JPH0991901A - Data recording / reproducing apparatus and fast seek control method in the apparatus - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To prevent runaway of the head by detecting that the head has moved to the data zone even when the servo data cannot be read correctly during the first seek. SOLUTION: At the time of start-up, a current is passed through a VCM (voice coil motor) to start a first seek for moving a head out of a CSS zone of a disk and moving it to a data zone (step S1). When servo data is obtained from the head in response to the start, seek / positioning control is started in accordance with the servo data (steps S2 and S3), and when servo data is not obtained, it is caused by VCM acceleration. Based on the voltage across the coil of the VCM 15 that changes due to the back electromotive force, it is determined whether or not the head is out of control (steps S2 and S4). If it is determined that the head is out of control, VC is determined.
M is stopped and the first seek is stopped (steps S5 and S6).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data recording / reproducing apparatus and a data recording / reproducing apparatus for controlling seek / positioning of a head for recording / reproducing data on a specified position on the disk based on servo data recorded on the disk. According to the fast seek control method in the device, in particular, in a non-operating state, a head located in a specific zone where servo data is not recorded is allowed to escape from the specific zone (servo data is recorded) to a data zone. The present invention relates to a data recording / reproducing apparatus suitable for preventing head runaway during a first seek for moving and a fast seek control method in the apparatus.

[0002]

2. Description of the Related Art Generally, a data recording / reproducing apparatus, such as a magnetic disk apparatus (hard disk), for controlling seek / positioning of a head for recording / reproducing data to a specified position on the disk based on servo data recorded on the disk. In the device), when the head is in a non-operating state (disk rotation stop state), CSS (Contact StartS
It is located in a specific zone (specific area) where servo data is not recorded. This CSS zone is usually provided on the innermost side (or the outermost side) of the disc. Then, at startup (when the disk is rotating), the head is moved from the CSS zone to the data zone (data area where servo data is recorded). This movement is called first seek.

When not in operation, the head is mechanically fixed to the CSS zone by magnetic force or the like. Therefore, the fast seek cannot be performed by the normal seek operation. That is, in the fast seek, in order to escape the head fixed in the non-operating state from the CSS zone to the data zone side, it is necessary to flow a large current to the voice coil motor (VCM) for driving the head. Then, when the head moves to the data zone by applying a large current to the VCM, the servo data can be fetched from the data zone. Therefore, normal seek / positioning control, for example, a predetermined cylinder (generally, the outermost circumference Seek to position the head in the cylinder)
Move to positioning control.

However, despite the fact that the head has moved to the data zone in the above-mentioned first seek, there may be a case where the servo data cannot be taken in due to some cause such as noise. In this case, since the seek / positioning control is not performed, the VCM continues to accelerate. As a result, the head runs away and collides with a stopper provided on the opposite side of the CSS zone.

[0005]

As described above, in the conventional data recording / reproducing apparatus represented by the magnetic disk apparatus, although the head moves to the data zone in the first seek, the servo data is correctly written for some reason. When an unreadable state occurs, the VCM continues to accelerate as it is, so that the head may run away and collide with the stopper, which may damage the head itself or the disk.

The present invention has been made in consideration of the above circumstances, and an object thereof is to monitor the counter electromotive force of a VCM (voice coil motor) even when the servo data cannot be correctly read for some reason during the first seek. To provide a data recording / reproducing apparatus and a fast seek control method in the apparatus, which can detect the head moving to a data zone and prevent the head from running out of control, thereby preventing the head and the disk from being damaged. It is in.

[0007]

SUMMARY OF THE INVENTION The present invention is a data recording / reproducing apparatus for controlling seek / positioning of a head to a designated position on the disk based on servo data recorded on the disk, and by driving the voice coil motor, the head is driven. The head is moved from the CSS zone (a specific zone in which servo data is not recorded to keep the head in the non-operating state) at the time of startup by using the head moving means for moving the head in the radial direction of the disk. When the servo data is obtained from the head in response to the start of the first seek by the first seek means for performing a fast seek to move to the data zone, seek / positioning control is performed according to the servo data. Seek control means to start and back electromotive force of the voice coil motor If the servo data is not obtained from the head after the start of the first seek by the counter electromotive force monitoring means for monitoring the above, the first seek by the first seek means is stopped based on the monitoring result of the counter electromotive force monitoring means. And a first seek control means for controlling the seek.

