JPS62185217A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To improve the yield for manufacturing a head, and to execute a mass production at a low cost by providing a dummy head having the almost same structure as a head element, on both ends of plural head element arrays on a substrate. CONSTITUTION:Dummy heads 11A, 11B having the same constitution as head elements 8A, 8B are formed one by one on both sides of both end heads 8A, 8A. These dummy heads 11A, 11B are formed simultaneously together with the head elements 8A, 8B by a thin film accumulating method and a photolithography technique. The dummy heads 11A, 11B are not used for recording and reproduction fundamentally, therefore, it is unnecessary to execute a connection. In this way, in a manufacturing process of a magnetic head, a damage which is suffered at the time of adhesion, etc., of a protective plate is shared with the dummy heads 11A, 11B, and it is prevented that an influence of an uneven abrasion which is suffered in a process of use is exerted on the original head elements 8A, 8B, and a non-defective product can be produced with a high yield.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thin film magnetic head, and more particularly to a thin film magnetic head in which a plurality of head elements are formed on the same substrate by thin film technology. .

[Prior art] A still video floppy that records and plays still images is
One frame of video signal is recorded and reproduced on two tracks of the disc. Therefore, the magnetic head used in this type of device must be able to perform magnetic recording and reproduction in units of two tracks.

Thin-film magnetic heads are formed using thin-film deposition methods such as evaporation or sputtering, and photolithography technology, and can achieve higher density, smaller size, and lower crosstalk than conventional bulk-type heads. Because of this, it came to be used as a multi-trough magnetic head.

Taking advantage of these features, in recent years, two-channel thin film magnetic heads for video floppies have been commercialized in addition to magnetic heads for computer memories.

FIG. 2 shows an example of a conventional one-channel f8N film magnetic head. In FIG. 2, reference numeral 1 indicates a magnetic substrate on which a coil conductor 2 is formed in a spiral shape. Furthermore, an upper magnetic layer 3'' and an electrode 4 are fixed thereon. A magnetic gap 6 exists between the tip of the magnetic pole part 5 and the substrate l. The magnetic head shown here is a two-channel head. Therefore, two of each of the above members are provided on the magnetic substrate l.

The above-mentioned structure is formed by a thin film deposition method and photolithography, and then, after adhering the protective plate 7, a molding process is performed in which the contact portion with the recording medium is subjected to mechanical processing such as grinding.

When recording using such a thin-film magnetic head, a magnetic field is generated in the magnetic gap 6 by passing a recording current through the conductor 2 through the electrode 4, and a magnetic field (not shown) located near the gap is generated. The recording medium is magnetized for recording.

On the other hand, during reproduction of magnetic recording, the magnetic flux generated from the recorded magnetized portion of the magnetic recording medium located near the magnetic gap 6 passes through the magnetic substrate l and the upper magnetic layer 3, crosses the conductor 2 and the electrode 4, and this magnetic flux Since the voltage changes as the magnetic recording medium moves, an electromotive force is generated in the conductor 2.4, and reproduction is performed by detecting this voltage.

In this way, a 2-channel thin-film magnetic head can record and reproduce many still images by moving it in the track direction of a magnetic disk.Currently, so-called thin-film multi-track magnetic heads, in which several 2-channel heads are arranged in parallel, are used. has been devised, and this will solve problems such as long access times, the need for a high-precision drive system, and the tendency to cause track misalignment.

[Problems to be Solved by the Invention] However, in this thin film multi-track magnetic head, the yield of heads at both ends is statistically very poor, and there are problems with its durability. The cause of this is deterioration of head characteristics at both ends due to the manufacturing process.

Another problem is the wear resistance, which is based on the difference in circumferential speed between the inner and outer surfaces of the disk during use.

Next, this will be explained based on the drawings, and the same parts as in FIG. 2 or corresponding parts are given the same reference numerals, and the explanation thereof will be omitted.

