JPH08124329A - Head positioning control system and head moving control method for data recording and reproducing device - Google Patents

Abstract

PURPOSE: To shorten an access time by making a moving speed of a head a high speed at the time of speed control in the head positioning control system. CONSTITUTION: A memory 13 is stored with an information table for deciding a driving current amt. of a VCM 6 in response to a seek distance of the head 1. The seek distance of the head 1 is calculated at intervals of a sector pulse, and the driving current amt. is decided from the information table by a CPU 12. A driving current corresponding to the decided driving current amt. is supplied to the VCM 6 to move the head 1 to a target track by a VCM driver 7. In other words, the speed control for moving the head into a target position is executed by so-called feed forward control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk apparatus, and more particularly to a head positioning control system for a data recording / reproducing apparatus for moving and positioning a head at a target position on a disk.

[0002]

2. Description of the Related Art Conventionally, for example, a hard disk drive (HD
D) is a device that uses a disk as a recording medium, records data on the disk with a head, and reproduces data from the disk.

The HDD is provided with a head positioning control system for positioning the head at a target position (target track) on the disk to be accessed.
This system controls the drive current amount (control amount) of a voice coil motor (VCM) that gives a rotational drive force to a head actuator (carriage) that holds the head, and moves the head in the radial direction of the disk. Positioning control is performed on the target track.

In the HDD, each track on the disk is provided with a servo area in which servo information is recorded in advance, in addition to a user data area (data sector) for reading / writing user data. Servo information is roughly classified into a cylinder code (track address) and burst data. The cylinder code is data for detecting a current track of the head, which is used for speed control described later. The burst data is control data used for position control for positioning the head at the center of the target track and detecting a position error of the head with respect to the center.

The system executes head positioning control, which is roughly divided into speed control and position control. Speed control
Also called seek control, it is a movement control for moving (seeking) the head from the current position to the target track.
In speed control, the system (CPU) calculates a moving distance (seek distance) from the current position of the head to a target track, and obtains a target speed corresponding to the moving distance from a target speed table prepared in advance in a ROM or the like. The target speed table is composed of target speed data showing a speed curve consisting of acceleration, constant speed, and deceleration speed modes for each moving distance.

Every time the system reads servo information from the servo area, the system calculates an error between the obtained target speed and the actual head speed, converts the speed control amount, which is the error, into a drive current, and converts it into a VCM. Supply. That is, the system executes feedback control (so-called follow-up control) so that the speed error of the head is minimized. When the head is moved to the target track by this speed control, the position control is performed to position the head at the center of the target track.

[0007]

Conventionally, a head positioning control system for positioning a head at a target position on a disk performs speed control for moving a head to a target track as described above. This is executed by feedback control that minimizes the error between and.

In such feedback control, if a large amount of current is used to correct a small error, the head cannot be accurately positioned at the target position, so that the drive control cannot always reach the performance limit of the VCM, and the head cannot be controlled. Therefore, the moving speed cannot be increased beyond a predetermined speed. Due to such factors, it is difficult to shorten the time required for the head to move to the target track, and as a result, it has been difficult to shorten the access time.

Since the error correction is executed every time the servo area is read during the seek period, the number of control processing steps increases, and as a result, the moving speed of the head becomes slow. SUMMARY OF THE INVENTION It is an object of the present invention to increase the moving speed of the head during speed control in the head positioning control system, and consequently shorten the access time.

[0010]

The present invention is, for example, a VCM.
In the head positioning control system of the data recording / reproducing apparatus that controls the speed of the drive current to move the head to the target position, the drive current amount is calculated based on the speed characteristic according to the moving distance to the target position. Table storing means for storing an information table for determining the moving distance, moving distance calculating means for calculating the moving distance of the head from the current position, determining means for determining the drive current amount corresponding to the calculated moving distance, and the determined The system includes a drive control unit that supplies a drive current according to the drive current amount to the VCM to move the head to a target position.