Further, according to the present invention, in the case of a data recording / reproducing apparatus having a plurality of heads, the first seek control means stops the first seek and then switches to another head to retry the first seek by the first seek means. It is also characterized by having done.

In the above structure, when the first seek is started at the time of start-up and a current is applied to the VCM to escape the head from the CSS zone, the head moves to the data zone. When the head moves to the data zone, the servo data recorded in the data zone is normally obtained by the head, and therefore the normal seek / positioning control is performed based on the position information of the servo data.

However, if the servo data cannot be obtained for some reason, the normal seek / positioning control cannot be performed, and the VCM continues to accelerate, so if this state continues, the head collides with the stopper.

When the VCM is driven at high speed, a counter electromotive force is generated in the VCM, and the voltage at the coil end of the VCM changes due to the counter electromotive force. Therefore, the counter electromotive force means is
By monitoring the change in the voltage at the CM coil end, it is possible to monitor the VCM counter electromotive force during the first seek.

Therefore, the fast seek control means starts the fast seek, a current is passed through the VCM, and when the change in the VCM coil end voltage due to the back electromotive force is confirmed and the servo data is not obtained, the head is moved. It is possible to determine that the servo data is not obtained despite the movement from the CSS zone to the data zone and the VCM continues to be accelerated, that is, the head is out of control.
In this case, the first seek control means stops the VCM to stop the first seek, and prevents the head from continuing to runaway and colliding with the stopper.

As described above, in the above configuration, the head runaway during the first seek is detected immediately by monitoring the counter electromotive force of the VCM and the first seek is stopped, so that the head continues to run away. It is possible to prevent the collision with the stopper and prevent the head and the disk from being damaged.

In the case of a data recording / reproducing apparatus having a plurality of heads such that the heads are provided on both sides of one disk in the above structure, the heads at the time of first seek are When a runaway is detected and the first seek is stopped, the head is switched and another first seek is attempted again. In this case, since a head different from the previous head is used for the first seek, the probability of failing the first seek again is extremely low, and the reliability of the apparatus is improved.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a magnetic disk drive according to one embodiment of the present invention.

In FIG. 1, 11 is a disk which is a medium for recording data, and 12 is a head used for writing data to the disk 11 (data recording) and reading data from the disk 11 (data reproduction). The head 12 is provided corresponding to each data surface of the disk 11.

As shown in FIG. 2, a large number of concentric tracks are formed on both sides of the disk 11, and each track has a plurality of servo areas 112 in which servo data used for positioning control is recorded. Are arranged radially from the center at equal intervals. A user area 113 is provided between the servo areas 112. And
One servo area 112 and one user area 113 following it form one servo sector 111. A plurality of data sectors 114 are set in the user area 113 of each servo sector 111.

In the servo data recorded in the servo area 112, sector data indicating a servo sector number, cylinder data indicating a cylinder number (cylinder address), and position information (position error in the cylinder indicated by the cylinder data) are amplitude of a waveform. A burst signal (burst data), which is data for indicating, is included.

In the example of FIG. 2, the disk 11 is a CDR (Cons
(Tant Density Recording) method (format) is applied. Here, the disk 11
The upper part is radially divided into a plurality of zones Z1 to Z3, and the number of constituent data sectors is different for each zone Z1 to Z3.

Further, in FIG. 2, only the data zone in which the servo sector 111 is arranged is shown, but the servo area 112 is not provided, that is, the servo data is recorded, for example, on the innermost circumference side of the disk 11. No CSS zone (not shown) is reserved. The head 12 is mechanically fixed to this CSS zone by magnetic force or the like in the non-operating state (when the rotation of the disk 11 is stopped). That is, the head 12 is retracted to the CSS zone in the non-operating state.

Referring again to FIG. 1, the disk 11 is rotated at high speed by a spindle motor (SPM) 13.
The head 12 is attached to a head moving mechanism called a carriage 14 and moves in the radial direction of the disk 11 by the movement of the carriage 14. The carriage 14 is driven by a voice coil motor (VCM) 15.

