JPH06267037A - Head width measuring apparatus of magnetic disc device and head positioning controller - Google Patents

Abstract

PURPOSE:To obtain a head width measuring apparatus which enables the measuring of the width of a head mounted on a HDD to store the head width as results of the measurement as data. CONSTITUTION:In a head width measuring mode, a CPU 1 measures a head width of a head 4a mounted on a HDD based on a data for measuring the head width recorded previously on a specified track of a disc 7 to be stored into a memory 2. The data for measuring the head width comprises a data with the data width continuing, for example, to 50-100% of the interval of the track.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to a head positioning control device having a head width measuring device for measuring the width of a head and means for adjusting a servo signal based on the measured head width, particularly in a hard disk device. Regarding

[0002]

2. Description of the Related Art Conventionally, a hard disk device (HDD)
Is equipped with a head positioning control device for controlling the positioning of the head on a target track (cylinder) on the disk based on servo information recorded in advance on the disk. The servo information includes a sync signal, a track address (cylinder code), burst information and the like.

The head positioning control device generates a position signal from the burst information in the servo information and executes position control for positioning the head at the center of the target track based on this position signal. Specifically, as shown in FIG.
The head is driven and controlled so that the difference between the voltage levels of the position signals corresponding to burst 0 and burst 1 of the burst information becomes zero, and the head is positioned at the center of the track.

By the way, the range of the voltage level of the position signal changes according to the width of the head, as shown in FIG.
That is, when the heads A and B having different head widths reproduce the burst information, the position signal (solid line) SA corresponding to the head A having a relatively wide width has a wide range of linearity with respect to the track center. Have. On the other hand, the position signal (dotted line) SB corresponding to the head B having a relatively narrow width has linearity in a narrow range with respect to the track center. Further, the inclination of the position-to-signal changes according to the head width.

That is, when the maximum output level of the head is Vmax, the output level of each of the heads A and B is "Vmax / 2" when the position of the head is the center of the track. However, the position of the head at Vmax or output level 0 is
The position is moved by "head width / 2" from the center of the track. Therefore, the relationship between the position signal and the head position is
It depends on the head width.

[0006]

In an HDD in which head positioning control is performed based on servo information, the relationship between the position signal obtained by reproducing burst information and the head position depends on the width of the head attached to the HDD. is doing. For this reason, when the head width varies during the manufacturing process, the inclination of the position signal varies in a plurality of heads of the HDD, which causes a variation in the servo band in the positioning control. In order to suppress this fluctuation, it is desirable to adjust the servo gain according to the head width and perform position correction according to the head width, but there has been no means in the past.

An object of the present invention is to provide a head width measuring device capable of measuring the width of a head mounted on an HDD and storing the measured head width as data. Another object of the present invention is to provide a head positioning control device capable of performing position correction at the time of head positioning control using the measurement result of the head width.

[0008]

According to the present invention, there is provided a disk having head width measurement data recorded on a preset track, and the head width measurement is performed based on the head width measurement data. A head width measuring device of a magnetic disk device having a means.

Further, according to the present invention, there is provided a disk in which head width measuring data is recorded on a preset track and a servo signal for controlling head positioning, and the head width is measured based on the head width measuring data. Is a head positioning control device for a magnetic disk device, which is provided with a head width measuring means for measuring the head width and a positioning control means for performing position correction based on the head width measurement result.

[0010]

In the head width measuring device of the present invention, the head width measuring means reproduces the head width measuring data from the disk by the head in the head width measuring mode, and measures the head width based on the amplitude value of the reproduced signal. Then, the measurement result is stored.

In the head positioning control device of the present invention, the head width measuring means reproduces the head width measuring data from the disk by the head in the head width measuring mode, and measures the head width based on the amplitude value of the reproduced signal. Then, the measurement result is stored. In the head positioning control mode, the positioning control means adjusts the gain of the servo signal reproduced from the disk based on the measurement result stored by the head width measuring means, and performs the positioning control so as to correct the head position.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a main part of an HDD according to the embodiment, FIG. 2 is a conceptual diagram for explaining head width measurement data according to the embodiment, and FIGS. 6 is a flowchart for explaining the operation of the embodiment.

This device has a microprocessor (CPU) 1, a head drive mechanism 4, a carriage drive circuit 5, and a data reproduction circuit 6 which constitute a control unit of an HDD. C
The PU 1 constitutes a head width measuring device and a head positioning control device according to the present invention, and executes an operation related to each device based on a program stored in the program area 2a of the memory 2. The memory 2 has registers A and B used by the CPU 1 to execute the head width measurement process. CPU 1 is a disk controller (HDC) 3
And various interface signals are exchanged to read / write data from / to the disk 7.

