JPH0877509A - Magnetic head - Google Patents

Abstract

(57) [Abstract] [Purpose] A magnetic recording medium is less likely to be scratched or drop out of the magnetic powder by further reducing the minute irregularities on the sliding surface of the magnetic recording medium and making them as close as possible to a smooth surface. To provide a magnetic head that can make good contact with. [Structure] Centerline average surface roughness RA of a magnetic recording medium sliding surface Ra of a ferromagnetic oxide 12 sliding on a magnetic recording medium
Is 2 nm or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head incorporated in a magnetic recording / reproducing apparatus such as a video tape recorder (hereinafter referred to as "VTR").

[0002]

2. Description of the Related Art Conventionally, in a magnetic recording / reproducing apparatus such as a VTR, the wavelength of an information signal has been shortened for the purpose of improving the image quality. Ferrite head made of ferrite,
Further, a metal-in-gap head (so-called MIG head) in which a ferromagnetic oxide material is used as a main core and a ferromagnetic metal material is arranged in the vicinity of a magnetic gap has come into use.

For example, the MIG head has a front gap FG and a back gap B as shown in FIG.
A pair of magnetic core halves 1 and 1 which are separately formed on the left and right with G as a boundary are abutted and integrated with each other with a gap. The magnetic core halves 1 and 1 are composed of oxide magnetic materials 2 and 2 and ferromagnetic metal films 3 and 3, and the ferromagnetic metal films 3 and 3 provided on the opposing surfaces of the magnetic core halves 1 and 1. Front gap FG between the 3 butting surfaces
And a back gap BG is formed. The front gap F is formed on the abutting surface of the magnetic core halves 1, 1.
Track width regulating grooves 4 and 4 for regulating the track widths of G and the back gap BG are provided.

Further, a fused glass 5 is melt-filled in the track width regulating grooves 4, 4 and the magnetic core halves 1, 1 are joined by the fused glass 5. Further, the winding groove 6 for coil winding is formed on the abutting surface side of the magnetic core halves 1, 1.
6 is provided, and the coil insertion hole 7 is formed by aligning both winding grooves 6, 6. This coil insertion hole 7
A coil (not shown) is inserted through the coil, so that the coil is wound around each of the magnetic core halves 1, 1.

By the way, the magnetic head having the above-mentioned structure is usually used by being mounted on a cylindrical rotary drum, and comes into contact with a magnetic recording medium (magnetic tape) running so as to surround the rotary drum. By doing so, it is possible to record / reproduce signals. Therefore, in order to improve the contact state at this time, as shown in FIG. 20, the magnetic recording medium sliding surface of the magnetic head is given a curvature in the x direction and the y direction.

The curvature of the sliding surface of the magnetic recording medium of this magnetic head is usually formed by polishing. First, a rough curved surface is formed in the x direction by cylindrical polishing, and then
The curvature is given by forming a suitable curved surface in both the x-direction and the y-direction using a precision polishing tape.
In the polishing with the above-mentioned precision polishing tape, it is necessary to consider the processing cost and workability and to remove the scratches caused by the cylindrical polishing. Therefore, in general, for finishing containing abrasive grains of about 6000 to 8000 mesh. Precision polishing tape is used.

[0007]

The surface roughness of the ferromagnetic oxide on the sliding surface of the magnetic recording medium of the conventional magnetic head thus polished was as shown in FIG. This FIG. 21 is a surface roughness measuring device (WYKO).
Is a measurement of the surface of the ferromagnetic oxide on the sliding surface of the magnetic recording medium of the magnetic head, where the x direction represents the sliding direction of the magnetic recording medium and the y direction represents the track width direction.

In this conventional magnetic head, the surface of the ferromagnetic oxide has irregularities of about 30 nanometers (nm), the center line average surface roughness (RA) is 2.78 nm, and the mean square roughness ( RMS) is 3.59 nm, and the height difference (P-V) between the highest position and the lowest position is 33.1 nm. Generally, in the magnetic head that has been subjected to the above-described polishing treatment, the center line average surface roughness of the surface of the ferromagnetic oxide on the sliding surface of the magnetic recording medium is 2 to 10 nm.