3(A) and 3(B) show the characteristic deterioration of the head at both ends during the manufacturing process of the multi-track magnetic head. The bonding of the protective plate 7 onto the head elements 8A and 8B consisting of the gap 6 and others is shown from the direction of the sliding surface of the magnetic recording medium. Here, reference numeral 8A indicates head elements at both ends of the heads arranged on the substrate, and reference numeral 8B indicates other head elements.

As shown in FIG. 3(A), in the process of bonding the protective plate, molten glass 9 is placed on top of the magnetic substrate l, and the protective plate 7 is pressed onto it. Due to heating and pressurization, the protection plate 7 is extremely bent as shown in FIG. 3(B), and the head elements 8A at both ends of the substrate are subjected to an excessive load and deteriorate.

On the other hand, FIGS. 4(A) and 4(B) show wear on the recording medium during use. That is, in the process of using the head, the gap portion 6 at the tip of the head elements 8A, 8B is softer than the others, so when the magnetic recording medium lo is slid on the head as shown in FIG. 4(A), the recording medium Due to the friction with 10, the vicinity of gear lug portion 6 is gradually polished. However,
The parts other than the gap are hard and difficult to polish, so
), there is a difference in abrasion resistance between the both-end head element 8A portion adjacent to the end region of the substrate and the other head element 8B portion, and the medium sliding surface becomes non-uniform. This non-uniformity causes non-uniformity in gap depth, which causes a problem of variation in the recording and reproducing characteristics of the heads of each channel.

[Means for solving the problems] In order to solve the above problems, in the present invention,
A thin-film magnetic head in which a plurality of head elements are formed on a magnetic substrate using thin-film technology, employs a configuration in which dummy heads having a structure substantially similar to the head elements are provided at both ends of an array of the plurality of head elements on the substrate. did.

[Function] According to the above WIr#:, in the manufacturing process of the magnetic head, the dummy head is made to bear the damage caused when the protective plate is bonded, and the uneven wear caused in the process of use is can be prevented from affecting the original head element.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

FIG. 1 shows an embodiment of a multi-track thin film magnetic head according to the present invention, and in the figure, the reference numeral 1 indicates a magnetic substrate 1 as in the conventional example.

In this embodiment, in order to configure a 4-channel thin film magnetic head, coil conductors 2 are placed on the substrate 1 in the same manner as in the past.
．． Upper magnetic layer 3. Head elements 8A, 8 consisting of electrodes 4
Four pieces B are formed. Here, numerals 8A and 8B respectively indicate the heads at both ends and the other intermediate head.

Furthermore, in the example of FIG. 1, rads 8A are attached to both ends.

One dummy head IIA and one IIB having the same configuration as the head elements 8A and 8B are further formed on both sides of the head element 8A. These dummy pads 11A and IIB are formed simultaneously with the head elements 8A and 8B by thin film deposition and photolithography. Dummy head I
Since IA and IIB are basically not used for recording and reproduction, there is no need to connect them, and in some cases, the dummy head is connected to the coil conductor 2. Upper magnetic layer 3. The electrodes 4 and the like do not need to be composed of different members, and may be formed of a suitable magnetic material having the same shape as the head elements 8A and 8B.

According to the configuration as shown in FIG. 1, although it is necessary to make the magnetic substrate l wider than before, the productivity and durability of the thin film multi-track head can be greatly improved than before.

That is, in the manufacturing process, the above-mentioned FIG. 3(A).

When the protective plate 7 is bonded as shown in (B), the deterioration caused by the warping and bending of the protective plate 7 will be handled by the dummy heads IIA and IIB at both ends of the board, so it will not be possible to reduce the deterioration caused by the warping and bending of the protective plate 7. 8A and 8A are not affected.

Therefore, it is possible to produce good products with high yield using the same equipment as in the past without employing complicated manufacturing processes.

Also, in the process of using the head, the above-mentioned FIG. 4(A),
When the magnetic recording medium is slid as shown in (B), the dummy disks 11A and 1 at both ends of the substrate are affected by uneven wear.
1B, and the four intermediate head elements 8A and 8B all wear out at approximately the same rate. Therefore, stable recording and reproducing characteristics can be maintained over a long period of time without causing variations in the recording and reproducing characteristics of each channel due to non-uniform gap depths as in the conventional case.

