JPH0991905A - Magnetic disc apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performance of a magnetic disc apparatus by using a difference of an estimated position and an actually measured position of a sector of each head to calculate a control parameter to control the apparatus when a magnetic head reading positional data is switched to another magnetic head. SOLUTION: Positional data are read from the magnetic disc apparatus, and a present position is calculated. Whether a head is switched or not is confirmed. If the head is switched, a difference of the actually measured position and an estimated value (Pe-d) 22 calculated at one earlier sector is obtained. The difference is added as a parameter for an observer to calculate to a position between heads (Pe-d) 22. The observer calculates with the use of the estimated value (Pe-d) 22, and a control current value 17 is set. When the head is switched, the observer makes calculations and the control current value 17 is set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sector servo type magnetic disk device, and more particularly to correction of head-to-head offset when switching magnetic heads.

[0002]

2. Description of the Related Art Conventionally, in a sector servo type magnetic disk device, the head-to-head offset is measured in advance when the power is turned on and the head-to-head offset is added to the control calculation parameter when the head is switched. It was

The position control of this conventional magnetic disk device will be described with reference to the drawings.

FIG. 5 is a block diagram of a predictive observer control circuit used in a conventional magnetic disk device.

The predictive observer control circuit of the magnetic disk device of this conventional example is composed of a velocity profile generating means 15
A current data generating means (current gain) 16, a digital-analog converting means (DAC) 19, a current generating means (AMP) 20, and a driving means (actuator) 23.
And an analog-digital conversion means (ADC) 25, an observer calculation means (observer) 28, and an inter-head offset setting means 29b.

A velocity profile is obtained from the calculated parameter estimated position (Pe) 27 and estimated velocity (Ve) 26 calculated by the observer 28, and the control current value (Upv) 17 is calculated, and the estimated disturbance (Dist) 21 is added to this. In addition, the disturbance control current value (Udst) 18 is calculated. The calculated Udst 18 outputs a current from the DAC 19 to the actuator 23 via the AMP 20.

The actuator 23, to which a current is applied, moves the magnetic head to obtain new position information from the magnetic head. This position information is sent to the observer 28 to calculate the control parameter to output next.

If the head is switched at this time, Pe_d22 which is the feedback data of the estimated position information.
Then, the head-to-head offset setting means 29b adds the head-to-head offset information previously measured to correct the head-to-head offset.

Next, the operation of the conventional magnetic disk device will be described with reference to the drawings.

FIG. 4 is a flow chart for explaining the operation of the conventional magnetic disk device.

The position data is read from the magnetic disk (step 8) and the current position is calculated (step 9).
Whether or not the head is switched is confirmed (step 10), and when the head is switched (step 10, Yes), the offset amount between the heads is read (step 11), and the offset between the magnetic heads is corrected (step 12). Observer calculation is performed based on the result (step 13), and the control current value is set (step 14). When the head is not switched (step 10, No), observer calculation is performed (step 13) and the control current value is set (step 14).

[0012]

In the above-described conventional magnetic disk device, since the head-to-head offset is measured in advance, time is required to measure the head-to-head offset, and the magnetic disk device is also required. Since the amount of head-to-head offset changes due to temperature changes, the head-to-head offset must be remeasured at regular intervals, and the head-to-head offset correction amount may not be accurate depending on the measurement time interval. However, there is a problem that the reliability of the device is reduced.

[0013]

A magnetic disk apparatus according to the present invention comprises at least one magnetic disk activated by a spindle, a magnetic head for reading and writing data in the vicinity of the surface of the magnetic disk, and It has an actuator mechanism that moves the magnetic head to a desired cylinder position, a position control circuit that drives this actuator mechanism, a data read / write circuit, and an interface circuit with a host device, and performs position control calculation in each servo sector. In a magnetic disk device that uses the position control calculation of the estimated observer method as the calculation method performed inside the microcomputer, when the magnetic head that is reading position information is switched to another magnetic head and read, the offset between magnetic heads Estimated position of this sector with correction calculated in the previous sector When is characterized by performing control a difference between the measured position detected by the position detecting means of this sector by using the control parameter calculation follows sector.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a flow chart for explaining the operation of an embodiment of the magnetic disk device of the present invention, FIG. 2 is a block diagram of the magnetic disk device of the present embodiment, and FIG. 3 is of the present embodiment. 3 is a block diagram of a predictive observer control circuit used in the magnetic disk device. FIG.

First, the magnetic disk device of the present embodiment will be described with reference to FIG.

The magnetic disk device of the present embodiment has at least one magnetic disk 30 activated by a spindle motor 42, and a magnetic head 31 for reading and writing data in the vicinity of the surface of the magnetic disk 30.
An actuator mechanism 32 for moving the magnetic head 31 to a predetermined cylinder position, a position control circuit 41 for driving the actuator mechanism 32, a data read / write circuit 35, and an interface circuit 60 with a host device. To be done.

The position control circuit 41 comprises a servo decoder 36, an ADC 38, a microcomputer 39, a DAC and a power amplifier 33. And the spindle motor 4
2 from the magnetic disk 30 to the magnetic head 3
The signal obtained by using 1 is input to the servo decoder 36 through the R / W circuit 35 and is input to the microcomputer 39.
The control current value 18 obtained by calculating the control parameters inside the microcomputer 39 is passed through the DAC 34 to the power amplifier 33.
Is output, and the actuator 32 is driven.