[0011]

In the present invention, V is previously determined according to the moving distance of the head.
A table storage means for storing an information table for determining the CM drive current amount is prepared. In the information table, speed characteristics according to the moving distance are set, and the driving current amount data is set based on the speed characteristics. The moving distance calculating means calculates the moving distance to the target position based on the current position of the head detected at a predetermined sample interval. The drive current amount corresponding to this moving distance is searched and determined from the information table. The drive control means supplies a drive current according to the determined drive current amount to the VCM to move the head to the target position. That is, in the present invention, the speed control for moving the head to the target position is executed by so-called feedforward control (open loop control).

[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. 2A is a conceptual diagram for explaining speed control according to the embodiment, and FIG. 2B is information about the embodiment. FIG. 3 is a conceptual diagram for explaining the contents of the table, FIG. 3 is a flow chart for explaining the operation of the same embodiment, and FIGS. 4 and 5 are views showing characteristic diagrams of speed control according to the same embodiment. (Structure of HDD) In this embodiment, an HDD head positioning control system is assumed. As shown in FIG. 1, the HDD has a head 1 for reading / writing data from / to a disk 2 which is a recording medium. One or a plurality of disks 2 are provided, and in the same embodiment, there is one disk 2 for convenience. The disk 2 is rotated at a high speed by the spindle motor 3. The spindle motor 3 is driven by a motor driver.

The head 1 is held by a head actuator 5, and a plurality of heads 1 are provided on both sides of one disk 2. The head actuator 5 is the head 1.
Is a carriage that moves in the radial direction of the disk 2, and is rotationally driven by the driving force of the voice coil motor (VCM) 6. The VCM 6 is driven by the drive current supplied from the VCM driver 7. The VCM driver 7 is a D / A
The control circuit 14 converts the control amount output from the CPU 12 into an analog signal and supplies the analog signal.

The read / write circuit 8 usually comprises a dedicated integrated circuit and executes signal processing of read / write data. That is, the read / write circuit 8 writes the write data (N) transferred from the disk controller (HDC) 9.
RZ encoded data) is converted into a write signal (write current) and output to the head 1, and the read signal output from the head 1 is converted into digital read data. Further, the read / write circuit 8 outputs a read signal for generating the burst data BD of the servo information and the cylinder code CD to the servo controller 11, as described later.

The HDC 9 constitutes an interface between the HDD and the host system (host computer) 10,
Data and various interface signals are transferred between the HDD and the host system 10. The HDC 9 receives the write data transferred from the host system 10 and outputs it to the read / write circuit 8. In addition, the read data reproduced by the read / write circuit 8 is transferred to the host system 1
Transfer to 0. Further, the HDC 9 transfers a command or the like issued from the host system 10 to a control device (CPU) 12 that controls the HDD.

The CPU 12 is a control microprocessor for executing various control processes such as servo control.
The head positioning control related to the embodiment is executed. C
The PU 12 operates according to a program stored in the memory (for example, ROM) 13. The memory 13 stores an information table (see FIG. 2B) necessary for speed control according to the embodiment.

The D / A conversion circuit 14 converts the speed control amount output from the CPU 12 into an analog signal (voltage signal) and outputs it to the VCM driver 7. VCM driver 7
Converts the analog signal output from the D / A conversion circuit 14 into a drive current and supplies the drive current to the VCM 6.

The CPU 12 outputs burst data BD and cylinder code CD output from the servo controller 11.
And head positioning control is performed using sector pulses. The servo controller 11 has a function of extracting the cylinder code CD from the read signal (read pulse train) output from the read / write circuit 8 and generating a sector pulse. Further, the servo controller 11 subjects the read signal (analog signal) output from the read / write circuit 8 during position control to A / D conversion processing to generate burst data BD. The CPU 12 uses the burst data B
The position error of the head 1 with respect to the center of the target track is calculated from D.

Next, the operation of the embodiment will be described with reference to FIG.
It will be described with reference to FIG. (Basic operation of head positioning control) As described above, the head positioning control is roughly divided into speed control (seek control) and position control (narrowly defined positioning control). The present invention relates to speed control, and is, so to speak, a feedforward control system (open loop control system) as compared with a conventional feedback control system.

