JP2834261B2 - Composite magnetic head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite magnetic head for performing high-density recording and reproduction on a rotating magnetic recording medium such as a floppy disk. Above all, it relates to the structure of the slider.

[Conventional technology]

A conventional composite magnetic head includes a composite magnetic core including a recording / reproducing magnetic core and an erasing magnetic core, a recording / reproducing coil and an erasing coil for applying a magnetomotive force to the composite magnetic core,
The magnetic circuit has a back core that forms a closed magnetic circuit, a slider that fixes the magnetic core, slides on a magnetic recording medium to maintain the attitude of the magnetic core, and a shield ring that is arranged to surround the outer periphery of the slider. For the slider, a calcium titanate-based ceramic or a barium titanate-based ceramic was used as a material, and for the shield ring, a permalloy or the like was used.

[Problems to be solved by the invention]

However, the floppy disk drive device uses a spindle motor which is a drive source for rotating the floppy disk, a pulse motor which is a drive source for moving a predetermined track of the floppy disk which rotates the composite magnetic head, and the like. Electromagnetic noise is generated from these motors and drive circuits. In addition, word processors and personal computers that incorporate floppy disk drives
CRT displays are attached, but they also generate strong electromagnetic noise. These electromagnetic noises jump into the composite magnetic core, lowering the signal-to-noise ratio (signal noise level ratio), or changing the waveform symmetry of the write waveform, thereby causing an error in reading. The shield ring is used to prevent these electromagnetic noises from reaching the composite magnetic core.However, due to space constraints, the thickness cannot be increased unnecessarily, and is usually about 0.2 mm. It was made from thick material. In addition, bending or deep drawing is often employed from the viewpoint of ease of processing, and permalloy has been used from that point. However, Permalloy has a high magnetic permeability in the DC or low-frequency range, but has a low magnetic permeability in the high-frequency range of several tens to several hundred KHz used for writing and reading with floppy disk drives, so a practical magnetic shield There was a drawback that the effect was weak.

As described above, in the conventional composite magnetic head,
The object of the present invention is to improve the noise resistance and obtain a more advantageous structure than the conventional composite type magnetic head in terms of the manufacturing cost as well as the disadvantage that the electromagnetic noise resistance is inferior. That is, it is to manufacture a composite magnetic head that is even cheaper than the conventional one.

[Means for solving the problem]

To achieve the above object, the gist of the present invention is a composite magnetic core comprising a recording / reproducing magnetic core and an erasing magnetic core,
A recording / reproducing coil and an erasing coil that apply a magnetomotive force to the composite magnetic core, a back core that forms a magnetic circuit as a closed magnetic circuit, a slider that fixes the magnetic core and slides on a magnetic recording medium to maintain the attitude of the magnetic core In the composite type magnetic head, the slider is made of a soft magnetic material such as MnZn ferrite and has a substantially rectangular parallelepiped outer shape, a concave portion on the back side, and a magnet penetrating to the front side in the concave portion. It has a core insertion hole, and the magnetic core insertion hole has a substantially rectangular shape, with at least two protrusions on each of its long sides, and at least one protrusion on each of its short sides. And a structure in which the composite magnetic core is inserted into the magnetic core insertion hole of the slider, and both are fixed with sealing glass or the like.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The configuration of the present invention will be described with reference to FIG. Figure 1
FIG. 1A is a perspective view of a composite magnetic head according to the present invention, and FIG. 1A is a diagram showing each component separately, and FIG.
FIG. 2 is a perspective view from the front side showing a state where each component is assembled, and FIG. 2C is a perspective view from the back side.

In FIG. 1, reference numeral 10 denotes a recording / reproducing magnetic core. The recording / reproducing magnetic core 10 comprises an outer core 11 and an inner magnetic core 12, and a recording / reproducing gap 13 interposed therebetween. A recording / reproducing coil 14 for applying a magnetomotive force to the recording / reproducing magnetic core 10 is provided on an outer side core 11 of the recording / reproducing magnetic core 10.
Is wound.

Reference numeral 20 denotes an erasing magnetic core. The erasing magnetic core 20 includes an outer-side core 21, an inner-side core 22, and an erasing gap 23 interposed therebetween. The outer-side core 21 of the erasing magnetic core 20 has an erasing coil 24 for applying a magnetomotive force to the erasing core.
Is wound.

The recording / reproducing magnetic core 10 and the erasing magnetic core 20 are joined by an adhesive or glass or the like to form an integral unit. The united unit is called a composite magnetic core 40.

The coils 14 and 24 are not shown in FIG. 1C because the drawing becomes complicated and difficult to understand.

The magnetic core for recording / reproducing 10 and the magnetic core 20 for erasing as they are do not close the magnetic circuit, and the magnetic resistance of the entire magnetic circuit becomes excessive. 31 forms a closed magnetic circuit.

Slider 32, as the material is represented by MnZn ferrite, magnetic permeability mu, the maximum saturation magnetic flux density B _s is large, the coercive force H _c is made smaller magnetic material or soft magnetic material. This is one of the features of the present application. According to the present invention, the slider is not made of calcium titanate-based ceramics or barium titanate-based ceramics which have been conventionally used, but a soft magnetic material such as MnZn ferrite. It is based on the idea that it will not be replaced or that by doing so, the slider itself will have the function of a magnetic shield ring and that the use of the conventional Permalloy magnetic shield ring can be abolished. It is a thing.

By the way, the outer shape of the slider 32 is almost a rectangular parallelepiped,
The back side 33 has a recess 34 (FIG. 1 (c)), and the recess 34 has a magnetic core insertion hole 36 penetrating to the front side 35,
The structure is such that the composite magnetic core 40 is inserted into the magnetic core insertion hole 36, and both are fixed with the glass 50 for sealing. The magnetic core insertion hole 36 is substantially rectangular, and has at least two or more long-side protrusions 37 on each of its long sides, and at least one or more short-side protrusions on each of its short sides. The shape has a tension 38.

FIG. 2 is a top view as seen from the front part in FIG. 1 (b). Here, since both the composite magnetic core 40 and the slider 32 use a similar material, that is, a soft magnetic material such as MnZn ferrite, the magnetic flux can sufficiently flow inside the slider, as shown by a solid line 51 with an arrow. The magnetic flux may flow from the recording / reproducing magnetic core 10 to the erasing magnetic core 20 via the slider 32, and again to the recording / reproducing magnetic core 10 via the slider 32. Each gap 39 between the section and the magnetic core may be a secondary recording / reproducing gap. If so, harmful information will be written and it will be a defective product. Then, the slider is molded and fired once, and then subjected to an oxidation treatment to demagnetize the surface in a range of several tens of μm to rice, thereby increasing the magnetic resistance near the gap 39 and the protrusion, and FIG. The flow of the magnetic flux shown by the solid line 51 with an arrow can be virtually eliminated. Also, by controlling the temperature of the oxidation treatment and the oxygen partial pressure to appropriate values, the range of several tens of μm on the slider surface can be demagnetized, and the other parts can be kept from losing the properties of the soft magnetic material. It can also have a function of absorbing electromagnetic noise.
And the efficiency of absorbing electromagnetic noise is different from the permalloy conventionally used, the magnetic permeability μ in the high frequency band is large, and its magnetic properties are almost the same as the composite magnetic core, so the noise absorption efficiency is low. It will be very good.

Incidentally, the temperature of the oxidation treatment is in the range of 500 to 1000 ° C. The oxygen partial pressure is in the range of 1% to 50%. When the temperature is low, the oxygen partial pressure is high, and when the temperature is high, the oxygen partial pressure is low. The degree of demagnetization can be controlled by the fact.

Also, protrusions on the long and short sides of the magnetic core insertion holes 37, 38
Plays a role in accurately positioning the magnetic core at a predetermined position, and at the same time, the gaps become large in portions other than the long side and short side protrusions 37 and 38, so that the glass easily flows in during glass molding. It's easier.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, since the external noise absorption efficiency is good, the SN ratio of the magnetic head is good. As a result, the recording / reproducing waveform symmetry of the magnetic head is improved, and even if the magnetic shield spacer at the center of the back core is abolished, the magnetic head can sufficiently be used, so that the cost reduction effect is large.

Conventionally, a slider made of calcium titanate ceramics or the like and a magnetic shield ring made of permalloy or the like can function only with one slider made of a soft magnetic material such as MnZn ferrite. The cost of parts assembly can be greatly reduced.
Conventionally, when a magnetic core and a slider are glass-molded, the temperature coefficient of thermal expansion coefficient of the two is different, so that cracks may occur in the molded glass, although slightly, but in the present invention, the magnetic core Since the slider and the slider are made of the same material, the temperature coefficient of the coefficient of thermal expansion can be made exactly the same, so that cracks and the like are almost completely eliminated.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the configuration of the present invention, FIG. 1 (a) is a perspective view showing each component separately, and FIG. 1 (b) is a state in which each component is assembled. (C) is a perspective view as seen from the back side. FIG. 2 is a top view as seen from the front side. 10: Magnetic core for recording / reproducing, 20: Magnetic core for erasing, 40: Composite magnetic core, 14: Coil for recording / reproducing, 24: Coil for erasing, 31: Back core, 32: Slider, 34 ... recess on the back side, 36 ... magnetic core insertion hole, 37 ... projection on the long side, 38 ... projection on the short side, 50 ... glass for sealing.

Claims (1)

(57) [Claims] A composite magnetic core comprising a recording / reproducing magnetic core and an erasing magnetic core; a recording / reproducing coil and an erasing coil for applying a magnetomotive force to the composite magnetic core; a back core forming a magnetic circuit as a closed magnetic circuit; In a composite magnetic head comprising a slider which fixes the magnetic core and slides on a magnetic recording medium to maintain the attitude of the magnetic core, the slider is made of a soft magnetic material such as MnZn ferrite and has an outer shape. It has a substantially rectangular parallelepiped shape with a concave portion on the back side, and has a magnetic core insertion hole penetrating to the front side in this concave portion, the magnetic core insertion hole is substantially rectangular, and at least each of the long sides thereof has Two or more protrusions, at least one on each of its short sides
A composite magnetic head having a plurality of protrusions, wherein a composite magnetic core is inserted into a magnetic core insertion hole of a slider, and both are fixed to each other with sealing glass or the like.