The SPM (spindle motor) 13 is connected to an SPM driver 16 for supplying a control current to the SPM 13 to drive the SPM 13, and the VCM (voice coil motor) 15 supplies a control current to the VCM 15. It is connected to a VCM driver 17 for driving the VCM 15. Value of this control current (control amount)
Is determined by a calculation process of the CPU (microprocessor) 21 and given as an analog value.

Each head 12 is connected to a head IC 18 mounted on, for example, a flexible printed wiring board (FPC). The head IC 18 has a head amplifier 181 that amplifies the analog output read by the head 12.

The head IC 18 is a read / write IC 19
Is connected to The read / write IC 19 inputs the analog output (read signal of the head 12) amplified by the head amplifier 181 in the head IC 18, and performs signal processing necessary for data reproducing operation, for example, analog output to N
Signal processing for conversion into RZ data is performed. The read / write IC 19 also performs signal processing necessary for data recording operation, for example, data that modulates NRZ data (write data) sent from the HDC (disk controller) 26 and writes it on the disk 11 (for example, 2-7 and 1). -7
Signal processing for conversion into modulated data) is also performed.

The read / write IC 19 also reproduces information (servo data) in the servo area 112 necessary for servo processing such as head positioning control, in addition to the normal user data recording / reproduction processing described above (read from the head 12). A process of extracting a data pulse by pulse peak detection targeting a signal and a process of sampling and holding the peak of the read signal and outputting an analog signal including a burst signal) are performed.

The read / write IC 19 is connected to a servo processing circuit 20 which executes signal processing required for servo processing. This servo processing circuit 20 is a read / write I
It has a decoding function of extracting and decoding cylinder data (cylinder number) and the like from (the servo data included in) the data pulse from C19.

The CPU 21 is, for example, a one-chip microprocessor. The CPU 21 constitutes a servo processing system (head positioning control mechanism) that executes head positioning control together with the servo processing circuit 20.
The cylinder data extracted by the servo processing circuit 20 is read from the servo processing circuit 20 to read / write IC.
The peak hold signal of the burst signal is read from 19 and the current position is calculated. In addition to head positioning control, the CPU 21 also controls read / write data transfer by controlling the HDC 26.

The CPU 21 also controls a first seek for moving the head 12 out of the CSS zone of the disk 11 and moving to the data zone at the time of startup. CPU2
1 is an A / D converter 24 which will be described later with reference to the voltage change across the coil of the VCM 15 during the first seek control.
The counter electromotive force of the VCM 15 is monitored by monitoring via V., and the control for stopping the first seek by detecting the runaway of the head 12 is also performed depending on the monitoring result and the presence or absence of the servo data read by the servo processing circuit 20.

The CPU 21 includes a D / A converter 22 for converting the data representing the control amount obtained by the servo processing, that is, the value of the current to be passed through the SPM 13 by the SPM driver 16 into analog data and outputting the analog data to the SPM driver 16. , D / A converter 2 for converting the data representing the value of the current to be passed through the VCM 15 by the VCM driver 17 into analog data and outputting the analog data to the VCM driver 17.
3 are connected.

The CPU 21 is also connected to an A / D converter 24 for converting the voltage across the coil of the VCM 15 into digital data that can be read by the CPU 21, and a ROM 25 as a non-volatile memory. A control program for the CPU 21 and the like are stored in the ROM 25 in advance.

The disk controller (HDC) 26 serves as an interface between the host device and the magnetic disk device, and mainly controls the transfer of read / write data. Next, the operation of the configuration of FIG. 1 will be described with reference to the flowchart of FIG.

First, at startup, the CPU 21 controls the SPM driver 16 through the D / A converter 22 to execute S
The PM 13 is driven to start the rotational movement of the disk 11. Then, the CPU 21 starts the first seek for causing the head 12 retracted to the CSS zone of the disk 11 in the non-operating state to escape from the CSS zone and move to the data zone. At this time, CP
In order to make the head 12 escape from the CSS zone, the U 21 controls the D / A converter 23 with a control amount corresponding to a current value sufficient to withstand a force such as a magnetic force fixing the head 12 in the CSS zone. The VCM driver 17 supplies a current (constant current in this case) determined by this control amount to V
It is made to flow to CM15 (step S1).

When a current flows through the VCM 15, the VCM
15 drives (generates a rotational force) to move the carriage 14. Then, the head 12 attached to the carriage 14 moves in the radial direction of the disk 11, and eventually comes out of the CSS zone of the disk 11 and moves to the data zone. When the head 12 moves to the data zone, it becomes possible to acquire the data (servo data) of the servo area 112 recorded on the disk 11.

When a current is passed through the VCM 15 to start the fast seek, the CPU 21 reads the voltage across the coil of the VCM 15 in the form of digital data through the A / D converter 24 after a predetermined time tc, and the voltage ( Reference voltage (reference voltage value) Vc
Set as Here, the time tc will be described.

First, when a large current flows through the VCM 15 and the VCM 15 is driven at a high speed, a counter electromotive force is generated in the coil of the VCM 15, and the VC causes the counter electromotive force.
The voltage at the coil end of M15 changes. Figure 4 shows this situation.
Shown in (a) and (b).

FIG. 4A shows normal seek / positioning control because servo data is not captured by the head 12 even if the head 12 moves out of the CSS zone and moves to the data zone by driving the VCM 15. As a result of not being able to move and VCM15 continuing to accelerate, VCM15
It shows a state in which the voltage at the coil end of 15 increases.

On the other hand, as shown in FIG. 4B, as a result of the head 12 escaping from the CSS zone and moving to the data zone by the driving of the VCM 15, servo data is taken in by the head 12 and shifts to normal seek / positioning control. Then, the voltage at the coil end of the VCM 15 falls within a substantially constant range.

As is apparent from FIGS. 4 (a) and 4 (b),
The voltage value at the coil end of the VCM 15 decreases at the beginning when a current starts flowing through the VCM 15. This is VCM
This is due to the transient response of the 15 coils. When the transient response time has passed, the voltage value at the coil end of the VCM 15 is VCM1 until the seek / positioning control is performed.
It increases with the back electromotive force accompanying the acceleration of 5. Therefore, even though the head 12 moved to the data zone, seek
If the current of the same value as that at the start of the fast seek is flowing in the VCM 15 without shifting to the positioning control, the VCM 1
The voltage value at the coil end of No. 5 increases more and more as shown in FIG. Then, if the state as it is continues, the head 12 collides with the stopper.

Therefore, in the present embodiment, after the current starts flowing through the VCM 15 (from the start point of the first seek).
Time t until the voltage at the coil end of the VCM 15 becomes minimum t
By measuring c at the manufacturing stage of the disk device and setting it in the ROM 25, from the time when this time tc has elapsed,
The CPU 21 can monitor the voltage change at the coil end of the VCM 15.

That is, when the time tc elapses after the current starts flowing through the VCM 15, the CPU 21 first detects the V at that time.
The voltage across the coil of the CM 15 is read in the form of digital data through the A / D converter 24, and the voltage (voltage value) is set as the reference voltage (reference voltage value) Vc.
After that, the CPU 21 sequentially reads the voltage V across the coil of the VCM 15 through the A / D converter 24, and determines whether the difference between the voltage V and the reference voltage Vc (that is, the voltage change amount) exceeds a predetermined threshold value Vth. Find out. As a result, although the head 12 escapes from the CSS zone and moves to the data zone, servo data is not taken in by the head 12 (including control of the VCM 15) and thus shifts to normal seek / positioning control. No, it can be determined whether the head 12 is out of control. Here, the threshold value Vth is the VCM when the head 12 collides with the stopper.
VCM15 in the state where the voltage is smaller than the voltage value between both ends of the coil of No. 15 and Vc and the seek / positioning control is performed.
A value larger than the difference between the maximum voltage value across the coil and Vc is used and is preset in the ROM 25 together with tc.

Data (servo data) in the servo area 112 recorded on the disk 11 is read by the head 12, and its read output (read signal) is amplified by the head IC 18 and supplied to the read / write IC 19.

In the read / write IC 19, the head I
From the read signal (analog output) from the head 12 amplified by C18, a data pulse (which may include cylinder data in the servo data) is extracted by pulse peak detection. In the read / write IC 19, the read signal from the head 12 is sampled and held to output an analog signal including a burst signal (positional information). An analog signal including the burst signal is converted into digital data by an A / D converter (not shown) and sent to the CPU 21, which is used to control the position error of the head with respect to the track center to zero.

The data pulse extracted by the read / write IC 19 is sent to the servo processing circuit 20. The servo processing circuit 20 inputs and decodes this data pulse, and extracts (decodes) the cylinder data and the like (servo data thereof). If the cylinder data etc. (servo data thereof) can be normally decoded, the servo processing circuit 20 sends the decoded cylinder data etc. (servo data thereof) to the CPU.
Send to 21.

When the time tc elapses after the current starts flowing through the VCM 15, the CPU 21 detects the VCM as described above.
When the voltage across the coils of 15 is read through the A / D converter 24 and the voltage is set as the reference voltage Vc, thereafter, it is determined whether or not the servo data is fetched by the head 12 and extracted and decoded by the servo processing circuit 20. That is, it is checked whether or not the servo data necessary for seek / position control has been acquired (step S2).

If the servo data can be obtained, C
The PU 21 shifts to normal seek / positioning control for positioning the head 12 on a predetermined cylinder, for example, the outermost circumference of the disk 11 according to the servo data (step S3).

On the other hand, if the servo data cannot be obtained, the CPU 21 may be because the head 12 has not escaped from the CSS zone, or may have escaped from the CSS zone and moved to the data zone. In order to check whether the servo data could not be acquired for some reason (that is, whether the head 12 may runaway), the voltage V across the coil of the VCM 15 at that time is set to A /
It is read through the D converter 24. And the CPU 21
Is the difference between the read voltage V and the reference voltage Vc (V-Vc
) Is larger than the threshold value Vth, that is, VCM1
It is determined whether or not the head 12 is out of control depending on whether or not a large counter electromotive force higher than the reference is generated with the acceleration (runaway) of 5 (step S4).

If it cannot be determined that the head 12 is out of control, the CPU 21 returns to step S1 and continues the first seek. On the other hand, because the difference (V−Vc) between the voltage V across the coil of the VCM 15 and the reference voltage Vc is larger than the threshold Vth, that is, the voltage across the coil of the VCM 15 increases above the threshold Vth due to the back electromotive force, and the head 12
When it is determined that the head 12 is out of control because the servo data cannot be obtained even when it is detected that the VCM15 has escaped from the CSS zone, the CPU 21 stops supplying the current to the VCM15 and stops the VCM15. Stop (step S5) and stop the first seek (step S5).
6). As a result, the head 12 can be prevented from running away and colliding with the stopper, and the failure of the head 12 and the disk 11 can be prevented.

Further, the voltage across the coil of the VCM 15 does not change (the voltage V across the coil of the VCM 15 and the reference voltage V
When the difference from c is less than the threshold value Vth) and the servo data cannot be obtained, the VCM 15 cannot be driven and the counter electromotive force does not occur, that is, the head 12 cannot escape from the CSS zone. You can also judge that.

In the case of a magnetic disk device having a plurality of heads 12 as in the configuration of FIG. 1, runaway of the head 12 (due to failure of first seek) is detected as shown in the flowchart of FIG. After the VCM 15 is stopped (steps S12, S14, S15), the head 12 may be switched through the servo processing circuit 20 (step S16), and another head 12 may try a new first seek. That is, when the VCM 15 is temporarily stopped (step S15), head switching is performed (step S16), and then the current is supplied to the VCM 15 again (step S11) to restart the first seek with another head 12 different from the previous time. You may do so. In this case, since a head different from the previous head is used for the first seek, the probability of failing the first seek again is extremely low, and the reliability of the apparatus is improved.

In the above embodiment, VCs that are sequentially detected
The case where the runaway of the head 12 is determined based on whether the difference between the voltage V at the coil end of M15 and the reference voltage VC is larger than the threshold value Vth has been described. However, the detection voltage V itself is set as a preset threshold value. It is also possible to judge the runaway of the head 12 by comparing.

Although the magnetic disk device has been described in the above embodiments, the present invention seeks a head at a specified position on the disk based on servo data recorded on the disk, such as a magneto-optical disk device. The present invention is generally applicable to data recording / reproducing devices that control positioning.

[0052]

As described in detail above, according to the present invention, a runaway of the VCM (voice coil motor) (and hence a runaway of the head) that occurs when servo data cannot be obtained for some reason during the fast seek is promptly detected. Then, since it is possible to prevent the head from colliding with the stopper,
It is possible to prevent the trouble of the head and the disk.

Further, in the data recording / reproducing apparatus having a plurality of heads, if the first seek fails, the other heads try the first seek, so that the reliability of the apparatus can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a magnetic disk drive according to an embodiment of the present invention.

2 is a conceptual diagram showing a format of a disk 11 in FIG.

FIG. 3 is a flowchart for explaining an operation in the case of quickly detecting that the first seek has failed and stopping the first seek in the embodiment.

FIG. 4 shows the VCM15 due to a back electromotive force generated by the VCM15 being driven at a high speed during the first seek.
FIG. 6 is a diagram showing how the voltage at the coil end changes in an abnormal state in which normal seek / positioning control cannot be performed and a normal case in which normal seek / positioning control can be performed.

FIG. 5 is a flowchart for explaining an operation when a first seek is attempted by another head when the first seek fails.

[Explanation of symbols]

 11 ... Disk, 12 ... Head, 13 ... SPM (spindle motor), 14 ... Carriage, 15 ... VCM (voice coil motor), 18 ... Head IC, 19 ... Read / write IC, 20 ... Servo processing circuit, 21 ... CPU , 24 ... A / D converter, 25 ... ROM, 26 ... HDC, 111 ... Servo sector, 112 ... Servo area.

Claims (4)

[Claims] 1. A disk in which a data zone in which servo data is recorded and a specific zone in which servo data is not recorded for keeping a head for recording / reproducing data in a non-operating state are secured. And head moving means for moving the head in the radial direction of the disk by driving a voice coil motor, and seeks the head to a specified position on the disk based on servo data recorded on the disk. In a data recording / reproducing apparatus for controlling positioning, at startup, a fast seek means for performing a fast seek for moving the head out of the specific zone and moving to the data zone by the head moving means, and a fast seek means by the fast seek means At the start of seek, the servo Seek control means for starting seek / positioning control according to the servo data, counter electromotive force monitor means for monitoring counter electromotive force of the voice coil motor, and fast seek means for fast seek. If no servo data is obtained from the head after the start of seek, a fast seek control means for stopping the fast seek by the fast seek means based on the monitoring result of the counter electromotive force monitoring means is provided. Data recording / reproducing device. 2. A data recording / reproducing apparatus having a plurality of the heads, wherein the fast seek control means switches to another head after stopping the fast seek and restarts the fast seek by the fast seek means. The data recording / reproducing apparatus according to claim 1, wherein 3. A disk in which a data zone in which servo data is recorded and a specific zone in which servo data is not recorded for keeping a head for recording / reproducing data in a non-operating state are secured. And head moving means for moving the head in the radial direction of the disk by driving a voice coil motor, and seeks the head to a specified position on the disk based on servo data recorded on the disk. A first seek control method in a data recording / reproducing apparatus for positioning control, wherein at start-up, a first seek for moving the head out of the specific zone and moving to the data zone is started by the head moving means. Servo data was obtained from the head in response to the start of seek. In this case, seek / positioning control is started according to the servo data, the counter electromotive force of the voice coil motor is monitored according to the start of the first seek, and servo data is obtained from the head after the start of the first seek. A fast seek control method in a data recording / reproducing apparatus, characterized in that the fast seek is stopped based on the result of monitoring the back electromotive force if there is not. 4. A fast seek control method in a data recording / reproducing apparatus having a plurality of heads, wherein after stopping the fast seek, the head is switched to another head to restart the fast seek. 4. A fast seek control method in the data recording / reproducing apparatus according to item 3.