First, when a command (read / write command) including a logical address to be accessed is issued from the host system 10, the HDC 9 performs a target address to be accessed (a sector to be accessed) by an address conversion process into a physical address. Including).

As will be described later, the CPU 12 moves (seeks) the head 1 to a target track on the disk 2 by speed control. When you move to the target track, CP
U12 shifts to position control. For position control, CPU1
2 receives the burst data BD and calculates the position error between the head 1 and the center of the target track. The head 1 is drive-controlled so as to minimize this position error.

By such head positioning control, the head 1 positioned at the center of the target track reads / writes data to / from the target sector included in the target track.
Perform a write. (Operation of Speed Control) Next, the speed control of the embodiment will be described.

First, as shown in step S1 of FIG.
The HDC 9 determines the target track to which the head 1 should move. The CPU 12 calculates the moving distance (seek distance) to the determined target track (step S).
2).

That is, as shown in FIG. 2A, for example, if the current position of the head 1 obtained based on the cylinder code is the track number (1) and the target position is the track number (n). , CPU 12 calculates the number of tracks, which is the seek distance from the current position to the target position.

Next, the CPU 12 searches the information table 13a stored in the memory 13 to obtain the drive current amount corresponding to the calculated seek distance (step S3). This drive current amount is a control amount for determining the drive current supplied to the VCM 6 for driving the head 1.

Here, as shown in FIG. 2B, the information table 13a stored in the memory 13 has the drive current amount data (I) for the seek distance (D1, D2, D3 ...).
D1, ID2, ID3 ...). In the embodiment, the drive current amount data is S1 to S as shown in FIG.
It is set as data corresponding to 6 sample intervals. Specifically, the drive current amount data is set by an experimental method such as simulation using a computer. Therefore, as a result, the velocity characteristic is obtained as a velocity curve with respect to the seek distance (D) as shown in FIG. 5 (B). In FIG. 5B, S1 to S6 represent sample intervals.

The sample interval corresponds to the sector pulse interval in the case of HDD (see FIG. 4A). HDD
Then, the CPU 12 detects the current track position of the head according to the cylinder code CD read by the head 1 in synchronization with the detection timing of the sector pulse SP. As shown in FIG. 2A, the sector pulse SP is generated by the sector pattern (including the index pattern) recorded in the servo area SA provided on each track. That is, the servo controller 11 generates the sector pulse SP based on the sector pattern read from each servo area SA by the head 1.

The CPU 12 generates and detects the sector pulse S while the head 1 is moving to the target track.
At the timing P, the current position of the head 1 is detected. In the present invention, the update of the drive current according to the seek distance to the target track is performed in 6 stages at the timing of the sector pulse SP. Specifically, as shown in FIG. 4A, until the target track is reached (until seek end)
For example, 6 sector pulse SP (sample intervals S1 to S
The amount of drive current for 6) is updated. In this case, the velocity characteristic up to the target track with respect to the sample intervals S1 to S6 becomes a velocity curve as shown in FIG. Also,
The seek distance for the sample intervals S1 to S6 is shown in FIG.
The characteristic curve is as shown in FIG.

The CPU 12 supplies the drive current of the drive current amount determined at the timing of the sector pulse SP as described above to the V / V converter 7 via the D / A conversion circuit 14 and the VCM driver 7.
It is supplied to the CM 6 and the head 1 is moved to the target track (step S4).

That is, based on the drive current amount determined according to the seek distance, for example, when the moving distance is D1,
As shown in FIG. 4A, a current value (+ I1) is supplied to the VCM 6 at the initial stage (+ indicates an increase in the drive current amount). This current value (+ I1) is the next sector pulse SP
Is supplied, that is, during the period of one sector interval S1. Then, when the next sector pulse is detected, the current value is changed to (+ I2) and similarly supplied for the period of one sector interval S2.

Similarly, the current value (+ I1) is supplied in the sector interval S3, and the current value (-I) is supplied in the sector interval S4.
1) is supplied (-indicates a decrease in drive current amount). A current value (-I2) is supplied in the sector interval S5, and a correction current amount (-I1 + x or-) as described later is supplied in the sector interval S6.
I1-x) to move to the target track.

