JPH043302A - Core for magnetic head and its production - Google Patents

Abstract

PURPOSE:To improve the productivity, extend the life, and to prevent the crosstalk by subjecting plural ferrite junction bodies to track working and providing a protection part having the same height as tracks and making the edges of the protection part in nonparallel with a magnetic gap. CONSTITUTION:Ferrite blocks 20 and 22 are joined with a winding groove 28 between them by a proper method to form a magnetic gap 32. A slide face 37 is polished to set the depth of the gap 32 to prescribed dimensions, and track width prescribing grooves 40A and 40B are provided and reach the groove 28. Grooves 40 and the gap 32 form an angle theta corresponding to the azimuth angle. A nonmagnetic gap 42 reaching the groove 28 is provided across grooves 40A and 40B at a prescribed angle to prevent the crosstalk. A nonmagnetic filler 44 is fused and packed in the groove 42, and a slide face 37 is finished to an objective slide face 47 by prescribed rounding work. By this constitution, the productivity is improved, and wear in the early stage of the nonmagnetic filler due to slide on a recording medium is avoided, and the crosstalk due to the pseudo gap effect is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a magnetic head core suitable for application to magnetic heads for VTRs and RDDs, and a method for manufacturing the same, and particularly to a magnetic head having excellent productivity and durability. This is related to the core.

(Prior Art) A magnetic head core used in a magnetic head for a VTR or an RDD is generally made of a ferrite material and formed into an annular shape with a hole for coil winding formed in the center. A sliding surface on which the magnetic recording medium is brought into sliding contact is formed on its outer peripheral surface, and the sliding surface portion includes:
A magnetic gap with a predetermined gap is formed across the annular magnetic path formed by the ferrite.

By the way, such a core for a magnetic head usually has a first core.
As shown in Figure 2, two ferrite members 2,
4 are joined to each other to form an annular structure, and a magnetic gap 6 is formed between the abutting surfaces of the ferrite members 2 and 4. Conventionally, as shown in the figure, the magnetic gap 6 is The width of the track portion 80 that regulates the width of the gap 6 is the notch groove 12 of the ferrite members 2 and 4 formed in the longitudinal center of the sliding surface 10 of the magnetic recording medium.
．． 12.

For this reason, in this type of conventional magnetic head core, before the ferrite member 2.4 is bonded,
It is necessary to perform track machining to form the notch grooves 12.12 in each ferrite member 2.4, making the machining extremely troublesome. In addition, in the magnetic head core having such a structure, the ferrite member 2
．． Because extremely high precision is required to match 4,
The matching process had become extremely difficult.

In addition, in FIG. 12, 11 is a coil winding hole for winding a coil winding, and 13 is a nonmagnetic filler such as glass filled in the notch groove 12.

On the other hand, in order to eliminate such problems with the conventional magnetic head core, the applicant of the present application previously published Japanese Patent Application Laid-Open No. 60-15
In Japanese Patent No. 0212, a core for a magnetic head having a structure as shown in FIG. 13 was proposed.

As shown in the figure, the core for a magnetic head having such a structure has a pair of track width definitions provided on the magnetic recording medium sliding surface 10 so as to extend in the magnetic recording medium sliding direction (horizontal direction in the figure). Since the width of the track portion 8 is defined by the grooves 14, 14, it is possible to perform track processing on both the ferrite members 2, 4 at the same time after the ferrite members 2, 4 are joined. Moreover, since the width of the magnetic gap 6 is regulated by track processing after the ferrite members 2 and 4 are joined, extremely high butting accuracy is not required when joining the ferrite members 2 and 4. .

Therefore, according to the magnetic head core having the structure disclosed in this publication, it is possible to obtain superior productivity than the magnetic head core having the conventional structure, and the magnetic gap 6 has a high width dimensional accuracy. can be obtained more stably than before.

However, in the magnetic head core disclosed in this publication, as shown in FIG. A VTR that has a high sliding speed with the magnetic recording medium because the track width defining groove 14.
When used in a rotary magnetic head for use in other applications, the non-magnetic filler 13 wears out quickly and has poor durability.

(Problem to be solved) The present invention was made against the background of the above-mentioned circumstances, and the problem to be solved is to solve the problem of a pair of sliding surfaces extending in the sliding direction of a magnetic recording medium. The width of the track part is defined by the track width regulation groove of
It is an object of the present invention to provide a structure of a magnetic head core that is highly productive and has excellent sliding surface durability, and an advantageous manufacturing method thereof.

(Solution Means) In order to solve this problem, the core for a magnetic head according to the present invention forms an annular magnetic path as described above, and a part of the outer peripheral surface forms the sliding surface of the magnetic recording medium. A plurality of ferrite members are joined in an annular shape to form a coil winding hole, and a magnetic gap with a predetermined gap is formed on the sliding surface of the magnetic recording medium so as to cross the magnetic path. is formed, and the width of the track portion that regulates the width of the magnetic gap is defined by a pair of track width defining grooves provided on the sliding surface so as to extend in the sliding direction of the magnetic recording medium. A core for a magnetic head having a structure in which a predetermined non-magnetic filler is filled in a pair of track width defining grooves, the core being located on the outside in the width direction of each of the pair of track width defining grooves; A non-contact hole of a depth reaching the coil winding hole is located at both ends of the moving surface in the sliding direction of the magnetic recording medium, and the opposing edge portions are non-parallel to the magnetic gap. The structure is such that ferrite protection parts are provided at the same height as the track part and are separated from each other by a magnetic gap groove.

Further, in the method of the present invention, (a) first and second ferrite blocks each having a coil winding groove formed in at least one abutting surface are abutted against each other at their abutting surfaces, and the coil winding is The ferrite blocks are joined together by joining the abutting surfaces separated by the coil winding groove, and a magnetic gap with a predetermined gap is formed between the other abutting surfaces separated by the coil winding groove. (b) preparing a ferrite bonded body made of
A pair of parallel track width defining grooves reaching the coil winding groove are formed in the magnetic gap forming portion of the ferrite assembly, and the width of the magnetic gap is adjusted so as to extend across the magnetic gap. (C) Before or after forming the pair of track width defining grooves, forming a track portion having a constant width on the outside of each of the pair of track width defining grooves is formed. so that the ferrite portions located outside the track width defining groove forming portion are separated from each other in the extending direction of the track portion, and such that opposing edge portions of the ferrite portions are non-parallel to the magnetic gap; (d) filling the track width defining groove with a predetermined nonmagnetic filler; (e) cutting out a magnetic head core with a predetermined thickness from the ferrite bonded body so that the ferrite portion separated by the non-magnetic gap groove remains with a predetermined width outside the pair of track width defining grooves; We decided to include it.

Note that the term "non-magnetic gap groove" as used herein means a groove having a groove width sufficiently large that substantially no magnetic flux leakage occurs when used as a magnetic head.

(Operations/Effects) The magnetic head core according to the present invention has a width of the track portion that regulates the width of the magnetic gap, similar to the magnetic head core disclosed in the above-mentioned publication (Japanese Unexamined Patent Publication No. 60-150212). Since it is defined by a pair of mutually parallel track width defining grooves extending in the sliding direction of the sliding surface of the magnetic recording medium, the width of the magnetic gap (track width ) The track machining (groove machining of the track width defining groove) that defines the track width can be performed on a joined body in which multiple ferrite members are joined in an annular shape, and particularly high butting accuracy is required when joining these ferrite members. Never. Therefore, if the structure of the magnetic head core according to the present invention is adopted, similarly to the magnetic head core disclosed in the same publication, a magnetic head core with high magnetic gap width accuracy can be stably produced, and moreover, excellent productivity can be achieved. It can be manufactured with

Further, in the magnetic head core according to the present invention, on both end sides of the magnetic recording medium sliding surface in the magnetic recording medium sliding direction,
Since a ferrite protection part having the same height as the track part is provided so as to sandwich the track width defining groove between the track part and the track width defining groove, the non-magnetic filler filled in the track width defining groove protects the ferrite protecting part from each other. The non-magnetic filler is well protected by the magnetic recording medium and the track portion, and wear of the non-magnetic filler due to sliding contact with the magnetic recording medium is well prevented. Therefore, the sliding speed between the magnetic recording medium and the R is relatively low.
Of course, when used in magnetic heads for DDs, and even when used in magnetic heads for VTRs, which have a high sliding speed between the magnetic recording medium and the Early wear of the magnetic filler can be effectively avoided, and the life of the magnetic head core can be greatly extended.