The fine irregularities on the sliding surface of the magnetic recording medium of this magnetic head damage the magnetic recording medium and cause the magnetic powder to fall off.
This causes the magnetic powder that has fallen off to adhere to the magnetic head and the resulting contact failure between the magnetic head and the magnetic recording medium (the reduction in signal output due to this is called head clog).

The present invention has been made in view of the above conventional problems, and solves the above problems by further reducing the minute irregularities on the sliding surface of the magnetic recording medium to make it as close as possible to a smooth surface. It is an object of the present invention to provide a magnetic head capable of performing the above.

[0011]

In order to solve the above-mentioned problems and the like and to achieve the above-mentioned objects, the present invention comprises, for example, a ferromagnetic oxide 12 as shown in FIGS. Magnetic recording of a ferromagnetic oxide 12 sliding on a magnetic recording medium in a magnetic head formed by joining and integrating magnetic core halves 11 so as to abut each other and forming magnetic gaps FG and BG between the abutting surfaces. The center line average surface roughness RA of the medium sliding surface Ra is set to 2 nm or less.

Further, according to the present invention, for example, as shown in FIGS. 9 to 18, a magnetic core half body 31 composed of a ferromagnetic oxide 32 and a ferromagnetic metal film 33 disposed on at least the gap forming surface 41 is formed. In a magnetic head having ferromagnetic metal films 33, 33 joined so as to abut against each other and integrated, and magnetic gaps FG, BG are formed between the abutting faces, a ferromagnetic oxide 32 that slides on a magnetic recording medium. Center line average surface roughness RA on the sliding surfaces Ra and Ra1 of the magnetic recording medium
Is 2 nm or less.

[0013]

The present invention has the above-mentioned configuration,
Center line average surface roughness R on the magnetic recording medium sliding surfaces Ra and Ra1 of the ferromagnetic oxides 12 and 32 of the magnetic heads H1 and H2.
Since A is set to 2 nm or less, damage to the magnetic recording medium due to sliding is reduced, and foreign matter such as magnetic powder attached to the magnetic recording medium sliding surfaces Ra and Ra1 of the magnetic heads H1 and H2 is reduced.
The time to fall into the head clog state can be extended.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 9 show the first embodiment of the present invention and the drawings related thereto, FIGS. 10 to 17 show the second embodiment of the present invention and the drawings related thereto, and FIGS. It is a figure which shows the 3rd and 4th Example of this invention.

The first embodiment is applied to a magnetic head whose magnetic core half body is composed of magnetic ferrite, and FIG. 1 is an overall configuration diagram of a magnetic head H1 according to the first embodiment, FIGS. 5 is a diagram for explaining a method of manufacturing the magnetic head H1, and FIGS. 6 to 9 show the magnetic head H1.
FIG. 4 is a diagram for explaining characteristics and the like of FIG.

The magnetic head H1 shown in the first embodiment is shown in FIG.
, The pair of magnetic core halves 11, which are formed with the front gap FG and the back gap BG as boundaries,
The magnetic core halves 11 and 11 are made of magnetic ferrites 12 and 12 and are joined together by abutting with a gap. On the facing surfaces of the magnetic core halves 11, 11, there are track width regulating grooves 14, 14 for regulating the track widths of the front gap FG and the back gap BG, and winding grooves 16, 1 for coil winding.
6 are provided respectively. The track width regulating grooves 14, 14 are melt-filled with fused glass 15, 15, and the pair of magnetic core halves 11, 11 are joined by the fused glass 15, 15. Further, a coil (not shown) is inserted into the coil insertion hole 17 formed by aligning the winding grooves 16, 16 of the magnetic core halves 11, 11, whereby the abutting surfaces of the magnetic core halves 11, 11 are joined together. A coil is wound around each side.

The magnetic head H1 having such a structure
Can be manufactured, for example, according to the following manufacturing method. First, as shown in FIG.
In order to form, the magnetic gap forming surface 21 of the magnetic ferrite substrate 20 is filled with glass to form a plurality of track width regulating grooves 14 having a substantially V-shaped cross section for regulating the width of the magnetic gap with a predetermined interval. . Then, as shown in FIG.
The fused glass 15 is poured into the track width regulating groove 14 of the magnetic ferrite substrate 20.

Next, as shown in FIG. 4, a winding groove 16 for winding the coil is formed so as to be orthogonal to the track width regulating groove 14 to form a magnetic core half block 18. The winding groove 16 determines the depth of the front gap, and one side surface 16a is formed as an inclined surface such that its open end is at the zero depth position of the front gap. Then, the magnetic gap forming surface 21 of the magnetic core half block 18 is subjected to smooth polishing, and a gap spacer (not shown) is formed by a vacuum thin film forming method such as a sputtering method.

Next, as shown in FIG. 5, the pair of magnetic core half blocks 18, 18 are joined. On this occasion,
Magnetic gap forming surfaces 21 and 21 of both blocks 18 and 18
Are aligned to face each other, and the track width regulating grooves 14 and 14 are aligned, and heating is performed in a temperature range of 450 to 650 ° C. in a nitrogen atmosphere while applying pressure in the butting direction to fuse the blocks 18 and 18 together. The glasses 15 and 15 are joined by fusing. As a result, the pair of magnetic core half blocks 18, 18 are joined and integrated, and
A front gap FG that functions as a reproducing gap and a back gap (not shown) are formed between the abutting surfaces.

After that, the pair of magnetic core half blocks 1
Cylindrical polishing is performed on the front gap side of the joints 8 and 18 to remove the hatched portion in FIG. 5 and form a curved surface having a predetermined curvature. Then, by cutting the magnetic core half blocks 18, 18 along the cutting lines indicated by the lines AA and BB in FIG.
The magnetic head H1 is formed.

The magnetic head H1 manufactured in this way
Is attached to the magnetic head base 22 so as to project the front gap portion, and then, as shown in FIG. 6, the rotary drum of the cylindrical magnetic head wrapping device 23 composed of the rotary drum 24 and the fixed drum 25. Two
It is attached to 4. The rotary drum 24 comes into contact with the precision polishing tape 26 and rotates at a high speed to polish the sliding portion of the magnetic recording medium of the magnetic head H1, which has a predetermined curvature and the center line average surface of the magnetic ferrite portion. The magnetic head H1 having a roughness of 2 nm or less is completed.

The following experiment was conducted to confirm the effect of the magnetic head H1 thus completed. That is, the magnetic head H manufactured by the process shown in FIGS.
Forty pieces of No. 1 were prepared, and these were divided into four groups of 10 pieces, respectively, and at the time of final surface finishing shown in FIG. Then, with respect to these magnetic heads H1, the center line average surface roughness Ra of the shaded portion shown in FIG. 7 was measured by the surface roughness measuring instrument WYKO. After that, the magnetic head H1 was attached to the camcorder, and the temperature was 40 ° C and the humidity was 40%.
The magnetic tape (P6-120HMP tape) was run under the above environment, and the time until falling into the head clog state was measured, and the average life by Weibull evaluation was calculated for each group.

The relationship between the centerline average surface roughness and the average life thus obtained is shown in FIG. It can be seen from FIG. 8 that the average life is greatly extended when the center line average surface roughness of the magnetic ferrite surface in the sliding portion of the magnetic recording medium of the magnetic head H1 is 2 nm or less.

FIG. 9 shows that the sliding surface Ra of the magnetic recording medium of the magnetic head H1 is polished using a precision polishing tape for finishing containing abrasive particles of about 20000 mesh. According to this, the center line average surface roughness (RA) of the ferromagnetic oxide is 1.68 nm, and the root mean square roughness (RMS) is 2.38 nm.
The height difference (P-V) between the highest level and the lowest level of the unevenness was 4.56 nm. Therefore, it was revealed that the unevenness on the sliding surface of the magnetic recording medium was significantly smaller than that on the sliding surface of the conventional magnetic head shown in FIG.

In this embodiment, the winding grooves 16 and 16 are provided in both of the pair of magnetic core half blocks 18 and 18, but the winding groove 16 may be used in either one of the magnetic core blocks. It may be provided in the core half block 18.

Next, a second embodiment of the present invention will be described. This second embodiment is applied to a magnetic head in which the magnetic core half body is composed of a magnetic ferrite and a ferromagnetic metal film arranged on the gap forming surface, and FIG. 10 shows a magnetic head according to the second embodiment. Head H2 overall configuration diagram, FIG.
14 to 14 are diagrams for explaining the method of manufacturing the magnetic head H2, and FIGS. 15 to 17 are diagrams for explaining the characteristics of the magnetic head H2.

The magnetic head H2 shown in the second embodiment is shown in FIG.
As shown in 0, the pair of magnetic core halves 3 formed with the front gap FG and the back gap BG as boundaries.
The magnetic core halves 31 and 31 are composed of a magnetic ferrite 32 and a ferromagnetic metal film 33. The ferromagnetic metal film 33 is arranged on the facing surfaces of the pair of magnetic core halves 31, 31.
Further, track width regulating grooves 34, 34 for regulating the track widths of the front gap FG and the back gap BG, and winding grooves 36, 36 for coil winding are provided on the opposing surfaces of the pair of magnetic core halves 31, 31. Each is provided.

The track width regulating grooves 34, 34 are melt-filled with the fused glass 35, 35 via the ferromagnetic metal film 33, and the pair of fused glass 35 and the fused glass 35 are interposed therebetween. The magnetic core halves 31, 31 are joined together. Furthermore, the winding groove 3 of the magnetic core halves 31, 31
A coil (not shown) is inserted through the coil insertion hole 37 formed by combining the six and 36, whereby the coils are wound around the abutting surfaces of the magnetic core halves 31, 31, respectively.

The ferromagnetic metal film 33 is provided substantially along the shape of the facing surface of the magnetic ferrite 32.
Front gap F that functions as a reproducing magnetic gap
It is formed so as to be parallel to G and the back gap BG. Therefore, the pair of ferromagnetic metal films 33, 33
A front gap FG and a back gap BG are formed between the butting surfaces of.

As the material forming such a ferromagnetic metal film 33, various materials shown in the following (1) to (3) can be used. (1) Fe-Al-Si, Fe-Ni-Al-Si, F
e-Ga-Si, Fe-Al-Ge, etc., and 8
Co, Ti, Cr, Nb, Mo, Ta, R of atomic% or less
u, Au, Pd, N, C, O, etc., one or several kinds of crystalline materials added, (2) Co mainly Zr, Ta, Ti,
An amorphous material formed by adding one or several kinds of Hf, Mo, and Nb, (3) Co, Fe, mainly Zr,
A microcrystalline material formed by adding one or several kinds of Ta, Ti, Hf, Mo, Nb, Si, Al and B and one or several kinds of N, C and O is selected. Then, the ferromagnetic metal film 33 is formed by depositing on the magnetic ferrite 32 by a vacuum thin film forming method such as a sputtering method.

The magnetic head H2 having such a structure
Can be manufactured, for example, according to the following manufacturing method. First, as shown in FIG. 11, the magnetic core half 3
In order to form No. 1, a plurality of track width regulating grooves 34 having a substantially V-shaped cross section for regulating the width of the magnetic gap by filling the magnetic gap forming surface 41 of the magnetic ferrite substrate 40 with glass are formed at a predetermined interval. To do. Then, as shown in FIG. 12, a magnetic gap forming surface 41 of the magnetic ferrite substrate 40.
Then, a ferromagnetic metal film 33 is deposited by vacuum thin film forming method such as sputtering. Then, the fused glass 15 is poured into the track width regulation groove 34 of the magnetic ferrite substrate 40.

Next, as shown in FIG. 13, a winding groove 36 for winding the coil is formed so as to be orthogonal to the track width regulating groove 34, and a magnetic core half block 38 is formed. Then, the magnetic gap forming surface 41 of the magnetic core half block 38 is subjected to smooth polishing, and a gap spacer (not shown) is formed by a vacuum thin film forming method such as a sputtering method. The winding groove 36 determines the depth of the front gap, and one side surface 16a is an inclined surface, and its open end is at the position where the depth of the front gap is zero.

Next, as shown in FIG. 14, the pair of magnetic core half blocks 38, 38 are joined. At this time, the magnetic gap forming surfaces 41, 41 of the blocks 38, 38 are opposed to each other to align the track width regulating grooves 34, 34, and the ferromagnetic metal films 33, 33 are opposed to each other. , 38 are abutted and heated in a temperature range of 450 to 650 ° C. in a nitrogen atmosphere while pressurizing in the abutting direction to fuse the fused glasses 35, 35 of both blocks 38, 38 for joining. . As a result, the pair of magnetic core half blocks 38, 38 are joined and integrated, and the front gap FG that functions as a reproducing gap is provided between the abutting surfaces (between the abutting surfaces of the ferromagnetic metal films 33, 33). Also, a back gap (not shown) is formed.

After that, the pair of magnetic core half blocks 3
Cylindrical polishing is performed on the front gap side of the joined objects 8 and 38 to remove the hatched portion in FIG. 14 and form a curved surface having a predetermined curvature. Then, by cutting the magnetic core half blocks 38, 38 along the cutting lines indicated by lines AA and BB in FIG.
The magnetic head H2 is formed.

The magnetic head H2 manufactured in this way
Is attached to the magnetic head base 22 so as to project the front gap portion, and then, as shown in FIG. 15, the rotary drum of the cylindrical magnetic head wrapping device 23 composed of the rotary drum 24 and the fixed drum 25. Two
It is attached to 4. The rotating drum 24 is brought into contact with the precision polishing tape 26 and rotates at a high speed, so that the sliding portion of the magnetic recording medium of the magnetic head H2 is polished, so that the center line average surface of the magnetic ferrite portion has a predetermined curvature. The magnetic head H2 having a roughness of 2 nm or less is completed.

The following experiment was conducted to confirm the effect of the magnetic head H2 thus completed. That is, 40 magnetic heads H2 produced by the process shown in FIGS. 11 to 14 are prepared, and these are divided into four groups of 10 each, and at the time of final surface finishing shown in FIG. Lapping processing was performed using different precision polishing tapes. Then, for these magnetic heads H2, the center line average surface roughness Ra, R of the shaded portion shown in FIG.
a1 was measured by the surface roughness measuring instrument WYKO. After that, the magnetic head H2 is attached to the camcorder, and the temperature is set to 40
Magnetic tape (P6-120H)
(MP tape) was run, the time until it fell into a head clog state was measured, and the average life by Weibull evaluation was calculated for each group.

The relationship between the center line average surface roughness and the average life thus obtained is shown in FIG. According to FIG. 17, it can be seen that the average life is greatly extended when the center line average surface roughness of the magnetic ferrite surface on the sliding surface of the magnetic recording medium of the magnetic head H2 is 2 nm or less.

In this embodiment, the winding grooves 36, 36 are provided on both the pair of magnetic core half blocks 38, 38, but the winding groove 36 may be formed on either one of the magnetic core half blocks 38, 38. It may be provided in the core half block 38.

Further, although the MIG head in which the ferromagnetic metal film is arranged in parallel with the magnetic gap has been described in the second embodiment, the present invention, as shown in FIG. 18, shows the ferromagnetic metal film. Magnetic head H3 with X-shaped arrangement
Alternatively, as shown in FIG. 19, it can be applied to a magnetic head H4 in which a ferromagnetic metal film is obliquely arranged. The magnetic heads H3 and H4 having the configurations shown in FIGS. 18 and 19 can also achieve the same effects as those of the above embodiment.

As described above, the present invention is not limited to the above embodiments, but various modifications can be made without departing from the spirit of the present invention.

[0041]

As described above, according to the present invention,
Since the center line average surface roughness of the ferromagnetic oxide on the sliding surface of the magnetic recording medium is set to 2 nm or less, damage to the magnetic recording medium due to sliding on the sliding surface of the magnetic recording medium can be reduced. At the same time, it is possible to reduce the amount of foreign matter such as magnetic powder adhered to the sliding surface of the magnetic recording medium and to extend the time until the magnetic head falls into the head clog state.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a perspective view showing a manufacturing process of the magnetic head of FIG. 1 and showing a state in which a substantially V-shaped groove is formed in a magnetic ferrite substrate.

FIG. 3 is a perspective view of a magnetic core half block manufactured by filling glass with the same.

FIG. 4 is a perspective view of a magnetic core half block in which winding grooves are formed.

FIG. 5 is a perspective view showing a state in which magnetic core half blocks are butted to each other via a gap spacer to manufacture a magnetic core block.

FIG. 6 is an explanatory diagram showing a step of finish polishing the sliding surface of the magnetic head.

FIG. 7 is an enlarged front view showing a portion for measuring the surface roughness of the sliding surface of the magnetic recording medium of the magnetic head according to the first embodiment.

FIG. 8 is a graph showing the relationship between the center line average surface roughness and the average life of the sliding surface of the magnetic recording medium.

FIG. 9 is an enlarged perspective view showing a surface shape of a sliding surface of a magnetic recording medium of a magnetic head according to the present invention.

FIG. 10 is a perspective view showing a second embodiment of the present invention.

11 shows a manufacturing process of the magnetic head of FIG.
FIG. 6 is a perspective view showing a state in which a substantially V-shaped groove is formed on a magnetic ferrite substrate.

FIG. 12 is a perspective view showing a state in which a magnetic film is formed in a substantially V-shaped groove and then glass is filled to produce a magnetic core half block.

FIG. 13 is a perspective view of the magnetic core half block in which winding grooves are formed.

FIG. 14 is a perspective view showing a state in which magnetic core half blocks are butted to each other via a gap spacer to produce a magnetic core block.

FIG. 15 is an explanatory diagram showing a step of finish polishing the sliding surface of the magnetic head.

FIG. 16 is an enlarged front view showing a portion for measuring the surface roughness of the sliding surface of the magnetic recording medium of the magnetic head according to the second embodiment.

FIG. 17 is a graph showing the relationship between the center line average surface roughness and the average life of the sliding surface of the magnetic recording medium.

FIG. 18 is a perspective view showing a third embodiment of the present invention.

FIG. 19 is a perspective view showing a fourth embodiment of the present invention.

FIG. 20 is a perspective view showing a conventional magnetic head.

FIG. 21 is an enlarged perspective view showing a surface shape of a sliding surface of a magnetic recording medium of a conventional magnetic head.

[Explanation of symbols]

 11,31 Magnetic core half body 12,32 Magnetic ferrite 14,34 Track width regulation groove 15,35 Fused glass 16,36 Winding groove 17,37 Coil insertion hole 18,38 Magnetic core half block 20,40 Magnetic ferrite Substrate 21, 41 Magnetic gap forming surface 22 Magnetic head base 23 Magnetic head lapping device 26 Precision polishing tape 33 Ferromagnetic metal film H1, H2, H3, H4 Magnetic head FG Front gap BG Back gap

Claims (2)

[Claims] 1. A magnetic head comprising magnetic core halves made of a ferromagnetic oxide, which are joined to each other so as to abut each other, and a magnetic gap is formed between the abutting faces, which slides on a magnetic recording medium. A magnetic head having a center line average surface roughness of a ferromagnetic oxide of 2 nm or less on a sliding surface of a magnetic recording medium. 2. A magnetic core half body composed of a ferromagnetic oxide and a ferromagnetic metal film disposed on at least a magnetic gap forming surface is joined and integrated so that the ferromagnetic metal films are abutted to each other, and the abutting is performed. In a magnetic head having a magnetic gap between the surfaces, the center line average surface roughness of the sliding surface of the ferromagnetic oxide sliding on the magnetic recording medium is 2 nm or less. Magnetic head.