The CPU 12 compares the current position of the head 1 with the target position, and if they match, determines that the target track has been reached, and ends seek (YES in step S5).
That is, the speed control operation is shifted to the position control operation (step S6). (Correction operation) When approaching the target track, the CPU 12 compares the target seek distance with the distance actually moved by the head 1 (actual movement distance) (step S7).

Since the speed control of the embodiment is a feedforward control system, it is basically executed by the processing from step S2 to step S5. However, in the actual control operation, since the drive current amount is updated every time the sector pulse SP is generated, a situation in which the head 1 passes the target track or, conversely, a situation in which the head 1 does not reach immediately before the target track may occur. There is a nature.

Therefore, in the same embodiment, as shown in FIG. 4A, in the case of a seek operation for completing a series of seeks with 6 sector pulses, for example, the CPU 12 executes
At the sector pulse (fifth sample), the above step S
The process of 7 is executed. According to the comparison result, the actual moving distance of the head 1 is the target seek distance (the distance to move at this point)
If it matches with, the speed control is continued as it is (YES in step S8).

On the other hand, if the comparison results do not match, CP
U12 determines the correction current amount for executing the speed control correction process (step S9). This corrected current amount is stored in the memory 13 as an information table 13a for speed control.
It is determined by a correction table prepared separately from (see FIG. 7). Alternatively, using the information table 13a, the CP
U12 is the amount of error (±) between the actual movement distance and the target seek distance
The correction current amount may be calculated based on According to the comparison result, when the head 1 is passing the target track, the CPU 12 determines the correction current amount (-) for reducing the drive current amount at the time of the next 6 sector pulse SP.
On the other hand, if it has not arrived, the CPU 12 determines the correction current amount (+) for increasing the drive current amount at the time of the next 6-sector pulse SP.

By such processing, at the time of the sixth generation of the sector pulse SP, the CPU 12 supplies the drive current including the determined correction current amount to the D / A conversion circuit 14 and the VC.
The voltage is supplied to the VCM 6 via the M driver 7, and finally the head 1 reaches the target track (step S4). (Modification) In the above-described embodiment, the amount of drive current supplied to the VCM 6 is determined so that the movement is completed at 6 pulse intervals according to the movement distance to the target track. Therefore, regardless of the length of movement, it is necessary to switch the drive current in six steps to move to the target track.

However, when the moving distance is long, in order to complete the moving in six steps, the driving current amount must be made very large. Also, if the travel distance is short,
In some cases, it is not necessary to move in 6 stages.

Therefore, as a modified example of the embodiment, the content of changing the supply pattern of the drive current (that is, the number of steps according to the sector pulse) according to the seek distance will be described.

First, as shown in FIG. 9, the information table 13a stored in the memory 13 stores the drive current data corresponding to the pattern according to the length of the moving distance. Specifically, drive current data ID1 to IDA corresponding to D1 to DA having a relatively short moving distance are stored. As shown in FIG. 6, the drive current data ID1 to IDA are used during speed control in which the movement is completed at 4-sector pulse intervals (4 stages).

The drive current data IDA + 1 to IDB corresponding to the movement distances DA + 1 to DB are used at the time of speed control in which the movement is completed at 6 sector pulse intervals (6 steps) in the above embodiment.

Further, DB + 1 to DB + 1 to which the moving distance is relatively long.
The drive current data IDB + 1 to IDN corresponding to DN are
As shown in FIG. 8, it is used during speed control in which movement is completed at 8-sector pulse intervals (8 stages).

According to such a modification, the pattern of the drive current data obtained from the information table 13a is switched according to the moving distance. Therefore, when the movement distance of the head is relatively short, the movement can be completed with a small sector pulse interval, and thus the movement time can be shortened. Further, when the moving distance of the head is relatively long, the movement is completed at a relatively large number of sector pulse intervals, and as a result, the maximum current value to be supplied to the VCM 6 can be reduced. This allows
It is possible to reduce the power consumption of the entire device or reduce the size of the VCM 6.

