JPH06124436A - Magnetic recording medium and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a highly reliable magnetic recording medium which has a long service life of a stamper and can perform a tracking servo properly, and a manufacturing method thereof. [Structure] A base 9 made of a non-magnetic material and a magnetic layer 10a formed above the base 9 are provided, and a large number of magnetic head tracking recesses 23 are formed on the surface of the magnetic layer 10a at predetermined intervals. A data track 14 for recording desired information is formed between the magnetic head tracking recess 23 and an adjacent magnetic head tracking recess 23. The magnetic head tracking recess 23 and the data track 14 are formed. In a magnetic recording medium that irradiates light onto the magnetic head and tracks the magnetic head based on the reflected light,
An escape protrusion 38 protruding toward the base 9 side is formed at a position corresponding to the magnetic head tracking recess 23 on the lower side of the magnetic layer 10a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a flexible magnetic disk, and more particularly to a magnetic recording medium having a magnetic head tracking recess for optically tracking the magnetic head and a method of manufacturing the same. It is a thing.

[0002]

2. Description of the Related Art In a flexible magnetic disk, a refrain track is formed on the innermost circumference of a toroidal recording band, and is separated from the refrain track by a predetermined distance toward the outer side in the radial direction. It is known that a large number of concentric optical recesses for magnetic head tracking are formed in a ring shape, and a data track is provided between the respective ring-shaped optical recesses for magnetic head tracking (for example, JP-A-2-187969). reference).

10 and 11 are an enlarged sectional view and a plan view for explaining this kind of magnetic disk.

As shown in these drawings, a magnetic layer 101 is provided on the surface of the base film 100, and a groove 102 for a tracking servo extends in the magnetic layer 101 so as to extend in the rotating direction of the magnetic disk. , For example, by laser processing or the like. A data track 103 is provided between the grooves 102 (FIG. 11).
reference).

On the other hand, in the magnetic recording / reproducing apparatus, a beam 104 for tracking servo is formed on the surface of the magnetic disk.
And a light receiving element 106a, 10 for receiving the reflected light 105 from the surface of the magnetic disk.
6b, 106c, 106d (see FIG. 11).

The light beam 1 emitted from the light emitting element
Apply 04 to the magnetic disk surface, and the reflected light from it 1
05 to the light receiving elements 106a, 106b, 106c, 106
Light is received at d.

As described above, since the tracking servo groove 102 is formed in the magnetic layer 101, the light intensity reflected on the data track 103 and the light intensity reflected on the groove 102 are different. In the example shown in FIG. 11, the light receiving element 106
a and the total output value of 106b, and the light receiving elements 106c and 10
A tracking servo of a magnetic head (not shown) is performed so that the output values of both are equalized by constantly comparing with the total output value of 6d.

In this conventional magnetic disk, the groove 10 is used.
A method such as a laser cut is used to form 2, and therefore a laser light source and an optical scanning system for irradiating a predetermined position with the laser light are required, which results in high cost and high productivity. It has problems such as badness.

In order to solve such a problem, a method of forming a recess for magnetic head tracking at once with a stamper is being studied.

That is, innumerable small tooth portions corresponding to the recesses for magnetic head tracking are formed in the stamper, and the stamper is pressed against the magnetic layer,
In this method, the magnetic layer is locally compressed by the teeth to form the magnetic head tracking recess.

Although this stamper system has been able to greatly improve the productivity, it is not without its drawbacks.

[0012]

That is, a relatively hard base film such as a polyethylene terephthalate (PET) film is used for the magnetic disk in order to impart a predetermined flexibility, and a magnetic layer is formed by coating on the base film. It comes from things. Then, this magnetic disk is set on the metal base with the magnetic layer side facing up, and the stamper is lowered from above the base with a predetermined pressure, and each small tooth portion is bitten into the magnetic layer so that the magnetic head trat. Although the king concave portion is formed, the tip of the small tooth portion is deformed by dripping outward while the stamper is repeatedly used. If this happens, the depth of the magnetic head tracking recess will become shallow, or the shape (size) will change, and as a result, the desired S / N cannot be obtained, and proper tracking cannot be performed, and there is a problem in operational reliability. .

Further, in order to prevent the depth of the magnetic head tracking recess from becoming shallow, the pressure contact force of the stamper is increased to increase the bite amount of the stamper with respect to the magnetic layer, so that the magnetic head tracking recess is formed around the magnetic head tracking recess. The bumps that get hit are higher. Therefore, the spacing loss between the magnetic layer and the magnetic head becomes large, which adversely affects the recording / reproducing characteristics.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, to provide a highly reliable magnetic recording medium which has a long service life of the stamper and can properly perform a tracking servo, and a manufacturing method thereof. It is in.

[0015]

In order to achieve the above object, the present invention has a substrate made of a non-magnetic material and a magnetic layer formed above the substrate, and the surface of the magnetic layer has a predetermined shape. A large number of magnetic head tracking recesses are provided at intervals of, and between the magnetic head tracking recess and the adjacent magnetic head tracking recess, a data track for recording desired information is formed, Irradiating the magnetic head tracking recess and the data track with light,
The present invention is intended for a magnetic recording medium that tracks a magnetic head based on the reflected light.

[0016] A relief protrusion projecting toward the base is formed at a position corresponding to the magnetic head tracking recess on the lower side of the magnetic layer.

In order to achieve the above object, the present invention further comprises a base made of a non-magnetic material and a magnetic layer formed above the base, and the surface of the magnetic layer is provided with a predetermined space. Multiple magnetic head tracking recesses are provided,
Between the magnetic head tracking recess and the adjacent magnetic head tracking recess, a data track for recording desired information is formed, and the magnetic head tracking recess and the data track are irradiated with light, and The present invention is directed to a method of manufacturing a magnetic recording medium that tracks a magnetic head based on reflected light. When a stamper having a large number of teeth corresponding to the magnetic head tracking recess is pressed against the magnetic layer to form the magnetic head tracking recess, for example, a heater for heating is incorporated in the stamper to increase the temperature. By stamping in an atmosphere, escape protrusions protruding toward the substrate side are formed at positions corresponding to the magnetic head tracking recesses on the lower side of the magnetic layer. is there.

[0018]

As described above, according to the present invention, a part of the material forming the magnetic layer moves (escapes) to positions corresponding to the magnetic head tracking recesses on the lower side of the magnetic layer.
Since the protrusion is formed, the load on the tooth portion of the stamper is substantially reduced, which reduces the sagging, and the magnetic head tracking recess having a predetermined shape is formed neatly, and the tracking of the magnetic head is performed. Servo is performed properly.

Further, by performing this stamping in a high temperature atmosphere, the escape protrusion can be formed easily and reliably, and the productivity can be improved.

[0020]

Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 is a perspective view of a magnetic disk cartridge according to the embodiment, in which a part of the magnetic disk cartridge is disassembled, FIG.
FIG. 4 is a plan view of a magnetic disk.

As shown in FIG. 1, a magnetic disk cartridge is composed of a cartridge case 1, a flexible magnetic disk 2 rotatably housed therein, and a shutter 3 slidably attached to the cartridge case 1.
And a cleaning sheet (not shown) welded to the inner surface of the cartridge case 1.

The cartridge case 1 is an upper case 1
a and a lower case 1b, which are, for example, AB
It is injection molded from hard synthetic resin such as S resin.

An opening 4 for inserting the rotary drive shaft is formed in a substantially central portion of the lower case 1b, and a rectangular head insertion opening 5 is formed in the vicinity thereof. Although not shown, a head insertion opening 5 is similarly formed in the upper case 1a.

In the vicinity of the front surfaces of the upper case 1a and the lower case 1b, a recess 6 is formed which is slightly lowered in order to regulate the sliding range of the shutter 3, and the head insertion port 5 is located at an intermediate position of the recess 6. It is open.

The magnetic disk 2 is, as shown in FIG.
It is composed of a donut-shaped flexible magnetic sheet 7 and a center hub 8 made of metal or synthetic resin, which is inserted into a central hole of the magnetic sheet 7 and adhered thereto.

The magnetic sheet 7 includes a base film 9
And an intermediate layer 36, which will be described later, and magnetic layers 10a and 10b formed by coating on both sides of the base film 9. The base film 9 is made of, for example, polyethylene terephthalate (PET).

The magnetic layers 10a and 10b are made of ferromagnetic powder,
It is composed of a mixture of binder, polishing powder and lubricant.

Examples of the ferromagnetic powder include barium ferrite, strontium ferrite, α-Fe and Co.
-Ni, Co-P, γ- Fe 2 O 3, Fe 3 O 4, Co
Γ-Fe ₂ O ₃ containing, γ-Fe ₃ O ₄ containing Cr, CrO
₂ , fine powders of Co, Fe-Ni, etc. are used.

As the binder, for example, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, urethane resin, polyisocyanate compound, radiation curable resin and the like are used.

As the polishing powder, for example, aluminum oxide, chromium oxide, silicon carbide, silicon nitride or the like is used. The addition rate of the polishing powder was about 0.
1-25% by weight is suitable.

Examples of the lubricant include higher fatty acids such as stearic acid and oleic acid, higher fatty acid esters thereof, liquid paraffin, squalane, fluorine resin,
Fluorine oil can be used. The appropriate addition rate of this lubricant is about 0.1 to 25% by weight with respect to the magnetic powder.

The specific composition of the magnetic paint is as follows.

Example of Magnetic Coating Composition Barium Ferrite 100 parts by weight (Hc: 530 [Oe], saturation magnetization: 57 [emu / g], average particle size: 0.04 [μm]) Vinyl chloride-vinyl acetate-vinyl alcohol Copolymer 11.0 parts by weight Urethane resin 6.6 parts by weight Trifunctional isocyanate compound 4.4 parts by weight Aluminum oxide powder (average particle size 0.43 [μm]) 15 parts by weight Carbon black 2 parts by weight Oleyl oleate 7 parts by weight Cyclohexanone 150 parts by weight Toluene 150 parts by weight The composition of the above-mentioned magnetic coating composition example is well mixed and dispersed in a ball mill to prepare a magnetic coating, which is applied to both sides of a 62 μm polyethylene terephthalate (PET) base film. , Apply so that the dry average thickness is 0.89 μm, dry, and then calender Magnetic layer 10 Te
a and 10b are formed respectively.

The magnetic disk 2 constructed in this way
On the surface of the magnetic layer 10a, as shown in FIG. 3, a refraction track 11 and a large number of optical head tracking optical tracks 12 are formed by embossing or the like. The reference track 11 and the optical track 12 for magnetic head tracking are used for the magnetic disk 2
Are provided concentrically around the rotation center 13 of the.

A data track 14 on which desired information can be recorded is formed between one magnetic head tracking optical track 12 and the adjacent magnetic head tracking optical track 12.

As shown in FIG. 3, the reference track 11 is formed on the innermost peripheral portion of the recording band 15 provided on the magnetic disk 2, and is radially outward from the reference track 11, that is, in the direction orthogonal to the running direction of the magnetic head. A large number of magnetic head tracking optical tracks 12 and data tracks 14 are alternately formed on the outer side.

As shown in FIG. 4, the refractor track 11 extends along the traveling direction X of the magnetic head, and is rectangular in a point symmetry with respect to an arbitrary point 17 on the center line 16 of the refractor track 11. The reference recessed region 18A and the reference recessed region 18B are formed in a pair. Adjacent to the reference concave area 18A (in front of the reference concave area 18B) and adjacent to the reference concave area 18B (reference concave area 1)
8A) and the flat portion 19A and the flat portion
There is B.

These sets of reference recessed regions 18
A plurality of A, 18B and plane portions 19A, 19B are formed intermittently or continuously along the traveling direction X of the magnetic head, thereby forming the refraction track 11.

In this embodiment, the length L1 of the reference recessed portions 18A and 18B in the magnetic head running direction is 2.4 mm and the length L2 in the width direction is 18 .mu.m.

A predetermined signal is recorded in advance on the reference lens track 11, and the reference head 11 is scanned by the magnetic head, and the center position of the magnetic head (magnetic gear) is scanned based on the output waveform at that time. Can be directed onto the centerline 16 of the refractor track 11.

In this way, the magnetic head (magnetic gear) is aligned on the center line 16 of the reference lens 11, that is, at the reference position, and at the same time, an optical detector comprising a light emitting element and a light receiving element group connected to the magnetic head. The current position of the optical detector between the optical heads 12 for magnetic head tracking is detected (described later). Then, the positional deviation amount of the optical detector with respect to the optical track 12 is calculated, and based on the deviation amount, the tracking servo of the magnetic head is performed as described below.

Thereafter, the motor for transferring the magnetic head carriage is rotated to move the center position of the magnetic head to a position near the center line 24 of the data track at the innermost circumference.

The tracking servo of the magnetic head is performed for each track by using the optical head 12 for magnetic head tracking.

The reference recess region 18A,
18B and the recess 23 for tracking are simultaneously formed by press working as shown in FIG.

FIGS. 5 to 7 are views for explaining the tracking servo of the magnetic disk 2.

At the time of recording / reproducing, as shown in FIG. 5, the magnetic disk 2 rotates while being sandwiched between the magnetic heads 30a and 30b. On the magnetic head 30a, a light emitting element 31 that outputs light for tracking servo, such as an LED, and a light receiving element group 32 that receives the reflected light from the magnetic layer 10a are integrally attached. .

The light emitting element 3 of the magnetic head 30a
1 and the portion to which the light receiving element group 32 is attached is open toward the magnetic disk 2 side.

As shown in FIG. 6, the light receiving element group 32 is composed of four light receiving elements 32a, 32b, 32c and 32d, and the light reflected on the data track 14 and the tracking recess 23 is received by the light receiving elements 32a, 32a. 32b,
Light is received by 32c and 32d, and the light receiving elements 32a and 32a
The outputs of b, 32c and 32d are input to the servo signal calculation unit 33 as shown in FIG. The position correction signal obtained by the servo signal calculation unit 33 is applied to the head drive control unit 3
4 and tracking control of the magnetic head 30 is performed based on the control signal from the input. In addition, 3 in the figure
Reference numeral 5 is a motor for rotating the magnetic disk 2.

Next, the formation of the tracking recess 23 will be described with reference to FIGS. 8 and 9.

In the case of this embodiment as shown in FIG.
Base film 9 made of polyethylene terephthalate
And the magnetic layer 10a in which the tracking recess 23 is formed.
An intermediate layer 36, which is softer than the base film 9 and is easily plastically deformed, is provided on the entire surface between and.

The polyethylene terephthalate film constituting the base film 9 has a Young's modulus of 400 to 7
The film has physical properties such as 00 Kg / mm ² and is a relatively hard film.

On the other hand, the intermediate layer 36 is formed by adding a suitable amount of filler such as carbon black, red iron oxide, calcium carbonate, magnesium carbonate, barium carbonate, barium sulfate, talc, shirasu, aluminum, tin and copper.
For example, it is composed of a resin layer of urethane, vinyl chloride or the like, or a resin layer softer than the base film 9 such as epoxy resin, ultraviolet curing resin, electron beam curing resin, polyethylene naphthalate or vinyl chloride. The thickness of the intermediate layer 36 is not particularly limited, but is 0.1
The range of up to 1.0 μm is suitable.

In particular, since the intermediate layer 36 containing the filler has an appropriately porous structure as described above, the relief protrusion 38, which will be described later, can be formed easily and reliably.

FIG. 9 is a diagram for explaining how the magnetic disk 2 having the intermediate layer 36 is stamped. As shown in the figure, the magnetic disk 2 to which the center hub 8 is attached is set on the metal base 25 with the magnetic layer 10a side on which the intermediate layer 36 is formed facing up. A center pin 27 to be inserted into a center hole 26 (see FIG. 3) of the center hub 8 is provided on the base 25 so as to project from the center hole 26 of the center hub 8.
The magnetic disk 2 is positioned on the base 25 through 7.

A stamper 28 is arranged above the base plate 25 so as to be vertically movable in parallel therewith, and the vertical movement of the stamper 28 is guided by the center pin 27. On the lower surface of the stamper 28, the reference recess regions 18A, 18B and the tracking recess 23 are formed.
A large number of small tooth portions 29 for forming the are formed.

A heater 37 for heating is built in the vicinity of the group of small teeth 29.

From the state shown in the figure, the stamper 28 is lowered, and the magnetic disk 2 is strongly pressed between the base 25 and the stamper 28 at a predetermined pressure. As a result, the tooth portion 29 formed on the stamper 28 digs into the surface of the magnetic layer 10a, and by compression, the reference concave portions 18A and 18B and the tracking concave portion 23 are simultaneously formed.

In this way, the reference recess region 18 is formed.
When forming A, 18B and the recess 23 for tracking, the heater 37 is previously energized, so that the surface of the group of small teeth 29 is kept in a high temperature state (for example, around 60 ° C.).

Further, by making the small tooth portion 29 bite into the magnetic layer 10a, the portion corresponding to the small tooth portion 29 is compressed with a high density, and the intermediate layer 36 is compressed by the compressed portion.
Is pressed and deformed, and an escape protrusion 37 protruding toward the base film 9 is formed on the lower side of the magnetic layer 10a (see FIG. 8). Since the intermediate layer 36 is configured to be easily plastically deformed as described above, a part of the magnetic layer 10a easily escapes to the intermediate layer 36 side by press fitting the small tooth portion 29 as shown in FIG. (Shifted) state, and as a result, the escape protrusion 38 is formed (see FIG. 8).

The heating of the small tooth portion 29 described above promotes the formation of the escape protrusion 38. It is possible to heat the base 25 side without heating the small tooth portion 29 side, but since the base 25 is in contact with the magnetic disk 2 for a longer time than the stamper 28, the base film 9 is thermally deformed (contracted). Therefore, it is better to heat the small tooth portion 29 side.

If the intermediate layer 36 is formed between the base film 9 and the magnetic layer 10a as in the above-mentioned embodiment and the reference recessed regions 18A and 18B are formed by the stamper 28, the back spring in that portion is reduced. Or disappear. When the bottoms of the reference recess regions 18A and 18B project in a mountain shape by a back spring, a signal for reference stroke detection is also magnetically recorded on the projecting part,
Proper reference position detection may not be performed.

However, as described above, the reference concave portions 18A, 18 are formed with the intermediate layer 36, which is easily plastically deformed, interposed therebetween.
If B is formed, the adverse effect of the back spring is eliminated, and proper reference position detection is performed.

In the above embodiment, the intermediate layer 36 is provided between the base film 9 and the magnetic layer 10a and the stamping is performed in a high temperature atmosphere. However, if the material of the base film 9 is appropriately selected, the intermediate layer 36 By performing stamping in a high temperature atmosphere without providing 36, it is possible to form the escape protrusion 38 on the lower side of the magnetic layer 10a.

Although the disk-shaped magnetic recording medium has been described in the above embodiment, the present invention can be applied to other forms of magnetic recording medium such as a magnetic card.

[0065]

As described above, according to the present invention, a part of the material constituting the magnetic layer moves (escapes) to the positions corresponding to the magnetic head tracking recesses on the lower side of the magnetic layer. Since the protrusion is formed, the load on the tooth portion of the stamper is substantially reduced, which reduces the sagging, and the magnetic head tracking recess having a predetermined shape is formed neatly, and the tracking of the magnetic head is performed. Servo is performed properly.

Further, by performing this stamping in a high temperature atmosphere, the escape protrusion can be easily and surely formed, and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a partially exploded perspective view of a magnetic disk cartridge according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a magnetic sheet.

FIG. 3 is a plan view of a magnetic disk.

FIG. 4 is a diagram for explaining a refractor track and an optical track for magnetic head tracking.

FIG. 5 is a sectional view for explaining a tracking servo of a magnetic head.

FIG. 6 is an explanatory diagram showing an arrangement state of light receiving elements.

FIG. 7 is a sectional view for explaining tracking control of the magnetic head.

FIG. 8 is an enlarged cross-sectional view near the magnetic layer.

FIG. 9 is a cross-sectional view showing an apparatus for forming a refraction track and an optical track for magnetic head tracking.

FIG. 10 is a partially enlarged sectional view of a conventionally proposed magnetic disk.

FIG. 11 is a partially enlarged plan view of the magnetic disk.

[Explanation of symbols]

 2 magnetic disk 7 magnetic sheet 9 base film 10a. 10b magnetic layer 11 refraction track 12 optical track for magnetic head tracking 14 data track 15 recording band 23 tracking recess 36 intermediate layer 37 heater 38 escape protrusion

Claims (7)

[Claims] 1. A base comprising a non-magnetic material and a magnetic layer formed above the base, and a large number of magnetic head tracking recesses are provided at predetermined intervals on the surface of the magnetic layer. , Between the magnetic head tracking recess and the adjacent magnetic head tracking recess, a data track for recording desired information is formed, and the magnetic head tracking recess and the data track are irradiated with light, In a magnetic recording medium that tracks a magnetic head based on the reflected light, an escape protrusion that protrudes toward the substrate side is formed at a position corresponding to the magnetic head tracking recess on the lower side of the magnetic layer. A magnetic recording medium characterized by the above. 2. The magnetic recording medium according to claim 1, wherein an intermediate layer that is more easily plastically deformed than the base is provided between the base and the magnetic layer. 3. The magnetic recording medium according to claim 2, wherein the intermediate layer contains a filler. 4. A base made of a non-magnetic material and a magnetic layer formed above the base, and a large number of recesses for magnetic head tracking are provided at predetermined intervals on the surface of the magnetic layer. , Between the magnetic head tracking recess and the adjacent magnetic head tracking recess, a data track for recording desired information is formed, and the magnetic head tracking recess and the data track are irradiated with light, In a method of manufacturing a magnetic recording medium for tracking a magnetic head based on the reflected light, a stamper having a large number of teeth corresponding to the magnetic head tracking recess is pressed against the magnetic layer to form the magnetic head tracking recess. Stamping is performed in a high temperature atmosphere during formation, and at a position corresponding to the magnetic head tracking recess on the lower side of the magnetic layer, Method of manufacturing a magnetic recording medium, characterized in that the formation of the relief protrusion protruding toward the body side. 5. The method of manufacturing a magnetic recording medium according to claim 4, wherein a heater is built in the stamper side. 6. The method according to claim 4 or 5,
A method of manufacturing a magnetic recording medium, characterized in that an intermediate layer that is more easily plastically deformed than the base is provided between the base and the magnetic layer. 7. The method of manufacturing a magnetic recording medium according to claim 6, wherein the intermediate layer contains a filler.