JPH04366402A - Shield structure of magnetic head - Google Patents

Abstract

PURPOSE:To enable a CRT noise to be shielded by placing a frame-type metal magnetic material shield body and a conductive material shield body outside a slide assembly body where a head core portion is incorporated overlappingly. CONSTITUTION:An inside shield body 1 according to a metal magnetic material such as permalloy, etc., which is formed in frame shape so that it covers an outside of a slider assembly body of a magnetic head and an outside shield body 2 of a conductive material such as Cu and Al which is formed in frame shape so that it covers this inside shield body 1 are combined in this shield structure. Then, in the inside and outside shield bodies 1 and 2, bottom surfaces 1b and 2b are opened and a pair of rectangular window holes 1c are formed at a front surface 1a of the inside shield body 1 so that a pair of rail-shaped sliding portions of the slider are exposed, thus enabling a magnetic gap portion at the front of the core portion to be exposed from a rectangular window hole 1c of the inside shield body 1 and obtaining a magnetically shielded magnetic head.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield structure for a magnetic head, particularly for a magnetic head for a floppy disk drive.

0002

[Prior Art] Conventionally, in this type of magnetic head,
It is common practice to surround the outside of a non-magnetic slider incorporating a head core with a magnetic material such as permalloy or ferrite so that the surface of the core in contact with the magnetic medium is exposed to form a magnetic shield. It has also been proposed to process a metal clad material in which a conductive material is adhered to one side of a plate-shaped metal magnetic material into a frame shape and arrange it outside the slider assembly. Figure 7
1 is a perspective view showing the above-mentioned metal clad material, in which a conductive material 5 such as Cu is adhered to one side of a permalloy 4, which is a metal magnetic material, by a known method to form a plate-shaped clad material 6. As shown in FIG. 8, such a cladding material 6 is bent into a frame shape to surround the outer periphery of a slider assembly (not shown) to form a shield body 7, and the slider assembly is The magnetic head is housed in a shield body 7 so as to be exposed, and has a shielding function against external magnetic fields.

0003

[Problem to be Solved by the Invention] A floppy disk drive device is often used together with a CRT or near a CRT, and the magnetic field generated by the CRT becomes noise for the magnetic head built into the floppy disk drive device. , the closer the CRT is to the magnetic field, the more it will be affected by the magnetic field, causing errors. Therefore, the quality of the shielding function of this type of magnetic head has a great impact on the quality of the floppy disk drive, but in recent years, as the number of this type of equipment installed within the limited installation space of users has increased, , conventional shield structures made only of magnetic materials such as permalloy and ferrite cannot
It is no longer possible to exhibit sufficient shielding effect against T noise. That is, permalloy is weak against shielding of high frequency components, and ferrite is effective at high frequencies, but in absolute terms it is generally weak against magnetic fields. Especially C
RT noise components have frequency components in a wide range up to high frequencies, and metal materials such as permalloy have a limited shielding effect due to eddy currents and the like. On the other hand, since the frame-shaped shield body 7 made of metal clad material 6 shown in FIG. 8 is formed into a frame shape by processing the clad material 6, distortion during processing remains.
The characteristics are greatly deteriorated, and the conductive material attached is thin, so the shielding effect has not reached a level that can be put to practical use.

[0004] The present invention provides a CRT by overlapping frame-shaped shield bodies made of magnetic material and conductive material, respectively.
It is an object of the present invention to provide a shielding structure for a magnetic head that exhibits high shielding properties against a wide range of frequency components such as noise and is easy to manufacture.

[0005]

[Means for Solving the Problems] A magnetic head shield structure according to the present invention includes a frame-shaped metallic magnetic material shield and a conductive material shield that are stacked on the outside of a slider assembly incorporating a head core portion. It has a structure arranged in such a way that

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be explained with reference to the drawings. FIG. 1 is a perspective view showing the assembly process of a magnetic shield structure for a magnetic head according to an embodiment of the present invention, and FIG. 2 is a perspective view of the magnetic shield structure obtained in the embodiment shown in FIG. An inner shield body 1 made of a metallic magnetic material such as permalloy is formed into a frame shape so as to cover the outside of the slider assembly of the magnetic head, and an inner shield body 1 made of a metal-based magnetic material such as permalloy is formed in a frame shape so as to cover the outside of the slider assembly of the magnetic head. The outer shield body 2 made of a conductive material such as
A heavy magnetic shielding structure 3 is obtained. Both the inner and outer shield bodies 1 and 2 have open bottom surfaces 1b and 2b,
Further, in this embodiment, a pair of rectangular window holes 1c are formed in the front surface (the side facing the magnetic medium) of the inner shield body 1 so that a pair of rail-shaped sliding parts of the slider are exposed. The front surface 2a is the front surface 1a of the inner shield body 1
It has a large rectangular opening in the center, leaving the periphery exposed. The slider assembly incorporating the core part is inserted from the bottom opening of the double shield structure 3 as described above, and the sliding part on the front surface of the slider, and hence the magnetic gap part on the front surface of the core part, is inserted into the inner shield body 1. Rectangular window hole 1
A magnetic head that is exposed and magnetically shielded from c is obtained.

[0007] For the permalloy and Cu of the inner and outer shield bodies 1 and 2, thin plates having a thickness of about 0.15 mm are used, for example. The specific thickness varies depending on the applied magnetic head, and other thicknesses can also be effectively used, but experiments show that both permalloy and Cu are saturated at a thickness of 0.5 mm or more, so the thickness is 0.5mm
The following is fine. Therefore, for example, the outer shield body 2 made of Cu material may not be manufactured separately from the inner shield body 1, but may be attached to the outside by Cu plating after the inner shield body 1 is formed.

In the embodiments shown in FIGS. 1 and 2, the inside of the double structure is made of permalloy material, and the outside that covers this is made of conductive material, but as in the embodiments shown in FIGS. 3 and 4, The outer shield body 2 may be made of a metallic magnetic material such as permalloy, and the inner shield body 1 may be a frame made of a conductive material. Further, the present invention is not limited to the form in which a pair of rectangular window holes through which the rail-like sliding portion of the slider is exposed is formed on the front surface of one shield body as in the above-mentioned embodiments.
As shown in FIG. 6, both the inner and outer shield bodies 1 and 2 may have a large rectangular opening at the center of their front surfaces. In the embodiments shown in FIGS. 5 and 6, the outside is made of permalloy and the inside is made of a conductive material such as Cu or Al, or this relationship is reversed and the outside is made of a conductive material and the inside made of a magnetic material such as permalloy. It has a double structure.

[0009]

Effects of the Invention: Conventional shielding bodies made only of magnetic materials have little effect on external magnetic field noise with high frequency components such as magnetic fields generated from CRTs due to eddy currents, etc.; By adopting a shield structure in which the magnetic material frame is doubled, it is extremely effective in shielding CRT noise. Figure 9 compares the wind margins of floppy disk drive devices for the double shield structure of the present invention, a conventional shield body made only of metal magnetic materials, and a shield body whose frame is formed by bending the metal clad material described above. This is a diagram. In the figure, A is the permalloy + Cu double structure of the present invention,
B is the case of the metal clad material, and C is the case of the conventional shield body made only of permalloy material. CRT on horizontal axis
The distance (cm) between and the floppy disk drive device is taken, and the vertical axis is the wind margin (nanoseconds ns).
is shown. The wind margin of the present invention is larger when the CRT distance is 15 cm or less, and the effect is particularly significant as the CRT distance becomes smaller. This also shows that the floppy disk drive device incorporating the magnetic head of the present invention maintains high quality with little noise influence even when placed very close to a CRT. In addition, unlike shield bodies made of metal clad materials, the characteristics do not deteriorate due to the effects of distortion during cladding processing, and manufacturing is extremely simple since only two frames are overlapped. It has the advantage that one shield body can be attached to the other shield body by plating.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an assembly process of a shield structure according to an embodiment of the present invention.

FIG. 2 is a perspective view of the magnetic shield structure obtained by the assembly process of FIG. 1;

FIG. 3 is a perspective view showing an assembly process of a shield structure according to another embodiment of the present invention.

4 is a perspective view of the shield structure obtained in the assembly process shown in FIG. 3. FIG.

FIG. 5 is a perspective view showing an assembly process of a shield structure according to still another embodiment of the present invention.

6 is a perspective view of the shield structure obtained in the assembly process shown in FIG. 5. FIG.

FIG. 7 is a perspective view of a metal clad material in which Cu is attached to one side of permalloy.

FIG. 8 is a perspective view of a shield body obtained by pressing a metal clad material.

FIG. 9 is a diagram showing the wind margin of the floppy disk drive device with respect to the CRT distance for the shield structure of the present invention and the conventional shield body.

[Explanation of symbols]

1 Inner shield body 2 Outer shield body 3 Magnetic shield structure 1a, 2a Front of shield body 1c Rectangular window hole 6 Metal clad material 7 Shield body

Claims (1)

[Claims] 1. A shield structure for a magnetic head, characterized in that a frame-shaped shield body made of a metal-based magnetic material and a shield body made of a conductive material are placed overlappingly on the outside of a slider assembly incorporating a head core portion.