JPH09320011A - Magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a constitution for suppressing increase in external induction noise and cost even if a track width is increased in a magnetic head. SOLUTION: In a magnetic core 1, nearly U-shaped sides of core half bodies 1a and 1b formed in nearly U-shape are mutually jointed through a spacer 3 to be formed into a nearly square shape for forming a magnetic gap. The horizontal two side part of nearly U shape of the core half bodies 1a and 1b overlap in the direction of an arrow (a) in the sliding direction of a magnetic recording medium and a magnetic gap is formed by the spacer 3 between the side part at one of the above two sides. Since a track width Tw can be increased without changing the thickness of the core half bodies 1a and 1b and without changing the diameter of the cavity of a coil winding coil 2 that is wound around the core half bodies, the increases in external induction noise and that in cost can be suppressed even if the track width is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head for magnetically recording or reproducing information by slidingly contacting a magnetic core with a magnetic recording medium.

[0002]

2. Description of the Related Art Conventional magnetic heads are shown in FIGS.
As shown in (d), a magnetic core 1 for forming a magnetic circuit, a winding coil 2 for performing electromagnetic conversion, a spacer 3 for forming a magnetic gap, and a magnetic core 1 at predetermined positions. Core holder 4 for positioning and fixing to
And a magnetic shield case 5 for accommodating these components and reducing externally induced noise. The magnetic core 1 is formed by abutting and joining, via a spacer 3, the front end faces of the two lateral sides of the pair of substantially U-shaped core halves 1a and 1b, each of which is formed in a substantially U-shape. The core halves 1a and 1b are formed by processing a rectangular block-shaped core material made of a high-permeability magnetic material into a substantially U-shaped cross-section and then slicing it into a thickness corresponding to the track width Tw. .

When performing magnetic recording on a magnetic recording medium, a magnetic flux is generated by passing a signal current through the winding coil 2, which is guided to the magnetic gap portion via the magnetic core 1 and leaks onto the magnetic gap. Magnetic flux is generated, and thereby magnetic recording is performed on the magnetic recording medium that slides on the magnetic head. When reproducing, the magnetic flux on the magnetic recording medium is captured in the magnetic gap and passed through the winding coil 2 via the magnetic core 1 to convert the change in the magnetic flux into a signal current, and a predetermined amplifier or conversion is performed. It is converted into a reproduction signal current according to the magnetic recording data through a device, a filter, etc.

Here, depending on the structure of the magnetic head and the required specifications, the winding coil 2 is arranged at the positions shown in FIGS.
As shown in (c), there are three types of stagger type (side winding), semi-balanced type (back winding), and balanced type (both sides balanced winding), and the directivity for external induction noise in each type is as shown in the figure. It is shown below. Usually, in order to suppress the cost and improve the performance against external induction noise, the winding position of the winding coil 2 is often the back winding of (b).

[0005]

However, in the conventional magnetic head as described above, as the track width Tw increases, the thickness of the core half increases, and the core that can be formed by slicing from one core material is formed. Since the number of halves to be taken is reduced, the cost of the magnetic core is increased. In addition, the components other than the magnetic core become large in proportion to the track width, and the component cost increases.

As the track width Tw increases, the diameter of the cavity of the winding coil 2 whose width and height are indicated by the symbols Cw and Ch in FIG. 3 (a) also increases in proportion thereto. There was a flaw.

[0007] 1. The magnetic flux of induction noise passing through the cavity of the winding coil 2 increases, and the amount of induction noise received from the outside increases.

2. In order to reduce externally induced noise, it is necessary to add a magnetic shield plate inside or outside the magnetic head, or to use the winding method as the balanced type method shown in Fig. 4 (c), which greatly increases the cost. turn into.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above problems and to provide a magnetic head structure capable of suppressing an increase in externally induced noise and an increase in cost even if the track width is increased.

[0010]

In order to solve the above problems, according to the present invention, a magnetic head for slidingly contacting a magnetic core with a magnetic recording medium to magnetically record or reproduce information is provided. Is formed into a substantially U-shape by joining the substantially U-shaped side surfaces of a pair of substantially U-shaped core halves through a spacer for forming a magnetic gap. 2 side portions of the two sides overlap each other in the sliding direction of the magnetic recording medium, and a magnetic gap is formed by the spacer between the one side portions of the two sides.

According to this structure, in the pair of core halves, the track width is determined by the lengths of the lateral sides of the substantially U-shape that overlap in the sliding direction of the magnetic recording medium with the magnetic gap forming spacers interposed therebetween. To be In other words, the thickness of the core half is independent of the track width, and when increasing the track width, it is possible to cope with it without changing the thickness of the core half and without changing the diameter of the corresponding winding coil cavity. . Therefore, even if the track width is increased, it is possible to suppress an increase in externally induced noise. Further, even if the track width is increased, the thickness of the core halves is not changed, and the number of core halves taken from the core material can not be reduced.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of an embodiment of a magnetic head according to the present invention. In FIG. 1, reference numeral 1 is a magnetic core for forming a magnetic circuit. The magnetic core 1 is composed of a pair of core halves 1a and 1b each formed in a substantially U shape as shown in FIG. 1 (a). Butt via a spacer 3 made of a non-magnetic material for forming a magnetic gap,
They are joined together to form a generally square shape. The two lateral sides of the substantially U-shaped core halves 1a and 1b are shown in FIG.
(B) Overlapping in the sliding direction of the magnetic recording medium indicated by the middle arrow a,
The spacer 3 is arranged between the upper side portions in FIGS. 1A and 1B among the two lateral sides, and the magnetic gap having the gap width Gw shown in FIG. Has been formed.

The manufacturing process of the core halves 1a and 1b will be described with reference to FIGS. First, as shown in (a), a groove 11 is formed in a rectangular block-shaped core material 10 made of a high-permeability magnetic material so that the core material 10 has a substantially U-shaped cross section. To process. Then core material 1
After slicing 0 into a predetermined thickness as shown in (c), only one of the two sides of the substantially U-shape is cut, and the core half 1
As a joining surface to be joined by abutting with each other a and 1b, the core halves 1a and 1b are completed by finishing the surfaces (flatness and surface roughness) that do not affect the magnetic gap width. As shown in (c), the length of one side of two substantially U-shaped sides of the core halves 1a and 1b (the side joined later with the spacer 3 sandwiched therebetween), that is, the core material 10 in (a). Is the track width Tw.

Referring again to FIG. 1, reference numeral 2 is a winding coil for performing electromagnetic conversion, which is wound around the coil bobbin 6. The coil bobbin 6 has a hollow body for winding the winding coil 2, and the spacer 3 is formed in the body half hole 1a, 1b in the two sides of the substantially U-shaped side to the hole 6a of the body.
1 faces the side on which the magnetic gap is formed by
(A), (b) The lower side parts of the middle are fitted and the side parts are joined. The hole 6a substantially coincides with the cavity inside the winding coil 2. In reality, the size of the cavity of the winding coil 2 is larger than the hole 6a by the thickness of the body of the coil bobbin 6, but here, for convenience, the width and height of the hole 6a are set to the winding coil 2.
As the width and height of the cavity of FIG.
It is shown by w and Ch. As is apparent from FIGS. 1A and 1B, the central axis direction of the cavity of the winding coil 2, that is, the central axis direction of the hole 6a is parallel to the track width Tw direction of the magnetic core. Further, the coil bobbin 6 has two terminals 7
Are planted, and both ends of the winding coil 2 are connected to each.

Further, in FIG. 1 (d), 4 is a magnetic core 1.
Is a core holder for positioning and fixing at a predetermined position, and holds the magnetic core 1 fitted with the coil bobbin 6 around which the winding coil 2 is wound.

Further, in FIGS. 1 (c) and 1 (d), reference numeral 5 is a magnetic shield case for accommodating the above-mentioned members and reducing induced noise from the outside. An assembly obtained by assembling the above-mentioned members is fitted into the case 5, and the magnetic core 1 is fitted into an opening 5a formed in the upper surface of FIG. 1D formed as a magnetic recording medium sliding surface of the case 5. The assembly is fixed so that the tip end surface provided with the magnetic gap is exposed.

According to the above embodiment, in the core halves 1a and 1b, the track width Tw is determined by the lengths of the lateral sides of the substantially U-shape which overlap in the sliding direction of the magnetic recording medium with the spacer 3 interposed therebetween. Can be decided That is, the core halves 1a, 1
The thickness of b is irrelevant to the track width, and when the track width is increased, the thickness of the core halves 1a and 1b is not changed,
This can be dealt with without changing the width Cw of the cavity of the winding coil 2 corresponding to twice that. Therefore, the width C of the cavity of the winding coil 2
By increasing the track width without changing w, the level of inductive noise received from the outside can be kept constant while the signal level is improved and the S / N can be improved.

In addition to the above, the resistance to external induction noise can be improved due to the reason of the magnetic shield. The reason will be described with reference to FIGS. FIGS. 5 and 6 are for explaining the operation relating to the magnetic shield in the conventional magnetic head of FIG. 3 and the magnetic head of the present embodiment, respectively.

In the conventional magnetic head shown in FIGS. 5A and 5B, an arrow A in FIG. 5A is in the direction of the central axis of the winding coil 2.
Direction, that is, the weakest against externally induced noise from a direction parallel to the sliding direction of the magnetic recording medium. Here, considering the case where the magnetic head is placed in a parallel magnetic field φA along the direction A as shown in (b), the upper surface of the magnetic shield case 5 forming the sliding surface of the magnetic recording medium and the tip of the magnetic core 1 are considered. Since the surface is curved in an arc shape along the direction A, the tip end portion of the magnetic core 1 is exposed to the parallel magnetic field φA in the range of the width W and is not magnetically shielded by the magnetic shield case 5. The induction noise that enters will increase.