The disk 7 is rotated by a spindle mechanism 7a. Servo information necessary for head positioning control and head width measurement data used in the head width measurement process of the present invention are recorded in advance on the disk 7.
The head width measurement data is recorded on a predetermined track (cylinder) that is not used for normal data read / write.

The head drive mechanism 4 comprises a head 4a, a head support member (suspension) 4b, a carriage 4c and a voice coil motor (VCM) 4d. The head support member 4b is fixed to the carriage 4c and supports the head 4a above the disk 7 with a predetermined flying height during seek or read / write. Carriage 4
For example, c is a rotary type, which is rotationally driven by the driving force of the VCM 4d to move (seek) the head 4a in the radial direction of the disk 7. The VCM 4d is driven by the carriage drive circuit 5.

The carriage drive circuit 5 has a D / A conversion circuit 5a, a compensation circuit 5b and a driver 5c. D /
The A conversion circuit 5a converts the head positioning control data output from the CPU 1 into an analog positioning control signal. The compensation circuit 5b is a circuit for compensating the transfer characteristic of the positioning control system. The driver 5c converts a voltage signal, which is a positioning control signal, into a drive current, and the VCM4
supply to d.

The data reproducing circuit 6 reproduces the read signal read by the head 4a into data. The data reproducing circuit 6 has an amplifier 6a for amplifying the read signal from the head 4a and an A / D conversion circuit 6b for converting it into digital data. The data reproducing circuit 6 reproduces the reproduced normal data, servo information and head width measurement data by C
Output to PU1. Next, the operation of the embodiment will be described.

First, in the present invention, after the power supply of the HDD is turned on, before the normal operation is started (before the ready state), the C
PU1 executes a head width measurement process as shown in FIG. 3 (head width measurement mode).

That is, the CPU 1 controls the carriage drive circuit 5
The head drive mechanism 4 is controlled through the head 4a so that the head 4a is sought to a predetermined track of the disk 7 in which the data for measuring the head width is recorded (step S1). The head 4a is
Head width measurement data is read from a predetermined track of the disk 7 and output to the data reproduction circuit 6. The data reproduction circuit 6 converts the head reproduction signal into digital head width measurement data and outputs it to the CPU 1.

The CPU 1 executes the process of measuring the head width of the head 4a attached to the HDD based on the head width measuring data corresponding to the head reproduction signal (see the flowcharts of FIGS. 4 and 5). CPU1
The head width data obtained by the measurement is stored in the register B of the memory 2 (step S3).

After that, when the head positioning control mode is entered, the CPU 1 uses the head width data stored in the register B to execute the adjustment of the servo gain in the positioning control operation (step S4). That is, the relationship (inclination) between the position of the head 4a and the position signal from the burst information changes according to the width of the head 4a. So C
PU1 executes position correction according to the head width based on the relational expression (1) shown below. R = Tr × {(head width H) ÷ 100} (1) where R is the distance moved in the range of level 0 to Vmax of the position signal corresponding to bursts 0 and 1, and Tr is the track interval. .

Here, the head width measuring process will be specifically described with reference to the flowcharts of FIGS. 4 and 5.
First, as shown in FIG. 2A, head width measurement data having a continuous data width of 50% to 100% of the track interval Tr is recorded on a predetermined track of the disk 7. When reproducing the data for measuring the head width from the disk 7, the head 4a has an amplitude (level) corresponding to the head width H.
And outputs the head reproduction signal (see FIG. 2B).

Based on the reproduction signal (reproduction data) from the head 4a, the CPU 1 sets the head width measurement data to 5
The amplitude value of the reproduction signal corresponding to the 0% data width is measured and set in the register A (steps S10 and S1).
1). This amplitude value is data 50D. In the same manner, the amplitude values corresponding to the respective data widths of 60% to 100% are calculated as data 60D, data 70D, and data 80, respectively.
D, data 90D, and data 100D.

Next, the CPU 1 measures the amplitude value corresponding to the data width of 60%, and the data 60D which is the measurement result.
And the data 50D of the register A are compared (step S
13). Based on this comparison result, the data 50 of the register A
If D is 60D or more (YE in step S13)
S), the CPU 1 sets the data 50D in the register B (step S17). In this case, the head width H of the head 4a is 50% or less of the data width, and the reproduction output of the head 4a is in a saturated state.

On the other hand, according to the comparison result, if the data 50D of the register A is less than the data 60D (step S13).
No), the CPU 1 sets the data 60D in the register A (step S14). Then, the CPU 1 sets 70
The amplitude value corresponding to the data width of% is measured, and the data 70D as the measurement result and the data 60D of the register A are compared (steps S15 and S16). In the embodiment, the data 60D of the register A is changed to the data 70D according to the comparison result.
Since it is less than (NO in step S16), the CPU 1 sets the data 70D in the register A (step S1).
9).

Next, the CPU 1 measures the amplitude value corresponding to the data width of 80%, and outputs the measured data 80D.
And the data 70D of the register A are compared (step S
20, S21). In the embodiment, as shown in FIG. 2A, the head width H of the head 4a corresponds to the data width of 70%, so the data 70D is the saturation level of the reproduction output. That is, according to the comparison result, the data 70D of the register A is
Becomes 80D or more (YE in step S21
S), the CPU 1 sets the data 70D in the register B (step S27). When the head H of the head 4a corresponds to the track interval Tr, the CPU 1 executes the processes of steps S22 to S26, S29, NO and S30.

As described above, in this embodiment, the head width H of the head 4a attached to the HDD can be measured based on the data 70D by the head width measuring process. The CPU 1 stores the measured data 70D in the register B and can always recognize the head width H of the head 4a.

In the present invention, based on the head width data obtained by the head width measurement processing, the position correction processing according to the head width can be performed in the head positioning control mode. As a result, the servo gain fluctuates due to the variation in the head width, and it is possible to suppress the position error that occurs in the head positioning control.

Further, by using the head width data obtained by the head width measuring process, a method of adjusting the flying height of the head 4a flying above the disk 7 can be realized. That is, when the head width H of the head 4a is larger than the predetermined track interval Tr, during the data read operation,
Crosstalk between adjacent tracks is likely to occur. Therefore, based on the head width data, the head 4
It is possible to suppress the crosstalk phenomenon by adjusting the flying height of a.

[0031]

As described above in detail, according to the present invention, the head width of the head attached to the HDD can be measured and stored based on the head width measurement data recorded in advance on the disk. Therefore, the HDD CP
U can always recognize the head width data of the head and can use it for various control operations.

Specifically, since the measured head width is utilized and the head width depends on the relationship between the position and the position signal, the head position can be corrected during the head positioning control.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of an HDD according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram for explaining head width measurement data according to the embodiment.

FIG. 3 is a flowchart for explaining the operation of the embodiment.

FIG. 4 is a flowchart for explaining the operation of the embodiment.

FIG. 5 is a flowchart for explaining the operation of the embodiment.

FIG. 6 is a conceptual diagram for explaining conventional head positioning control.

[Explanation of symbols]

1 ... CPU, 2 ... Memory, 4 ... Head drive mechanism, 5 ... Carriage drive circuit, 6 ... Data reproduction circuit, 7 ... Disk.

Claims (3)

[Claims] 1. A disk having head width measurement data recorded on a preset track, a head for reading / writing data from the disk, and a head for measuring the head width in the head width measurement mode. A head width measuring device for a magnetic disk device, comprising: a head width measuring means for measuring a width of the head based on an amplitude value of a reproduction signal obtained by reproducing data and storing a measurement result. 2. A head for executing data read / write, and when a reproduction signal is output by this head, an amplitude value of the reproduction signal corresponding to a width of the head changes at a predetermined ratio. A disk in which head width measurement data composed of data groups having different data widths is recorded on a preset track, and an amplitude of a reproduction signal obtained by reproducing the head width measurement data by the head in the head width measurement mode. A head width measuring device for a magnetic disk device, comprising: a head width measuring means for measuring the width of the head based on a value and storing the measurement result. 3. A head for reading / writing data, a disk having head width measurement data recorded on a preset track and servo information for controlling the positioning of the head, and a head width measurement mode. A head width measuring means for measuring the width of the head based on an amplitude value of a reproduction signal obtained by reproducing the head width measuring data by the head and storing the measurement result; and the disk in the head positioning control mode. Head positioning control means for performing position correction of the head based on the measurement result stored by the head width measuring means when positioning control of the head on a target track on the disk based on servo information reproduced from A head positioning control device for a magnetic disk drive, comprising: