KR20080000953A - Method for optimizing write parameter in data storage system and disk drive using the same - Google Patents

Abstract

A method for optimizing write parameter in a data storage system and a disc drive using the same are provided to monitor floating height of a magnetic head in real time and to compensate parameter which is related to a writing function to the optimum value. A method for optimizing write parameter in a data storage system includes a step of detecting a servo gain in real time in a data write mode(S403); a step of judging whether the detected servo gain is included in a standard design range which is set initially(S404); and a step of compensating the parameter which is related to a write function differently according to the conditions below the lowest value and over the highest value of the standard design range when the servo gain is out of the standard design range(S405,S406,S407). A disc drive using the method comprises a disc, a magnetic head, a pre-amplifier, a variable gain amplifier, and a controller. The magnetic head magnetize the disc or senses a magnetic field from the disc. The pre-amplifier generates the write current by applying a parameter value which is related to the writing function in the write mode, and supplies the write current to the magnetic head. The pre-amplifier amplifies a servo signal read from a servo field of the disc by the magnetic head at a fixed gain. The variable gain amplifier amplifies the servo gain to reach the servo signal which is amplified by the pre-amplifier to a target level. The controller compensates the parameter related to the writing function according to the servo gain value which is applied to the variable gain amplifier in the write mode.

Description

Method for optimizing write parameter in data storage system 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 write parameter optimization method according to the present invention is applied.

FIG. 3 is a circuit diagram illustrating a method of controlling servo signal automatic gain in the read / write channel circuit shown in FIG. 2.

4 is a flowchart of a write parameter optimization method in a data storage system according to the present invention.

5 shows a waveform of a write current applied to a disk drive.

The present invention relates to a parameter correction method and apparatus applied to a data storage system, and more particularly, to a method and apparatus for correcting a light parameter to be optimized in consideration of the flying height of a magnetic head 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 gradually increasing in capacity, density, and miniaturization, bit per inch (BPI) in the direction of disk rotation and track per inch (TPI) in the radial direction are increasing, so a more sophisticated mechanism is required. do.

Hard disk drives affect lead and write performance depending on the flying height of the magnetic head, which is the distance between the magnetic head and the disk. As the flying height of the magnetic head is lowered, the light performance in the lead and the corresponding track is improved, but the possibility of collision between the magnetic head and the disk is increased due to disturbance due to an impact, etc., and there is a disadvantage of being invaded by adjacent tracks. On the contrary, as the flying height of the magnetic head increases, the possibility of collision between the magnetic head and the disk can be reduced, but there is a disadvantage that the light performance of the lead and the corresponding track deteriorates.

Accordingly, in consideration of this point, the flying height of the magnetic head is determined in the design of the hard disk drive. Then, various parameter values related to the performance of data write and data read of the hard disk drive are determined based on the determined flight height of the magnetic head.

In general, the flying height of the magnetic head varies depending on user conditions such as use temperature and air pressure. In addition, the flying height of the magnetic head may be changed in a specific region of the disk even by the disk bending phenomenon.

This change in the flying height of the magnetic head affects the performance of the disk drive, especially the write performance rather than the data read performance.

However, according to the related art, the parameters related to the light performance are determined as a fixed value based on the flying height of the magnetic head determined at the time of designing the disk drive. There was a problem that the light performance deteriorated.

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a light parameter optimization method and a disk using the same in a data storage system for correcting parameters related to light performance to an optimal value while monitoring flight height of a magnetic head in real time. To provide a drive.

In order to achieve the above technical problem, a write parameter optimization method in a data storage system according to the present invention includes: (a) detecting a servo gain in real time in a data write mode; (b) determining whether the servo gain detected in step (a) falls within the initially set design specification range; And (c) when the servo gain is out of the design specification range as a result of the determination of step (b), each under the condition that falls below the lower limit of the design specification range and exceeds the upper limit of the design specification range. Differently correcting parameters related to light performance.

The present invention preferably further includes a step (d) of executing a write retry by applying the parameters related to the light performance corrected in the step (c).

In the present invention, step (c) (c1) corrects the parameter to reduce the initially set write current magnitude when the servo gain falls below the lower limit of the design specification range as a result of the determination of step (b). step; And (c2) if the servo gain exceeds the upper limit of the design specification range as a result of the determination of step (b), correcting the parameter to increase the initially set write current magnitude.

In the present invention, the parameter related to the light performance includes a parameter for determining the light current, and in detail, the size correction of the light current preferably corrects the magnitude of the DC component of the write current and the magnitude of the overshoot current, respectively.

Disc drive according to the present invention to achieve the above another technical problem is a disk for storing information; A magnetic head for magnetizing the disk or sensing a magnetic field from the disk; A preamplifier for generating a write current by applying parameter values related to write performance in a write mode, supplying a write current to the magnetic head, and amplifying the servo signal read from the servo field of the disc by the magnetic head with a fixed gain; A variable gain amplifier configured to vary and amplify the servo gain to reach a target level by amplifying the servo signal amplified by the preamplifier; And a controller for controlling to correct a parameter related to write performance according to a servo gain value applied to the variable gain amplifier in the write mode.

In the present invention, it is preferable that the controller is designed to control to execute the light retry by applying the parameter related to the corrected light performance.

In the present invention, the controller corrects the parameter to reduce the initial set write current magnitude when the servo gain value is less than the lower limit of the design specification range, and the servo gain value exceeds the upper limit of the design specification range. It is desirable to calibrate the parameter to increase the initially set write current magnitude.

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 recordable transducer (aka writer) for magnetizing the disc 12 and a separate read transducer (aka reader) for sensing the magnetic field of the disc 12. Should 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 surface of the disk 12. 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 to specify a 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.

2 shows an electrical system 40 capable of controlling a hard disk drive according to the present invention. The electrical system 40 includes a controller 42 coupled to the magnetic head 16 by a lead / write (R / W) channel circuit 44 and a preamplifier 46.

The controller 42 may be a digital signal processor (DSP), a microprocessor, a microcontroller, or the like. The controller 42 reads information from or writes information to the disk 12 according to a command received from a host device (not shown in the drawing) via the host interface circuit 54. The read / write channel circuit 44 is controlled.

The controller 42 is also coupled to a voice coil motor (VCM) driver 48 that supplies a drive current to the voice coil 26. The controller 42 supplies a control signal to the VCM driver 48 to control the movement of the magnetic head 16.

The ROM 50 stores firmware and various control data for controlling the disk drive. Of course, programs for executing the flowchart of the light parameter optimization method in the data storage system according to the present invention shown in Fig. 4 are also stored.

When power is supplied to the disk drive, the RAM 52 is loaded with disk drive information read from a maintenance cylinder position of the disk 12.

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

In the data read mode, the disc drive amplifies the electrical signal sensed by the reading element of the magnetic head 16 from the disc 12 by a fixed gain value in the preamplifier 46. Then, after performing the automatic gain control, the read / write channel circuit 44 converts the signal read out from the disk 12 into a digital signal according to the sector pulse generated by the controller 42, and then decodes it. The decoded data is executed as an example in the controller 42 by an error correction process using the Reed Solomon code, and then converted into stream data and transmitted to the host device through the host interface circuit 54.

Next, in the write mode, the disk drive receives data from a host device (not shown) through the host interface circuit 54 and adds a parity symbol for error correction by the Reed Solomon code in the controller 42. After the encoding process is performed by the read / write channel circuit 44 so as to be suitable for the recording channel, the recording current of the magnetic head 16 is amplified by the preamplifier 46 at the time when the sector pulse is generated. The disc 12 is recorded.

Then, the read / write channel circuit 44 directly related to the present invention will be described in detail with reference to FIG. 3.

The read / write channel circuit 44 of the disk drive directly related to the present invention includes a variable gain amplifier (VGA) 44-1, an equalizer 44-2, an analog / digital conversion circuit (ADC) 44 -3), gain controller 44-4 and decoder 44-5.

The variable gain amplifier 44-1 obtains a servo signal obtained by amplifying the servo signal read from the servo field of the disk 12 in the write mode with a fixed gain by the preamplifier 46 to reach the target level. Amplify by applying the servo gain determined in -4).

The equalizer 44-2 performs signal processing to correct the asymmetry of the input waveform, correct the timing delay, and reduce noise.

The analog-digital conversion circuit 44-3 converts the equalized processed analog signal into digital data, and the decoder 44-5 decodes the converted digital data.

The gain controller 44-4 varies the servo gain to be applied to the variable gain amplifier 44-1 in inverse proportion to the magnitude of the digital data value output from the analog / digital conversion circuit 44-3. According to an embodiment of the present invention, the servo gain is changed only in a preamble generation section included in the servo signal read in the write mode, and the servo gain is held in the other section.

Accordingly, the gain controller 44-4 controls the servo gain so that the magnitude of the servo signal (specifically, the preamble signal) becomes constant.

As a result, as the magnitude of the servo signal output from the preamplifier 46 decreases, the servo gain value applied to the variable gain amplifier 44-1 increases. It can be seen that the larger the signal, the smaller the servo gain value.

In addition, as the flight height of the magnetic head 16 decreases in the write mode, the magnitude of the servo signal output from the preamplifier 46 increases. On the contrary, as the flight height of the magnetic head 16 increases, the preamplifier 46 increases. The size of the servo signal outputted from F becomes smaller.

In the present invention, using this principle, the controller 42 optimizes the parameters related to the write performance as follows.

That is, the controller 42 corrects the parameters for determining the magnitude and overshoot current value of the DC component of the write current, which is a parameter related to the write performance, according to the servo gain value applied to the variable gain amplifier 44-1 in the write mode. And executes the light retry by applying parameter values related to the corrected light performance.

In detail, the controller 42 corrects the parameter to reduce the initial set light current magnitude and overshoot according to a predetermined rule when the servo gain value falls below the lower limit of the design specification range, and if the servo gain value is the design specification. If the upper limit of the range is exceeded, the parameter is corrected to increase the magnitude and overshoot current of the DC component of the initially set light current according to a predetermined rule.

The above-mentioned predetermined rule is, for example, a look-up table in which the parameter values for generating the magnitude of the optimal write current DC component (WC) and the overshoot current (OSC) value corresponding to the servo gain value are set. Parameter can be corrected, and this lookup table is stored in the maintenance cylinder area of the ROM 50 or the disk 12.

Another example of a given rule is to set the parameter to reduce the magnitude of the DC component (WC) and the overshoot current (OSC) of the initially set write current by a certain unit size when the servo gain value falls below the lower limit of the design specification range. To correct the parameter to increase the magnitude of the DC component (WC) and the overshoot current (OSC) of the initially set light current by a certain unit size when the servo gain value exceeds the upper limit of the design specification range. Can be designed.

Then, the design specification range of the servo gain is experimentally obtained from the relationship of the flight height of the magnetic head 16 to the amount of change of the servo gain in the disk drive design stage, and then the magnetic head 16 of the magnetic head 16 which will guarantee the write performance in the disk drive. The range of the gain specification corresponding to the flight height determines the design specification range of the servo gain. It is effective to determine the design specification range of the servo gain for each zone of the disk. The design specification range information of the servo gain thus determined is stored in the maintenance cylinder area of the ROM 50 or the disk 12.

5 shows a waveform of the write current of the disk drive.

As shown in Fig. 5, the write current at the turning point of the data recorded on the disc shows a sharp standing shape. In FIG. 5, the standing component of the write current is referred to as overshoot current (OSC).

The DC component (WC) of the write current maintains the strength of the magnetic field near the coercive force, and the overshoot current (OSC) serves as a trigger to elevate the strength of the magnetic field above the coercive force at the position where the recording direction is changed. do.

Next, the light parameter optimization method in the data storage system according to the present invention will be described in detail with reference to the flowchart of FIG. 4.

The controller 42 determines whether a write command is received from the host device through the host interface 54 (S401).

When the write command is received, the controller 42 controls the disk drive to read the servo signal recorded in the servo field of the sector to be written after searching for the target track to be written (S402).

The controller 42 reads the servo signal of the corresponding sector i in the write mode and is determined by the gain controller 44-4 embedded in the read / write channel circuit 44 and applied to the variable gain amplifier 44-1. The servo gain SG (i) value is detected (S403).

Then, the controller 42 determines whether the servo gain [SG (i)] value detected in step 403 (S403) is included in the design specification range of the servo gain set in the zone in which the corresponding sector i is included. It is determined (S404). That is, the servo gain [SG (i)] value is in the range below the lower limit THi (L) of the design specification range of the servo gain set in the zone in which the sector (i) is included and in the range below the upper limit THi (H). Determine if the value corresponds to

As a result of the determination in step 404 (S404), if the detected servo gain SG (i) value is outside the design specification range of the servo gain set in the zone in which the sector i is included, the servo gain SG ( i)] It is determined whether the value is smaller than the lower limit THi (L) of the design specification range (S405).

As a result of the determination in step 405 (S405), when the servo gain SG (i) value is smaller than the lower limit THi (L) of the design specification range, it can be estimated that the flying height of the magnetic head 16 is lower than the specified height. The parameters related to the write current are corrected to reduce the magnitude of the DC component WC and the overshoot current OSC of the write current (S406). As an example of a parameter correction method, a look-up table in which the parameter values for generating the magnitude of the DC component WC and the overshoot current OSC value of the optimal write current corresponding to the servo gain value are set. You can correct the parameter using. Another example of the parameter correction method is to reduce the magnitude of the DC component (WC) and the overshoot current (OSC) of the initially set light current when the servo gain value falls below the lower limit of the design specification range by a certain unit size. It can be designed to calibrate the parameters.

If the result of the determination in step 405 (S405) is that the servo gain [SG (i)] value is not smaller than the lower limit THi (L) of the design specification range, the servo gain [SG (i)] value is the upper limit value THi of the design specification range. H) is exceeded, which increases the magnitude of the DC component (WC) and the overshoot current (OSC) of the light current because it can be assumed that the flying height of the magnetic head 16 is higher than the specified height. To correct the parameter related to the write current so as to correct (S407). As an example of a parameter correction method, a look-up table in which the parameter values for generating the magnitude of the DC component WC and the overshoot current OSC value of the optimal write current corresponding to the servo gain value are set. You can correct the parameter using. As another example of the parameter correction method, when the servo gain value exceeds the upper limit of the design specification range, the size of the DC component (WC) and the overshoot current (OSC) of the initially set light current are respectively increased by a certain unit size. It can be designed to calibrate the parameters.

According to an embodiment of the present invention, when the servo gain SG (i) is out of the design specification range, the parameter is corrected to simultaneously change the magnitude of the DC component WC and the overshoot current OSC value of the write current. However, in some cases, it may be designed to correct only one parameter of the DC component (WC) or the overshoot current (OSC) of the write current.

After correcting the parameters in step 406 (S406) or step 407 (S407) to optimize the magnitude of the DC component (WC) and the overshoot current (OSC) value of the write current, apply the corrected parameters in the corresponding sector. The disk drive is controlled to execute a write retry (S408). Then, it is fed back to step 402 (S402) to execute the above steps again.

If, as a result of the determination in step 404 (S404), the servo gain [SG (i)] value detected as a result of the determination in step 404 (S404) is within the design specification range of the servo gain set in the zone including the corresponding sector (i) If included, the data is written to the data field of the corresponding sector since the flying height of the magnetic head 16 is normal (S409).

By the above method, it is determined indirectly by using the servo gain value that the flying height of the magnetic head 16 is out of the normal range, and the magnetic head is corrected by correcting the parameter related to the light performance based on the magnitude of the servo gain value. Even if the flight height changes, the light performance can be maintained at an optimal level.

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 to various disk drives including a hard disk drive.

As described above, according to the present invention, the servo gain value is monitored to indirectly determine the change in the flying height of the magnetic head, and the control is performed to optimize the parameter values related to the light performance based on the servo gain value. Even if the height of the flight changes, there is an effect that can maintain the optimal light performance.

Claims (9)

(a) detecting the servo gain in real time in the data write mode; (b) determining whether the servo gain detected in step (a) falls within the initially set design specification range; And (c) When the servo gain is out of the design specification range as a result of the determination of step (b), each of the servo gains is different depending on a condition that falls below the lower limit of the design specification range and a condition that exceeds the upper limit of the design specification range. And calibrating parameters related to write performance. The method of claim 1, further comprising the step (d) of executing a write retry by applying the parameters related to the corrected write performance in the step (c). The method of claim 1, wherein the parameter related to the write performance comprises a parameter for determining a write current. The method of claim 1, wherein step (c) (c1) correcting the parameter to reduce the initial set write current magnitude when the servo gain falls below the lower limit of the design specification range as a result of the determination of step (b); And (c2) if the servo gain exceeds the upper limit of the design specification range as a result of the determination of step (b), correcting the parameter to increase the initially set write current magnitude; and storing the data. How to optimize light parameters in your system. 5. The method of claim 4, wherein the magnitude of the write current includes the magnitude of the DC component of the write current and the magnitude of the overshoot current. A disk for storing information; A magnetic head for magnetizing the disk or sensing a magnetic field from the disk; A preamplifier for generating a write current by applying parameter values related to write performance in a write mode, supplying a write current to the magnetic head, and amplifying the servo signal read from the servo field of the disc by the magnetic head with a fixed gain; A variable gain amplifier configured to vary and amplify the servo gain to reach a target level by amplifying the servo signal amplified by the preamplifier; And And a controller for controlling to correct a parameter related to write performance according to a servo gain value applied to the variable gain amplifier in a write mode. 7. The disk drive of claim 6, wherein the controller controls to execute a write retry by applying a parameter related to the corrected write performance. 7. The method of claim 6, wherein the controller corrects a parameter to reduce an initially set write current magnitude when the servo gain value falls below a lower limit of the design specification range, and wherein the servo gain value is a lower limit of the design specification range. Disk drive, characterized in that to calibrate the parameter to increase the initial set write current magnitude in case of exceeding. 10. The disk drive of claim 8, wherein the magnitude of the write current includes a magnitude of the DC component of the write current and a magnitude of the overshoot current.

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