JPH09180373A - Method for setting r/w channel parameter of magnetic disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the yield, reliability, and stability by providing an R/W channel LSI and a write current control circuit and setting optimum values by head zones (cylinder) as to parameters of a recording and reproduction system. SOLUTION: The R/W channel LSI(RWC) 10 and write current control circuit(WC-CTL) 30 are provided. The RWC10 has a filter 12, a peak detector 13, a data synchronizer 14, and write precompensation 18 to adjust the delay quantity of the filter, set write compensation, adjust a slice level, and set fc and Boost values of the filter. And, a series of processes for the parameters is performed for every cylinder area (head address) to set them so that a window margin and an amplitude margin meet standards, thereby improving a margin deficiency due to variance in characteristics of a head and a medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting operating parameters of a magnetic disk device, and more particularly to a cutoff frequency (fc), a boost (Boost) and a delay (DL) of an active filter for equalizing the waveform of a read signal.
Y) and slice level (SLV) in the peak detector
And the window shift (W in the data synchronizer
SF) and write pulse timing
The present invention relates to a method of setting precompensation (WPC) and a write current (Ic).

[0002]

2. Description of the Related Art Recording and recording in a conventional magnetic disk device
The element for controlling the reproduction is fixed at a position determined to be optimum as a characteristic in consideration of variations in the magnetic head, the disk medium, the recording / reproducing system LSI, and survey data of the evaluation device. Therefore, in the case of each head of all devices and the multi-zone (MZR) system, fc, Boost, DLY and WPC, Ic, WS of the filter are used in all zones.
The center values of F and SLV were all set at the same place.

As a past technique, Japanese Patent Laid-Open No. 5-266 is known.
Japanese Patent No. 587 discloses a ROM in which a reading means reads out an isolated waveform and measures a half-value width of the read isolated waveform, and a circuit parameter which fixedly stores a circuit parameter giving optimum characteristics of an electric filter according to the half-value width of the isolated waveform.
Disclosed is a technique having a table, a means for creating an optimum table for each magnetic head, and a means for controlling the characteristics of an electric filter from the optimum table (prior art 1).

In Japanese Patent Laid-Open No. 64-76403, a characteristic characteristic of the head is measured, and a circuit characteristic value that gives the maximum phase margin / level margin is calculated and measured to obtain a recording element (ROM) in advance. When the specific head is selected, the optimum circuit characteristic value stored in the storage element is selected for the optimizing current means, and the current control means sets a constant in the write / read circuit according to the circuit characteristic value. , A technique for performing a write operation / read operation is disclosed (prior art 2).

Japanese Patent Laid-Open No. 59-198514 discloses that
By switching one or more circuit constants of the cosine equalization circuit, the differentiation circuit, and the reduction filter for each magnetic head / magnetic disk unit, the variation of the reproduced waveform due to the characteristic combination of the magnetic head and the magnetic disk is corrected. However, a technique for increasing the phase margin during the reproducing operation of the device is disclosed (prior art 3).

[0006]

In the above-mentioned conventional magnetic disk device, the recording / reproducing system parameters (fc, Bo) are used.
ost, DLY, WPC, Ic, WSF, and SLV centers) are magnetic heads, disk media, and recording / reproducing systems L.
This is an estimated value that is set to a value that is considered to be optimal, as judged from variations in SI and evaluation data of limited devices, so it does not necessarily apply to all devices or head zones. In some cases, a parameter value far from the estimated value may be the optimum value. When the density is further increased, the window margin and the amplitude margin due to the setting of the parameters may exceed the allowable values. In other words, the difference between the estimated value described above and the originally existing optimum value spreads, and this directly affects the performance of the device, so that it is satisfactory for the variations of the magnetic head, the disk medium, and the recording / reproducing system LSI. There is a problem that the error rate cannot be obtained.

More specifically, in the prior art 1, the parameters of the electric filter (cutoff frequency fc and boost Boost) are determined in correspondence with the half width of the isolated waveform. The output value) does not always correlate with the magnitude of the phase margin.
In other words, the pulse generated in a part of the track such as a solitary wave is different from the pulse written / read as normal data, so the filter setting condition judged by the measured half-width does not always mean the maximum phase margin. When there is a problem as a medium in the place to be set, for example, when a solitary wave different from the others such as a defect or a spring occurs, the parameter of the filter is not set to the optimum value and a satisfactory error rate cannot be obtained. is there.

In the prior art 2, the characteristics peculiar to each magnetic head are measured, and the circuit characteristic value for obtaining the maximum phase margin / level margin is stored in the storage element (ROM) in advance based on the measurement. Although there are variations in characteristics among the components other than the magnetic head, such as the disk medium, the recording / reproducing circuit, and the servo system, there is a problem that the circuit characteristic values stored in the ROM do not take them into consideration.

