the width WR of the reproducing head. It has a larger structure.

At the beginning of this article, it was stated that the magnetoresistive element has a large reproduction output, but this means that the magnetoresistive element responds sensitively to the leakage magnetic field of the medium. Normally, the magnetization state is considered to be slightly disordered at both ends of the area recorded on the medium, that is, the track, and there is a possibility that there is unerased information due to slight track deviation, but the leakage magnetic field generated from these areas is detected in the form of after-sound during playback, causing a deterioration of the signal-to-noise ratio. If the width of the information to be reproduced is limited to a part of the width of the recorded information, the influence of noise can be reduced as if the information were reproduced from a uniform area, and the influence of leakage magnetic fields from adjacent tracks can be reduced. can be reduced.

Since the reproduction output of the magnetoresistive element is sufficiently large, W
Even if R is half of Ww, it is still possible to obtain a sufficient signal-to-noise ratio. Another advantage of the present invention is that it is possible to prevent wire breakage when the magnetoresistive element is inserted into the magnetic gap as shown in the figure and when it is placed on the magnetic body 9. That is, the magnetoresistive element is generally used with a thickness of several hundred angstroms, and the magnetic bodies 2 and 9 are often 1 micron or more thick. There is a drawback that if it touches one end of 9, it tends to break at that part, and this drawback can be solved by setting WR<Ww.

[Brief explanation of drawings]

The figure is a configuration diagram showing an embodiment of the present invention. 1... Substrate, 2, 9... High permeability magnetic material, 3, 6, 8... Insulating film, 5, 7...
- Non-magnetic metal conductor, 4... Magnetoresistive element.

Claims (1)

[Claims] 1. In a recording/reproducing head in which an inductive magnetic head, most of which is made of a thin film, is used as a recording head, and a magnetoresistive element made of a ferromagnetic thin film is used as a reproducing head, the two are superimposed and integrated. The magnetoresistive element is inserted into a magnetic gap of an inductive magnetic head,
Moreover, the track width W_W of the inductive magnetic head is larger than the track width W_R of the magnetoresistive element, and a highly conductive metal conductor is provided above or below the magnetoresistive element, which becomes a coil of the inductive magnetic head. A magnetic head characterized in that: is arranged.