JPH0252351B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for adjusting the position of a magnetic head of a magnetic disk device (hereinafter referred to as a disk device) using a magnetic disk (hereinafter referred to as a disk). .

Conventional structure and its problems A disk used in a disk device has multiple recording tracks, and in order to maintain compatibility between disk devices and increase the reliability of the device, the track radius of the magnetic head from a predetermined track center is adjusted. The amount of deviation in direction (off-track amount) must be kept below a predetermined amount.

A conventional head position adjustment method will be described below with reference to the drawings. Figure 1 shows an example of how the amount of off-track changes depending on the track position of the disk device. It shows the change in the amount of off-track when it is sent from the center to the outer circumference. Regarding the off-track direction, the + direction is the outer circumferential side and the - direction is the inner circumferential side.

The conventional head position adjustment method uses an alignment disk called a cat eye for measuring the amount of off-track, focuses on one of the tracks near the center of multiple recording tracks, and measures when the amount of off-track on that track falls below a predetermined amount. I adjusted the head position so that it would be correct.

However, as shown in FIG. 1, the off-track amount of the disk device is not constant depending on the track, but shows periodic changes. This is caused by an imbalance in the magnetic attraction force applied to the rotor of the stepping motor that moves the magnetic head, vibration of the motor shaft, eccentricity of the pulley fixed to the motor shaft, etc. Since the disk device shown in FIG. 1 uses a four-phase stepping motor, the off-track amount changes periodically every four tracks. Furthermore, even for the same track, the amount of off-track varies depending on the direction of track movement of the head due to the hysteresis of the head movement mechanism. Therefore, even if the head position is adjusted so that the amount of off-track on a particular track becomes zero, it is not necessarily the case that the head position is adjusted to the optimum position for the entire track. but,
For example, in a disk device of the type that has 48 recording tracks per inch width (48 TPI), the track spacing is approximately 530 μm and the tolerance for off-track amount is as large as ±40 μm, so the conventional head position adjustment method was sufficient. . However, as the recording capacity of disk devices has become higher and the track spacing has become narrower, the allowable amount of off-track has also become smaller. In trucks, the amount of off-track sometimes exceeds a permissible value, and conventional head position adjustment methods have become insufficient in terms of overall balance.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for adjusting the head position of a magnetic disk device, which makes it possible to adjust the head position so that the off-track amount of the magnetic head of the disk device is well-balanced over all tracks and is minimized. It is to be.

Structure of the Invention The method for adjusting the head position of a magnetic disk device according to the present invention measures the amount of deviation (off-track amount) of the magnetic head in the track radial direction from a predetermined track center of the magnetic disk device for a plurality of tracks, and determines the maximum value of the measured values. The position of the magnetic head is adjusted so that the off-track amount is zero at the center of the minimum value, and as a result, the off-track amount of the magnetic head of the magnetic disk device is well-balanced and minimized over all tracks. This makes it possible to adjust the head position so that.

DESCRIPTION OF EMBODIMENTS First, the principle of the present invention will be explained. Figure 2 shows
It shows the relationship between a recording track and the amount of off-track on that track, with the vertical axis representing the off-track amount and the horizontal axis representing the recording track. The off-track direction is such that the outer circumferential direction is in the + direction and the inner circumferential direction is in the - direction with respect to the track center. Figure 2 a shows the case where the off-track is on both the inner and outer circumferential sides around a predetermined track center, b shows the case where the off-track is only in the outer circumferential direction, and c shows the case where the off-track is only in the inner circumferential direction. It shows. In Figure 2, P ₁₁ , P ₁₂ , P ₁₃ ,
And, P ₂₁ , P ₂₂ , and P ₂₃ represent the maximum and minimum values of the off-track amount in each case.
Further, Ca indicates the position (hereinafter referred to as the average center) where the amount of off-track becomes zero when the head position is adjusted by the head position adjustment method according to the present invention. The amount of off-track can be measured using the above-mentioned Cat Eye disk or the method of measuring the amount of off-track in a magnetic disk device as disclosed in Japanese Patent Application No. 173541/1983.

As shown in FIG. 2, there are three possible off-track patterns for disk devices: a, b, and c. In the case of a, the maximum value of off-track amount
_P11 means the maximum off-track value in the outer circumferential direction, and minimum value _P21 means the maximum off-track value in the inner circumferential direction. In the case of b, the maximum value P ₁₂ means the maximum value of off-track in the direction of the outer circumference, and the minimum value P ₂₂ means the minimum value of the off-track in the direction of the outer circumference. In the case of c, the maximum value P ₁₃ means the maximum value of off-track in the direction of the inner circumference. minimum value of quantity,
The minimum value _P23 means the maximum value of the off-track amount in the inner circumferential direction. Here, the maximum values P ₁₁ , P ₁₂ , and P ₁₃ are collectively referred to as P ₁ , and the minimum values P ₂₁ , P ₂₂ , and P ₂₃ are collectively referred to as P ₂
Then, the maximum value P ₁ and the minimum value P ₂ are detected from the measured off-track amount of multiple tracks, and the maximum value P ₁
If the center of the minimum value P ₂ is set as the average center Ca, and the head position is adjusted so that the amount of off-track becomes zero at the average center Ca, the off-track will be well balanced between the inner and outer sides around the average center Ca. The head is adjusted to a position where the off-track amount does not exceed 1/2 (P ₁ −P ₂ ) at the maximum.

Hereinafter, an embodiment of the present invention configured to input an off-track amount and display an adjustment amount will be described with reference to the drawings.

FIG. 3 is a block diagram showing the configuration of an apparatus for realizing the head position adjustment method of the present invention, which is configured to input an off-track amount and display an adjustment amount. In FIG. 3, 1 is an input section for inputting the amount of off-track, 2 is a disk device control section, and 3 is a microcomputer, which is composed of a central processing unit (CPU), ROM, RAM, etc. 4
5 is a display section for the amount of head position adjustment, and 5 is a start button.

The operation of the above configuration will be explained below. When you press the start button 5, the ROM of the microcomputer 3
As shown in the flowchart of FIG. 4, after step 1 of moving the head of the disk device to be measured to the outermost track, step 2 moves the head of the disk device under test to the outermost track, and then moves the head of the disk device under test to the outermost track. Move the head to the outermost track among the measurement tracks. When off-track data is input to the input section 1 in step 3, the microcomputer 3 takes in the input data and stores it on the RAM. The data may be input electrically from another off-track amount measuring device or manually using a keyboard or the like. Microcomputer 3 in step 4
refers to the measurement track table again, and if the track for which data was input in step 3 is not the innermost track of the measurement tracks stored in the table, returns to step 2 and performs the next measurement stored in the table. Send the head to the track and enter off-track data again in step 3. When the input of the off-track data of the innermost track stored in the measurement track table is completed, the head is moved to the innermost track of the disk device in step 5, and the steps 2 and 2 are performed in steps 6, 7, and 8.
In contrast to steps 3 and 4, the head is moved from the inner circumference to the outer circumference according to the measurement track table, and off-track data is input and stored on the RAM. Once all measurements have been completed, repeat steps 3 and 7 in step 9.
The maximum value _P1 and the minimum value _P2 are detected from the off-track data stored on the RAM in step 10, and the average center Ca is calculated in step 10.

In order to display the adjustment amount on the display section 4, the off-track amount of an arbitrary track was input, and the distance and direction of the track from the average center Ca were displayed.

As described above, according to this embodiment, the amount of off-track is measured by changing the moving direction of the head for a plurality of tracks, the maximum value _P1 and the minimum value _P2 are detected, and the average center Ca is obtained. A head position adjustment method has been realized that distributes the off-track of the device in a well-balanced manner around the track center.

Effects of the Invention As is clear from the above description, the present invention measures the amount of off-track of a disk device for a plurality of tracks, and positions the magnetic head so that the center of the maximum and minimum values of the measured values is zero. Since the off-track amount changes depending on the track due to the accuracy of the head moving mechanism, the off-track amount after head position adjustment is
The value does not exceed half of the difference between the maximum and minimum measured values. Furthermore, since the amount of off-track is measured while changing the moving direction of the head, the head position can be adjusted to the optimum position, taking into account the influence of hysteresis of the head moving mechanism.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the off-track amount change depending on the track position of the disk device, FIG. 2 is a diagram showing the relationship between the recording track and the off-track amount on that track, and FIG. 3 is a diagram showing the realization of the head position adjustment method of the present invention. A block diagram of an embodiment of a device for
FIG. 4 is a flowchart showing the operation of a microcomputer in one embodiment of the present invention. 1...Input unit, 2...Disk device control unit, 3
...Microcomputer, 4...Display section, 5...
...Start button.

Claims (1)

[Scope of Claims] 1. The amount of deviation in the track radial direction (off-track amount) of the magnetic head from a predetermined track center of the magnetic disk device is measured for a plurality of tracks,
A method for adjusting the head position of a magnetic disk device, characterized in that the position of the magnetic head is adjusted so that the center of the maximum and minimum measured values becomes zero off-track. 2. Regarding the measurement of the amount of off-track, the measurement is performed both when the magnetic head is moved to the track to be measured from the inner circumference side of the track and when it is moved from the outer circumference side of the track. A method for adjusting the head position of the magnetic disk device described above.