Next, the predictive observer control method of the position control circuit 41 used in the magnetic disk device of this embodiment will be described with reference to FIG.

The position control circuit 41 of the predictive observer control system has an estimated position (Pe) 27 and an estimated speed (Ve).
Observer calculating means (observer) 28 for calculating 26
, A speed profile generating means 15 for generating a target speed from the estimated position (Pe) 27, and a current data generating means for generating a control current value from the target speed and the estimated speed (Ve) 26 calculated by the observer 28 ( Current gain)
16 and the control current value (U
pv) 17, the estimated disturbance (Dist) 21 output from the observer 28, the disturbance control current value (Udst) 18 generated by Upv 17 and Dist 21, and Udst
Digital-analog conversion means (D-A conversion of 18) (D
AC) 19, current generating means (AMP) 20 for converting the output of the DAC 19 into a current, and drive means (actuator) 2 driven by the current flowing by the AMP 20.
3, an analog-digital conversion means (ADC) 25 for A / D converting the position information obtained by driving the actuator 23, and the estimation of the previous sector based on the position information (Pa) 24 obtained by the ADC 25. Position (Pe_
d) The head-to-head offset setting means 29a calculated from the difference from 22).

The difference between the estimated position (Pe_d) 27 calculated by the observer 28 in the previous sector and the measured position (Pa) 24 of this sector is used as head-to-head offset information to estimate the position (Pe_d) 2 of the previous sector when the head is switched.
In addition to 2. As a result, in the calculation by the observer 28 at the time of head switching, a sudden parameter change due to head offtrack (Pe_d22 of the previous sector).
And the difference between Pa24) can be eliminated, and smooth control can be performed.

Next, the operation of the magnetic disk device of this embodiment will be described with reference to FIG.

The position data is read from the magnetic disk device (step 1) and the current position (step 2) is calculated. Whether or not the head is switched is confirmed (step 3), and when the head is switched (step 3, Yes), the difference between the measured position and the estimated position (Pe_d) calculated one sector before is calculated (step 4). This difference is added to the estimated position (Pe_d) one sector before as the correction of the off-track between heads as a parameter for observer calculation (step 5).
Observer calculation is performed using this estimated position (Pe_d) (step 6), and the control current value is set (step 7). When the head is not switched (step 3,
No), observer calculation is performed (step 6), and the control current value is set (step 7).

[0024]

As described above, the magnetic disk device of the present invention does not require measurement of correction data for head-to-head offset correction, can save time for measurement of correction data when power is turned on, and An effect that the rise time of the disk device can be shortened is achieved.

Further, the magnetic disk device of the present invention is not affected by the deterioration of the response of the head switching operation due to the head-to-head offset change such as temperature change, and it is not necessary to re-measure the head-to-head off-track correction data. It is possible to perform optimum head switching and improve the reliability of the head switching operation of the magnetic disk device.

[Brief description of drawings]

FIG. 1 is a flow chart for explaining the operation of an embodiment of a magnetic disk device of the present invention.

FIG. 2 is a block diagram of a magnetic disk device according to the present embodiment.

FIG. 3 is a block diagram of a predictive observer control circuit used in the magnetic disk device of the present embodiment.

FIG. 4 is a flowchart for explaining the operation of a conventional magnetic disk device.

FIG. 5 is a block diagram of a predictive observer control circuit used in a conventional magnetic disk device.

[Explanation of symbols]

 15 speed profile generation means 16 current data generation means 16 (current gain) 17 control current value (Upv) 18 disturbance control current value (Udst) 19 digital-analog conversion means (DAC) 20 current generation means (AMP) 21 estimated disturbance value (Dist) 22 Estimated position (Pe_d) 23 Drive means (actuator) 24 Measured position (Pa) 25 Analog-digital conversion means (ADC) 26 Estimated speed (Ve) 27 Estimated position (Pe) 28 Observer calculation means (observer) 29a , 29b Head-to-head offset setting means 30 Magnetic disk 31 Magnetic head 32 Actuator 33 Power amplifier 34 DAC 35 R / W circuit 36 Servo decoder 37 Decoder / encoder 38 ADC 39 Microcomputer (microprocessor) 40 Interface Over scan circuit 41 position control circuit 42 a spindle motor

Claims (1)

[Claims] 1. At least one magnetic disk activated by a spindle, a magnetic head for reading and writing data in the vicinity of the surface of the magnetic disk, and an actuator mechanism for moving the magnetic head to a desired cylinder position. And a position control circuit for driving this actuator mechanism, a data read / write circuit, and an interface circuit with a higher-level device. Position control calculation is performed inside each microcomputer in each servo sector, and the estimation method uses an estimated observer as the calculation method. In a magnetic disk drive that uses the method position control calculation, when the magnetic head that is reading position information is switched to another magnetic head and read, the offset correction between the magnetic heads is calculated in the previous sector and the estimated position of this sector is calculated. And detected by the position detection means of this sector Magnetic disk device characterized by performing control using the difference between the measured position to the control parameter calculation follows sector.