On the other hand, the magnetic head of this embodiment shown in FIGS. 6A and 6B is parallel to the arrow B direction in FIG. 6A which is the central axis direction of the winding coil 2, that is, the track width Tw direction. The weakest against externally induced noise from various directions. Here, considering the case where the magnetic head is placed in a parallel magnetic field φB along the B direction as shown in (b), the upper surface of the magnetic shield case 5 and the tip of the magnetic core 1 forming the sliding surface of the magnetic recording medium. Since the surface is flat along the B direction, the tip of the magnetic core 1 is not exposed to the parallel magnetic field φB (W = 0) and is completely magnetically shielded, so that external induction noise does not increase.

As described above, according to this embodiment, the resistance to external induction noise can be improved. By the way, the magnetic heads of the present embodiment and the conventional example have the same track width of 4 mm.
As a result, when an external induction noise test was performed in a parallel magnetic field of 50 Hz and 3 Oe, an improvement effect of about 10 dB was confirmed in this embodiment over the conventional example. Further, when the same width was compared for other track widths, the similar improvement effect was confirmed.

On the other hand, according to the present embodiment, even if the track width is increased, it is not necessary to change the thickness of the core halves 1a and 1b and to reduce the number of core halves taken from the core material. The cost increase of the core can be suppressed. Further, as is clear from the comparison between FIG. 1 of the present embodiment and FIG. 3 of the conventional example, the size of the magnetic core 1 and other components is the same as the conventional example even if the track width is increased, and the cost of the components increases. Can be suppressed.

By the way, in the present embodiment, the winding coil 2
Arrangement of semi-balanced type (back winding) in Fig. 4 (b)
However, the coil bobbin wound with the winding coil is fitted to at least one of the substantially U-shaped vertical side portions of the core halves 1a and 1b, and the stagger type (side winding) of FIG.
Alternatively, the balance type of (c) (both sides balanced winding) may be used. In this case, as described above, since the cavity width CW of the winding coil does not depend on the track width, the noise magnetic flux passing through the cavity of the winding coil does not increase in proportion to the increase of the track width, The same effect as the semi-balanced type can be obtained. However, the directional characteristics with respect to the external induction noise are different because the central axis direction of the cavity of the winding coil is perpendicular to the sliding direction of the magnetic recording medium and the track width direction.

In the above embodiment, the core halves 1a and 1a
Although the lengths of the lateral sides of the substantially U-shape that determine the track width in b are the same, the length of the lateral sides of one core half may be shorter than that of the other core half, This makes it possible to handle narrow track widths.

Further, in the above embodiment, the magnetic core 1 is set to 1
Although only one is provided, it is needless to say that a plurality may be provided to form a multi-track.

[0027]

As is apparent from the above description, according to the magnetic head of the present invention, the thickness of the pair of core halves forming the magnetic core is not changed, and the winding coil wound around the pair of core halves is not changed. The track width can be increased without changing the diameter of the cavity, and even if the track width is increased, it is possible to suppress the increase of externally induced noise and improve the S / N ratio. It is possible to obtain an excellent effect that it is possible to suppress the cost increase of the magnetic core and the cost increase of the other parts without reducing the number of pieces to be taken.

[Brief description of drawings]

FIG. 1 is an exploded perspective view, a perspective view, a top view, and a vertical side view showing a structure of an embodiment of a magnetic head according to the present invention.

FIG. 2 is a perspective view illustrating a manufacturing process of the core half body of the same embodiment.

FIG. 3 is an exploded perspective view showing a structure of a conventional magnetic head, a perspective view, a top view, and a vertical side view.

FIG. 4 is an explanatory diagram showing the arrangement of different winding coils in the magnetic head and the directivities with respect to respective external induction noises.

5A and 5B are a top view and a vertical cross-sectional side view for explaining an operation relating to a magnetic shield in a conventional magnetic head.

6A and 6B are a top view and a vertical cross-sectional side view for explaining the operation related to the magnetic shield in the magnetic head of the embodiment.

[Explanation of symbols]

 1 magnetic core 1a, 1b core half body 2 winding coil 3 spacer for magnetic gap formation 4 core holder 5 magnetic shield case 6 coil bobbin 7 terminal 10 core material

Claims (3)

[Claims] 1. A magnetic head for magnetically recording or reproducing information by slidingly contacting a magnetic core with a magnetic recording medium, wherein each of the magnetic cores is a substantially U-shaped pair of core halves. The side surfaces of the U-shape are joined to each other through a spacer for forming a magnetic gap to form a substantially rectangular shape, and the two side portions of the pair of core halves, which are substantially U-shaped, overlap each other in the sliding direction of the magnetic recording medium. A magnetic head characterized in that a magnetic gap is formed between the two side portions of one side by the spacer. 2. A winding coil is wound around a portion of the two sides of the pair of core halves where the side portions facing each other on the side where a magnetic gap is formed overlap each other. The magnetic head according to claim 1, wherein the center axis direction of the cavity is parallel to the track width direction. 3. A winding coil is wound around at least one vertical side portion of the pair of core halves, and the central axis direction of the cavity of the winding coil is the magnetic recording medium sliding direction. The magnetic head according to claim 1, wherein the magnetic head is substantially perpendicular to the track width direction.