JPH1031803A - Magnetic disk distortion inspection method and apparatus - Google Patents

Abstract

(57) [Problem] To provide a method and apparatus capable of inspecting the distortion of a magnetic disk. An apparatus (10) for inspecting a distortion of a magnetic disk (3) on which signals are recorded and reproduced by a magnetic head (11) includes a head control unit (12) for controlling a movement of the magnetic head in a radial direction on the magnetic disk; A timing control unit for generating a timing signal indicating a distortion amount inspection area based on a reproduction inspection signal from a head; and a radial position on the magnetic disk having the same level of the inspection signal based on the timing signal. And a distortion amount calculation unit 15 for calculating a distortion amount from a radial position of the magnetic head on the magnetic disk at that time. Then, the calculation is repeated every time the magnetic head moves by one track pitch or less, and the distortion of the magnetic disk is inspected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method and an apparatus for inspecting distortion of a magnetic disk on which signals are recorded and reproduced by a magnetic head.

[0002]

2. Description of the Related Art As a magnetic disk device used in a computer system, for example, there is a hard disk device or the like. Magnetic films are formed on both surfaces of the magnetic disk built into this hard disk drive, and signals are track-like formed on the magnetic film by a magnetic head mounted on a head slider floating above the surface of the magnetic disk. The signal recorded on the magnetic film and recorded on the magnetic film in the form of a track is reproduced.

In recent years, miniaturization and large recording capacity of hard disk drives have been desired.
The track width of the magnetic disk may be reduced and the number of tracks may be increased. However, in a flat magnetic disk, a problem of crosstalk between tracks occurs. Therefore, as shown in FIG. 8, a data recording area (hereinafter, referred to as a data zone) composed of uneven portions on both surfaces of the magnetic disk 3 and a control signal. A so-called pre-emboss type magnetic disk 3 in which recording areas (hereinafter, referred to as servo zones) are formed radially has been proposed.

[0004] The data zone and the servo zone are formed by a stamper attached to a molding die when a ring-shaped substrate is injection-molded using plastic as a material. 6 per lap
About 0 to 300 pieces are transferred and formed. In the data zone, concentric data tracks DT for recording signals are formed so as to be convex portions, and guard bands GB for separating adjacent data tracks DT are formed so as to be concave portions. Have been.

In the servo zone, a gray code for specifying the data track DT, a clock mark as a reference for generating a servo clock, a fine pattern for tracking control of a magnetic head, etc. (Referred to as a servo pattern SP) is formed as a convex portion or a concave portion.

FIG. 9 is a perspective view showing an example of the configuration of a hard disk drive incorporating the above-described pre-emboss type magnetic disk. The hard disk drive 1 is provided with a spindle motor 9 disposed behind a plane portion of a housing 2 formed of an aluminum alloy or the like, and a magnetic disk 3 driven to rotate at a constant angular velocity by the spindle motor 9. Have been. Furthermore, this housing 2 includes
An arm 4 is swingably mounted around a vertical axis 4a.

One end of the arm 4 has a voice coil 5
A head slider 6 and a magnetic head 8 are attached to the other end of the arm 4. Magnets 7a and 7b are mounted on the housing 2 so as to sandwich the voice coil 5. Voice coil 5
The voice coil motor 7 is formed by the magnets 7a and 7b.

In such a configuration, when the head slider 6 approaches the surface of the rotating magnetic disk 3,
With the rotation of the magnetic disk 3, the rail and the magnetic disk 3
The buoyancy is received by the airflow flowing between the surface and the surface.
With this levitation force, the head slider 6 and the magnetic head 8 levitate and travel from the surface of the magnetic disk 3 at a minute interval (flying amount).

Further, when a current is supplied to the voice coil 5 from the outside, the arm 4 moves around the vertical axis 4a based on the magnetic field of the magnets 7a and 7b and the force generated by the current flowing through the voice coil 5. Is rotated. Thereby, the head slider 6 attached to the other end of the arm 4 moves substantially in the radial direction of the magnetic disk 3.
Therefore, the magnetic head 8 mounted on the head slider 6 performs a seek operation on the magnetic disk 3. Then, the magnetic head 8 is controlled to be located at the center of the data track DT by a positioning signal obtained from the reversal of the magnetization of the servo pattern SP, and performs recording / reproducing of the signal with respect to the data track DT.

When the substrate of the magnetic disk 3 is injection-molded, the shape of the data track DT may be distorted in the radial direction from the originally desired perfect circle. This distortion is
There is a possibility that the recording and reproduction of signals on the data track DT of the magnetic head 8 may be adversely affected. However, since the width of the conventional magnetic disk 3 is relatively wide with respect to the amount of distortion, if the magnetic head 8 is controlled to be located at the center of the data track DT by the servo pattern SP, the magnetic head 8 will not move to the adjacent track. Without hanging on
The distortion did not become a tracking error.

[0011]

However, recently, the width of the magnetic disk 3 has been reduced in order to cope with a further increase in the recording capacity of the hard disk drive 1. It can no longer be ignored. In other words, even if the magnetic head 8 is controlled to be located at the center of the data track DT by the servo pattern SP, the magnetic head 8 is applied to an adjacent track, and a problem arises in that distortion causes a tracking error.
Therefore, inspecting the amount of distortion is important for realizing a large recording capacity of the hard disk device 1, but there has been a problem that there is no appropriate method or device conventionally.

In view of the above, it is an object of the present invention to provide a method and an apparatus capable of inspecting a magnetic disk for distortion.

[0013]

According to the present invention, there is provided a method for inspecting a distortion of a magnetic disk in which a signal is recorded / reproduced by a magnetic head, comprising: reproducing a test signal from the magnetic disk; Based on the inspection signal, a timing signal indicating a distortion amount inspection area is generated, and based on the timing signal, a radial position on the magnetic disk at which the level of the inspection signal is equal, and the magnetic head of the magnetic head at that time. A series of processes for obtaining the amount of distortion from the radial position on the magnetic disk is achieved by repeating the magnetic head every time the magnetic disk moves by one track pitch or less in the radial direction, and inspecting the distortion of the magnetic disk. Is done.

According to the above configuration, since the radial position on the magnetic disk at which the level of the test signal is equal and the radial position of the magnetic head at that time on the magnetic disk are determined, the amount of distortion in the radial direction of the magnetic disk can be reduced. Can be determined accurately.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The embodiments described below are preferred specific examples of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. It is not limited to these forms unless otherwise stated.

FIG. 1 is a block diagram showing an embodiment of a magnetic disk distortion inspection apparatus according to the present invention. The movement of the magnetic disk 3 in the radial direction with respect to the inspection magnetic head 11 of the magnetic disk distortion inspection apparatus 10 is controlled by the head controller 12.
Recording of an inspection signal on the magnetic disk 3 by the inspection magnetic head 11 and the magnetic disk 3
Of the inspection signal from the R / W (Read / Write)
e) It is controlled by the unit 13.

The timing of signal recording on the magnetic disk 3 and the timing of calculating the amount of distortion on the magnetic disk 3 are controlled by the timing control unit 14. Then, the distortion amount of the magnetic disk 3 is calculated by the distortion amount calculation unit 1.
5 is calculated.

Here, the inspection magnetic head 11 has a width capable of recording an inspection signal over several data tracks DT (hereinafter, referred to as a first inspection magnetic head). A magnetic head having a width capable of reproducing the inspection signal for the data track DT (hereinafter, referred to as a second inspection magnetic head) is used for exchange. The head slider 16 on which the inspection magnetic head 11 is mounted has, for example, a shape as shown in FIG. 2, and rails 16a and 16b acting as air bearing surfaces are formed on both sides of the lower surface thereof. The tapered portion 1 is provided on the air inflow end side of the rails 16a and 16b.
6c and 16d are formed.

The head slider 16 having such a structure is
When approaching the surface of the rotating magnetic disk 3, the magnetic disk 3 receives a levitation force due to the airflow flowing between the rails 16 a and 16 b and the surface of the magnetic disk 3 as the magnetic disk 3 rotates. With this buoyancy, the head slider 16
The magnetic disk 3 levitates and travels at a small interval (flying height) from the surface. The head slider 1
The dimension 6 is, for example, the length (in the circumferential direction of the magnetic disk 3).
Is 2000 μm and the width (radial direction of the magnetic disk 3) is 1
600 μm, thickness 400 μm, rails 16a, 16b
Has a height of 100 μm and rails 16a and 16b have a width of 20 μm.
Those having a size of 0 μm to 250 μm are used.

An operation example of such a configuration will be described with reference to a flowchart of FIG. First, the first inspection magnetic head 11 is mounted on the head controller 12 (step STP1), and the magnetic disk 3 is set on the magnetic disk distortion inspection device 10 and rotated at a constant cycle (step STP2). Then, the head control unit 12 moves the first inspection magnetic head 11 to an arbitrary position in the radial direction of the magnetic disk 3, for example, a position on the data track DT of the innermost diameter (step STP3).

The R / W unit 13 sends a reproduction signal SRS from the first inspection magnetic head 11 to the timing control unit 14. The timing control section 14 extracts the timing of the servo zone based on the reproduction signal SRS from the R / W section 13 and outputs the recording control signal SWC of the inspection signal which inhibits signal recording to the servo pattern SP as shown in FIG. R / W
To the unit 13. The R / W unit 13 responds to the recording control signal SWC of the inspection signal from the timing control unit 14,
The inspection signal is recorded on the data track DT by the first inspection magnetic head 11 (step STP4).

When the recording of the inspection signal for one round on the data track DT is completed (step STP5),
The head control unit 12 moves the first inspection magnetic head 11 by, for example, a few track pitches in the outer diameter direction of the magnetic disk 3 (steps STP6 and STP7), and returns to step STP4 to be described above. Repeat the process. Then, after recording the inspection signal on all the data tracks DT formed on the magnetic disk 3 (step S
TP6), the first inspection magnetic head 11 is detached from the head controller 12, and the second inspection magnetic head 11 is mounted on the head controller 12 (step STP8). The head control unit 12 moves the second inspection magnetic head 11 to an arbitrary position in the radial direction of the magnetic disk 3, for example, to a position on the innermost data track DT (step STP).
9).

Then, the R / W unit 13 sends the reproduction inspection signal SRD from the second inspection magnetic head 11 to the timing control unit 14 and the distortion amount calculation unit 15 (step STP10). Here, when the data track DT of the magnetic disk 3 is distorted, as shown in FIG. 5, the second inspection magnetic head 11 does not trace the data track DT accurately, but partially deflects the guard band GB. pass. As a result, the reproduction inspection signal SRD from the second inspection magnetic head 11 has an amplitude fluctuation component based on the distortion.

The timing control unit 14 generates a timing signal ST indicating a distortion amount inspection area for the magnetic disk 3 based on the reproduction inspection signal SRD from the R / W unit 13 and sends it to the distortion amount calculation unit 15 (step STP11). ).
Here, the distortion amount inspection area is an area having the same relative position in each data track DT of the magnetic disk 3, for example, FIG.
A time period T1 time from the servo pattern SP shown in FIG. 1 indicates a region of time T2 in which inspection signals for a plurality of cycles are observed.

The distortion amount calculation unit 15 includes a reproduction inspection signal SRD from the R / W unit 13, a timing signal ST indicating a distortion amount inspection area from the timing control unit 14, and a second inspection signal from the head control unit 12. Based on the radial position DP of the magnetic head 11 on the magnetic disk 3, the distortion amount in the distortion amount inspection area is calculated (step STP12). Here, as shown in FIG. 6, the amplitude of the reproduction inspection signal SRD becomes maximum when the second inspection magnetic head 11 is positioned on the data track DT, Signal S
The amplitude of the RD becomes minimum when the second inspection magnetic head 11 is located on the guard band GB.

Therefore, the data tracks DT having the same level of the reproduction inspection signal SRD obtained from the distortion amount inspection area.
In this case, the positional relationship between each data track DT and the second inspection magnetic head 11 is equal. And
When the inspection for one round is completed (step STP13), the head control unit 12 moves the second inspection magnetic head 11 in the outer diameter direction of the magnetic disk 3, for example, by a movement amount of one track pitch or less (step STP14). , 15), and returns to step STP10 to repeat the above-described processing.

Thus, the distorted magnetic disk 3 shown in FIG.
As shown in the waveform diagram of the signal ARD indicating the amplitude of the reproduction inspection signal SRD in the distortion amount inspection area of the data track DT over one round of FIG. The data track D having the same radial position on the magnetic disk 3 (the portion indicated by a white circle in the drawing), that is, the same positional relationship with the second inspection magnetic head 11
The number of T and the radial position of the second inspection magnetic head 11 on the magnetic disk 3 from the head control unit 12 are sequentially obtained, and the amount of distortion of the magnetic disk 3 in the radial direction can be obtained. When the obtained amount of distortion is larger than a predetermined specified value, it can be determined that the object is a defect.

[0028]

As described above, according to the present invention,
Since the distortion amount of the magnetic disk can be accurately obtained, the quality of the magnetic disk can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a magnetic disk distortion inspection apparatus according to the present invention.

FIG. 2 is a perspective view showing an example of a head slider of the magnetic disk distortion inspection apparatus shown in FIG.

FIG. 3 is a flowchart showing an operation example of the magnetic disk distortion inspection device shown in FIG. 1;

FIG. 4 is a first diagram showing the concept of measurement by the magnetic disk distortion inspection device shown in FIG. 1;

FIG. 5 is a second diagram showing the concept of measurement by the magnetic disk distortion inspection device shown in FIG. 1;

FIG. 6 is a third diagram showing the concept of measurement by the magnetic disk distortion inspection device shown in FIG. 1;

FIG. 7 is a fourth diagram showing the concept of measurement by the magnetic disk distortion inspection device shown in FIG. 1;

FIG. 8 is a plan view showing an example of a general magnetic disk.

FIG. 9 is a perspective view showing an example of a general magnetic disk drive.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hard disk device, 2 ... Housing, 3 ...
Magnetic disk, 4 ... arm, 4a ... vertical axis, 5
... voice coil, 6 ... head slider, 6a
..Rail, 6b ... rail, 6c ... tapered part,
6d: tapered portion, 7: voice coil motor, 7
a: magnet, 7b: magnet, 8:
Magnetic head, 9 ... motor, 10 ... magnetic disk distortion inspection device, 11 ... magnetic head for inspection, 12 ...
· Head control unit, 13 ··· R / W unit, 14 ··· timing control unit, 15 ··· distortion amount calculation unit, 16 ··· head slider

Claims (2)

[Claims] 1. A method for inspecting a distortion of a magnetic disk in which a signal is recorded and reproduced by a magnetic head, wherein a signal for inspection is reproduced from the magnetic disk, and a timing indicating a distortion amount inspection area based on the signal for inspection. A series of processing for generating a signal and calculating a distortion amount from a radial position on the magnetic disk at which the level of the inspection signal is equal and a radial position of the magnetic head on the magnetic disk at that time based on the timing signal; The distortion of the magnetic disk by inspecting the magnetic disk for a displacement of one track pitch or less in the radial direction of the magnetic head. 2. An apparatus for inspecting distortion of a magnetic disk on which a signal is recorded / reproduced by a magnetic head, comprising: a head controller for controlling a movement of the magnetic head in a radial direction on the magnetic disk; A timing control unit that generates a timing signal indicating a distortion amount inspection area based on the reproduction inspection signal; and, based on the timing signal, a radial position on the magnetic disk having the same level of the inspection signal. A distortion amount calculating unit for calculating a distortion amount from a radial position of the magnetic head on the magnetic disk; and repeating the calculation for each movement of the magnetic head by one track pitch or less to inspect the magnetic disk for distortion. A magnetic disk distortion inspection device, characterized in that: