JPH0581783A - Method and device for testing off-track characteristic - Google Patents

Abstract

PURPOSE:To test a characteristic without using a servo mechanism, etc., by detecting a signal recorded on the track of a magnetic disk with a magnetic head and observing the change of a detective signal in accordance with the minute displacement of the magnetic head. CONSTITUTION:By a displacing device 25, the magnetic head 24 is supported to the magnetic disk 10 so as to be readable/writable and simultaneously the magnetic head 24 is driven to be moved along the direction of the radius of the magnetic disk 10. By the displacing device 25, the magnetic head 24 is moved to an optional position on the magnetic disk so as to be accessible, further, is displaced slightly and discretely in the same direction in the case of reading at a specified position. Thus, by measuring the signal level corresponding to the displacement of the magnetic head 24, the off-track characteristic of the magnetic disk 10 is measured correctly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk used in a magnetic disk drive, and more particularly to a method and apparatus for testing the off-track characteristics of a magnetic disk having grooves between adjacent tracks.

With the recent increase in the amount of information processed by computer systems, the amount of information recorded in magnetic disk devices has also increased rapidly, and in response to this, the capacity and size of magnetic disk devices have been increased. There is. And
In order to increase the capacity of the magnetic disk device, the gap between the tracks of the magnetic disk is reduced to increase the recording density.

However, as the gap between the tracks is reduced, the influence of signal leakage (crosstalk) from the adjacent tracks cannot be ignored, but in order to reduce the crosstalk, a groove is provided between the adjacent tracks. Development of magnetic disks is in progress.

However, for example, the deeper the groove is, the more the crosstalk is reduced, but it is difficult to manufacture the magnetic disk due to the formation of the groove, and the cost is increased. Therefore, it is desired to develop a method for measuring, evaluating, or testing the effect of the groove in order to optimize the design of the magnetic disk having the groove.

[0005]

2. Description of the Related Art Conventionally, for measuring crosstalk of a magnetic disk, a distance (off-track amount) at which a magnetic head is away from a track along the surface of the magnetic disk.
And the relationship (off-track characteristic) with the magnitude of the detection signal of the magnetic head at that time are measured.

In order to measure (test) such an off-track characteristic, a spindle and a motor for rotating a magnetic disk, a displacement device for slightly displacing the magnetic head in the radial direction of the magnetic disk, and a magnetic head. A test device including an oscilloscope or a spectrum analyzer for observing the detection signal from is used.

In order to perform an off-track characteristic test using this test apparatus, a magnetic disk is attached to a spindle, and then a signal of an arbitrary constant frequency (wavelength) is written on one track of the magnetic disk by a magnetic head. Record with. Then, while the magnetic head is discretely slightly displaced along the radial direction of the magnetic disk, the signal recorded on the track is read and detected by the magnetic head, and the level change of the detection signal from the magnetic head is analyzed by a spectrum analyzer. To observe.

[0008]

However, in the above-mentioned conventional test apparatus, in order to measure the off-track characteristics of the magnetic disk having the groove, the magnetic head is moved by following the track of the track of the magnetic disk. A high-precision servo mechanism for moving is required.

That is, in a magnetic disk having no groove,
Since it is possible to form a track at an arbitrary position when a signal is written by the magnetic head, there is no problem even if the concentricity of the magnetic disk attachment to the spindle is bad, but there is a groove. In the magnetic disk, since the positions of the tracks on the magnetic disk are physically predetermined, the concentricity when mounting the magnetic disk on the spindle becomes a problem.

When the magnetic disk is mounted on the spindle, the magnetic disk always has some eccentricity (mounting error) with respect to the spindle. Therefore, when the position of the magnetic head is fixed on the rotating magnetic disk, the magnetic head cannot normally trace the track of the magnetic disk. Therefore, the magnetic head detects the signal across the groove, and the level of the detection signal is greatly reduced by the groove (see FIGS. 3 and 4).

To prevent this, a servo mechanism for moving the magnetic head following the track of rotation of the track is required as described above. However, the magnetic head follows the track of rotation of the track, and At the same time, it is extremely difficult to make a minute displacement in the radial direction of the magnetic disk, which is very expensive and unrealistic.

In view of the above problems, the present invention is for testing the off-track characteristics of a magnetic disk having a groove without using a servo mechanism for moving the magnetic head following the track of the track. It is an object of the present invention to provide a method and a device.

[0013]

In order to solve the above-mentioned problems, the method according to the invention of claim 1 is a magnetic disk 10 having grooves 10b between adjacent tracks 10a as shown in FIGS. Is a method for testing the off-track characteristics of the magnetic disk 10, the signal recorded in the track 10a of the magnetic disk 10 is detected by the magnetic head 24, and the signal is recorded along the radial direction of the magnetic disk 10. The change of the detection signal S2 of the magnetic head 24 due to the minute displacement of the magnetic head 24 is observed, and the change of the detection signal S2 is observed for the portion S2a of the magnetic disk 10 not including the groove 10b. ..

An apparatus 1 according to a second aspect of the present invention comprises a rotating means 22 for rotating the magnetic disk 10, a magnetic head 24 for detecting a signal recorded on a track 10a of the rotating magnetic disk 10, and the magnetic head. Displacement means 25 for slightly displacing the magnetic disk 24 along the radial direction of the magnetic disk 10, and a detection signal S2 of the magnetic head 24.
From among the above, there is provided a signal extraction means 32 for extracting a detection signal S2a corresponding to a specific angular range in one rotation of the magnetic disk 10 and an observation means 14 for observing the detection signal S2a. ..

In the apparatus 1 according to the third aspect of the invention, the rotating means 22 for rotating the magnetic disk 10 and the magnetic head 24 for recording a signal on the track 10a of the rotating magnetic disk 10 or for detecting the recorded signal. A displacement means 25 for slightly displacing the magnetic head 24 in the radial direction of the magnetic disk 10, and a signal recorded on the track 10a of the magnetic disk 10 during one rotation of the magnetic disk 10. In the erasing signal output means 36 for outputting to the magnetic head 24 an erasing signal S6 for erasing a signal corresponding to a specific angle range in
And a detection signal S2 detected by the magnetic head 24.
And an observing means 14 for observing.

[0016]

The signal extracting means 32 detects the detection signal S2a corresponding to a specific angular range during one rotation of the magnetic disk 10.
To extract.

The erase signal output means 36 is used for the magnetic disk 1.
Of the signals recorded on the track 0a of 0, the erase signal S6 for erasing the signal corresponding to the specific angular range in one rotation is output to the magnetic head 24.

By these, the groove 1 of the magnetic disk 10
The signal corresponding to the portion S2a not including 0b is the observing means 1
4 is output. The observation by the observing means 14 is performed by detecting the detection signal S2 by the magnetic head 24 or a specific portion thereof.
It suffices if the change is made according to the displacement of the magnetic head 24. The observation by the observing means 14 is performed by looking at the display screen, the display panel, the printed recording paper, or the like, or by accumulating the data on the memory or the recording paper based on these.

[0019]

1 is a block diagram showing the configuration of a test apparatus 1 according to the present invention. The test apparatus 1 includes a disk drive control device 11, a signal control device 12, an oscilloscope 13, and a spectrum analyzer 14.

The disk drive control device 11 has a motor 21 whose rotation speed is controlled by a control device (not shown), a spindle 22 which is rotationally driven by the motor 21, and a rotational angle position of the spindle 22 which is zero degrees, that is, the spindle 2
2 includes an angular position signal output device 23 that outputs a pulse signal S1 at the origin position, a magnetic head 24 that detects a signal recorded on a track of the magnetic disk 10 and outputs a detection signal S2, and a displacement device 25. ing.

The displacement device 25 supports the magnetic head 24 so that the magnetic head 24 can be read from and written to the magnetic disk 10, and drives the magnetic head 24 to move in the radial direction of the magnetic disk 10. The magnetic head 24 is a displacement device 25.
By this, the magnetic disk 10 is moved so that it can be accessed at an arbitrary position, and is finely displaced in the same direction discretely during reading at a specific position.

The signal controller 12 includes an amplifier 31 for amplifying the detection signal S2 from the magnetic head 24 and a gate circuit 3.
2. A gate signal generation circuit 3 that generates a gate signal S4 synchronized with the pulse signal S1 from the angular position signal output device 23.
3, a switching circuit 34, and a write signal generation circuit 35 that outputs a write signal having a constant frequency to the magnetic head 24.

The gate circuit 32 passes only the portion of the output signal S3 from the amplifier 31 corresponding to the gate signal S4 and outputs the extraction signal S5. FIG. 4 shows the track 10a and the groove 10b of the magnetic disk 10 and the magnetic head 24.
It is a figure which shows typically the example of the reading locus | trajectory 10c by.

A large number of concentric tracks 10a are formed on the surface of the magnetic disk 10.
A groove 10b is provided between a and a. Spindle 22
The magnetic disk 10 attached to the
Since it is eccentric to the rotation center of
The rotation of the magnetic head 24 detects and reads the signal of the portion of the read locus 10c indicated by the alternate long and short dash line, for example.

Since the read locus 10c crosses the plurality of tracks 10a across the groove 10b, the detection signal S2 read from the read locus 10c is the groove 10b.
The signal level is lowered in the portion including.

FIG. 3 is a diagram showing an example of the relationship between the detection signal S2 read from the read track 10c and the gate signal S4. The detection signal S2 is almost flat and has a high signal level in the portion S2a where the magnetic head 24 has passed directly above the track 10a, but the magnetic head 24 has the groove 10b.
The signal level is lower than that in the portion S2b crossing the line.

The gate signal S4 is a signal which rises after being delayed by the time T1 with respect to the pulse signal S1, and is turned on for the time T2. Of the output signal S3 from the amplifier 31, only the portion S2a corresponding to the gate signal S4 is extracted by the gate circuit 32 and output as the extraction signal S5. The times T1 and T2 can be changed by an operation key not shown.

In the figure, the position P1 indicates the origin position of the magnetic disk 10. Next, a test method by the test apparatus 1 will be described. First, the motor 22 rotates the spindle 22 and the displacement device 25 positions the magnetic head 24 at a predetermined position. In that state, a signal is written and recorded on the magnetic disk 10 by the write signal from the write signal generation circuit 35.

Next, the switching circuit 34 is switched to the side of the output signal S3, the output signal S3 is observed by the oscilloscope 13, and the gate signal S4 is output corresponding to the flat portion S2a not including the groove 10b. Time T1, T
Adjust 2.

Then, the switching circuit 34 is operated to extract the extraction signal S5.
, And the extracted signal S5 is observed or measured by the spectrum analyzer 14. In this state, the displacement device 25 displaces the magnetic head 24 a minute distance, for example, about 1 μm, and the spectrum analyzer 14 observes the extracted signal S5 in the same manner as described above, and thereafter, this is repeated.

Then, of the detection signal S2 read from the magnetic disk 10, only the signal of the portion S2a of the track 10a of the on-track portion which does not include the groove 10b is output to the spectrum analyzer 14, so that the magnetic head By measuring the signal level corresponding to the displacement of 24, the off-track characteristic of the magnetic disk 10 can be correctly measured.

For example, the magnetic head 24 is used as the track 10a.
When the signal level of the extraction signal S5 when the displacement of the magnetic head 24 is zero is 0 dB, until the signal level is attenuated to about -60 dB or to a practical level of -30 dB. , The signal level is measured for each minute displacement.

When the magnetic head 24 is first positioned with respect to the magnetic disk 10, the flat portion S2a of the detection signal S2, that is, the groove 10b of the read locus 10c.
Adjust so that the part that does not include is as large as possible.

FIG. 2 is a block diagram showing the configuration of a signal controller 12a of another embodiment used in the test apparatus 1.
The signal control device 12a includes an amplifier 31, a write signal generation circuit 35, and an erase signal output circuit 36 that operates in synchronization with the pulse signal S1 from the angular position signal output device 23.

The erase signal output circuit 36 erases a signal corresponding to a specific angular range during one rotation of the magnetic disk 10 among the signals written on the magnetic disk 10 by the write signal generation circuit 35. This is a circuit that outputs S6.

The output timing of the erase signal S6 is opposite to that of the gate signal S4 of the gate signal generating circuit 33 described above.
The operator adjusts while observing the oscilloscope 13 so that the detection signal S2 is output corresponding to the portion S2b including the groove 10b.

When this signal control device 12a is used, after the signal is written to the magnetic disk 10 by the magnetic head 24, the signal written by the magnetic head 24 is read to obtain the detection signal S2, which is used by the oscilloscope 13 And adjust the timing of the erase signal S6 of the erase signal output circuit 36.

Then, the portion S2b recorded on the magnetic disk 10 is erased by the erase signal S6. As a result, a signal is written on the magnetic disk 10 in correspondence with the portion S2a of the track 10a only, which does not include the groove 10b.

Then, the magnetic disk 10 is read by the magnetic head 24, and the output signal S3 is observed or measured by the spectrum analyzer 14. Then, in the same manner as described above, the magnetic head 2 is moved by the displacement device 25.
4 is displaced a minute distance and spectrum analyzer 14
Observe by and repeat this.

Then, only the signal of the portion S2a of the track 10a of the on-track portion which does not include the groove 10b is output to the spectrum analyzer 14, and the off-track characteristic of the magnetic disk 10 can be correctly measured.

Therefore, by using the test apparatus 1 and changing various parameters such as the width of the track 10a, the width and depth of the groove 10b, the shape or material of the magnetic head 24, and the like, the off-track characteristic test is performed. This can be used for the optimization design of the magnetic disk 10 having 10b.

In the above-mentioned embodiment, the origin position of the magnetic disk 10 is detected by the angular position signal output unit 23, but the origin signal is written in the magnetic disk 10 beforehand.
It may be detected by the magnetic head 24 or the like.

In the signal controller 12a, the write signal generating circuit 35 writes a signal for one rotation to the magnetic disk 10 and then the gate signal generating circuit 33 erases the portion S2b including the groove 10b. Instead of this, the write signal generation circuit 35 may write a signal corresponding to only the flat portion S2a not including the groove 10b.

In the above-described embodiment, as the portion of the detection signal S2 to be observed by the spectrum analyzer 14, another flat portion S2aa may be extracted instead of or together with the flat portion S2a. Instead of or together with the spectrum analyzer 14,
Various other measuring instruments including the oscilloscope 13 may be used.

[0045]

According to the present invention, it is possible to test the off-track characteristics of a magnetic disk having a groove without using a servo mechanism or the like for moving the magnetic head to follow the track of rotation of the track.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a test apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration of a signal control device of another embodiment of the test apparatus according to the present invention.

FIG. 3 is a diagram showing an example of a relationship between a detection signal read from a read track and a gate signal.

FIG. 4 is a diagram schematically showing an example of tracks and grooves of a magnetic disk and a read locus by a magnetic head.

[Explanation of symbols]

 1 Test Equipment 10 Magnetic Disk 10a Track 10b Groove 14 Spectrum Analyzer (Observation Means) 22 Spindle (Rotation Means) 24 Magnetic Head 25 Displacement Device 32 Gate Circuit (Signal Extraction Means) 36 Erase Signal Output Circuit (Erase Signal Output Means) S2 S2a detection signal S6 erase signal

Claims (3)

[Claims] 1. A groove (10) between adjacent tracks (10a).
A method for testing the off-track characteristics of a magnetic disk (10) having b), comprising: rotating a magnetic disk (10) to obtain a signal recorded on a track (10a) of the magnetic disk (10). The magnetic disk (1) is detected by the magnetic head (24).
0) the detection signal (S) of the magnetic head (24) according to the minute displacement of the magnetic head (24) along the radial direction.
Off-track characteristics characterized by observing the change of 2) and observing the change of the detection signal (S2) for a portion (S2a) not including the groove (10b) of the magnetic disk (10). Test method. 2. A groove (10) between adjacent tracks (10a).
An apparatus (1) for testing the off-track characteristics of a magnetic disk (10) having b), comprising: rotating means (22) for rotating the magnetic disk (10).
And the track (10) of the rotating magnetic disk (10).
a) a magnetic head (24) for detecting a signal recorded in a), and a displacement means (2) for finely displacing the magnetic head (24) in the radial direction of the magnetic disk (10).
5) and the detection signal (S2) of the magnetic head (24),
A signal extraction unit (32) for extracting a detection signal (S2a) corresponding to a specific angular range in one rotation of the magnetic disk (10) and an observation unit (14) for observing the detection signal (S2a). An off-track characteristic testing device having. 3. A groove (10) between adjacent tracks (10a).
An apparatus (1) for testing the off-track characteristics of a magnetic disk (10) having b), comprising: rotating means (22) for rotating the magnetic disk (10).
A magnetic head (24) for recording a signal on a track (10a) of a rotating magnetic disk (10) or for detecting a recorded signal; and a magnetic head (24) for radiating the magnetic disk (10). Displacement means (2
5) and an erasing signal for erasing a signal corresponding to a specific angular range during one rotation of the magnetic disk (10) among the signals recorded on the track (10a) of the magnetic disk (10). Erase signal output means (36) for outputting S6) to the magnetic head (24), and a detection signal (S) detected by the magnetic head (24).
An off-track characteristic testing device comprising: an observing means (14) for observing 2).