JPH02214018A - Magnetic recording disk - Google Patents

Abstract

PURPOSE:To prevent the electromagnetic noises from a data head of a servo head and to read an exact positioning signal by forming electromagnetic shielding layers on a base material where electromagnetic waves are liable to pass. CONSTITUTION:The disk-shaped glass base material 2 is used as the base material and Ni-P alloy layers are formed by electroless plating as the electromagnetic shielding layers 22 on both surfaces of the base material 2 and are subjected to polishing. Magnetic layers 3 and protective layers 4 are formed by sputtering, by which the magnetic recording disk 21 is produced. The data and servo heads 12, 13 are so disposed as to be symmetrical above and below and a writing current is passed to the head 12 to generate the leak magnetic flux. The induced electromotive force generated in the head 13 is measured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a 1M1 magnetic recording disk, particularly a magnetic recording disk built into a fixed magnetic disk device, which uses glass, ceramics, resin, etc. as a base material. The present invention relates to a magnetic recording disk.

[Prior Art] Aluminum alloys have been put to practical use as base materials for magnetic recording disks built into fixed magnetic disk drives, but from the viewpoint of light weight and surface smoothness, glass, ceramics, The application of base materials such as resins is being reconsidered.

The use of glass, ceramics, and FM resin as base materials for magnetic recording disks is disclosed, for example, in Japanese Patent Publication No. 43-4621 and Japanese Patent Application Laid-Open No. 48-197.
-35807, Special Publication No. 5123161, etc. have already been proposed.

An example of this configuration is shown in woodworking and 4th tA.

In the figure, (1) is a magnetic recording disk, (2) is a gaff base material using glass as a base material, (3) is a magnetic layer, and (4) is a gaff base material using glass as the base material.
) is a protective layer, (6) is a magnetic head with a minute gap (9) placed opposite to (1), and (7) is a magnetic head (6) with a magnetic flux (8 ), +101 indicates magnetization.

As shown by this factor, the principle of magnetic recording between the magnetic recording disk (1) and the magnetic head (6) is as follows:
The number of electric currents is applied to the winding (7), and the magnetic flux (8) is applied to the magnetic head (6).
), thereby causing leakage magnetic flux arising from a minute gap (93).

The magnetic layer (3) is magnetized (lO) in an arbitrary direction.

When reading information, contrary to the above-mentioned writing, the magnetic field generated from the magnetized magnetic layer (3) causes one winding (7) to
), and this induced current is read as an electrical signal.

FIG. 5 is a block diagram of a fixed magnetic disk device incorporating the magnetic recording disk (1) and magnetic head (6) shown in FIG. 4.

In FIG. 5, reference numeral (1) is the magnetic recording disk explained above, (11) is a spindle that fixes the magnetic recording disk (1), and (12) is a magnetic layer on the magnetic recording disk (1). (13) is a servo head that reads positional information recorded on the - side of a predetermined magnetic recording disk (1); (14) is a data head (
12) and a head arm that supports the servo head (13); (15) is an actuator that fixes and moves the head arm (14);
) is the voice coil motor that moves the device to the target position, (17) is the data surface for reading and writing data information,
118) is a servo surface for reading position information.

Next, these operations will be explained.

As shown in FIG. 5, the data head (12) and servo head (13) are supported by a helad arm (14),
All heads are simultaneously inserted diametrically on each side of the magnetic recording disk (1). In this case, positioning of the data head (12) to a predetermined track is achieved by reading position information written in advance on the servo surface (18) facing the servo head (13) with the servo head (13), This is done by controlling the coil motor (16) and moving the actuator (15) to a predetermined position.

Further, the reading and writing of data information as shown in FIG. 4 is carried out simultaneously with the position detection of the servo head (13) described above by the data head (12) which has been selected and supported in advance.

[Problem to be Solved by the Invention J] The conventional fixed magnetic disk drive is configured as described above, and the reading of positional information by the servo head (13) and the writing of positional information by the opposing data head (12) are performed. done at the same time. Therefore, the data head (12
) The electromagnetic waves generated when writing on the magnetic recording disk (1
), it affects the reading of the position signal of the servo head as electromagnetic noise, resulting in a positioning error.Therefore, we had a problem that we would like to solve.

This invention was made to solve the above-mentioned problems, and its purpose is to obtain a magnetic recording disk in which a servo head is shielded from electromagnetic waves and can read accurate positioning signals. be.

[Means for Solving the Problems] The magnetic recording disk according to the present invention has an electric shielding layer, a magnetic layer, and a protective layer formed on a base material made of glass, ceramics, resin, etc. be.

[Function] The magnetic recording disk of the present invention blocks electromagnetic waves generated from the data head by providing an electric shielding layer, so that the electromagnetic noise caused by the electromagnetic waves does not affect the reading of the positioning signal of the servo head. I won't let you.

[Example] Next, the present invention will be described using figures showing one example.

First, a magnetic recording disk according to the present invention was manufactured.

Prior to evaluation, a conventional magnetic recording disk is created and evaluated.

As a base material (2), the outer diameter is 95 with an average surface thickness of 0.2 μm or less! A disk-shaped glass substrate of IIIφ and 1.2 mm thick was prepared, and using a sputtering device, a Cr layer of 2,000 layers was coated as the underlayer of the magnetic layer (3), and a Co alloy of 600 layers was coated as the magnetic layer (3). A magnetic recording disk (1) was produced by successively sputtering 500 layers of carbon as a protective layer (4).

Furthermore, a position signal was written on one side of this magnetic recording disk (1) using a servo writer, and the disk was incorporated into a disk tester.

When the conventional magnetic recording disk (1) constructed as described above was first attached with only the servo head (13) and the signal position was read, the position signal was read normally.

Next, attach the data head (12) to the surface opposite to the servo head (13), and attach the data head (12) to the servo head (13).
While writing information with the servo head (13
), the position signal could not be read accurately.

The track was misaligned.

Therefore, a write current is applied to the data head (12),
At the same time as leakage magnetic flux was generated, we measured the electromotive force induced in the winding with the servo head (13) placed on the opposite side, and found that it was large enough to have a sufficient effect on the induced electromotive force generated when reading the position signal. I understand.

This is because electromagnetic waves generated from the data head (12) penetrate the magnetic recording disk (1) and act on the servo head (13) as electromagnetic noise. Accordingly, the magnetic recording disk of the present invention was fabricated based on the above-mentioned content, in which an appropriate amount of electromagnetic waves is applied to prevent position signal reading errors.

In the above measurements, both the servo head (13) and the data head (12) were monolithic heads made of &+n-Zn ferrite.

Next, the present invention will be explained with reference to FIG. 1 showing a first embodiment.

FIG. 1 shows the structure of a magnetic recording disk according to the present invention.

In the figure, the reference numeral (21) is a magnetic recording disk according to the present invention, and (221 is an electromagnetic shielding layer provided between a base material such as a glass base material (3) and a magnetic layer (3)). , which is constructed using non-magnetic materials.

Note that the items indicated by the symbols (2i to (4), (6) to (lO)) are the same as or equivalent to those indicated by the same symbols in the conventional device.

The magnetic recording disk (21) of the present invention configured as described above
5.As an example, it is created as follows.

First, as a base material, a disk-shaped glass base material (2) with an outer diameter of 95 mmφ and a thickness of 1.2 + amt, finished with an average surface roughness of 0.2 μl or less, is used. Both sides of this glass base material (2) are provided with electromagnetic shielding. As the interlayer (22), N1 was applied by electroless plating.
A -P alloy layer was formed and polished to an average surface roughness of 0.06 μm or less. The thickness of the N1-P alloy layer at this time was 0.5 μm on one side and 5 μm on each side.

15μm and 3F thickness! I made a version that was changed to B.

Next, use a sputtering device to coat these.

2000 layers of Cr layer as the underlayer of the magnetic layer (3), 600 layers of CO alloy as the magnetic layer (3), and a protective layer (4)
A magnetic recording disk (21) was fabricated by continuously forming a carbon film by 500 people.

In addition, in order to understand the effect, as a conventional magnetic recording disk,
The magnetic recording disk of the present invention was prepared as a comparative example by preparing the above-mentioned magnetic recording disk (1) in which all the steps were the same as those described above except for removing the electric wire closing. (21)
Similar to the detection in the conventional example described above, the data and servo heads +121 and T131 are arranged vertically symmetrically, and a write current is applied to the data head (12) to generate leakage magnetic flux, and at the same time, the data and servo heads (12) are arranged on the opposite side. The induced electromotive force generated in the servo head (13) was measured, and the effect of the appropriate amount of electromagnetic waves was measured.

The measured value in this case is 100% of the electromotive force of the above comparative example.
By comparing with this, the electromotive force according to the present invention was determined.

The results of the measurements made in this way were 0.5μ on one side,
For the magnetic recording disk (21) with an electromagnetic shielding layer (22) of 5μ■ and 15μ■, 99.7%, 42%,
An electromotive force of 0.12% was obtained. A graph of this is shown in Figure 2. In Figure 6, the horizontal axis represents the total on both sides of the electromagnetic shielding layer (22), and the vertical axis represents the induced electromotive force ratio. From this, the electromagnetic shielding layer (22) has a total thickness of both sides lO
It was found that exceeding μl was extremely effective.

In the first embodiment, a non-magnetic material was used as the electromagnetic shielding layer (22), but first, a second embodiment in which a magnetic material was used as the electromagnetic shielding layer was investigated.

In place of N1-P constituting the electromagnetic shielding layer (22) described in the first embodiment, in this second embodiment, the electromagnetic shielding layer (
22) permalloy (Ni 50% by weight, balance Fe)
is formed by sputtering, and all other parts are formed by the above first method.
A magnetic recording disk (21) identical to that of the example was produced.

In this case, the thickness of permalloy is 0.025μ on one side,
They were 0.25 μm and 2.5 μI, and were formed on both sides.

The induced electromotive force ratio of the magnetic recording disk (21) thus produced was measured in the same manner as in the first example.

As a result, the electromagnetic shielding layer was 0.025μta on one side, 0.2
5μ soda.

For 2.5 μ weight, the induced electromotive force ratio is 95% and 2
0% and 0.4% were obtained.

A graph of this is shown in Figure 3.

In the figure, the horizontal axis shows the total thickness of both sides of the permalloy electromagnetic shielding layer, and the vertical axis shows the induced electromotive force ratio. in this way,
Even in the case where a magnetic material is used for the electromagnetic shielding layer (22), it has been found that it is extremely effective if the thickness of the electric tB appropriate amount layer (22) exceeds 1 μm.

In the second embodiment, a magnetic material was used for the electromagnetic shielding layer, but the appropriate amount of electromagnetic noise due to the magnetic material is highly dependent on the relative magnetic permeability. When used as an interlayer, a thin film can be created.

In addition, here we have shown an example in which a non-magnetic material and a magnetic material are used individually as the electromagnetic shielding layer, but the same effect is not limited to this, and the same effect can be obtained even if the above-mentioned two are used in a layered manner. .

[Effects of the Invention] As described above, according to the present invention, since the magnetic recording disk is configured to form an electromagnetic shielding layer on a base material through which electromagnetic waves easily pass, it is possible to This has the effect of providing a magnetic recording disk in which electromagnetic noise is prevented and the reading of positioning signals by the servo head is improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a combination of a magnetic recording disk and a magnetic head according to an embodiment of the present invention, and FIG. 2 is a relationship between the induced electromotive force ratio and the thickness of the N1-P layer in the first embodiment. 3 is a relationship diagram of the induced electromotive force ratio with respect to the film thickness of the permalloy layer in the second embodiment. FIG. 4 is a cross-sectional view of a combination of a conventional magnetic recording disk and a magnetic head. FIG. 5 1 is a configuration diagram of a fixed magnetic disk device incorporating a magnetic recording disk and a magnetic head. In the figure, (2)...base material (glass base material). (3)...magnetic layer, (4)...protective layer, (6)
...magnetic head, (21) ...magnetic recording disk,
(22)...Electromagnetic shielding layer. In each figure, the same reference numerals indicate the same or corresponding parts. Trap 1 picture representative Rihito So Wado Teruaki 4
Figure N1-P Toughness (μm) Inscription Figure 5 Permalloy Shield La (I'm) Contents of Amendment The specification is amended as follows. Display of the case Patent application No. 1-32767 Name of the invention Person who corrects magnetic recording disks Relationship to the case Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Moriya Shiki

Claims (1)

[Claims] A magnetic recording disk built in a fixed magnetic disk device and made of glass, ceramics, resin, etc. as a base material, characterized in that an electromagnetic shielding layer, a magnetic layer, and a protective layer are formed on the base material. magnetic recording disk.