Note that the edges of the ferrite protection parts that face each other in the sliding direction of the magnetic recording medium are non-parallel to the magnetic gap, so crosstalk may occur due to the pseudo-gap effect of these edges. It is also well prevented.

According to the method of the present invention, a core for a magnetic head having such a structure can be advantageously manufactured with good productivity.

(Example) Hereinafter, an example of the present invention will be described in more detail based on the drawings. Here, while explaining embodiments of the method of the present invention, the structure of the core for a magnetic head according to the present invention will be clarified.

That is, in manufacturing the magnetic head core according to the present invention, first, two ferrite blocks 20 and 22 are prepared as shown in FIG. As shown in FIG. 2, these ferrite blocks 20.
A coil winding groove 30 that constitutes a coil winding hole 28 (see FIG. 11), which will be described later, is formed on at least one abutting surface 24, 26 of the blocks 20, 22 so as to extend in the longitudinal direction of the blocks 20, 22. be done.

Note that the ferrite constituting the ferrite block 20.22 may be either single crystal or polycrystal, but if the intended magnetic head core is for a VTR, wear-resistant ferrite may be used. Those made of single-crystal ferrite, which has superior properties, are generally used.

Ferrite block 2 in which coil winding groove 30 is formed
0.22 are then abutted against each other at their abutment surfaces 24.26, as shown in FIG.
One abutment surface 2 separated by a coil winding groove 30
The ferrite blocks 20 and 22 are joined together by a known appropriate joining method such as a joining method using a spacer such as a silica film or a solid phase reaction method between the ferrite blocks 20 and 22. The other abutting surface 24.2 of the ferrite block 20.22 is separated by the coil winding groove 30.
A magnetic gap 3 with a predetermined gap is formed between 6 and 6 by their joining.
2 is formed, and by this joining, a coil winding hole 28 is formed in the coil winding groove 30.

Note that the magnetic gap 32 is formed by forming the ferrite blocks 20 and 22 in the same manner as in the conventional manufacturing method of a core for a magnetic head.
Prior to joining, the gap 32 is formed by chemical etching or machining to form a step with a depth equivalent to the gap length, or when joining the ferrite blocks 20 and 22, a step with a thickness equivalent to the gap length is applied. The gap 32 is formed by interposing a non-magnetic spacer such as a piece of glass in the area where the gap 32 is formed.

Once the ferrite blocks 20, 22 are bonded, the bonded body 34 then includes, as shown in FIG.
A filler 36 made of a non-magnetic material such as glass is optionally filled into the magnetic gap 32.

Then, the depth length (depth) of the magnetic gap 32 is determined on the surface of the joined body 34 on the side facing the magnetic gap 32, that is, on the magnetic recording medium sliding side surface 37 on which the magnetic recording medium is made to slide.
Polishing is performed so that it has a predetermined size.

Furthermore, as shown in FIG. 5 (see FIG. 6), the polished bonded body 34 has two grooves so as to define the width of the track portion 38 that regulates the width of the magnetic gap 32. A set of track width defining grooves 40A and 40B are formed in parallel to each other at a predetermined distance apart from each other in the length direction of the joined body 34, with a depth that reaches the coil winding hole 28.

At this time, if it is necessary to give an azimuth angle to the magnetic gap 32, the track width defining grooves 40A and 40B are inserted into the magnetic gap 32, as shown in the figure.
Angle corresponding to its azimuth angle: θ (for example,
In other words, the track width defining grooves 40A and 40B, and the track portion 38 whose widthwise ends are defined by the track width defining grooves 40A and 40B, are formed in an inclined state (θ=60''). Hereinafter, the extending direction of the trunk portion 38 (track width defining grooves 40A, 40B) will be simply referred to as the sliding direction of the magnetic recording medium.

Joined body 3 in which track width defining grooves 40A and 40B are formed
4, as shown in FIG.
4 adjacent sets of track width defining grooves 40A in the longitudinal direction;
Non-magnetic gap grooves 42 are formed with a depth that reaches the coil winding grooves 28 so as to straddle each of the coil winding grooves 40B. The non-magnetic gap groove 42 is formed to have a sufficiently large groove width in the sliding direction of the magnetic recording medium so as not to substantially cause magnetic flux leakage when used as a magnetic head. Edges 4 opposite in direction
When 2A and 42B are used as magnetic heads,
To avoid crosstalk due to pseudo gap effect,
They are each formed at a predetermined angle with respect to the magnetic gap 32.