In the above embodiment, a four-channel head is illustrated, and one dummy head is provided at each end of the head. However, the number of head elements is N, and the number of dummy heads is nl+n.
2 is not limited to this, and various modifications can be considered.

First, the number n1pn2 of dummy data IIA and IIB is n
1=n2=2 or more. In that case, the original stability of the head elements 8A and 8B against the influence of deformation during manufacturing or uneven wear during sliding of the medium can be greatly improved. In reality, it is not practical to provide too many dummy heads, so it is desirable to have up to three dummy heads.The number of dummy heads may be determined as appropriate depending on the relative speed between the paddle media, the material of the head element, etc.

Further, the dummy heads IIA and IIB do not need to be provided at both ends, and one side can be omitted. That is, the number n1 or n2 of the dummy heads may be set as nl(n2)=0, and nt(n2), which is not O, may be selected as an appropriate value from about 1 to 3.

Alternatively, select nl and n2 from values of about 1 to 3, and nr+
Such an asymmetric structure, which may also be referred to as n2, is used, for example, in a still video floppy disk device, etc., where there is a difference in circumferential speed between the inner and outer circumferences of the disk, and the wear conditions are different between the head elements on the inner and outer circumferences. It is useful for obtaining uniform wear characteristics in different cases. In this case, it goes without saying that a large number of dummy heads are provided on the outer peripheral side of the disk where the circumferential speed is high.

There is no limit to the number N of head elements, but in order to obtain the effect of preventing deformation and uneven wear, N should be at least 2 or more, and a large value is about 52, the total number of tracks on a still video floppy disk (or more). ) are possible. Specifically, assuming that N is the full track number 52 of the current still video floppy disk, anx and n2 of the dummy heads at both ends of the head are nl+
It is considered that if the ratio is about 12≧1 (or 2), the effect of preventing element deterioration and uneven wear caused by the deformation described above can be sufficiently achieved. The total width of a multi-track head of this size (N=52) is at most about 51,111 mm, and it is easy to add one or two dummy heads using current thin film forming technology.

The configuration of the present invention is not limited to still video floppy disk devices, but can be applied to thin film magnetic heads for various uses.

In addition, in the above, the dummy head is not wired and is not actually used, but it is also possible to wire it and use it for other purposes such as head positioning.

[Effect] As is clear from the above description, according to the present invention, in a thin film magnetic head in which a plurality of head elements are formed on a substrate by thin film technology, both ends of the plurality of head element arrays on the substrate Since a dummy head having a structure similar to that of the head element is provided at the top of the head element, it is possible to improve the head manufacturing yield and mass-produce thin-film magnetic heads at low cost. Due to the uniform abrasion resistance of the material, an excellent effect of stable magnetic recording and reproduction over a long period of time can be obtained.

[Brief explanation of drawings]

FIG. 1 is a top view of a magnetic head showing an embodiment of a thin film multi-track magnetic head according to the present invention, FIG. 2 is an overall perspective view illustrating the structure of a conventional two-channel thin film magnetic head, and FIG. ) and CB) are front views of the magnetic head, respectively, illustrating the deterioration of head characteristics in the conventional multi-track magnetic head manufacturing process, and FIGS. 4(A) and 4(B) are
FIG. 3 is a top view including a magnetic sheet, illustrating non-uniform wear resistance in the process of using a conventional multi-track magnetic head. l...Magnetic substrate 2...Coil conductor 3...Top magnetic layer 4...Electrode 5...Magnetic pole part 6...Magnetic gap 7...
Protective plate 8A, 8B...\RAD element 9...
・Adhesive glass 10...Magnetic media 11A, IIB...Dummy head (A) (B) To magnetism...Front opening of throat Figure 3 (A) (B) To air, top opening of 7th door Figure 4

Claims (1)

[Claims] A thin film magnetic head comprising a plurality of head elements formed on a substrate by thin film technology, characterized in that a dummy head having a structure substantially similar to that of the head elements is provided at both ends of the plurality of head element arrays on the substrate. Thin film magnetic head.