According to this embodiment, the information table 13a prepared in advance is used to determine the drive current amount according to the seek distance to the target track at sector pulse intervals, and this drive current is supplied to the VCM. As a result, the head 1 is moved to the target track based on the speed characteristic according to the seek distance (see FIG. 5B). That is, in the embodiment, the processing for obtaining the error between the actual speed of the head 1 and the target speed each time the servo information is detected during the seek period as in the conventional case is not executed, but a predetermined value is determined based on the seek distance. A drive current that is updated stepwise at the sample interval (sector pulse interval) is supplied to the VCM. In other words, in contrast to the speed control by the conventional feedback control method, the embodiment is speed control by the feedforward control method. As a result, the drive current amount can be determined in consideration of the performance limit of the VCM, and the number of control steps during seek is reduced, so that the moving speed of the head 1 can be increased as compared with the conventional case. Become.

In order to improve the accuracy of speed control, in this embodiment, a correction process for determining a correction current amount based on an error amount (±) between the actual movement distance and the target seek distance immediately before the arrival of the target track. I do. By adding this correction current amount to the final stage drive current amount, the movement accuracy of the head 1 can be improved.

[0045]

As described above in detail, according to the present invention, in the head positioning control system, the speed control is executed by the so-called feedforward control, so that the motor for driving the head is drive-controlled to the performance limit. It becomes possible. Therefore, it is possible to increase the moving speed when moving the head to the target position by speed control. As a result, when the head is positioned at the target position to be accessed and the access is executed, the access time can be shortened as a result.

[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. 2A is a conceptual diagram for explaining speed control according to the embodiment, and FIG. 2B is a conceptual diagram for explaining contents of an information table according to the embodiment.

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

FIG. 4 is a characteristic diagram of speed control according to the embodiment.

FIG. 5 is a characteristic diagram of speed control according to the embodiment.

FIG. 6 is a conceptual diagram for explaining speed control according to a modified example of the same embodiment.

FIG. 7 is a conceptual diagram for explaining a correction operation according to the embodiment.

FIG. 8 is a conceptual diagram for explaining speed control according to a modified example of the embodiment.

FIG. 9 is a conceptual diagram for explaining the contents of an information table according to a modified example of the same embodiment.

[Explanation of symbols]

1 ... Head, 2 ... Disk, 5 ... Head actuator, 6 ... Voice coil motor (VCM), 7 ... VCM driver, 8 ... Read / write circuit, 9 ... Disk controller (HDC), 11 ... Servo controller, 12 ...
Control device (CPU), 13 ... Memory, 14 ... D / A conversion circuit.

Claims (7)

[Claims] 1. A head positioning control system for a data recording / reproducing apparatus, which controls a head for reading / writing data at a target position on a disk which is a recording medium based on servo information recorded on the disk. Motor means for moving the head; current position calculation means for calculating the current position of the head based on the servo information; movement distance calculation means for calculating a movement distance from the current position of the head to the target position; Table storage means storing an information table showing the relationship between the moving distance of the head and the amount of drive current to be supplied to the motor means, and the moving distance calculated by the moving distance calculating means by accessing the information table. Determining means for determining the drive current amount corresponding to, and the determining means determined by the determining means. A head positioning control system for a data recording / reproducing apparatus, comprising: a drive control unit that supplies a drive current according to a drive current amount to the motor unit to move the head to the target position. 2. A head positioning control system for a data recording / reproducing apparatus, which controls the position of a head for reading / writing data at a target position on a disk which is a recording medium based on servo information recorded on the disk. Motor means for moving the head, current position calculating means for calculating the current position of the head based on the servo information detected at a predetermined sample interval, and calculation of a moving distance from the current position of the head to the target position And a driving current amount to be supplied to the motor means set based on the moving distance of the head, the driving current amount being set at predetermined sampling intervals for sampling the moving distance. Table storage means for storing an information table in which the information table is set stepwise, and the information table is accessed. Then, a determining unit that determines the driving current amount corresponding to the moving distance calculated by the moving distance calculating unit at the sampling interval, and a driving current corresponding to the driving current amount determined by the determining unit A head positioning control system for a data recording / reproducing apparatus, comprising: a drive control unit that supplies the motor unit to move the head to the target position. 3. A head positioning control system of a data recording / reproducing apparatus, which controls a head for reading / writing data at a target position on a disk which is a recording medium based on servo information recorded on the disk. Motor means for moving the head; current position calculation means for calculating the current position of the head based on the servo information; movement distance calculation means for calculating a movement distance from the current position of the head to the target position; A table storage unit storing an information table for determining the amount of drive current to be supplied to the motor unit set based on the moving distance of the head based on the moving distance, and accessing the information table, Determining the drive current amount corresponding to the moving distance calculated by the moving distance calculating means Determining means, and when the head approaches the target position by the motor means based on the drive current amount determined by the determining means, the actual moving distance of the head and the target position The target current is compared with the target moving distance, and a correction current calculation unit that calculates a correction current amount according to the error of the comparison result; and a drive current according to the correction current amount is supplied to the motor unit to drive the head. A head positioning control system for a data recording / reproducing apparatus, comprising: a drive control unit for moving the head to the target position. 4. A head positioning control system of a data recording / reproducing apparatus, which controls a head for reading / writing data at a target position on a disk which is a recording medium based on servo information recorded on the disk. Motor means for moving the head, moving distance calculating means for detecting the current position of the head from the servo information at the timing of a sector pulse, and calculating a moving distance to the target position, and based on the moving distance of the head Table storage means for storing an information table for determining the amount of drive current to be supplied to the motor means set based on the moving distance, and accessing the information table to perform the operation based on the moving distance. A determining means for determining the drive current amount that increases or decreases for each sector pulse; Drive control means for supplying a drive current according to the determined drive current amount to the motor means to move the head to the target position. Control system. 5. A motor means for moving the head,
A head of a data recording / reproducing apparatus that controls the amount of drive current supplied to the motor means to move the head in the radial direction of the disk and position-controls the head at a target position based on servo information recorded on the disk. In the positioning control system, a step of calculating the current position of the head by detecting the servo information at a predetermined sample interval, and a step of calculating a moving distance from the current position of the head to the target position at the sample interval And an information table for determining the drive current amount set based on the moving distance of the head based on the moving distance in advance, and accessing the information table,
Determining the drive current amount corresponding to the calculated moving distance at the sample interval; supplying a drive current according to the determined drive current amount to the motor means to move the head to the target position. A head movement control method comprising the steps of: 6. A motor unit for moving the head,
A head of a data recording / reproducing apparatus that controls the amount of drive current supplied to the motor means to move the head in the radial direction of the disk and position-controls the head at a target position based on servo information recorded on the disk. In the positioning control system, a step of calculating the current position of the head by detecting the servo information at a predetermined sample interval, and a step of calculating a moving distance from the current position of the head to the target position at the sample interval And an information table for determining the drive current amount set based on the moving distance of the head based on the moving distance in advance, and accessing the information table,
Determining the drive current amount corresponding to the calculated moving distance at the sample interval; supplying a drive current according to the determined drive current amount to the motor means to move the head to the target position. Up to the target position, and when the head approaches the target position, the actual moving distance actually moved by the head and the target moving distance to the target position are compared, and a correction is made according to the error of the comparison result. A head movement control method comprising: a step of calculating a current amount; and a step of supplying a driving current according to the calculated correction current amount to the motor means to execute movement correction of the head. . 7. A head positioning control system of a data recording / reproducing apparatus, which controls a head for reading / writing data at a target position on a disk which is a recording medium based on servo information recorded on the disk. Motor means for moving the head; current position calculation means for calculating the current position of the head based on the servo information; movement distance calculation means for calculating a movement distance from the current position of the head to the target position; A drive current amount pattern that is a drive current amount to be supplied to the motor means based on the moving distance of the head and that gradually changes the drive current amount at every predetermined sampling interval for sampling the moving distance. A table storage unit that stores an information table for determining each moving distance; Determining means for determining the drive current amount pattern corresponding to the moving distance calculated by the moving distance calculating means, and a drive current corresponding to the driving current amount pattern determined by the determining means. And a drive control means for moving the head to the target position by supplying the motor to the motor means.