JPH0256708A - Manufacture of core for magnetic head and core obtained by this manufacture - Google Patents

Abstract

PURPOSE:To reduce the manday of manufacturing by arranging a first ferrite block and a second ferrite block, protruding two ferrite blocks and forming a magnetic path. CONSTITUTION:A joining groove 32A of prescribed depth to extend in the lengthwise direction of a ferrite block raw material 12B is formed, and a same groove 32B is formed in the position corresponding to a ferrite block raw material 12B. Next, ferrite block raw materials 12A and 12B are mutually protruded at the protruding surfaces, and in the protruding condition, into the clearance between the protruding surfaces, namely, the clearance between facing track parts 22A and 22B and the clearance between the concave convex parts of both sides and the space of grooves 32A and 32B for joining a block, a non- magnetic material made prescribed packing/joining material is flown and charged and integrally joined. At this time, the joining operation of a ferrite block is sufficient only one time.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for manufacturing a core for a magnetic head and a core for a magnetic head obtained thereby, and particularly to a method for manufacturing a core suitable for use in a magnetic head for a floppy disk drive. The present invention relates to a method that can be manufactured by the method, and a core for a magnetic hex F obtained by such a method.

(Background Art) In a floppy disk drive (FDD), if new data is simply written over old data using a magnetic head for recording/reproducing, the magnetic head may be misaligned in the track width direction with respect to the floppy disk as a recording medium. (Off-track) causes unerased portions of old data, as shown in FIG. If there is an unerased portion of the old data, the unerased portion of the old data is read out together with the new data during data reproduction, resulting in a decrease in the S/N ratio and making reading errors more likely to occur. Therefore, in magnetic heads for FDDs, in order to prevent the S/N ratio from decreasing due to such unerased old data, the erasing magnetic head is generally used in pairs with the recording/reproducing magnetic head. As shown in FIG. The data is forcibly erased using an erasing magnetic head.

On the other hand, if adjacent tracks on a floppy disk are too close to each other, the erasing magnetic head may erase more data than necessary on the adjacent track when off-track, or the recording/reproducing magnetic head may become adjacent to each other. When track data is read, so-called crosstalk occurs, which lowers the S/N ratio and makes reading errors more likely to occur.

Therefore, in an FDD floppy disk, a guard band of a predetermined width is provided between each adjacent track in order to prevent such a problem from occurring (see FIG. 25).

For example, the currently popular 3 and 5 inch, IMBy
In TE FDDs, the maximum off-track amount of the magnetic head is usually about 30 [μm], but in order to prevent the above-mentioned problems, a guard of about 60 [μm] is installed between each adjacent track of the floppy disk. A band is provided. The track density of this 3.5-inch IMByte floppy disk is 135 (TPI), the track pitch is 188 [μm], and the track width is about 125 [μm].
m], and the tracks are 80 tracks ρ from the outer circumferential side to the inner circumferential side.

Incidentally, in recent years, bulk type magnetic heads have become mainstream as the magnetic heads used in such FDDs have become more popular due to higher density recording and larger capacity. As shown in FIG. 26, the core 2 for recording and reproducing and the core 4 for erasing are joined and integrated back to back with their respective magnetic gaps 2a and 4a aligned. Because of its unique structure, there were problems in that it required a large number of manufacturing steps and the manufacturing cost was inevitably high.

That is, when manufacturing the recording/reproducing core 2 of the magnetic head core shown in FIG. 26, a pair of ferrite blocks are first prepared, and a track width defining groove is formed in each of the ferrite blocks. glass is buried in
At the same time as removing the buried excess glass, the surface facing the gap is polished to a mirror finish, and then a depth length defining groove is formed in one block. Next, after a gap spacer is formed with a predetermined thickness on the gap-opposing surface of at least one of the blocks, glass is poured into the depth-length defining groove, the two ferrite blocks are joined together, and the core 2 for recording and reproduction is formed. A core block is manufactured that gives Further, the core block that provides the core 4 for erasing is also manufactured in the same manner as the core block that provides the core 2 for recording and reproducing.

Then, after aligning the magnetic gaps 2a and 4a, the core block providing the recording/reproducing core 2 and the core block providing the erasing core 4 are integrally joined back to back with glass or resin, and then they are joined together. After the integrated cores 2 and 4 are subjected to foot warming processing, the integrated core block is cut at a predetermined position, thereby producing a magnetic head core as shown in FIG. You can get it.

Therefore, when manufacturing such conventional magnetic head cores for FDDs, grooving to define the track width is required.
It is necessary to perform the grooving process twice for each of the core block that provides the core 2 for recording and reproducing and the core block that provides the core 4 for erasing, and the grooving process for the depth length regulation groove must be performed once for each. In addition, it is necessary to perform gap joining twice, and joining both core blocks once.
A total of three bonding steps are required, which inevitably increases the number of man-hours and increases costs.

In addition, when manufacturing such conventional magnetic head cores for FDDs, it is necessary to align the magnetic gaps 2a and 4a of the core block providing the recording/reproducing core 2 and the core block providing the erasing core 4. , the alignment of the magnetic gaps 2a, 4a is carried out in a state in which the magnetic gaps 2a, 4a are separated, that is, in a state in which each ferrite block of each core block is sandwiched. There were also problems in that the work was extremely difficult and the alignment accuracy was poor.

(Problem to be Solved) With this background in mind, the present invention provides a method for solving problems without an automatic tracking function using a servo mechanism.
A magnetic head core suitable for use as a magnetic head core for an FDD, capable of recording new data on old data using an override method and reproducing the data with a good S/N ratio. The problem to be solved is to provide a structure that can be manufactured at a low price by significantly reducing the number of manufacturing steps, and to provide an industrially advantageous manufacturing method for such a core. It is something that

(Solution Means) In order to solve this problem, the present invention arranges a first ferrite block and a second ferrite block, and forms a predetermined magnetic path by butting these two ferrite blocks. In addition, when manufacturing a core for a magnetic head in which a magnetic gap for recording and reproducing with a predetermined gap is formed at the abutting portion of two ferrite blocks, it is necessary to A mask defining a recording/reproducing track portion for forming the recording/reproducing magnetic gap between the abutting surface of the other ferrite block is applied to the recording/reproducing magnetic gap forming region;
By applying at least one mask to each side of the mask and performing etching, the recording/reproducing track portion is formed in the recording/reproducing magnetic gap formation region, and the recording/reproducing magnetic gap is formed on both sides of the track portion. The gist of the present invention is a method for manufacturing a core for a magnetic head, which is characterized in that a convex portion corresponding to a mask is formed, and then two ferrite blocks are butted and joined.

Moreover, the present invention arranges a first ferrite block and a second ferrite block so that a predetermined magnetic path is formed by abutting these two ferrite blocks, and also arranges a predetermined magnetic path between the two ferrite blocks. In a magnetic head core in which a magnetic gap for recording and reproducing with a predetermined gap is formed at the abutting portion, a recording and reproducing track whose both side surfaces are inclined surfaces is provided at the magnetic gap forming portion of at least one of the two ferrite blocks. At the same time, waveform-shaped uneven portions are formed on both sides of the recording/reproducing track portion, and the recording/reproducing magnetic gap is formed on the abutting surface of the recording/reproducing track portion and the other ferrite block. A predetermined recording and reproducing function lower than that of the recording and reproducing magnetic gap is provided between the corrugated uneven portion and the abutting surface of the other ferrite block. The object of the present invention is also to provide a core for a magnetic head characterized by the following characteristics.

(Example) Hereinafter, the present invention will be described with reference to the example shown in the drawings.
Let's clarify more specifically. Here, we will first explain a manufacturing example using the FDD magnetic head core shown in FIG. The structure of the core will be explained in detail.

That is, when manufacturing the core for the magnetic head shown in FIG. 1, first, in order to obtain the ferrite blocks 10A and IOB as the first and second ferrite blocks, the ferrite blocks IOA and IOB are prepared in the following manner. As shown in FIG. 2, block-shaped ferrite block materials 12A and 12B each having a predetermined thickness and having mirror-finished abutting surfaces are prepared.

In addition, these ferrite block materials 12A.

12B, that is, the ferrite block IOA, 10B is made of a conventional high permeability ferrite material, such as Mn.
Single crystals, polycrystals, or composites thereof such as -Zn ferrite and Ni-Zn ferrite are preferably used, but single crystals have high etching accuracy and can advantageously improve track accuracy. Ferrite (single crystal) is particularly preferably employed. And those ferrite blocks IOA, IOB (12A, 12
When single crystal ferrite is adopted as B), (100), (110), (2
Crystal planes such as 11), (311), (332), and (611) are advantageously selected.

In addition, here, each ferrite block material 12A, 1
In order to take three ferrite blocks IOA and 1OB from 2B, those ferrite blocks IOA
, ferrite block material 1 with a length more than three times that of IOB
2A and 12B are prepared, each ferrite block material 12A.

1 ferrite block 10A each from 12B,
Of course, it is possible to obtain only IOB, or it is also possible to obtain both ferrite blocks IOA and IOB from one ferrite block material.

First, a predetermined resist is applied to the abutting surfaces of the prepared ferrite block materials 12A and 12B. Then, as shown in FIG. 3, the ferrite block material 12A is removed from the end on the recording medium (floppy) sliding section side.

The strip-shaped (longitudinal rectangular) ferrite exposed portions 14A, 14B extend in the width direction of the ferrite block material 12A, each having a predetermined width dimension and a constant length.
A plurality of ferrite exposed portions 12B are formed in the longitudinal direction, and as a result of the formation of these ferrite exposed portions 14A and 14B, each recording/reproducing magnetic gap forming portion is covered with one strip-shaped mask 16A and 16B of residual resist. Further, the side opposite to the recording medium sliding portion side is arranged so that the regions on both sides of each magnetic gap formation region for recording/reproduction are covered with at least one (in this case, a plurality of strip masks 18A and 18B, respectively) of residual resist. The end portion is made of ferrite block material 12A.

The resist is exposed, developed, and removed so that the remaining resist is covered with band-shaped masks 2OA and 20B of a predetermined width over the entire length of the resist 12B in the longitudinal direction.

After applying each mask by exposing and developing the resist, these ferrite block materials 12A, 12B
On the other hand, through each ferrite exposed portion 14A, 14B,
Etching processing is performed to a predetermined depth, and as a result of this etching processing, as shown in FIG. While recording and reproducing track portions 22A and 22B having trapezoidal cross-sections with sloped surfaces on both sides, in which the etching surface is left as a non-etched surface,
These recording/reproducing magnetic gap forming portions (track portion 2
2A, 22B), respectively, the masks 18A, 22B).
A chevron-shaped convex portion 24A having a predetermined height and having a top portion located at a portion corresponding to the middle portion in the width direction of the portion 18B, and having sloped surfaces on both side surfaces.

24B is formed. In other words, at the same time that the recording/reproducing track portions 22A and 22B are formed at each magnetic gap forming site, on both sides of these magnetic gap forming sites,
A wave-shaped uneven portion having at least one chevron-shaped convex portion 24A, 24B is formed.

When this etching process is completed, one of the ferrite block materials 1 is then removed as shown in FIG.
A resist mask 26 is applied to the abutting surface of 2A in the same manner as the above-mentioned masks, covering the applied part of the mask 2OA, and a part of a predetermined width at the end of the recording medium sliding part. A resist mask 28 is applied so as to cover the ferrite block material 12A in a band-like manner in the longitudinal direction. After applying the masks 26.28, the ferrite exposed portions not covered by the masks 26.28 are given a depth corresponding to the gap length of the recording/reproducing magnetic gap 30 of the intended magnetic head core. Etching is applied.

Note that the etching process for forming the recording/reproducing magnetic gap 30 is performed using the ferrite block material 12B.
It is also possible to apply it to the side, or it is also possible to apply it to both the ferrite block materials 12A and 12B. In addition, ferrite block material 12A,
The above etching treatment for 12B can be carried out by ordinary electrolytic etching or chemical etching.
This will be carried out by chemical etching using a phosphoric acid-based aqueous solution as disclosed in No. 388. Furthermore, for the formation of each mask applied prior to the etching process, an exposure method using photoresist is preferably adopted as described above due to pattern accuracy and process simplicity. , Instead of this method, it is also possible to adopt other methods such as screen printing,
In addition, each mask can be made of not only positive or negative photoresists, but also metals such as Cr, SiO or 5i formed by vacuum evaporation, sputtering, CVD, etc.
It is possible to employ various masks such as 02.

When the etching process for forming the magnetic gap 30 is completed, the etched ferrite block material 12A (see FIG. 6) is
As shown in the figure, a bonding groove 32A of a predetermined depth extends in the longitudinal direction of the ferrite block material 12A in a state that defines the gap depth position of the magnetic gap 30.
is formed, and a similar groove 32B (see FIG. 8) is formed in the corresponding portion of the ferrite block material 12B.
are grouped together.

Next, the ferrite block materials 12A and 12B processed in this way are butted against each other at their abutting surfaces, and in this abutting state, the gap between the abutting surfaces,
That is, the gap between the corresponding track parts 22A and 22B, the gap between the uneven parts on both sides thereof, and the groove 32A for joining the blocks.

A predetermined filling bonding material 3 made of non-magnetic material is placed in the space 32B.
4 is flowed in and filled, and they are integrally joined.

After such joining, the ferrite block material 12
An unnecessary portion of a predetermined width on the floppy sliding portion side of the joined body of A and 12B, that is, a portion that has not been etched to form the magnetic gap 30 is cut and removed.

As a result, the corresponding track portions 22 of the ferrite block materials 12A and 12B as shown in FIG.
Between A and 22B, facing the magnetic medium sliding surface,
The recording/reproducing magnetic gaps 30 of the intended magnetic head core are formed, and between the concave and convex portions on both sides of each magnetic gap 30, the magnetic gaps 3
A joined body of ferrite block materials 12A and 12B is obtained in which a gap having a gap length greater than 0 (hereinafter, this gap is referred to as a track width defining gap) is formed.

Note that here, the groove 32A for connecting the blocks.

It is also possible to form only one of the grooves 32B, and the gap depth length of the magnetic gap 30 does not necessarily have to be defined by the grooves 32A and 32B, but by the track portion 22A.

It is also possible to define the track portions 22A and 22B simultaneously with the formation of the track portions 22A and 22B by etching to form the groove 22B. In addition, the ferrite block material 1
As the joining filler 34 for joining 2A and 12B, it is possible to use glass, ceramic-based inorganic adhesive, hard resin, etc. However, from the viewpoint of stability of the running performance of the recording medium, Usually, glass will be used.

Ferrite block material 12 obtained as described above
The joined body of A and 12B is then subjected to groove processing to form a U-shaped magnetic path along the break line 36 as shown in FIG. After the groove-extending process, the ferrite block materials 12A, 12 that have been subjected to the groove-extending process are
The bonded body B forms the track width defining gap forming portions on both sides of the trough portions 22A and 22B, that is, the chevron-shaped convex portions 24.
A.

Both ferrite blocks IOA and IOB are cut to have a predetermined core width at the formation site of 24B (for example, by cutting along the break line 38 in FIG. 10), and both ferrite blocks IOA and IOB are cut as shown in FIG. Recording/reproducing track section 22
A recording/reproducing magnetic gap 30 having a predetermined length and gap length is formed between A and 22B, and between the corrugated concave and convex portions on both sides of the magnetic gap 30,
Three magnetic head cores each forming a U-shaped magnetic path in which a track width defining gap having a gap length larger than the magnetic gap 30 is formed are obtained.

In addition, in the above process, the gap length of the magnetic gap 30 for recording and reproduction is the same as that of the ferrite block materials 12A and 12B.
However, instead of performing such etching, a non-magnetic film corresponding to the gap length of the magnetic gap 30 is formed on the end surface of at least one of the track parts 22A, 22B. It is also possible to define the gap length of the magnetic gap 30 by depositing it by a method such as sputtering.

In addition, when joining the ferrite block materials 12A and 12B, the filling portion of each ferrite block material 12A and 12B is first filled with the filling bonding material 34, and the filling bonding material 34 is
After removing and polishing the unnecessary parts of 4, both ferrite block materials 12A.

It is also possible to butt the parts 12B and join them together.

Furthermore, the magnetic head core manufactured in this manner may have asymmetric track width defining gaps on both sides of the magnetic gap 30, as shown in FIGS. 11 and 12. It is possible, and it is also possible to make it symmetrical.

When a magnetic head core manufactured according to such a method is for 3.5 inches, IMByte, the gap length of the defined gap for the track width:
A (see Figure 12) is expressed by the following equation (1) (Karqvis
The size is set to be smaller than the size that satisfies the calculation formula for t, preferably 10 [μm] or less. Thereby, during recording, a sufficiently large recording function can be exerted not only in the recording/reproducing magnetic gap 30 but also in the track width defining gaps on both sides of the magnetic gap 30.

Here, Hc is the coercive force of the recording medium (floppy disk); α is the effective gap length: the core efficiency determined by A; N is the number of turns of the coil; I is the recording current; δ is the magnetic film of the floppy disk. It's the thickness.

Here, for a 3.5-inch IMByte floppy disk, HC=700 (Oe: +, N
=320 (times), I=O, OO4CA, -p), δ=
2 [μm], and α is 0.6 when the gap length A of the track width regulation gap is 10 [μm], so the gap length A of the track width regulation gap is 10
[μm], the track width regulation gap is 2[μm].
m] The strength of the magnetic field above: H is 730 (Oe). Therefore, if the gap length A of the track width regulation gap is set smaller than 10 [μm], sufficient recording capacity can be achieved even in the track width regulation gap. You can get it.

By the way, magnetic heads to which such magnetic head cores are applied will adopt an override recording method in which new data is written directly over old data, but in this case, unlike conventional magnetic heads, is not provided with an erasing function, but is merely provided with a recording/reproducing function, and as described above, not only the recording/reproducing magnetic gap 30 but also the track width defining gaps on both sides thereof. Since a sufficient recording function is provided, Fig. 13 (a)
), there is basically no guard band between each track. Therefore, the same figure (b
), when there is no off-track, the data of the adjacent track is read through the gap defined by one track width, and when off-track occurs as shown in (C) of the same figure, data on one track is read. In addition to reading data on adjacent tracks using the track width defining gap, the other track width defining gap reads data of the same track with a different phase or data on an adjacent track, and the recording/reproducing magnetic gap 30 reads data of different phases on the same track written in any of the track width regulation gaps, and the data of adjacent tracks read or the phase of the same track is read by the track width regulation gap or the magnetic gap 3o. Different data becomes noise and reduces the S/N ratio.

Therefore, in order to avoid such problems and ensure a good S/N ratio, the gap length A of the track width regulation gap is set to the recording/reproducing magnetic gap 30.
It is set to a size that is approximately 3 times or more than the gear lug length 2B,
12 (dB) at such track width specified gap
The angle formed by the magnetic gap 30 and each inclined surface of the chevron-shaped convex portions 24A and 24B forming the concave and convex portion of the track width defining gap: θ, T (12th (see figure) are each 20
When the track width defining gap reproduces the signal recorded by the recording/reproducing magnetic gap 30 and is set at an angle of 30° or more, and the recording/reproducing magnetic gap 30 reproduces the recorded signal, the recording/reproducing magnetic gap 30, it is possible to obtain an azimuth loss of about 13 (dB) or more, preferably about 18 [dB] or more, and as a result, within the allowable off-track range, the magnetic gap 30 for recording and reproduction can be used. 25 (dB), which is sufficient for practical use, when reproducing a recorded signal using the track width specified gap and when reproducing a signal recorded using the track width specified gap using the recording/reproducing magnetic gap 30.
This results in more than a certain amount of playback loss.

In other words, for 3.5 inch FDD, IMByte, the gap length of the gap width specified gap is A.
, the recording wavelength is λ, and when A/λ>0.8, the gap loss in the track width defined gap is 12 (d
B) It becomes more than moderate. On the other hand, in FDD, the recording wavelength is the shortest on the innermost track, and asymmetry and
The margins of other items such as peak shift become smaller, and the resolution required for the system deteriorates the most. To avoid this, the gap length B of the recording/reproducing magnetic gap 30 is set to B = 0. It is required that the relationship 3λ1,7 be satisfied. Therefore, the above A/λ>0.8
and B = 0.3λ1,. A> derived from the relationship
If the gap length A of the track width regulation gap is set to satisfy the relationship 8B/3, that is, as described above, the gap length A of the track width regulation gap is set to the gap length of the magnetic gap 30 for recording and reproduction: By setting the size to approximately three times or more of B, it is possible to obtain a gap loss of about 12 (dB) or more in the track width specified gap while securing the specified resolution, and the gap loss in the track width specified gap and recording This reduces the probability that the track width defining gap will reproduce the signal recorded in the reproducing magnetic gap 30.

In addition, in the case of 3.5 inch FDD and IMByte, the gap length of the magnetic gap 30 for recording and reproduction is:
Since B months is generally 7 [μm], the gap length A of the track width regulation gap is usually 5 [μm].
m] or more.

Also, here, the gap length of the track width specified gap:
A depends on the shape of the uneven parts of the ferrite blocks IOA and IOB that form each track width defining gap, but the effective gap length: A is 1/2 of the sum of the shortest distance and the maximum distance. On the other hand, depending on the shape of the uneven part, 0.5~
It can be thought of as being multiplied by a coefficient of about 0.8.

On the other hand, as described above, the angles θ and γ formed by the magnetic gap 30 and the inclined surfaces of the angular convex portions 24A and 24B forming the uneven portion of the track width defining gap are set to angles of 20° or more, respectively. For example, an azimuth loss of about 13 (dB) or more can be obtained on the outermost track with the smallest azimuth loss, while an azimuth loss of about 25 (dB) or more can be obtained on the innermost track, which requires the lowest noise. and their angles:
If θ and γ are set to an angle of 30° or more, the outermost track will have a power of about 18 (dB) or more, and the innermost track will have a power of about 35 (dB) or more.
(dB) or more can be obtained,
The probability that the recording/reproducing magnetic gap 30 reproduces a signal recorded in the track width defining gap and the probability that the track width defining gap reproduces a signal recorded in the recording/reproducing magnetic gap 30 are both reduced. As a result, in addition to the gap loss, the signal recorded in the recording/reproducing magnetic gap 30 can be reproduced in the track width specified gap, and the signal recorded in the track width specified gap can be reproduced in the recording/reproducing magnetic gap 30. During reproduction, a practically sufficient reproduction loss of 25 [dB] or more can be obtained, and a sufficiently good S/N ratio can be obtained.

On the other hand, here, in order to reduce the probability that the track width defining gap itself reproduces the signal recorded by the track width defining gap during off-track, the following measures are taken. Together with the gap loss, when reproducing a signal recorded by the track width defining gap itself, a practically sufficient reproduction loss of 25 [dB] or more can be obtained.

That is, if secondary angular projections 40A, 40B as shown in FIG. 14 are not formed with respect to the angular projections 24A, 24B of the uneven portion of the track width defining gap, Even if the chevron-shaped protrusions 40A and 40B are formed, the gap length of the track width regulation gap: A
Their height with respect to: If ΔA is low enough, e.g. Δ
In the case where the relationship A/A<0.1 is satisfied, the chevron-shaped convex portion 2 in the concavo-convex portion of at least one of the ferrite blocks IOA and IOB forming the track width defining gap.
The pitch of 4A, 24B: C, DC (see Figure 12) is approximately 1/3 or less of the corresponding track width regulation gap length 20 (see Figure 12), more preferably 11B.
The size is set to less than or equal to

Pitch of at least one of the chevron-shaped convex portions 24A and 24B: C
, D is set to be less than about 20 1/3 of the length of the corresponding track width regulation gap.
When the amount of off-track is less than [μm], the probability that the track width defining gap reproduces the signal recorded by the track width defining gap becomes low, resulting in a loss of approximately 6 (dB) or more, and less than approximately 11 B. If the magnitude is set to , a loss of about 8 to 10 (dB) can be obtained, and the reproduction loss can be increased and the S/N ratio can be improved. However, those chevron-shaped protrusions 24
When the pitches of A and 24B: C and D are approximately 3 [μm] or less, masks (18A, 18B) are formed to form these chevron-shaped convex portions 24A, 24B, and these chevron-shaped convex portions 24A, 24B are formed by etching. Therefore, pitches C and D of the chevron-shaped convex portions 24A and 24B are usually set to a size of about 3 [μm] or more.

Further, as described above, the secondary chevron-shaped convex portion 40A.

When the height ΔA of 40B is sufficiently lower than the gap length A of the track width defining gap, the chevron-shaped convex portion 24A in one track width defining gap.

Pitch of 24B: cl, I) Pitch of chevron-shaped protrusions 24A and 24B at I and the other track width regulation gap:
Cz and Dz are made different. In this case, the ratio between pitch: cl, I)l and pitch: Cz, Dz is
Usually 1:1.2 or more, preferably 1:1°5 to 1:4
(See Figure 15: Here, only the ferrite block IOA is provided with the chevron-shaped convex portion 24A, and therefore only the pitches of the chevron-shaped convex portions 24A: C1 and C2 are different. ing).

Chevron-shaped convex portion 24A in one track width regulation gap
, 24B pitch: C1, D+ and the chevron-shaped convex portion 24A at the other track width defining gap.

If the pitches of 24B: Cz and Dz are made different, the probability that a signal recorded in one track width defined gap will be reproduced in the other track width defined gap will be reduced.゜If set to 2 or more, the loss will be about 3 (dB) or more, or 1:1.5 to 1
:4, a loss of about 5 to 7 (dB) or more can be obtained.

Furthermore, the pitches C and D of the convex portions 24A and 24B are made different even in the same track width defining gap for the respective convex portions 24A and 24B. Usually, the ratio of those pitches is l:1.2 or more,
The ratio is preferably set to 1:1.5 to 1:4 (see Figure 15).

As shown in this figure, if the pitches: C1D of the convex portions 24A and 24B are set differently within the same track width regulation gap, the signal recorded in one track width regulation gap can be recorded in the same track width regulation gap. The gap itself reduces the probability of reproduction, and if the ratio is set to 1:1゜2 or more, the probability of reproduction decreases by 3 (dB).
If the ratio is set to 1:1.5 to 1:4, a loss of about 5 to 7 (dB) or more can be obtained.

In addition, in order to increase reproduction loss, as shown in FIG. 16, the pitches of the chevron-shaped convex portions 24A and 24B in the concavo-convex portions facing each other within the same track width regulation gap: C, [ ] are made to have different ratios. The ratio is usually 1:1.2 or more, preferably 1:
The ratio is set to 1.5 to 1:4.

Pitch of chevron-shaped convex portions 24A, 24B in opposing concavo-convex portions within the same track width regulation gap: C, D
By making the ratios different, the magnetic field in the track width defining gap will become more random, the azimuth effect will increase, the reproduction loss will increase, and the i-side track width defining gap will suppress the recorded signal. The probability that the track width defining gap itself will be reproduced and the probability that the other track width defining gap will be reproduced are both reduced. As described above, the chevron-shaped convex portions 24A, 24B
If the ratio of pitch:C and D is set to 1:1.2 or more, a loss of 3 (dB) or more can be obtained;
:1.5 to 1:4, a loss of 5 to 7 (dB) or more can be obtained.

Also, the trailing side or both side chevron-shaped convex portions 24A in the track width defining gap on both sides of the magnetic gap 30.
The angles 20 and T of the inclined plane of are set to different sizes (see Fig. 17), and furthermore, these angles: θ and γ are as follows.
Even the same track width defining gap is set to different sizes. And in this case, magnetic gap 3
Angle of the slope of the angular convex portion 24A on the trailing side or both sides in the track width regulation gap on both sides of 0: θ,
The angular difference of T is usually set to 20° or more, preferably 30° or more, and the angular difference between the slopes in the track width defining gap on the same side is also usually 20" or more, preferably 30" or more. Set.

If the angles 20 and γ of the slopes of the chevron-shaped protrusions 24A on the trailing side or both sides of the track width defining gap on both sides of the magnetic gap 30 are set to different sizes,
The probability that a signal recorded with one track width regulation gap will be reproduced by the other track width regulation gap becomes small, and if the angular difference between θ and γ is set to 20° or more, the signal recorded with one track width regulation gap will be reproduced. If the loss is set to 30° or more, a loss of 12 (dB) or more can be obtained. Also, if the angles θ and T of each slope are made different from each other in the track width regulation gap on the same side,
The probability that the signal recorded by one track width regulation gap will be reproduced by the other track width regulation gap becomes smaller, and if the angular difference between them is set to 20 degrees or more,
(dB) or more, if the loss is set at 30° or more, 6 (
dB) or more can be obtained in each case.

Here, by using the above-mentioned measures to increase the reproduction loss and the gap loss, when off-track occurs, when the track width regulation gap reproduces the signal recorded by the track width regulation gap, it is possible to achieve a practically sufficient level. A reproduction loss of 25 (dB) or more can be obtained.

Note that it is not necessary to employ all of the methods for increasing the reproduction loss as described above, and it is sufficient to appropriately combine them to obtain a reproduction loss of about 25 (dB) or more, which is practically required.

On the other hand, the height of the secondary chevron-shaped protrusions 40A and 40B is ΔA with respect to the gap length A of the track width regulation gap.
is sufficiently high, and the pitch of these chevron-shaped convex portions 40A and 40B is:
The height of these secondary chevron-shaped protrusions 40A and 40B with respect to ΔB: If ΔA is sufficiently high, that is, ΔA is l/
4 If the following relationships are satisfied: ∆A/A x 1 and 1/2 ∆A/∆B < 2, the gap loss itself in the track width defining gaps does not increase, but the magnetic field in these track width defining gaps is effectively random. Therefore, the probability that data recorded with one track width defined gap will be reproduced with that track width defined gap or the other track width defined gap becomes extremely small, and the azimuth loss becomes extremely large, at 20 to 30 (dB). This alone makes it possible to ensure a practically sufficient S/N ratio. In this case, it is also possible to form the chevron-shaped protrusions 24A and 24B in the uneven portion of at least one of the track width defining gaps to have an arc-shaped chevron cross-sectional shape (see FIG. 18).

Furthermore, in order to increase the reproduction loss in the track width defining gap, as shown in FIG. The convex portions of one concave and convex portion and the convex portions of the other concave and convex portion are such that the distance between the convex portion of one concave and convex portion and the convex portion of the other concave and convex portion is such that It is also possible to configure both ferrite blocks IOA and IOB so that the distance between them is less than 1/2. In this way, as shown in FIG. 20, the direction of the magnetic field in the track width defining gap becomes random, making it possible to effectively increase the azimuth loss during reproduction. This makes it possible to improve the N ratio.

Although the embodiments of the present invention have been described above in detail based on the drawings, the present invention is not limited to such illustrative examples, and various changes and modifications can be made without departing from the spirit thereof. Of course, the present invention can be implemented in a modified form.

For example, in the above description, the ferrite block 10A,
Etching is performed on both sides of the IOB to form recording/reproducing track portions (22A, 22B) and chevron-shaped convex portions (24A, 2).
4B), but as shown in FIGS. 21, 22, and 15, only one of the ferrite blocks IOA and 10B consists of the recording/reproducing track portion and the chevron-shaped convex portion. It is also possible to form uneven portions. Even in this manner, the object of the present invention can be achieved to a certain extent.

In addition, in the case where the uneven portion is not formed on one side of the ferrite block, the ferrite block having the uneven portion (here, the ferrite block 10A) is arranged on the trailing side. This is because if there is a part parallel to the recording/reproducing magnetic gap 30 in the uneven part of the ferrite block on the trailing side, the reproducing function of the track width defining gap increases due to the edge effect, and the S/N ratio increases. This is because it decreases. Further, in such a magnetic head core, the effective gap length A of the track width defining gap is approximately 1/2 of the sum of the shortest distance and the longest distance in the direction perpendicular to the magnetic gap 30.

Furthermore, in the above description, the ferrite blocks 10A, I
Although the description has been made assuming that no magnetic film is arranged on any of the abutting surfaces of OB, these ferrite blocks IOA, I
A ferrite block 10A is provided so as to cover at least one of the abutting surfaces of the OB, at least the surface facing the track width defining gap.

A magnetic film (of a predetermined thickness) with a higher saturation magnetic flux density than that of
Usually, it is also possible to arrange a metal magnetic film). However, when forming a magnetic film only on one abutting surface of the ferrite block 10A and IOB, the 23rd
As shown in the figure, the magnetic film 42 is arranged only on the ferrite block IOA on the trailing side. If such a magnetic film 42 is provided, the gap length of the track width defining gap can be made larger to obtain the necessary recording function than when it is not provided, and therefore, the gap length can be made larger. By increasing the gap loss of the gap specified by the track width, and even the playback loss, the S/N
This makes it possible to improve the ratio. Note that the magnetic film 4
When the saturation magnetic flux density of 2 is 8000 C Gauss 1 or more,
It is desirable that the magnetic film 42 be provided with a thickness of 2 [μm] or more, more preferably 4 [μm] or more. Also,
Such a magnetic film 42 includes a ferrite block IOA,
It can be easily formed by a known method such as sputtering at a stage before the IOB is bonded.

(Effects of the Invention) As explained above, according to the method for manufacturing a magnetic head core according to the present invention, it is only necessary to process at least one of the two ferrite blocks, that is, at most two ferrite blocks. In addition, since the ferrite blocks only need to be bonded once, the number of manufacturing steps can be significantly reduced compared to manufacturing cores for conventional magnetic heads of this type. The core can be advantageously manufactured at low cost.

Furthermore, by combining masking technology such as photolithography with etching technology, the ferrite block can be precisely processed into the desired shape, and the joints can be made into one piece.
Since it only needs to be done in one place, it has the advantage that it is possible to stably obtain a core for a magnetic head with uniform precision.

In addition, the magnetic head core according to the present invention does not require a separate erasing head or an automatic tracking mechanism using a servo mechanism, unlike conventional magnetic head cores, and can erase old data. Adopts an override method that directly records new data to provide excellent S/
By employing such a core for a magnetic head, it is possible to advantageously achieve compactness and simplification of FDDs and the like.

It goes without saying that the magnetic head core according to the present invention can be used in conjunction with an automatic tracking mechanism or an erasing head.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a magnetic head core according to the present invention. FIG. 2 to FIG. 1O are explanatory views of each step in an embodiment of the method for manufacturing a magnetic head core according to the present invention, and FIG. 2 is a diagram for manufacturing the magnetic head core shown in FIG. 1. 3 is a perspective view showing an example of a ferrite block material prepared for etching, FIG. 3 is a perspective view showing a form of applying a mask for etching the ferrite block material of FIG. 2, and FIG. 3 is a perspective view showing a ferrite block material obtained by etching under the mask application mode shown in FIG. 3, and FIG.
FIG. 6 is a perspective view showing a form in which a mask for forming a magnetic gap for recording and reproduction is applied to the ferrite block material shown in the figure, and FIG. FIG. 7 is a perspective view showing the shape of the ferrite block material in which a groove for joining is formed in the ferrite block material of FIG. 6, and FIG. 8 is a perspective view showing the groove for joining. FIG. 9 is a perspective view showing an integrally joined product of ferrite block materials obtained by integrally joining ferrite block materials formed with ferrite block materials, and FIG. FIG. 10 is a perspective view showing the form of processing, and FIG. 10 is a perspective view for explaining the cutting form of the magnetic head core shown in FIG. FIG. FIG. 11 is a schematic diagram showing an enlarged front view of one example of the magnetic head core shown in FIG. 1, and FIG. 12 is a schematic diagram showing an enlarged front view of another example. 1st
FIG. 3 is an explanatory diagram for explaining the state of recording/reproduction on a recording medium by the magnetic head core of FIG. 1. 14th
The figure corresponds to FIG. 11 and shows the main parts of another embodiment of the present invention. Figure 15, Figure 16, Figure 17, Figure 18
19 and 19 respectively correspond to FIG. 11 showing still another embodiment of the present invention, and FIG. 20 shows the generation of magnetic lines of force in the track width defining gap of the embodiment shown in FIG. 19. It is an explanatory view showing a form. 21 is a diagram corresponding to FIG. 1 showing still another embodiment of the present invention, and FIG. 22 is a diagram corresponding to FIG. 11 of the embodiment shown in FIG. 21. FIG. 23 is a diagram corresponding to FIG. 11 showing still another embodiment of the present invention. FIG. 24 is an explanatory diagram for explaining a malfunction when off-track occurs in the override method, and FIG. 25 is an explanatory diagram for explaining the recording form on a magnetic medium by a conventional magnetic head core. , FIG. 26 is a diagram corresponding to FIG. 1 showing a conventional magnetic head core. 10A, IOB: Ferrite block 12A, 12B: Ferrite block material 16A, 16
B, 18A, 18B, 2OA. 20B, 26.28: Mask 22A, 22B: Recording/reproduction track section 24A, 24B
: Convex convex part 30 : Magnetic gap for recording/reproduction 34 : Filling bonding material 40A, 40B: Secondary convex convex part 42 : Magnetic film FIG.

Claims (2)

[Claims] (1) A first ferrite block and a second ferrite block are arranged so that a predetermined magnetic path is formed by abutting these two ferrite blocks, and at the abutting portion of the two ferrite blocks. When manufacturing a core for a magnetic head in which a recording/reproducing magnetic gap with a predetermined gap is formed, a magnetic recording/reproducing gap is formed on the abutting surface of at least one of the ferrite blocks, and the abutting surface of the other ferrite block and the abutting surface of the other ferrite block are By applying a mask that defines a recording and reproducing track portion for forming the recording and reproducing magnetic gap between the two, and applying at least one mask on both sides of the mask, etching is performed. Forming the recording/reproducing track portion in the recording/reproducing magnetic gap forming region;
A method for manufacturing a core for a magnetic head, characterized in that convex portions corresponding to the masks are formed on both sides of the track portion, and then the two ferrite blocks are butted and joined. (2) A first ferrite block and a second ferrite block are arranged so that a predetermined magnetic path is formed by abutting these two ferrite blocks, and at the abutting portion of the two ferrite blocks. In a magnetic head core in which a magnetic gap for recording and reproducing having a predetermined gap is formed, a track portion for recording and reproducing whose both side surfaces are inclined surfaces is provided in the magnetic gap forming region of at least one of the two ferrite blocks. At the same time, waveform-shaped uneven portions are formed on both sides of the recording/reproducing track portion, and the recording/reproducing magnetic gap is in contact with the abutting surface of the recording/reproducing track portion and the other ferrite block. A predetermined recording and reproducing function lower than the recording and reproducing function in the recording and reproducing magnetic gap is provided between the corrugated uneven portion and the abutting surface of the other ferrite block. A core for a magnetic head characterized by: