JPH03259478A - Method for inspecting off-track - Google Patents

Abstract

PURPOSE:To prevent the position of an off-track inspection from being limited by executing the off-track inspection of a magnetic head over the entire surface of a disk for off-track inspection. CONSTITUTION:Noise signals NZ are recorded over the entire surface of the magnetic disk recording surface which can be mounted to a magnetic disk device of a medium exchange type of object. Servo information SB and sector data SCd are then recorded over the entire periphery of the recording surface of the magnetic disk by using the recording head HDb of a gap width Lb narrower than the magnetic head HDa for noise recording and the data writing of one cylinder is executed. The data writing of the one cylinder is then ended. The magnetic head HDb is moved by as much as a recording track spacing La in the radial direction of the disk and the data writing of this cylinder is executed. The data of the track Tr for off-track inspection is recorded over the entire surface of the recording surface of the magnetic disk by successively repeating such operations. The position of the off-track inspection is prevented from limited in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an off-track inspection method for a magnetic head used in a magnetic disk device with a replaceable storage medium.

[Prior Art] As a method for inspecting the positioning error of a magnetic head with respect to a recording track (cylinder), that is, the amount of off-track of a magnetic head used in a magnetic disk device with a replaceable storage medium, conventionally, for example, the following method has been used. method was used.

That is, as shown in FIG. 4, a disk for off-track inspection is provided with tracks for off-track inspection at appropriate locations such as the outermost circumference, the innermost circumference, and the center of the data area ARD on the data recording surface. The off-track amount of the magnetic head was determined based on the read signal of the off-track inspection track, which was attached to a magnetic disk drive to be inspected.

Here, as shown in FIG. 5, for the off-track inspection track, a plurality of consecutive sectors SCa, SCb, and SCc are set as off-track inspection sectors among the sectors of the recording track, and these sectors SCa, SCb
, SCc is recorded with the recording position shifted stepwise in the track alignment direction (disk radial direction) from the specified position at the center of the track.

In this case, sector SCa, sector SCb, sector S
The amount of deviation from the track center is set so that it increases in the order of Cc. In addition, each sector SCa
, SCb, and SCc record inspection data consisting of data patterns that are likely to cause data errors, such as so-called worst patterns.

Furthermore, in this case, a sector servo system is used to control the positioning of the magnetic head, and servo information SB for positioning control is recorded at the position dividing each sector.

Now, when determining the off-track amount of the magnetic head HD, the magnetic head HD is first moved to the off-track inspection track (seek operation).

At this time, the positioning control of the magnetic head HD is performed based on the servo information SB formed on the off-track inspection track, so the magnetic head HD is controlled by the servo information SB.
It is positioned at the position defined by B, that is, at the center of the track.

In this state, the data in the test sectors SCa, SCb, and SCc are read to check whether each data can be detected normally.

For example, if the data in the test sectors SCa and SCb can be detected normally, but the data in the test sector SCc cannot be read normally, the off-track amount of the positioning control of the magnetic head HD may be within the predetermined off-track margin. It can be determined that it is within.

On the other hand, when the data in the inspection sector SCc can be detected normally, it can be determined that the off-track has exceeded the range of the off-track margin even if positioning control is performed using the servo information SB. In this case, it can be determined that the positioning control is defective.

[Problems to be Solved by the Invention] However, such conventional methods have the following disadvantages.

That is, when recording the data of the inspection sectors SCa, SCb, and SCc on the off-track inspection track, it is necessary to use a recording device with extremely high positioning accuracy, and since such a recording device is expensive, the off-track inspection disk is becomes expensive.

Further, since off-track inspection cannot be performed on a track other than the off-track inspection track, the track position for off-track inspection is limited. Further, since the position of a sector that can be used as a sector for inspection is limited, the sector position for off-track inspection is limited.

Furthermore, in order to record the data in the inspection sector off-track, it is necessary to widen the interval between adjacent recording tracks.

For example, when the off-track amount of the magnetic head HD is small, the inspection sector S with the largest off-track amount may be
When reading the recorded data of Cc, as shown in FIG. 6, when the immediately preceding servo information SB is detected,
Since the output of the magnetic head HD is a relatively large value, the gain of the automatic gain amplifier circuit (AGC circuit) of the signal processing circuit that processes the output signal of the magnetic head HD is set to a small value. When recording data in sector SCc is detected, the output signal of magnetic head HD suddenly drops.

Along with this, the gain of the automatic gain amplifier circuit also increases rapidly, but if the gain change of the automatic gain amplifier circuit cannot follow the change in the output signal of the magnetic head HD, the signal will not be detected properly. A data error will occur.

In this way, a situation may arise in which an appropriate off-track amount determination process cannot be performed because the error occurrence situation in the inspection sector SCc is other than the data error of the read signal.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an off-track inspection method that can more appropriately inspect the amount of off-track.

[Means for Solving the Problems] The present invention records a noise signal on the entire recording surface of a disk, and then creates an off-track inspection track having a recording width of a predetermined dimension smaller than the recording track interval at least at the recording track interval. An off-track inspection disk with a recording surface formed by recording on the disk recording surface is installed in a magnetic disk device, and the magnitude of the signal obtained by reading the off-track inspection track of the off-track inspection disk is
When the off-track amount of the magnetic head of the magnetic disk device is smaller than a predetermined value, it is determined that the off-track amount of the magnetic head of the magnetic disk device is larger than the predetermined value.

[Operation] Therefore, off-track inspection of the magnetic head can be performed on the entire surface of the off-track inspection disk.
Off-track inspection locations are not restricted. In addition, since the off-track inspection disk is formed by recording the noise signal and then forming the signal for the off-track inspection track, the cost of the equipment for making the off-track inspection disk can be reduced. , a disk for off-track inspection can be realized at low cost.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, manufacturing of the off-track inspection disk will be explained.

A noise signal NZ is recorded on the entire recording surface of a magnetic disk that can be attached to a target medium-exchangeable magnetic disk device.

At this time, for example, as shown in FIG. 1, a noise recording magnetic head HDa having the same gap width as the recording track spacing La is used to apply a noise signal NZ to the entire circumference of the recording surface of the magnetic disk. Record. Next, the magnetic head HDa is moved in the disk radial direction by the recording track interval La to record the noise signal NZ, and by repeating this sequentially, the noise signal NZ is recorded over the entire recording surface of the magnetic disk.
Record.

Next, using a recording head HDb with a narrower gap @Lb than the recording head HDa for noise recording, servo information SB and sector data SCd are distributed all around the recording surface of the magnetic disk.
is recorded, and data writing for one cylinder is performed. Further, in this case, the sector data SCd is data in a predetermined format, and the contents thereof use test data such as the worst pattern.

When data writing for one cylinder is completed, the magnetic head HDb is moved in the disk radial direction by the recording track interval La, and data is written for that cylinder.By repeating this sequentially, the magnetic head HDb is turned off on the recording surface of the magnetic disk. Data of the track Tr for track inspection is recorded.

In this way, off-track inspection tracks Tr are recorded on the recording surface of the off-track inspection disk at recording track intervals La, and a noise signal NZ is generated between adjacent off-track inspection tracks Tr. recorded.

When performing an off-track inspection using such an off-track inspection disk, first, the off-track inspection disk is mounted on a magnetic disk device to be inspected, and the magnetic head HD is moved to any track.

As a result, the magnetic head I (D
Positioning control is performed, and based on the positioning results,
Inspection data is detected from the magnetic head HD.

For example, as shown by arrow A in FIG.
When D is on track, the magnetic head HD
The output signal from includes only the test data component.

In addition, as shown by arrows B and C in the figure, the magnetic head HD
When the magnetic head HD is off-track, the output signal of the magnetic head HD includes a noise signal NZ component depending on the amount of off-track.

Therefore, when the level of a specified signal component included in the output signal of the magnetic head HD is below the specified value, it is possible to determine that the off-track amount of the magnetic head HD has exceeded the predetermined off-track margin. can.

In addition, in this case, in a state where the magnetic head HD is off-track exceeding the off-track margin limit value NG,
The recording width Lb of the off-track inspection track T' is set so that the signal component included in the output signal from the magnetic head HD is smaller than a specified value.

In this way, in this embodiment, after the noise signal is recorded on the entire surface of the off-track inspection disk, the signal of the off-track inspection track is recorded in a predetermined width, so that the noise signal is recorded. There is no need to match the position of the magnetic head in the radial direction of the disk for recording noise with the position of the magnetic head in the radial direction of the disk when recording signals on the off-track inspection track. There is no need to use expensive equipment as a machine for manufacturing disks, and disks for off-track inspection can be provided at low cost.

In addition, since the servo information SB and sector data SCd are read continuously, there is no fluctuation in the output signal of the magnetic head.
Appropriate off-track inspections can be performed.

[Effects of the Invention] As explained above, according to the present invention, the off-track inspection data is recorded over the entire surface of the off-track inspection disk, so the off-track inspection position is not limited. In addition, since the off-track inspection disk is formed by recording the noise signal and then forming the signal for the off-track inspection track, the cost of the equipment for making the off-track inspection disk can be reduced. , it is possible to realize an off-track inspection disk at low cost.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing an example of recording a noise signal on an off-track inspection disk, and Figure 2 is a diagram of recording data on an off-track inspection track with noise signals recorded on the entire recording surface. FIG. 3 is a schematic diagram for explaining off-track inspection. FIG. 4 is a schematic diagram showing a conventional example of a disk for off-track inspection. FIG. 5 is a schematic diagram for explaining off-track inspection. FIG. 6 is a schematic diagram showing a conventional example of a track, and is a waveform diagram for explaining one of the disadvantages of the conventional method.

Claims (1)

[Claims] In an off-track inspection method for a magnetic head used in a magnetic disk device with a replaceable storage medium, after recording a noise signal on the entire disk recording surface, off-track inspection is performed with a recording width of a predetermined dimension smaller than at least the recording track interval. A disk for off-track inspection having a recording surface formed by recording tracks on the disk recording surface at recording track intervals is mounted on a magnetic disk device, and the off-track inspection tracks of the off-track inspection disk are read. 1. An off-track inspection method characterized in that when the magnitude of the signal is smaller than a predetermined value, it is determined that the off-track amount of a magnetic head of a magnetic disk device is larger than a predetermined value.