JP2551582B2 - Thin film magnetic head - Google Patents

Description

The present invention relates to a thin film magnetic head suitable for a double azimuth magnetic head for a high density recording VTR, and more particularly, to a contact with a recording medium such as a magnetic tape. Relates to a stable thin film magnetic head.

[Conventional technology]

Conventionally, as a rotary head of a high-density recording VTR, JP-A-61
A double azimuth head is known as described in Japanese Patent Publication No. 150113. This is to perform normal reproduction by providing heads A and B having different azimuth angles 180 ° apart from each other on the rotary drum, and also providing auxiliary head B'having the same azimuth angle as head A near head B for still reproduction. In order to improve the S / N by using the heads A and B'for slow reproduction, the heads B and B'are so-called gear-bonded blocks of ferrite or magnetic alloy. It is made in a bulk type, and a coil is wound by manual winding, and is attached on a support plate so as to face each other with a gap along the relative direction of the tape. This type of double azimuth magnetic head is a bulk type with a large magnetic core volume consisting of a block-shaped magnetic core body, and the winding radius of the coil is inevitably large, so the magnetic flux leakage between the two heads is large. However, there was a problem that the crosstalk was large.

On the other hand, as a magnetic head used for a VTR, etc.
-176524 and Japanese Patent Application Laid-Open No. 60-138714 disclose thin film magnetic heads, and those disclosed in these publications are mounted on a substrate in order to stabilize contact with a recording medium. A protective plate (glass layer) is integrally bonded onto the thin-film magnetic head element formed in step 1 by using the glass bonding technique. The coil is also made relatively thin and small by thin film technology.

[Problems to be solved by the invention]

In the thin film magnetic head described in JP-A-57-176524 or JP-A-60-138714, the magnetic core and the conductor coil are made thin and small by the thin film technique. It is not known to apply it to a double azimuth magnetic head for a VTR as described in Japanese Patent No. 150113 to remove crosstalk between two magnetic heads that are butted together.

Therefore, the inventors of the present invention have previously described the double azimuth 2
We proposed a method of making individual butted magnetic heads by thin film technology to eliminate crosstalk between both heads.In that case, the problems of stable contact with the recording medium and life of the magnetic head are It was never considered. Of course, in the heads described in the above publications, no consideration is given to not only the problem of wear life but also the problem of stable contact. Further, although providing the protective plate by the glass bond method is slightly advantageous in reducing head wear, it is disadvantageous in the point of stable contact described above.
In addition to the complicated manufacturing process, there is a problem that the magnetic material, conductive material, and insulating material used must have high heat resistance because the temperature must be raised to the glass melting point.

Therefore, the present invention solves the above-mentioned problems of the prior art,
In a thin film magnetic head in which two heads are brought into contact with each other, stable contact between both heads and a recording medium is ensured, wear life is improved, and at the same time, a thin film head whose manufacturing process is simplified is provided. .

[Means for solving problems]

In order to achieve the above object, the thin film magnetic head of the present invention has first and second heads mounted on a mounting base with a predetermined gap in the relative running direction of the recording medium. The width of the recording medium sliding surface of the second head is gradually narrowed along the relative running direction from the entrance side and the exit side of the recording medium to the central portion. At least one of the first and second heads constitutes a thin film magnetic head capable of substantially recording and reproducing, but the other magnetic head may be a so-called dummy head made of a material which does not record or reproduce. . In the case of the double azimuth magnetic head, of course, both the first and second heads are magnetic heads on which recording and reproduction are substantially possible. The operating magnetic gears of the magnetic recording / reproducing head are located near the center, that is, near the facing surfaces of both heads. The front surface shape (FIG. 2 described later) of the sliding surface where the first and second heads are combined has an arc shape that is low at the entrance side and exit side of the recording medium and high at the center.
It should be noted that there is no member for supporting the recording medium in the above-mentioned predetermined gap between both heads, and it is a recess. In order to form a so-called thread-wound sliding surface that is wide at the entrance side and narrow at the center, a magnetic head is made by thin-film technology, and then polished so that both sides have arcuate tapering in the center. Good.

In the preferred embodiment, the cross-sectional shape of the sliding surface (Fig. 3 below).
Can have a curvature.

[Action]

By narrowing the widths of the sliding surfaces of the first and second heads on the inlet and outlet sides and narrowing them toward the center, the contact with the recording medium becomes good and the life against wear can be extended. That is, when the recording head presses the magnetic head with a force of a predetermined strength when the magnetic head starts to be used, the area near the center where the operating magnetic gear is relatively narrower than the relatively wide recording medium entrance / exit side. Since the pressure applied to the sliding surface by the recording medium is large, the operating magnetic gap is larger than that of a constant width (the dimension is a value between the wide portion and the narrow portion). The contact relationship in the vicinity of the center where there is is extremely good.

Also, during use, the wear amount near the center is larger than near the outlet side and the inlet side of the magnetic head due to the above-mentioned working pressure relationship, so the wear starts from the center and gradually increases toward the outlet side. Proceed toward the entrance side. Along with this, the area of the effective contact surface with the recording medium starts from the center and gradually expands toward the exit side and the entrance side. In this case, it will be scraped while contacting the tape,
The characteristics are hardly deteriorated. When the both side surfaces are tapered as described above, this spread is further promoted in the width direction. In this way, since the head sliding contact area (sliding area) is effectively increased, it is possible to ensure stable contact with the recording medium, and at the same time, as the sliding contact area increases, the amount of wear increases. Gradually decreases, resulting in a lower head wear rate and increased wear life.

When both heads are made of double azimuth thin film magnetic heads, the magnetic core and the coil can be made smaller and thinner, and the magnetic flux leakage between both heads can be reduced, as in the magnetic head proposed above. . Further, since the thin film forming surfaces are faced to each other and a gap is provided between them so as to be integrally attached to the head mount, it is not necessary to glass bond the thin film magnetic head element with the protective plate as in the prior art, and the manufacturing process Is simplified.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

1, 2, 3, and 4 are a plan view, a side view, and A--A of FIG. 2, respectively, as seen from the head sliding surface direction of the thin film magnetic head according to the embodiment of the present invention. It is a'sectional view and a BB 'section (thin film forming surface). 1a is a thin film magnetic head having an azimuth angle + θ and a track width Tw ₁ and 1b having an azimuth angle −θ and a track width Tw _2. Configure. Circled shaded area 5
a, 5b are thin film magnetic head elements, 6a, 6b are protective films for protecting the thin film magnetic head elements, 11a, 11b are non-magnetic substrates, 2a,
2b is a head sliding surface that contacts the recording medium (tape), 4a, 4
Reference numeral b is a head taper surface processed with a taper angle α required to obtain the head slide surfaces 2a and 2b, and 7 is a tape running direction. Reference numeral 8 is an upper core, 9 is a thin film coil, 10 is a coil drawing portion, and 14a and 14b are operating magnetic air gaps.

This example is manufactured as follows. FIG. 5 is a sectional view of the thinned surface of FIG. First, the method of manufacturing the thin film magnetic head 1a is performed by using a non-magnetic substrate (in this embodiment, a good contact with a tape such as glass, ceramic, or ferrite).
An MnO-NiO ceramic was used. ) 11 on the bottom core
It starts with forming an amorphous alloy 12 such as Co—Nb—Zr as 12 by about 20 μm by a method such as sputtering. Then, after forming a _{S i O 2, Al 2 O} 3 or the like insulating layer 13 made of at Supatsutaringu etc., to form a thin film coil 9 made of Cu, and further forming an insulating layer 13, the thin film coil 9 and the magnetic Ensure electrical insulation between cores 8 and 12. Next, as Giyatsupu member 14 for regulating the Giyatsupu _{length, S i O 2, Al 2} O 3 or the like to 0.3μm formed, further form the same material as the lower core 12 in a predetermined shape as the upper core 8. At this time, as shown in FIG.
If an amorphous alloy made of the same material as the upper core 8 is used as the upper core 10, the upper core 8 can be simultaneously formed in the patterning process, so that the manufacturing process is simplified. Next, as the protective film 6, MgO-S is used as a material having good contact with the tape.
_The TO ₂ -based ceramic layer is formed to a thickness of about 10 to 60 μm by a method such as sputtering or vapor deposition. When the film thickness of the protective film 6 is 10 μm or less, the protective film 6 is abruptly abraded due to abrasion due to running of the tape, and a stable contact with the tape cannot be obtained due to chipping or the like. On the other hand, 60 μm
When the protective film 6 having the above-mentioned thickness is formed, problems occur such that the substrate 11 warps due to the internal stress of the protective film 6 and the time for forming the protective film increases to complicate the manufacturing process.
A film thickness range of up to 60 μm is suitable.

The thin-film magnetic head substrate obtained as described above is cut into individual heads and then machined to form the head taper surface 4a at an angle α so as not to cut the thin and thin coil 9 as shown in FIG. . The angle α is selected to be 30 to 60 degrees. The larger the angle α is, the larger the area for disposing the thin-film coil 9 is, the smaller the electric resistance of the thin-film coil 9 is, and the more the impedance noise of the head can be reduced. However, if the angle α exceeds 60 degrees and becomes too large, the head sliding surface width W suddenly increases as the head wears, and stable tape contact cannot be achieved. Next, the thin film magnetic heads 1a and 1b are placed on the head base 3 at predetermined positions (gap spacing Lg is 0.3 to 0.3 in this embodiment).
0.75mm) so that it is attached. Further, the head sliding surfaces 2a, 2b are shaped by machining such as cylindrical grinding or cylindrical polishing with tape to have a radius R _{1 in} the direction of the tape running 7 and a radius R _{2 in} the width direction of the tape running. The thin film magnetic head of the first embodiment is obtained. In this embodiment, R ₁
8 to 13 mm and R _{2 of 2} to 4 mm showed the most stable contact with the tape.

In the thin magnetic head constructed in this way, the double azimuth head is a thin film magnetic head composed of a thin film, so that crosstalk between both heads is reduced, and it is about 10 dB or more compared with the conventional bulk type head. Improve. Also,
With the head sliding surface shapes 2a and 2b, the head sliding surface width W is configured to become gradually narrower from the entrance side and the exit side of the tape as it reaches the gap, so that it is similar to the conventional thin film magnetic head. Since it is not necessary to use a protective plate, a manufacturing process such as glass bonding can be omitted, and contact with the tape can be stabilized and head wear life can be increased. Figure 10 and
FIG. 11 shows the relationship between the level deterioration amount and the head sliding width W in the initial state of contact with the tape of the thin film magnetic head of the embodiment of the present invention, and the conventional head (the head sliding width W is a constant value, The width of the head of the present invention equal to the width W at the center of the sliding surface) and the wear characteristics of this embodiment are shown. When the head sliding width W exceeds 250 μm, the level deterioration starts and stable contact with the tape cannot be obtained. On the other hand, when the sliding width W becomes smaller, stable contact with the tape becomes possible, but the head wear life becomes shorter. Therefore, in this embodiment, the sliding width W was selected to be 100 to 200 μm. Comparing the head wear characteristics of the head-shaped thin-film magnetic head of the present example and the conventional example, as shown in FIG. 11, the head wear amount decreases with the passage of the tape as compared with the conventional example,
It can be seen that the head wear life is increased while ensuring good contact with the tape.

FIG. 7 is a head sliding surface of the thin film magnetic head according to the second embodiment of the present invention. The thin film magnetic head 1a is the first
1c has the same structure as that of the first embodiment, except that the thin-film magnetic head 1b
It is a non-magnetic substrate having the same shape as, and does not function as a magnetic head, and should be called a dummy head, so to speak. With this structure, even if a normal single magnetic head other than the double azimuth magnetic head is used, good contact with the tape, increased head wear life, and glass bonding of the protective plate can be achieved as in the first embodiment. Effects such as omission of steps can be obtained. Further, FIG. 6 shows a cross-sectional view when the protective film 6 of the thin film magnetic head shown in FIG. 5 is flattened by a technique such as a lap method.
Although the shapes of the protective films 6a and 6b near the thin film magnetic head elements 5a and 5b in FIG. The effect of the present invention does not change. In addition, in FIG.
Another embodiment in which the shape which gave a flat portion at the bottom of the Hetsudotepa surface 4a, the FIG. 9, a side cross section of another embodiment in which a tapered surface 4a and shape which gave a curvature radius R ₃ Although the figures are shown, it is apparent that the head sliding surface shapes 2a and 2b shown in the first and second embodiments can be realized and the effect of the present invention is not changed even with such a configuration. .

On the other hand, FIG. 12 shows a head sliding surface of a thin film magnetic head as another embodiment. In the figure, one of the pair of heads is omitted. As shown in the figure, the magnetic head 1a located on the output side in the tape running direction (it is assumed to run from right to left in the figure) is provided by rounding the tip portion 15 of the head sliding surface 2a of the protective film 6a. It is possible to prevent the damage of the tape, which is likely to occur when the tip has an acute angle, because the tip 15 of the tape comes into more stable contact with the tape. Although FIG. 12 shows only the thin film magnetic head 1a located on the tape exit side, the same applies to the thin film magnetic head 1b located on the tape entry side and the non-magnetic substrate 1c of the dummy head. It goes without saying that the effect can be obtained.

〔The invention's effect〕

As described above in detail, in the thin film magnetic head of the present invention, two heads having at least one substantial recording / reproducing function are provided between the heads so that the thin film forming surfaces face each other. The head is mounted integrally on a head mount (head base) with a predetermined gap, and the shape of the sliding surface that combines both heads gradually increases from the entry side and exit side of the recording medium to the above-mentioned gap in the center. Since the sliding surface width is narrowed, not only the crosstalk can be reduced, but also stable contact with the recording medium and the wear life of the magnetic head can be increased. When the head travels in contact with the recording medium, the catalytic pressure with the recording medium is larger before and after the head in the traveling direction of the head than in the central portion of the head, and as a result, wear is faster than in the central portion. Therefore, in order to give stable tape contact to the two magnetic gap portions located in the central portion of the head, uniform pressure is applied to the entire sliding surface with the recording medium,
And it is necessary to remove unnecessary contact parts. Further, it was conventionally thought that a strong contact pressure was concentrated on the front side of the head running. However, depending on the conditions such as the sliding speed between the recording medium and the head and the characteristics of the recording medium, the rear side may be the same as the front side. A strong contact pressure is applied. For this reason,
Since a uniform pressure is applied to the entire sliding surface of the head, narrowing sliding surfaces are formed on the front and rear sides of the central portion of the head.

Further, since the gap interval is a recess space, glass bonding or the like is not required, and the manufacturing process can be simplified, which is an excellent effect.

[Brief description of drawings]

1 is a plan view of a thin film magnetic head according to a first embodiment of the present invention, FIG. 2 is a front view of the same thin film magnetic head, and FIG. 3 is a sectional view taken along the line AA 'in FIG. FIG. 4 shows BB ′ of FIG.
5 and 6 are sectional views of the thin film magnetic head element, FIG. 7 is a plan view of the second embodiment of the present invention, and FIGS. 8 and 9 are the third embodiment of the present invention. FIG. 2 of the fourth embodiment AA ′ in FIG.
10 and 11 are explanatory views of characteristics of the first embodiment of the present invention, and FIG. 12 is a plan view of the head sliding surface of the fifth embodiment of the present invention. is there. 1a, 1b ... Thin-film magnetic head, 2a, 2b ... Head sliding surface, 3
...... Head base (head mount), 5a, 5b …… Thin film magnetic head element, 6a, 6b …… Protective film, 8, 12 …… Thin film magnetic core (upper core and lower core, second magnetic body and first Magnetic material), 9 ... thin coil, 11,1c ... non-magnetic substrate, 13 ...
… Insulating layers, 14,14a, 14b …… Operating magnetic gears.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Konishi, 292 Yoshida-cho, Totsuka-ku, Yokohama City, Home Appliances Research Laboratory, Hitachi, Ltd. (72) Inventor, Akifumi Uchimura 1410, Inada, Katsuta-shi, Hitachi Ltd. 56) References JP 62-47813 (JP, A) JP 57-189325 (JP, A)

Claims (4)

(57) [Claims] 1. A head in which first and second heads having the same contour shape face each other so that their thin film forming surfaces face each other so as to be symmetrical along a relative running direction of a recording medium, and a predetermined gap is provided between both heads. At least one of the first and second heads is integrally attached to the mounting base, and includes at least one of a first magnetic body, an insulator, a thin film coil layer, a second magnetic body, and a protective film laminated on the substrate. A thin film magnetic head which constitutes a substantial thin film magnetic recording / reproducing head, wherein the predetermined gap distance between the two heads is the protective film and a recess space where a sliding contact member with a recording medium does not exist. The widths of the recording medium sliding surfaces of the first and second heads are along the relative running direction from the entrance side of the recording medium to the central recess space and from the exit side of the recording medium. It gradually narrows as it reaches the recessed space in the center Uni configured thin-film magnetic head. 2. A thin film magnetic head according to claim 1, wherein the other of said first and second heads constitutes a substantial thin film magnetic recording / reproducing head having the same structure as said one head. 3. A thin-film magnetic head according to claim 1, wherein the other of said first and second heads is made of a substrate material that does not substantially constitute a magnetic head. 4. The magnetic gap surfaces of the first and second heads constituting the substantially thin film magnetic recording / reproducing head have a required azimuth angle with respect to the relative traveling direction. 2. The thin film magnetic head according to item 2.