Note that, for processing the non-magnetic gap groove 42, a method such as chemical etching, laser processing, or ultrasonic processing using a jig to which diamond abrasive grains are attached is preferably employed.

When the processing of the non-magnetic gap groove 42 is completed, as shown in FIG. , a non-magnetic filler 44 such as glass similar to the filler 36 is melt-filled. After solidification, the unnecessary non-magnetic filler 44 is removed as shown in the 8th section, and then the magnetic recording medium sliding side surface 37 of the bonded body 34 is coated as shown in FIG. Predetermined 8-sided processing is performed as necessary so that the magnetic recording medium sliding side surface 37 of the bonded body 34 has the final surface shape, that is, the magnetic recording medium sliding surface of the intended magnetic head core. It is finished in the same shape as surface 46 (see FIG. 11).

When the eight-sided processing is completed, a cutting line 48 parallel to the sliding direction of the magnetic recording medium as shown in FIG.
．． 48, each corresponding track width defining groove 40A,
A core for a magnetic head having a desired thickness is cut out so as to leave a pair of ferrite portions 48, 48 of a predetermined width on the outside of each of the cores 40B. FIG. 11 shows the magnetic head core cut out in this manner.

In the magnetic head core manufactured in this manner, as described above, the ferrite blocks 20 and 22 are joined to form the joined body 34, and then the track width defining grooves 40A and 40B are formed in the joined body 34. Since the width of the track portion 38 can be defined by forming the ferrite blocks 20 and 22, the track processing for defining the width of the track portion 38 is extremely simple, and when the ferrite blocks 20 and 22 are butted together, extremely high butting accuracy is required. Therefore, the joining operation of these ferrite blocks 20, 22 is extremely simple, and therefore, they can be manufactured with excellent productivity.

In the magnetic head core manufactured in this manner, as is clear from FIG.
Further outside the track width defining grooves 40A and 40B that define the width of the track portion 38, the track portion 38 and the track portion 38 are separated from each other in the sliding direction of the magnetic recording medium (the left-right direction in FIG. Each pair of ferrite parts 5 at the same height
0.50, the track width defining groove 40A
.

The non-magnetic filler 44 filled in 40B forms the track portion 38.
and a pair of ferrite parts 50 and 50, and wear due to sliding contact between the non-magnetic filler 44 and the magnetic recording medium is well prevented. Therefore, both sides of the track part Compared to conventional magnetic head cores in which a non-magnetic filler is simply placed on the core, its durability is significantly improved. Note that the width dimension of this ferrite portion 50.50 is generally set to be about 20 μm or more, preferably about 30 μm or more.

In addition, in the magnetic head core manufactured in this way, the edges 42A and 42B of the ferrite portions 50 and 50 facing each other across the non-magnetic gap groove 42 are in a non-parallel state with respect to the magnetic gap 28. Because it is formed in
It is also possible to effectively prevent the edges 42A and 42B from functioning as a false image gap.

Although the embodiments of the present invention have been described in detail above, the present invention can also be implemented in other embodiments.

For example, in the embodiment, the track width defining grooves 40A, 4
After forming 0B, non-magnetic gear knob grooves 42 are formed, and then non-magnetic filler 44 is applied to each of those grooves 40A, 4.
The track width defining groove 40A was supposed to be filled in the grooves 0B and 42.

It is also possible to form the non-magnetic gap groove 42 prior to forming the track width defining grooves 40B, or to form the non-magnetic filler 44 in the track width defining grooves 40A, 40B after forming the track width defining grooves 40A, 40B. It is also possible to form the non-magnetic gear knob groove 42 after filling.

Furthermore, in the embodiment described above, the opposing edges 42A and 42B of the ferrite portions 50 and 50 as ferrite protection portions are both straight-shaped, but they may be curved or wavy.

In short, the opposing edges 4 of the ferrite portion 50.50
2A and 42B are magnetic gaps 3 regardless of their shapes.
2, it is only necessary to be in a non-parallel state so as not to cause crosstalk due to the carrier gap effect.

In addition, although it is omitted to list specific examples one by one, the present invention can be carried out in various forms with various changes, modifications, improvements, etc. based on the knowledge of those skilled in the art without departing from the spirit thereof. Of course it can be done.

[Brief explanation of the drawing]

1 to 11 are explanatory diagrams of each process for explaining an example of the method of the present invention, and FIG. 1 shows first and second steps prepared for producing a core for a magnetic head. FIG. 2 is a perspective view corresponding to FIG. 1 showing a state in which a coil winding groove is formed in one of the ferrite blocks, and FIG.
The figure is a perspective view of a main part showing a joined body constructed by joining first and second ferrite blocks, and FIG.
5 is a diagram corresponding to FIG. 3 showing a state in which the unfilled side for reinforcement is filled in the joined body of FIG. 3, and FIG. 5 is a diagram showing a state in which track width defining grooves are formed in the joined body of FIG. 3, FIG. 6 is an enlarged plan view of a main part showing a non-magnetic gear knob groove formed in the joined body of FIG. 5, and FIG. 7 is a diagram corresponding to FIG. 8 is a diagram corresponding to FIG. 3 showing a state in which the sliding surface of the magnetic recording medium of the assembly shown in the figure is filled with a non-magnetic filler, and FIG. 9 is a diagram corresponding to FIG. 3 showing a state in which the agent has been removed, and FIG. 9 is a diagram corresponding to FIG. FIG. 10 is an enlarged plan view of the main part of the bonded body shown in FIG. 9, and FIG. 11 is a perspective view showing a core for a magnetic head cut out from the bonded body shown in FIG. 10. It is. FIGS. 12 and 13 are perspective views showing examples of conventional magnetic head cores, respectively. 20, 22: Ferrite block 24. 26: Butting surface 28: Coil winding hole 30: Coil winding groove 32: Magnetic gap 34: Joined body 38 Nidrac portion 40A, 40B:)
Rack width regulation groove 42: Non-magnetic gap groove 44: Non-magnetic filler 46: Sliding surface 50: Ferrite part

Claims (2)

[Claims] (1) A coil winding hole is formed by joining a plurality of ferrite members in an annular shape so as to form an annular magnetic path and a part of the outer peripheral surface forms a sliding surface for the magnetic recording medium. On the other hand, a magnetic gap with a predetermined gap is formed on the sliding surface of the magnetic recording medium so as to cross the magnetic path, and the width of the track portion regulating the width of the magnetic gap is equal to the width of the sliding surface. A magnetic recording medium having a structure defined by a pair of track width defining grooves extending in the sliding direction of a magnetic recording medium, and each of the pair of track width defining grooves being filled with a predetermined nonmagnetic filler. The head core has opposite ends located on the outside in the width direction of each of the pair of track width defining grooves and on both ends of the sliding surface in the sliding direction of the magnetic recording medium. Ferrite protection portions are provided at the same height as the track portion and separated from each other by non-magnetic gap grooves having a depth that reaches the coil winding hole so that edges thereof are non-parallel to the magnetic gap. A core for a magnetic head characterized by: (2) First and second ferrite blocks each having a coil winding groove formed on at least one abutting surface are abutted against each other at their abutting surfaces, and one abutting surface separated by the coil winding groove. A step of preparing a ferrite bonded body by bonding the ferrite blocks to each other, bonding the ferrite blocks together, and forming a magnetic gap with a predetermined gap between the other abutted surfaces separated by the coil winding groove. and forming a pair of track width defining grooves parallel to each other that reach the coil winding grooves in the magnetic gap forming portion of the ferrite joined body, so as to extend across the magnetic gap. forming a track portion with a constant width for regulating the width; and before or after forming the pair of track width defining grooves, forming a track portion with a constant width on the outside of each of the pair of track width defining grooves. The coil is arranged such that the ferrite portions located outside of the defined groove forming portion are separated from each other in the extending direction of the track portion, and such that opposing edge portions of the ferrite portions are non-parallel to the magnetic gap. forming a non-magnetic gap groove deep enough to reach the winding groove in the ferrite bond; filling the track width defining groove with a predetermined non-magnetic filler; cutting out a core for a magnetic head with a predetermined thickness from the ferrite bonded body so that a predetermined width of the ferrite portion remains outside the pair of track width defining grooves. method for manufacturing cores for