KR20060079635A - Method for controlling a write mode according to flying height of magnetic head and disk drive using the same - Google Patents

Abstract

The present invention relates to a method and apparatus for controlling a disk drive, and more particularly, to a method and apparatus for controlling data to be recorded without error while monitoring a flying state of a magnetic head in a recording mode of a disk drive.

In the recording control method considering the magnetic head flight state according to the present invention, in the disk drive control method, (a) determining whether a write command is received, (b) receiving a write command as a result of the determination of step (a); In the case of detecting the servo gain of the sector before sector to be recorded after the target track seek and (c) the difference between the servo gain of the sector before the sector to be recorded and the servo gain of the sector to be recorded. (D) stopping the write operation and executing the write retry routine when the difference calculated in step (c) exceeds a predetermined threshold; otherwise, executing the normal data write. It is characterized by including.

Description

Method for controlling a write mode according to flying height of magnetic head and disk drive using the same}

1 is a plan view of a head disk assembly of a disk drive to which the present invention is applied.

2 is an electrical circuit diagram of a disk drive to which the recording control method considering the magnetic head flying state according to the present invention is applied.

3 is a flowchart of a recording control method considering the magnetic head flying state according to the present invention.

FIG. 4 is a graph showing changes in DAGC, SAGC, BER, and write modulation characteristics according to contact between a magnetic head and a disk in a disk drive.

The present invention relates to a method and apparatus for controlling a disk drive, and more particularly, to a method and apparatus for controlling data to be recorded without error while monitoring a flying state of a magnetic head in a recording mode of a disk drive.

In general, a hard disk drive, which is one of data storage devices, contributes to computer system operation by reproducing data recorded on a disk by a magnetic head or recording user data on the disk. As such hard disk drives are increasingly high in capacity, high in density, and miniaturized, bit per inch (BPI) in the direction of disk rotation and track per inch (TPI) in the radial direction are increasing. In order to increase the recording density of the disc drive, the development of the disc drive is being progressed in the direction of lowering the flying height of the magnetic head and increasing the recording frequency.

By the way, one of the most troubles in ensuring the reliability of the disk drive is the generation of a recording failure due to the contact between the magnetic head and the disk. Contact between the magnetic head and the disk occurs more frequently in low atmospheric pressure environments.

In a hard disk drive, the recording magnetic head is made of metal and the slider supporting the magnetic head is made of nonmetallic material. Joule heat is generated when a write current flows through the coil during data writing. However, due to the difference in thermal expansion coefficient between the metal and the non-metal, the portion around the pole expands, which is called thermal pole tip expansion (TPTP). Due to the TPTP phenomenon, the flying height of the head, which is the distance between the head and the disk, is lowered.

Therefore, in general, there is a high possibility that the magnetic head and the disk come into contact with each other in the recording mode under a low air pressure condition, thereby causing an abnormal recording.

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a recording control method considering a magnetic head flight state for determining whether to execute a write retry by detecting a contact state between a magnetic head and a disk in a recording mode, and a disk using the same. To provide a drive.

In order to achieve the above technical problem, the write control method in consideration of the magnetic head flight state according to the present invention is a disc drive control method comprising: (a) determining whether a write command is received, (b) If the write command is received as a result of the determination, detecting the servo gain of the sector before sector to be recorded and the servo gain of the sector to be recorded after the target track seek, (c) the servo gain of the sector before the sector to be recorded and the record to be recorded. Calculating the difference in the servo gain of the sector; and (d) if the difference calculated in step (c) exceeds a predetermined threshold, stops the write operation and executes the write retry routine; And executing the data write.

Disc drive according to the present invention in order to achieve the above another technical problem, in the data storage device, a host interface for performing data transmission / reception process with a host device, a disk for storing information, magnetize the disk or the A magnetic head for sensing magnetic fields from a disk, signal processing for recording information on or reading information from the disk, and automatic gain control for amplifying the electric signal detected from the disk to a certain size. A write / read circuit comprising a circuit and a write command from the host device when receiving a write command, the servo gain value of the automatic gain control circuit in the previous sector of the sector to be recorded after seeking a target track and the automatic gain in the sector to be written. The difference between the servo gain values of the control circuit is calculated and the And a controller for stopping the write operation and executing the write retry routine when the difference in the calculated gain exceeds a predetermined threshold, and otherwise executing the normal data write.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Hard disk drives consist of a combination of electrical circuits and a head disk assembly (HDA) consisting of mechanical components.

1 shows a configuration of a head disk assembly (HDA) 10 of a hard disk drive to which the present invention is applied. HDA 10 includes at least one magnetic disk 12 that is rotated by spindle motor 14. HDA 10 also includes a transducer (not shown) located adjacent to the disk surface.

The transducer can read or write information on the rotating disk 12 by sensing and magnetizing the magnetic field of each disk 12. Typically the transducer is coupled to each disk surface. Although described as a single transducer, it consists of a write transducer (aka writer) for magnetizing the disc 12 and a separate read transducer (aka reader) for sensing the magnetic field of the disc 12. It must be understood. Read transducers are constructed from Magneto-Resistive (MR) devices.

The transducer may be integrated into the magnetic head 16. The magnetic head 16 is structured to create an air bearing between the transducer and the disk surface. The magnetic head 16 is integrated into the head stack assembly (HSA) 22. The head stack assembly 22 is attached to an actuator arm 24 having a voice coil 26. The voice coil 26 is located adjacent to the magnetic assembly 28 that specifies the voice coil motor 30 (VCM). The current supplied to the voice coil 26 generates a torque for rotating the actuator arm 24 relative to the bearing assembly 32. Rotation of the actuator arm 24 will move the transducer across the disk surface.

The information is typically stored in an annular track of the disc 12. Each track 34 generally includes a plurality of sectors. Each sector includes a data field and a servo field. A preamble, a servo address / index mark (SAM / SIM), a gray code, and a burst (A, B, C, D) signal are recorded in the servo field. The transducer is moved across the disk surface to read or write information on other tracks.

As shown in FIG. 2, the disc drive according to the present invention includes a disc 12, a magnetic head 16, a preamplifier 210, a write / read channel 220, a buffer 230, a controller 240, ROM 250A, RAM 250B, host interface 260, and voice coil motor (VCM) driver 270.

The ROM 250A stores firmware and control information for controlling the disk drive, and the RAM 250B stores information necessary for driving the disk drive read from the ROM 250A or the disk 12 at the initial stage of driving.

The controller 240 analyzes a command received from the host device through the host interface 260, and executes control corresponding to the analyzed result. The controller 240 supplies a control signal to the voice coil motor (VCM) driving circuit 270 to control the excitation of the voice coil motor and the movement of the magnetic head 16.

First, the operation of a general disk drive will be described.

In the data read mode, the disc drive primarily amplifies in the preamplifier 210 an electrical signal sensed by the read converter of the magnetic head 16 from the disc 12. Then, in the write / read channel 220, the gain is controlled by an automatic gain control circuit (not shown) to amplify the signal amplified by the preamplifier 210 to a constant level, and the constant by the automatic gain control circuit. The analog signal amplified to a level is encoded into a digital signal that can be read by a host device (not shown), converted into stream data, and temporarily stored in the buffer 230, and then, the host device is transmitted to the host device through the host interface 260. send.

Next, in the write mode, the disk drive receives data from the host device through the host interface 260 and temporarily stores the data in the buffer 230, and sequentially outputs the data stored in the buffer 230 to write / write the data. After conversion by the read channel 220 into a binary data stream suitable for the write channel, the write current amplified by the preamplifier 210 is recorded on the disc 12 via the write converter of the magnetic head 16.

The write / read channel 220 tracks tracks and tracks while reproducing preambles, servo addresses / index marks (SAM / SIM), gray codes, and bursts (A, B, C, D) recorded in the servo field. Information necessary for the control is provided to the controller 240. In particular, the write / read channel 220 determines the servo gain SAGC of the automatic gain control circuit as a preamble signal.

In particular, the controller 240 monitors the servo gain SAGC of the automatic gain control circuit output from the write / read channel 220 when a write command is received from the host device through the host interface 260. After the track seek, the difference between the servo gain value of the automatic gain control circuit in the sector before the sector to be recorded and the servo gain value of the automatic gain control circuit in the sector to be recorded is calculated so that the calculated gain difference exceeds the threshold value. Control to stop the write operation and execute the write retry routine, and otherwise execute the normal data write.

In the present invention, the controller 240 is designed to determine whether to execute the write retry routine by comparing the absolute value of the difference between the servo gain value in the previous sector of the sector to be recorded and the servo gain value in the sector to be recorded to a threshold. Is effective.

Next, a recording control method considering the magnetic head flight state according to the present invention will be described with reference to the flowchart of FIG.

First, the controller 240 determines whether a write command is received from the host device through the host interface 260 (S301).

When the write command is received as a result of the determination in step 301 (S301), the controller 240 executes the seek control routine for SEEK of the target track to be recorded (S302).

After seeking the target track, the controller 240 monitors the servo gain SAGC of the automatic gain control circuit of the write / read channel 220 (S303). The servo gain of the automatic gain control circuit means the AGC gain determined while reproducing the servo signal recorded in the servo field.

The controller 240 detects the servo gain value SAGC_pre of the sector before the sector to be recorded on the target track and the servo gain value SAGC_wr of the sector to be recorded, and calculates a difference SAGC_diff between the two servo gain values (S304). .

Then, the controller 240 compares the absolute value of the difference SAGC_diff between the two servo gain values with the threshold value TH (S305). At the time when the magnetic head 16 is in contact with the disc, the gain DAGC and the bit error rate (BER) in the data area of the automatic gain circuit, including the servo gain SAGC, change rapidly as shown in FIG. 4. The threshold value TH is a boundary value for detecting such a characteristic and can be obtained experimentally.

If the absolute value of the difference SAGC_diff of the two servo gain values exceeds the threshold TH as a result of the determination in step 305, the write operation is stopped because the magnetic head 16 is in contact with the disk 12. After executing the write retry routine, the write related parameters are changed and fed back to step 303 (S303).

If the absolute value of the difference SAGC_diff of the two servo gain values does not exceed the threshold value TH as a result of the determination in step 305, the magnetic head 16 does not correspond to the condition in which the disk 12 is in contact with the normal value. The data write operation is executed (S307).

By such a process, it is determined immediately before the data write that the magnetic head 16 is in flight, that is, whether the magnetic head 16 is in contact with the disk 12, thereby determining whether to execute the data write or the write retry. It becomes possible.

The invention can be practiced as a method, apparatus, system, or the like. When implemented in software, the constituent means of the present invention are code segments that necessarily perform the necessary work. The program or code segments may be stored in a processor readable medium or transmitted by a computer data signal coupled with a carrier on a transmission medium or network. Processor readable media includes any medium that can store or transmit information. Examples of processor-readable media include electronic circuits, semiconductor memory devices, ROMs, flash memory, erasable ROM (EROM), floppy disks, optical disks, hard disks, optical fiber media, radio frequency (RF) networks, Etc. Computer data signals include any signal that can propagate over transmission media such as electronic network channels, optical fibers, air, electromagnetic fields, RF networks, and the like.

Specific embodiments shown and described in the accompanying drawings are only to be understood as an example of the present invention, not to limit the scope of the invention, but also within the scope of the technical spirit described in the present invention in the technical field to which the present invention belongs As various other changes may occur, it is obvious that the invention is not limited to the specific constructions and arrangements shown or described. That is, it is a matter of course that the present invention can be applied not only to various disk drives including hard disk drives, but also to various kinds of data storage devices.

As described above, according to the present invention, the disk drive determines the flight state of the magnetic head before the data write and controls to execute the write retry routine when the magnetic head is in contact with the disk, thereby preventing abnormal data write. That effect is produced.

Claims (5)

In the disk drive control method, (a) determining whether a write command is received; (b) detecting a servo gain of a sector before a sector to be written and a servo gain of a sector to be written after a target track seek when a write command is received as a result of the determination of step (a); (c) calculating a difference between the servo gain of the sector before the sector to be recorded and the servo gain of the sector to be recorded; And (d) stopping the write operation and executing the write retry routine when the difference calculated in step (c) exceeds a predetermined threshold, otherwise executing the normal data write. The recording control method in consideration of the magnetic head flying state. 2. The recording control method of claim 1, wherein the servo gain includes a gain value of an automatic gain control circuit which amplifies the servo signal to a predetermined magnitude. The method of claim 1, wherein the step (d) stops the write operation and executes the write retry routine if the absolute value of the difference calculated in the step (c) exceeds a predetermined threshold value. Recording control method considering the magnetic head flight state, characterized in that performing a normal data write. In the data storage device, A host interface for performing data transmission / reception processing with the host device; A disk for storing information; A magnetic head for magnetizing the disk or sensing a magnetic field from the disk; A recording / reading circuit including a signal processing for recording information on the disk or reading information from the disk, and an automatic gain control circuit for amplifying the electrical signal sensed by the disk to a predetermined magnitude; And When a write command is received from the host device, the difference between the servo gain value of the automatic gain control circuit in the previous sector of the sector to be recorded after the seek of the target track and the servo gain value of the automatic gain control circuit in the sector to be recorded. And a controller for stopping the write operation and executing a write retry routine when the difference of the calculated gain exceeds a predetermined threshold, and otherwise executing a normal data write. Disk drive characterized in that. The controller of claim 4, wherein the controller is configured to stop a write operation and execute a write retry routine when the absolute value of the calculated difference exceeds a predetermined threshold, and otherwise execute a normal data write. Disk drive characterized in that the control box.

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