JPH05298648A - Magnetic head and its manufacture - Google Patents

Abstract

PURPOSE:To provide the core shield structure of the magnetic head which is suitably reducible in size and its manufacture. CONSTITUTION:A core shield 3 is so fixed to a slider 2 as to surround the outer periphery of the slider 2, which is fixed to the slider holding part of a gimbals spring 4. A gap (s) is formed between the core shield 3 and gimbals spring 4. The ridge between the outside wall and front surface of the core shield 3 has its edge cut to become smoothly round, and the floppy disk slide surface of the slider 2 and the front surface of the core shield 3 are smoothly finished having an extremely slight step. The core shield is fixed to the slider and the gap is formed between the core shield and gimbals spring to eliminate the need for a space for the core shield fixation of the gimbals spring, and consequently the external diameter of the gimbals spring is correspondingly reducible to reduce the size of the magnetic head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite type magnetic head, and more particularly to a core shield structure of a magnetic head in which a recording / reproducing and erasing head is used for a floppy disk drive and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, in order to perform recording / reproducing of a magnetic recording medium, for example, a floppy disk, a composite type magnetic head in which a recording / reproducing head and an erasing head are combined is mounted and used in a floppy disk drive. With the miniaturization and high density of the magnetic recording medium driving device, this magnetic head is also required to be small and highly reliable.

A magnetic head generally known as a bulk type head includes a ceramic slider that is in sliding contact with the recording surface of a floppy disk and a gimbal spring that supports the slider on a carriage arm. The slider has a recording / reproducing gap. And a composite magnetic core for forming an erase gap, a recording / reproducing coil assembly attached to the magnetic core, an erase coil assembly, and a back core for magnetically closing the open end of the magnetic core.

When such a composite magnetic head is mounted on a floppy disk drive and used in electronic equipment such as a personal computer, magnetic noise is generated in the floppy disk drive and the transformers and coils provided in the electronic equipment. Therefore, the magnetic core or coil of the magnetic head picks up this noise. For this reason, malfunctions may occur in recording / reproducing by the floppy disk drive, and abnormal recording may be performed due to noise.

A core shield structure intended to compensate for these disadvantages is disclosed in the specification of Japanese Patent Publication No. 3-70853 and the drawings (FIGS. 3 to 7). According to the present invention, a core holding part and an elastic plate (corresponding to a gimbal spring referred to in the present specification) having an opening except for a portion bridging to the core holding part, and a core holding part of the elastic plate are held. And a shield member surrounding the core (corresponding to the core shield in this specification), the shield member is fixed to the core supporting portion of the elastic plate. A structure composed of high permeability material is shown.

The structure of the magnetic head formed on both sides of the elastic plate shown in FIG. 7 of Japanese Patent Publication No. 3-70853 is described in FIG. 3 of Japanese Patent Publication No. 3-61247. However, there is a problem when it is used in a magnetic recording medium housed in a cartridge composed of a hard case, and as a solution to this problem, a configuration in which a magnetic head block is provided on the main surface side of a leaf spring is disclosed. Has been done.

Looking at the assembly structure of the front core half body, spacer and mask block shown in FIG. 5 (A) of Japanese Patent Publication No. 3-70853, this structure is disclosed in Japanese Patent Laid-Open No. 62-62-62. It is considered to be equivalent to the structure described with reference to FIG. 9 as a conventional example of a magnetic head in Japanese Patent No. 2145511, that is, the magnetic head core is sandwiched and fixed by two sliders. Japanese Patent Laid-Open No. 62-214511 discloses an example in which the slider structure is complicated and has a large number of steps, and the manufacturing yield is poor. ..

A conventional example corresponding to the present invention will be described with reference to FIG. The integrated slider 2 has a magnetic core insertion hole 2a provided so as to penetrate from the front surface to the back surface, and the composite magnetic core 1 including a recording / reproducing core and an erasing core serves as a floppy disk in the insertion hole 2a. It is incorporated with the sliding contact surface. The front surface of the slider 2 has an insertion hole 2a.
A main sliding contact surface 21 that surrounds the main sliding contact surface 21 and an auxiliary sliding contact surface 22 that is separated from the main sliding contact surface 21 by several tracks are provided at a position slightly higher than the reference surface 23. There is a recess (not shown) on the back side of the slider 2, and a recording / reproducing coil assembly having a recording / reproducing coil through which the core leg of the recording / reproducing core penetrates and a bobbin holding the recording / reproducing coil, and a core leg of the erasing core penetrates. The erasing coil and the erasing coil assembly having the bobbin holding the erasing coil are inserted into the core legs of the recording / reproducing core and the erasing core, respectively, and both core legs are magnetically connected to each other by the back core to form the recess. It is settled. This state is called a slider block. The slider 2 that has become a slider block is adhesively fixed on the gimbal spring 4, and the core shield 3 is also adhesively fixed on the gimbal spring 4 so as to surround the slider 2.
The gimbal spring 4 outside the core shield 3 has an opening 4a.
There is.

Here, the shield member will be described. The shield member is made by bending a metal permalloy plate which is a high magnetic permeability material or by powder-molding oxide ferrite. The frequency characteristics of the magnetic permeability of both are shown in FIG.
Comparing in (a), the former decreases sharply as the frequency increases, whereas the latter decreases gently.
The thickness of the shield member is about 0.2 mm in the former case, whereas the latter needs to be about 0.4 mm because the material is brittle.
The recording frequency of the magnetic head increases in proportion to the increase of the recording density of the floppy disk as shown in FIG. 10 (b), but in recent years, the recording density tends to increase, and therefore, as a material for the shield member. Recently, the choice of ferrite has increased.

[0010]

Since the core shield is fixed to the gimbal spring in the conventional magnetic head, the area of the slider fixing portion of the gimbal spring is increased by at least the amount necessary for fixing the core shield. It had the drawback of having to do it. With the increase in the density of the floppy disk, ferrite has come to be used as a material for the core shield, which is further disadvantageous because the thickness of the core shield becomes thicker as described above. Therefore, the gimbal spring as a whole becomes large, which is disadvantageous to the demand for miniaturization of the magnetic head.

The core shield is fixed to the gimbal spring at the same time as the slider block is fixed to the gimbal spring, or the core shield is fixed to the slider block in advance and then fixed to the gimbal spring. The core shield is brittle in shape and material and is easily broken. The coefficient of linear expansion of ferrite and ceramic, which are the materials of the core shield and slider, are both 11-12.
X10-6 / ° C, which is the same, whereas the linear expansion coefficient of stainless steel, which is the material of the gimbal spring, is 16 to 17x1.
Different from 0-6 / ° C. For this reason, when bonding the core shield to the gimbal spring, if it is attempted to fix it by increasing the adhesive strength, cracking or chipping of the core shield may occur due to thermal strain during the thermosetting process. However, if the adhesive strength is weakened and fixation is attempted, the fixing force or the positional accuracy cannot be secured, or the adhesive peels off easily. If the fixing fails once, the entire assembled magnetic head must be discarded, resulting in a large loss.

On the other hand, since the surface of the shield member is fragile and easily peels off as a foreign substance, and the ridgeline on the front side is an edge, once the floppy disk comes into contact with the magnetic recording. It will scratch the surface.
For this reason, it is necessary to set the mounting dimension from the sliding contact surface of the slider to the front surface of the core shield to a large size so that there is no risk of contact with the floppy disk in consideration of positional deviation during assembly. When such a magnetic head is used as a double-sided magnetic head so as to be in sliding contact with both sides of the floppy disk, the magnetic noise of the running direction of the floppy disk is increased because the interval between the core shields of the upper and lower magnetic heads is large. It was difficult to prevent this, and it was not possible to eliminate the problems in recording and playback.

An object of the present invention is to solve the above problems and provide a magnetic head suitable for downsizing of the apparatus.

[0014]

The gist of the present invention for achieving the above object is to provide a composite magnetic core composed of a recording / reproducing core and an erasing core, and a magnetic disk such as a floppy disk for fixedly supporting the composite magnetic core. A recording / reproducing coil assembly having an integral slider that slides in contact with a recording medium, a recording / reproducing coil through which a core leg of the recording / reproducing core penetrates, and a bobbin holding the recording / reproducing coil, and a core leg of the erasing core penetrates. An erasing coil, an erasing coil assembly holding the erasing coil, a back core magnetically closing the open end of the composite magnetic core, a gimbal spring to which the slider is adhesively fixed, a core shield for absorbing magnetic noise, In the magnetic head including, the core shield is fixed to the slider so that there is a gap between the core shield and the gimbal spring. And butterflies.

Further, in the manufacture of this magnetic head, the core shield is fixed in advance to the combined body of the slider and the composite magnetic core, and then the surface finishing is performed simultaneously with the slider.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a magnetic head showing an embodiment of the present invention, and FIG. 2 is a sectional view in the track direction at the center of this magnetic head. FIG. 3 is a perspective view showing the order of assembling the slider, the composite magnetic core and the core shield of this magnetic head.
FIG. 5 is an explanatory view of the front surface of the combined body of the core shield, slider and composite magnetic core of the present invention, and FIG. 5 is an explanatory view of the front surface finish processing. 6 is an exploded perspective view seen from the back side without the gimbal spring, and FIG. 7 is a back side perspective view without the gimbal spring shown in FIG.

First, the structure of the present invention will be described. In FIG. 1, reference numeral 2 is an integral type slider, and a core shield 3 is fixed to the slider 2 so as to surround the outer circumference of the slider 2. The slider 2 is fixed to the slider holding portion of the gimbal spring 4. There is an opening 4a just outside the slider holder. As shown in FIG. 2, there is a gap s between the core shield 3 and the gimbal spring 4.

The ridgeline formed by the outer wall of the core shield 3 and the front surface has a smooth edge, and the slide contact surface of the slider 2 and the core shield 3 are smooth.
It has a very slight step difference from the front surface of the and is finished smoothly.

The slider 2 with a core shield has a magnetic core insertion hole 2a penetrating from the front surface to the back surface, and the back side of the slider 2 has a recess as shown in FIG. The recording / reproducing core 11 is inserted into the insertion hole 2a.
The composite magnetic core 1 including the erasing core 12 and the erasing core 12 is incorporated. On the front surface of the slider 2, a main sliding contact surface 21 including an insertion hole 2a and an auxiliary sliding contact surface 22 which is a few tracks away from the main sliding contact surface 21 are located slightly higher than the reference surface 23. Each is provided. The recording / reproducing coil assembly 5 and the erasing coil assembly 6 are inserted in the outer core leg 13 of the recording / reproducing core 11 and the outer core leg 14 of the erasing core 12, respectively. Both cores 11 and 12
The open ends of the core legs are connected and fixed by the back cores 9 and 10 so as to close the respective magnetic circuits of the composite magnetic core, and are housed in the recesses of the slider 2 as shown in FIG.

Next, a method of manufacturing this magnetic head will be described. The both cores 11 and 12 include outer cores 13 and 14 penetrating the coils and inner cores 15 and 16 for closing a magnetic circuit. The inner cores 15 and 16 are integrally bonded and fixed by a glass adhesive as is well known. ing. The recording / reproducing gap 18 and the erasing gap 19 of both cores 11 and 12 shown in FIG. 3 perform the recording / reproducing / erasing action on the floppy disk. Both cores 11, 1
2 is preferably formed from a high magnetic permeability material such as ferrite.

The integrated slider 2 is made of a blank obtained by injection molding ceramics such as calcium titanate. Figure 3
As shown in FIG. 2, the trapezoidal portion 2b which is completed and becomes the main sliding contact surface 21 and the trapezoidal portion 2c which becomes the auxiliary sliding contact surface 22 are formed on the front surface of the blank slider 2. The composite magnetic core 1 is inserted into the insertion hole 2a of the slider 2 with its back surface aligned with each other, and fixed by adhesion with a glass adhesive. Next is the core
The field 3 is formed by powder molding and firing a high-permeability material such as ferrite, and is assembled so that the reference surface 23 of the slider 2 and the front surface of the core shield 3 are aligned with each other.
Glue and fix with a glass adhesive. The core shield 3 may be adhered to the slider 2 at the same time as the composite magnetic core 1 is adhered to the slider 2. After the core shield 3, the slider 2 and the composite magnetic core 1 are integrated, the front surface of the slider 2 is roughly processed by grinding so as to have a plus dimension of several μm from the completed thickness.

Next, a roughing process is performed, and FIG. 4 is an explanatory view of this process. The tool used for this processing is a brush 86 embedded in the base 85, and the brush 86 is made of materials such as pig hair, horse hair, plastics, and true chew with a wire diameter of several tens to several hundreds of μm. The selection of is appropriately determined according to the desired size of the arm and the like. Free abrasive grains such as paste diamond particles, chromium oxide particles, and cerium oxide particles are wetted into the brush 86, and the core shield 3 fixed to the fixing table 84, the slider 2, and the composite magnetic core 1 are bonded together. It hits the body and makes a rotational movement.

In such a method, steps are formed between the materials due to the difference in the material forming the front surface, and therefore, in order to eliminate these steps, wrapping is performed on a hard flat surface plate. The lapping allowance is several μm. In the finishing process, in order to prevent the surface of the floppy disk from being scratched when the floppy disk slides on the front surface of the magnetic head, an interference fringe pattern is formed on the front surface. As shown in FIG. 5, the processing tool is such that a cushion 81 made of a rubber material having a thickness of several mm is placed on a surface plate 80, and a polishing tape 82 coated with an abrasive such as chromium oxide is further placed thereon. The combined body of the core shield 3, the slider 2, and the composite magnetic core 1 is fixed to the base 83 so that a load of several to several tens of grams is applied to each combined body. Are rotated in opposite directions with X as a rotation axis. By this method, the surface roughness is finished to 0.01 to 0.02 μm.

The bobbin 55 shown in FIG. 6 has nickel-white terminals 51-53.
To polyphenylene sulfide (PP
It is formed by injection-molding plastics in which glass fiber is mixed with S) or the like. The recording / reproducing coil 7 and the erasing coil 8 are wound around the bobbin 55, and the coil ends are respectively the terminals 51 to 53 of the recording / reproducing coil 7 and the terminal 5 of the erasing coil.
The recording / reproducing coil assembly 5 and the erasing coil assembly 6 are formed by tying and soldering them to Nos. 1 and 53. Recording and reproducing core 11 and erasing core 1 with both coil assemblies 5 and 6
2 into the core legs of the respective outer cores 13, 14. Recording / reproducing core 11 and erasing core 12 of the composite magnetic core 1
The back cores 9 and 10 are assembled so as to sandwich the open ends of both core legs, and the connection is surely made with a silver paste. The slider 2 assembly thus assembled is adhesively fixed to the slider holding portion of the gimbal spring 4 using a UV adhesive.

According to this embodiment, when the core shield is fixed by glass bonding, the composite magnetic core can be simultaneously bonded to the slider, so that the manufacturing cost for fixing the core shield can be reduced. Is now possible.

Further, since the front surface of the core shield is finished at the same time by bonding and fixing the core shield to the slider and then finishing the front surface of the slider, the front surface of the core shield is finished at the same time. The advantage is that it is possible to omit the deburring process for removing foreign matters and edges that easily peel off the surface.

Further, according to the present embodiment, even if an assembling failure occurs during the assembling of the core shield, no other high value-added parts are assembled on the slider at this stage, so that the loss is small. The advantage was also obtained.

When fixing the core shield, a gap is provided between the core shield having a different linear expansion coefficient and the gimbal spring, and the core shield and the slider having the same linear expansion coefficient are fixed. As a result, it was possible to eliminate cracking and chipping defects when fixing the core shield.

The weight is reduced by the amount of the clearance left on the back side of the core shield, which enables more stable sliding contact between the floppy disk and the magnetic head.

Another embodiment of the present invention will be described with reference to FIG. A step portion 102a is provided on the outer circumference of the front side of the slider 102, and a step portion 103a corresponding to the step portion 102a is provided on the inner circumference of the front side of the core shield 103.
This has the advantage that the core shield 103 and the slider 102 can be easily aligned in the height direction when the core cord 103 is bonded and fixed to the slider 102.

[0031]

As described above, according to the present invention, the core shield is fixed to the slider and a gap is provided between the core shield and the gimbal spring.
The space for fixing the field is no longer necessary, and the outer diameter of the gimbal spring can be made smaller by that amount, and the magnetic head can be made smaller.

Further, since the core shield is preliminarily adhered and fixed to the slider and the front surface of the core shield is finished at the same time as the front surface of the slider, the front surface of the core shield has no edges and is smooth. As a result, even if the floppy disk and the core shield contact each other, there is no risk of damaging the magnetic recording surface. Therefore, the step between the core shield front surface and the sliding contact surface between the slider and the floppy disk is set to a minimum. It has become possible. Most of the influence of the magnetic noise is received by the magnetic gap of the composite magnetic core, so that it is possible to maximize the shield effect against the magnetic noise entering parallel to the floppy disk surface. Even if there is a slight gap between the gimbal spring and the core shield, the distance to the magnetic gap is large, and no problem occurs in the magnetic noise shielding effect.

Further, similarly, the core shield is preliminarily adhered and fixed to the slider, and the front surface of the core shield is finished at the same time as the front surface of the slider, so that the core shield fixing step and the core shield are fixed as described above. Since the burr treatment process can be omitted, the manufacturing cost can be reduced.

From these facts, it has become possible to provide a compact, highly reliable, and low cost magnetic head.

[Brief description of drawings]

FIG. 1 is a perspective view of a magnetic head showing an embodiment of the present invention.

FIG. 2 is a sectional view in the track direction at the center of FIG.

FIG. 3 is a perspective view showing the order of assembling the slider and the core shield of the present invention.

FIG. 4 is an explanatory diagram of an aling process of a combined body of a slider, a magnetic core and a core shield according to the present invention.

FIG. 5 is an explanatory view of the finishing process of the combined body of the slider, the magnetic core and the core shield of the present invention.

FIG. 6 is an exploded perspective view of the back side of FIG. 1 excluding a gimbal spring.

7 is a perspective view of the back side of FIG. 1 excluding a gimbal spring.

8 is a sectional view similar to FIG. 2, showing another embodiment of the present invention.

FIG. 9 is a perspective view of a magnetic head showing a conventional technique.

FIG. 10A is a graph showing frequency characteristics of magnetic permeability.

FIG. 10B is a table showing the relationship between recording density and recording frequency.

[Explanation of symbols]

 1 composite magnetic core 2, 102 slider 3, 103 core shield 4 gimbal spring 5 recording / reproducing coil assembly 6 erasing coil assembly 7 recording / reproducing coil 8 erasing coil 9, 10 back core 11 recording / reproducing core 12 erasing core 55 bobbin s gap

Claims (2)

[Claims] 1. A composite magnetic core consisting of a recording / reproducing core and an erasing core, an integral slider fixedly supporting the composite magnetic core and in sliding contact with a magnetic recording medium, and a recording through which a core leg of the recording / reproducing core penetrates. A recording / reproducing coil assembly having a reproducing coil and a bobbin holding the recording / reproducing coil, an erasing coil assembly having an erasing coil through which a core leg of the erasing core penetrates and a bobbin holding the erasing coil, and the composite magnetic A back core that magnetically closes the open end of the core, a gimbal spring to which the slider is adhesively fixed, and a core shield that surrounds the composite magnetic core,
In the magnetic head including the above, the core shield is fixed to the slider so that there is a gap between the core shield and the gimbal spring. 2. A method of manufacturing a magnetic head for fixing a core shield to a slider, comprising the step of fixing the core shield to the slider in advance and then finishing the front surface simultaneously with the slider. A method of manufacturing a magnetic head, characterized in that