JP3256998B2 - Magnetic disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive suitable for use in, for example, an external storage device of a computer using a sector servo system.

[0002]

2. Description of the Related Art For positioning servo of a head, using a voice coil motor as an actuator, sectors formed radially at equal angular intervals in order to correspond to a high recording track density are used. Are used. By dividing the disk surface for each sector, the magnetic disk device achieves higher recording density and higher capacity. With the increase in density and capacity, magnetic disk devices require advanced control technology. One way to meet this demand is to use a DSP (Digital Signal Processor) that performs high-speed digital arithmetic processing
ssor) is used.

[0003]

As described above, if a data defect occurs due to a scratch or the like due to some cause on a recording medium that requires advanced control technology as described above, a magnetic disk device of the sector servo system uses Even if there is a sector having a defective servo pattern, data has been written / read to / from the data sector of the defective servo sector without causing any head shift without taking any countermeasures. In addition, continuous recording / writing
Even if there is a sector that cannot be read, the magnetic disk device has not taken any measures. Therefore, even if a servo sector in which defective servo pattern data is written is different from an expected servo pattern, the servo for positioning the head acts as a disturbance to cause a seek error.

If a defect occurs in the servo pattern area as described above, for example, reading data written in a data sector in the defective servo sector is performed by
It becomes difficult.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a magnetic disk drive which prevents problems such as deterioration of an error rate and seek error of a head caused by having a defective servo pattern on a recording medium. Is what you do.

[0006]

In the magnetic disk drive according to the present invention, a servo pattern is provided in each sector, and in the magnetic disk drive which performs sector servo by detecting the servo pattern, a detection for detecting a defective servo pattern is performed. Means for relocating data in a sector in which the defective servo pattern is detected to a spare sector area in which data can be reserved and provided in the same track as a spare when the defective servo pattern is detected by the detection means. And
Further, when the detecting means detects a predetermined number or more of defective servo patterns per track, the data of each sector in the one track is rearranged in a spare track area in which data can be provided as a spare. To solve the above-mentioned problem.

If the servo pattern of a sector in an arbitrary track is different from the expected servo pattern of a sector, a reassign block (Reassign Block) is used.
One data sector per track is provided for ck). In addition, when a defective sector exceeding the number of sectors specified per rotation is detected, one sector per zone divided so as to make the recording density in the sector substantially constant is used for a reassign track. A book truck is provided.

[0008]

The magnetic disk drive according to the present invention has detecting means for detecting a defective servo pattern, and when a defective servo pattern is detected by the detecting means, data in a sector in which the defective servo pattern is detected is read. If the defective servo pattern is relocated to a spare sector area provided in the spare and on which data can be recorded in the same track and the detecting means detects a predetermined number or more defective servo patterns per track, each sector in the one track is relocated. Is relocated to a spare track area in which data can be recorded as a spare to allow data recording, and access to a defective servo sector before relocation is avoided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a magnetic disk drive according to the present invention will be described with reference to the drawings.

The track address pattern used in the magnetic disk drive of the present invention will be described with reference to the drawings.

According to the magnetic disk drive of the present invention, when a defective servo sector is detected by this sector servo method, the data of the data sector in the defective servo sector is relocated to a spare area in which spare data can be recorded. This is handled by appropriate processing. In this magnetic disk device, the recording medium is further divided into zones so that the recording densities on the inner peripheral side and the outer peripheral side of the equally divided sectors are substantially equal to each other and are recorded. Is used. In this zone bit recording method, a method is also adopted in which a fraction of a track generated by dividing each zone is used as a relocation track.

FIG. 1 shows the software for the rearrangement.
Before describing the flow chart shown in FIG. 1, the servo pattern proposed by the present applicant will be briefly described with reference to the schematic block diagrams of the magnetic disk drive shown in FIGS. 2, 3 and 4. FIG. The magnetic disk of the sector servo system is divided into 71 sectors at intervals of 241.5 μs, for example, 2.5 inches as shown in FIG. 2, and the total number of tracks is 1,391. In the case of 3.5 inches, the servo pattern S is divided into 90 sectors every 181.5 μs and
SP is written.

FIG. 3 shows various servo patterns written in the servo pattern SSP.
Here, as shown in FIG. 3, the predetermined reference signal becomes a preburst signal BS, a reference signal AGC for signal level correction, a synchronizing signal SYNC, etc. through a W / R settling area. In the synchronization signal SYNC, various signals are recorded separately for a servo header SH, a clock CLK, and a pattern sync PAT SYNC.

After this recording, in this case, the recording track width T _BW is set so that the track center TC matches the recording tracks of the even-numbered tracks 2, 4, 6,.
The first burst signal X and odd tracks 1, 3, 5,.
.. Recording the second burst signal Y with a recording track width T _BW so that the track center TC coincides with the recording track of..., And in the vicinity of the even-numbered track center TC in units of two tracks. First as the value changes
, And the second address information D0, D1, D2,... So that the value changes substantially near the odd-numbered track center TC. I have. The address AD obtained from the comparison result of the first level detection signal X and the second level detection signal Y is detected, and corrected by the second address information to detect the position of the magnetic head.

Furthermore, after the servo signals A and B for tracking control are recorded in a checkered pattern at different positions offset in opposite directions in the direction orthogonal to the track, three burst signals of a predetermined reference signal C are generated. These are recorded as a so-called fine pattern FP and form a servo sector as a whole.

As will be described in detail later with reference to FIG. 4, the magnetic disk device supplies a reproduced signal output from the magnetic head 12a to the head position detecting unit 13. The signal detected by the head position detection unit 13 is transmitted to a RAM 14 for storing data and a DSP 15 for performing high-speed digital signal arithmetic processing via a 16-bit DSP bus. The control of the DSP 15 is performed by the CPU 16. A digital signal as a result of arithmetic processing such as a correction amount for the detection signal from the head position detection unit 13 is supplied to the D / A converter 17 via the DSP bus. This D / A
The voice coil motor drive circuit 19 converts the control signal via the LPF 18 into an analog signal by the converter 17 and controls the current supply to the voice coil motor 20 to control the magnetic head 12.
The current position of the magnetic head 12a with respect to the target position of "a" is corrected, and the seek is performed efficiently at high speed.

A procedure for detecting a defective servo sector in the above-described magnetic disk drive using the sector servo method and its processing will be described with reference to FIG. In step S10, a servo pattern defect detection routine is started. In step S11, a servo sector area signal SV-PRT indicating a servo sector area and a servo error detection signal SV-ERR indicating whether servo sector information is detected indicate whether there is an abnormal servo sector due to a mechanical scratch or the like in one servo sector. Has been detected. In this detection, the magnetic disk device checks the address AD in each servo sector, the so-called fine pattern FP, and the first and second burst signals X and Y with a "maintenance command" for the device. At the same time, the status information is also checked, and information such as the detected address is stored.

The definition of a defect in each area item of the servo sector is, for example, that AGC has an error of half out of 8 bits, and that about 10% of up to an error of 3 bits out of 12 bits of the fine pattern C. However, when an error of 4 bits or more occurs, it is determined that there is a defect and that there is an abnormality.

In step S12, 1
It is determined whether or not the check of all the sectors in the circumference has been completed. If the entire circumference has not been checked yet, the process proceeds to step S13. Also, when the check of the whole circumference is completed,
Proceed to step S16. In step S13, for example, it is determined whether or not the servo is in the off state by checking how much time has been required since the start of the detection of the abnormal servo sector in step S11. That is, for example, when there is a defect of long information of three or more sectors, there is a possibility that the tracking servo may be deviated. As a result, three defects
If it is longer than a sector, the DSP 15 shown in FIG.
The servo control is stopped and the process proceeds to step S14. If the servo is on within the set time-out period, that is, if the servo is on, the process returns to step S11 to repeat the above routines.

In step S14, the data of the servo pattern of the track including the address of the defective part which required this time is rearranged. In step S15, a "start command" is supplied after the rearrangement, and the process returns to step S11 to check whether or not there is an abnormal sector in this track. When the check of all the circumferences is completed in step S12,
In step S16, it is determined whether an abnormal servo sector including a defective servo sector detected in hardware and a defective servo sector detected in software is detected. Here, if an abnormal servo sector is detected, in step S17, the data of the servo pattern of the defective track including the abnormal servo sector is rearranged. This rearrangement and step S18
Proceed to. If no defective servo sector is detected in step S16, the process proceeds to step S18.

In step S18, the magnetic head is sought to the next track or a new designated target position, and the flow advances to step S19. In step S19, it is determined whether or not all the tracks on the magnetic disk have been checked. If not, go to step S
Returning to step 11, the above-described routine is repeated. If the check has been completed, the process proceeds to step S20, and the routine for detecting a defect in the servo pattern is ended.

Incidentally, in order to remove this information defect, a servo pattern is detected in a burn-in (Burn-in) process, and when a defect extending over (n + 1) sectors or more is detected, a so-called re-assigned track, That is, the entire periphery of the track is rearranged, and when a defect of n sectors or less is detected, a process of forming a so-called reassign block is performed.

As described above, even when the sector servo system is used, the recording medium uses, for example, a zone bit recording system to increase the recording capacity, and a 3.5-inch magnetic disk has 1959 data cylinders.
One zone is provided for each zone, that is, rearrangement cylinders are prepared for a total of four cylinders. Also,
In the case of a 2.5-inch magnetic disk, one zone is prepared for each zone in 1289 data cylinders, that is, a total of eight cylinders for rearrangement are prepared. Here, the cylinder refers to a pair of tracks having the same number on a double-sided disk.

As described above, in the present invention, the data area of the magnetic disk is provided so as to have the above-mentioned rearrangement area even when the servo pattern data is lost.

The error rate of the magnetic disk device can be improved by rearranging the data of the track including the defective servo sector to the replacement track so that the defective servo sector is not accessed. . In addition, since a servo sector damaged by a defect of information is not accessed, a seek error can be eliminated.

In this manner, even if a defect occurs in the servo pattern, by relocating the entire track in which an error has occurred or the block area which is a part of the track as necessary, the data sector having the defective servo sector can be obtained. This makes it possible to prevent problems such as the inability to read / write data from / to the magnetic head and the inability to position the magnetic head due to the generation of long defects.

Head position control and the like are performed based on the reproduced RF signal when the sector servo pattern is scanned. A configuration for performing the above control will be described with reference to a schematic block diagram of the hard disk device shown in FIG. This hard disk device mainly includes a spindle motor 11, a magnetic head 12a at the tip of a head arm 12, which is a part of an actuator, a head position detector 13, a RAM 14, a digital signal processor (DS).
P) 15, CPU 16, D / A converter 17, LPF1
8, a voice coil motor (VCM) drive circuit 19, a voice coil motor 20, and the like.

As a recording medium for recording / reproducing with this apparatus, for example, a magnetic disk 10 is used. Magnetic disk 10
Are divided into several tens of sectors at equal intervals with respect to the track in the circumferential direction. In each of the sectors, information such as address information and a fine pattern necessary for each positioning is written in the sector servo pattern (SSP). Positioning control is performed according to information from the sector servo pattern.

Further, the head position detecting section 13 includes a read / write (R / W) amplifier 131, an equalizer circuit 1
32, a pulse detection circuit 133, a servo detection circuit 134,
Envelope detection circuit 135, integration circuit 136, A / D
It comprises a converter 137 and a position information generation circuit 138.

The operation of the above block configuration will be briefly described along the flow of signals. When the position of the head arm 12 is detected, a sector servo pattern (SSP) written on the magnetic disk 10 as a recording medium is reproduced, and position detection control is performed based on position information obtained from the sector servo pattern (SSP). It is carried out. A reproduction signal from the sector servo pattern (SSP) is supplied to the read / write amplifier 131 via the head 12a at the tip of the head arm 12, which is a part of the actuator.

The read / write amplifier 131 amplifies the reproduced signal and sends it to the equalizer circuit 132.

The equalizer circuit 132 detects information related to the track address AD and information related to the tracking of the head 12a by the burst signal from the fine pattern FP from the information of the sector servo pattern, and supplies it to the envelope detection circuit 135. At the same time, the signal is supplied to the pulse detection circuit 133.

The pulse detection circuit 133 determines the level of the RF signal with respect to the positive and negative slice levels and supplies the signal to the servo detection circuit 134. Servo detection circuit 134
Checks whether an input signal is a servo pattern, specifies an area, and outputs a detection signal to an envelope detection circuit 1.
35. An output signal from the equalizer circuit 132 is detected by an envelope detection circuit 135 in accordance with the timing of the detection signal. The detection output from the envelope detection circuit 135 is rectified by the integration circuit 136, and the voltage value is supplied to the A / D converter 137. The A / D converter 137 converts the sampled data into a digital amount in accordance with, for example, a signal synchronized with the system clock, and converts the data into a digital information.
8

This data is supplied to a digital signal processor (hereinafter abbreviated as DSP) 15 via a DSP bus consisting of, for example, 16 bits, and also to a RAM 14. The DSP 15 is controlled by the CPU 16. If necessary, the CPU 1
Reference numeral 6 reads data from the DSP 15 and checks and calculates various flags and the like. The DSP 15 is:
By calculating the position detection servo amount, the current position of the magnetic head 12a can be known. In addition, the control data is based on the above C
The position control data is also corrected by the calculation in the PU 16. With this correction, the DSP 15 can control the D / A converter 1 including a control signal for correcting, for example, an external force applied to the head.
7 is output.

A control signal is supplied to the voice coil motor drive circuit 19 via the LPF 18 after the D / A converter 17. In response to the control signal, the voice coil motor drive circuit 19 supplies a current for driving the voice coil motor 20 to control the position of the magnetic head 12a.
With this configuration, the magnetic disk device detects a servo sector defect while performing high-speed and accurate position control.

Further, the magnetic disk drive of the present invention uses a so-called gray-like code in which data used for an address pattern is divided into two bits and converted into a three-bit gray code by adding one bit as a dummy bit. . As a specific example of the gray-like code by the 2-3 modulation, two bits of the gray code, that is, (0
0), (01), (11), and (10) are input to an exclusive-OR inverting circuit (Exclusive NOR), and this output is inserted between the two bits of the Gray code to perform 2-3 conversion. ing. As a result, three channel bits (01
0), (001), (111), and (100) are generated. This gray-like code is written in the servo pattern. As described above, dummy bits are added to the gray-like code to read / write data using magnetic hysteresis. Therefore, when a defect is detected in the gray-like code, the dummy-like code is detected. One bit becomes undetectable. For example,
“0” where “1” is detected in the dummy bit portion
Is detected. In addition, one dummy bit cannot be detected when the magnetic head passes near the boundary between adjacent servo addresses at the time of seek. Therefore, the defect can be detected by detecting the undetectable number of the dummy bits and considering the specified value of the undetectable number depending on whether the DSP is on-track or seek.

Further, when the number of undetectable signals detected by the above-mentioned detection method exceeds the above-mentioned allowable range, it is easily determined that the servo address is destroyed due to a defect by the procedure of the flowchart shown in FIG. Then, an address error flag is set and taken into the DSP, the operation is performed so as not to use the position information of the sector where the defect error has occurred, and the sector where the defect error has occurred is rearranged for each block or track. Access to a servo sector having a lack of information is prevented, and the influence on the servo system due to a defective servo sector can be reduced.

[0038]

As is apparent from the above description, according to the track address pattern of the magnetic disk drive of the present invention, each sector is provided with a servo pattern, and the servo pattern is detected to perform the sector servo. The disk device has a detecting means for detecting a defective servo pattern, and when the defective servo pattern is detected by the detecting means, data in a sector where the defective servo pattern is detected is provided as a spare in the same track. When the defective servo pattern is relocated to a spare sector area where data can be recorded and the detecting means detects a predetermined number or more defective servo patterns per track,
By relocating the data of each sector in the track to a spare track area where data can be recorded as a spare,
It is possible to improve the error rate of the magnetic disk drive by avoiding access to the defective servo sector before the above rearrangement, and to prevent a seek error that occurs when there is a track whose head position cannot be controlled. Further, by sequentially performing the rearrangement for each track, it is possible to efficiently detect a servo pattern defect.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of a procedure for detecting and relocating a defect in a servo pattern in a magnetic disk drive according to the present invention.

FIG. 2 is a schematic diagram showing an example of an actual sector servo pattern written on a magnetic disk.

FIG. 3 is a diagram showing servo sectors of a magnetic disk.

FIG. 4 is a block diagram showing a schematic circuit configuration of head position control in the magnetic disk drive according to the present invention.

[Explanation of symbols]

 10: Magnetic disk 11: Spindle motor 12: Head arm 13: ········ Head position detection unit 14 ··· RAM 15 ···· DSP 16 ········ ... CPU 17 ... D / A converter 134 ... Servo detection circuit 135 ... Envelope Detection circuit 138 ・ ・ ・ Position information generation circuit

Continuation of the front page (56) References JP-A-62-188067 (JP, A) JP-A-62-188064 (JP, A) JP-A-62-192974 (JP, A) JP-A-1-112573 (JP) JP-A-1-317278 (JP, A) JP-A-2-53270 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 20/18 G11B 21/10 G06F 3/06 G06F 11/14

Claims (2)

(57) [Claims] A servo pattern provided in each sector;
By detecting the above servo pattern, sector servo
In a magnetic disk apparatus for performing comprises detecting means for detecting a defective servo pattern, when a defective servo pattern is detected by the detection means, de in the defective servo pattern is detected sector
Magnetic disk apparatus characterized by relocating over data to the spare sector area available spare provided data recorded on the same track. 2. A servo pattern is provided in each sector.
By detecting the above servo pattern, sector servo
In a magnetic disk apparatus for performing comprises detecting means for detecting a defective servo pattern, the predetermined number or more per track by said detecting means Niwata
When a defective servo pattern is detected, the data of each sector in one track is relocated to a spare track area provided for spare data recording.