Further, the prior arts 2 and 3 do not incorporate a method of changing parameters by the cylinder area in the same head. Therefore, when the recording / reproducing characteristics greatly differ depending on the cylinder as in the multi-zone recording system, depending on the cylinder. There is a problem that the parameters are not optimized.

Further, in the prior art 3, only the parameter of the filter such as the cosine equalizing circuit, the differentiating circuit and the reduction filter is switched between constants for each head, so that other slice levels, write precompensation and write current are There is a problem that it is not optimized, and it is not sufficient as a method for obtaining the maximum phase margin / level margin.

According to the present invention, recording / reproducing system parameters {filter cutoff frequency (fc), boost (Boost),
Delay, write precompensation, slice level, window shift, write current} are optimized for all heads and zones (or cylinders) individually, so that all head zones have the same parameters. The purpose is to achieve a wider window margin and level margin than when set, and reduce the error rate to improve reliability and stability.

[0012]

The R / W channel parameter setting method for a magnetic disk device of the present invention is a parameter for controlling the characteristics of an active filter for performing waveform equalization on a signal read from the disk medium. , Cutoff frequency (fc), boost (Boost), and delay amount (DLY), means for setting the slice level (SLV) in the peak detector, and window shift (WSF) in the data synchronizer. ), A write precompensation (WPC) that is the timing of the write pulse, and a write current (Ic) setting means. Change the error depending on the frequency of bit mismatch between read signal and write signal. By measuring over preparative, and calculating the Window margin at a given error rate,
The amplitude margin (LVM) at a predetermined error rate is calculated by changing the setting of the slice level (SLV), and the parameters (fc, Bo) of the filter are calculated.
ost, DLY) is changed to search and determine fc, Boost, DLY that optimizes the window margin (WDM), and search for a WPC set value that optimizes WDM when the WPC is changed. From the window center calculated from the parameter (fc, Boost) of the filter and the optimum WDM, by determining the Ic setting value for which WDM is optimum when Ic is changed. Fc and Bo for which SLV is optimal
It is characterized in that the set value of ost is searched and determined.

The boost is a value obtained by subtracting -3 dB from the gain at the cutoff frequency when the gain near the cutoff frequency is raised in the active filter.

According to the R / W channel parameter setting method of the magnetic disk drive of the present invention, the worst condition repetitive pattern is written, and then the group delay is set to a certain initial value to set a window margin at a constant error rate. Measure, then change the set value in the + direction, repeat the measurement of the window margin, and
After the delay reaches the maximum setting value in the + direction, it returns to the initial setting value, the setting value is changed in the − direction, and the measurement of the window margin is repeated until the maximum setting value in the − direction is reached. It is characterized by selecting the group delay value and the window center when the window margin takes the maximum value.

The R / W channel parameter setting method of the magnetic disk device of the present invention is the group setting method according to claim 2.
Using the delay, change the early side while keeping the write precompensation amount on the late side at 0, measure the window margin, and then set the early side to 0.
The window margin closest to the window center selected in claim 2 is measured by measuring the window center obtained by changing the late side while keeping it on, and moving the early side and the late side. Is selected, and the value of the write precompensation at this time is set as a temporary setting value.

In the method of setting the R / W channel parameter of the magnetic disk device of the present invention, the values on the early side and the late side of the pre-compensation temporarily set in claim 3 are used as initial values, and both the early direction and the late direction are added equally. And the window margin and window center are measured by changing the fc and Boost of the filter for each precompensation value, and the light when the window margin takes the maximum value is written. -When the amount of pre-compensation satisfies the standard, the value is set as the amount of write pre-compensation.

The method for setting the R / W channel parameter of the magnetic disk device of the present invention is the difference between the measured amplitude margin value and its preset standard value, and the measured window
If the product of the difference between the margin value and the preset standard value is larger than a certain standard value, the amplitude margin is judged to be the final pass, the level center at that time is calculated, and the slice
It is characterized by setting as a level.

According to the R / W channel parameter setting method of the magnetic disk device of the present invention, when the product of claim 5 is smaller than a certain standard value, fc and Boost of the filter are set.
The value of is changed sequentially from the minimum setting value, and the difference between the measured amplitude margin value in each state and its preset standard value, and the difference between the measured window margin value and its preset standard value When the product of is smaller than a certain standard value, the amplitude margin is judged to be provisionally acceptable, and fc and Boost of the filter at that time are set as set values, and the level center is calculated and set as a slice level. To do.

The R / W channel parameter setting method of the magnetic disk device of the present invention is to write the worst condition repetitive pattern in the device to be used, and then write the write current at a certain initial value with a constant error rate. The window margin is measured, and then it is sequentially added to the set value of the write current to increase it, and the measurement of the window margin is repeated until the write current reaches the maximum set value. Among these, the window margin has the maximum value. It is characterized in that the write current when taking is set to a set value.

The R / W channel parameter setting method of the magnetic disk device according to the present invention can be implemented in the device used.
The group delay amount is set by the method described in claim 3, the value of write precompensation is set by the method described in claim 3, and the fc, Boost is set by the method described in claim 4.
t and the value of write precompensation are set, the slice level is set by the method according to claim 5, and the slice level, fc and Bo are set by the method according to claim 6.
ost is set, and the write current value is set by the method according to claim 7.

The R / W channel parameter setting method of the magnetic disk drive of the present invention optimizes the value of each parameter for each device, each head, each cylinder or zone, that is, each aggregate of adjacent cylinders. The feature is that it can be set.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an R / W channel parameter setting method for a magnetic disk drive according to the present invention will be described with reference to the drawings. FIG. 2 is a block diagram showing an example of the internal configuration of the R / W channel LSI 10 (RWC) of the present invention and the hardware configuration of the magnetic disk device including the RWC. Inside the R / W channel LSI 10, a register 11 for setting parameters of each block, a filter 12 (FLT), a peak detector 13 (SLV-CTL) for controlling a slice level, and a data synchronizer 14 for controlling a window shift are provided. (DT-SYC), synthesizer 15 (TB that generates a write PLO clock)
G), an encoder 16 (EN that converts data input from the disk controller 60 (HDC) into a recording code
C), a decoder 17 (D which converts the recording code into data)
EC), write precompensation 18 (WPC) for controlling the timing of change of the write pulse according to the pattern of the recording code, read / write chip 40
An automatic gain control 20 (AGC) that keeps the amplitude value of the read signal input from the (R / W IC) constant, and a servo demodulator 19 (SV-DEM) that detects head positioning information on the output disk medium surface of the AGC. ). Around the periphery, a write current control circuit 30 (WC-CTL) that controls the write current, a current output control from the write pulse to the magnetic head, and a chip 40 (R that generates the read pulse from the magnetization reversal read from the medium).
/ WIC), a microprocessor 50 (MPU) for controlling the inside of the disk device, and a disk controller 60 (HD for inputting and outputting commands and data coming from the host device).
C), a servo control circuit 70 (SPM / SEEK CTL) for rotating the spindle motor and positioning the head is connected. Reference numeral 80 is a disk medium, and 90 is a magnetic head.

FIG. 1 shows an R / W channel LSI 1 of the present invention.
3 and 4 are flowcharts showing the outline of the parameter setting method of 0. FIG. 3 and FIG. 4 are flowcharts C of string shift correction for setting the group delay of the filter 12.
2 and 5 are diagrams showing the changing order of the variable registers in FIGS.

6 and 7 are a flowchart C3 of the bit shift correction (1) for obtaining the condition of the sum of (ELY, LTE) of the write precompensation, and FIG. 8 is the change of the variable register in FIGS. It is a figure which shows an order.

9 and 10 are a flowchart C4 of the bit shift correction (2) for determining the setting condition of the fc / Boost of the filter from the group delay decision value and the write precompensation decision value, and FIG. 11 is FIG. , 1
It is a figure which shows the change order of the variable register in 0.

In addition to the above, FIGS. 12, 13 and 14 show a flow chart C5 of amplitude / margin measurement for searching for the maximum amplitude / margin point from the filter fc / Boost decision value, and FIG. It is a figure which shows the change order of a variable register.

FIG. 16 is a write current setting flow chart C6 for obtaining the current value to be passed through the magnetic head for recording on the disk medium in a state where all the parameters in the R / W channel LSI are determined.

FIG. 17 is a diagram showing the change order of the write current in FIG.

The contents of the processing routine for each parameter of the R / W channel LSI 10 will be described from the next page in units of stages in FIG.

First of all, analog ETFC1 (Chapter 1)
, Write a single pattern on the disk medium, and read pulse missing (attenuation) and extra (bath)
Is checked, and the medium defect position is extracted.

In the string shift correction C2 (Chapter 2), first, in R / W channel LSI parameter initial setting [LSI initial setting] stage 1 (stage is hereinafter abbreviated as S), initial setting of parameters inside the LSI is performed. This is done in the control register 11. In the next string shift worst pattern writing S2, a repeating pattern of 3T / 2T / 6T is written, and in the margin measurement S3, the window margin at the error rate: E ₁ is measured (WDM). Data synchronizer 14 (DT-S
Wind shift control (WSFT) in YC
-CTL), based on the error rate data when the window position is shifted in the + and-directions,
Error rate: Calculate the margin width at E ₁ . Group delay (GDLY) + direction maximum check S4
And + direction addition S5 loop, filter 12 (FL
WDM is measured when DLY in T) is accelerated in the + direction. When the + direction maximum setting is reached, GDLY-direction maximum check S6 and-direction addition S7 loop are used to measure WDM in the case of acceleration in the-direction. When the −direction maximum is set, the WDM maximum value extraction S8 searches for a value W ₁ that maximizes WDM while accelerating in both directions. And G at W ₁
Select G ₁ in DLY setting condition selection S9, and
In the center calculation S10, the center value C ₁ when WDM is W ₁ is calculated, and the process proceeds to the next Chapter 3. By performing the above operation, it becomes possible to set the group delay of the filter 12 so that the peak shift step of each pattern after reading (that is, the difference between the peak shift values of adjacent peaks) is minimized. .

Bit shift correction (1) In C3 (Chapter 3), GDLY sets the value G ₁ obtained by the string shift correction in the control register 11 in the LSI initial setting S1, and 3 in the bit shift worst pattern writing S2.
After the T pattern, a continuous 2-bit pattern having different bit intervals is prepared. It is assumed that one part of this pattern will perform write precompensation on the early side (early timing), and another part will perform write precompensation on the late side (late timing). . Light pre-compensation 1
Set 8 (WPC) to the early side (early timing)
Or change only the late side (late timing) and write. Margin measurement / center calculation In step S3, the window margin (WDM) at the error rate: E ₁ is measured to calculate the center value C ₂ . Light pre-compensation (WPC): Early direction maximum check S4
And in the early direction addition S5, WDM in the case of addition in the early direction is measured. At this time, the late side remains 0. Early WPC When turned maximum setting direction: the late direction maximum check-S6 - by direction adder S7 loop, calculates the center value C ₂ by measuring the WDM in the case of adding the late direction. At this time, the early side remains 0. When the maximum setting in the late direction is reached, the window margin W ₂ closest to the window center calculated by the string shift correction is selected from the window centers C ₂ calculated in the WDM selection S8. WPC selection condition WPC setting condition when the window margin is W ₂ (EL
Y ₁ , LTE ₁ ) is selected. Finally, in WPC sum calculation S10, the early side of WPC is set to a negative number to calculate the sum of early and late. That is, (-ELY ₁ ) + L
The calculation formula is TE ₁ → Mwpc.

In the bit shift correction (2) C4, first, the standard of inspection pass / fail is determined in the setting S1 of the WDM standard. In the LSI initial setting S2, GDLY and WPC are values (G ₁ · ELY ₁ selected and calculated in the previous chapter (C3).
・ LTE ₁ ) is preset in CTL-REG11. In the bit shift worst pattern write S3, the same write pattern as the bit shift correction (1) is prepared, and the WPC 18 is written under the condition (ELY ₁ , LTE ₁ ) obtained in the bit shift correction (1). Error rate margin measurement center calculation S4: calculating a margin width W ₃ and WDM measurement at E _1. Filter (FLT)
fc / Boost maximum check S5, fc or B
Addition from the minimum value of ost
/ Measure WDM in Boost setting range. Light
Pre-compensation (WPC): In the early direction maximum check S6 and early late direction addition S7, add in the early late direction without changing the WPC early and late sum Mwpc calculated in the bit shift correction (1). . This state is shown in FIG. 5-3.

Fc / Boo for each setting of this WPC
Measure the WDM in the st setting range. Extraction of maximum value from measured WDM In S9, WPC, FLT fc
/ Boost Search for the maximum WDM: W _3x in the entire range. In the WDM standard determination S10, W _3x is compared with the WDM standard value (K ₁ ), and if W _3x is K ₁ or more, it is determined to pass,
If it is less than K ₁ , it is rejected. If it passes, the center value C when WDM is W _{3x in} the window center calculation S11
Calculate ₃ . Then, in the WPC selection S12 at the time of W _3x ,
Early and Late select ELY ₂ and LTE ₂ , respectively. Further, in the selection S13 of the filter 12 at the time of W _3x , fc
/ Boost selects the fc _2, BST ₂ each advance to the next chapter (C5). In case of failure, retry check S
When the number is 14 or more times, the head defect determination S18 is performed, and the parameter setting operation is ended. In the case of the first time, another cylinder movement S15 moves to the outer cylinder where the other settings of the R / W channel parameters do not change, and string shift correction retry S16 and bit shift correction (1) retry S17 are executed and S3 is executed. Return.

In the amplitude margin measurement C5, WDM, amplitude / margin (LVM), and final standard are first set in various standard settings S1, and the pass / fail of the inspection is determined. In the LSI initial setting S2, GDLY, WPC, FLT, and window center are values (G ₁ , E) calculated and selected in the previous chapter.
LY ₂ · LTE ₂ , fc ₂ · BST ₂ , C ₃ ) is used. Amplitude worst pattern writing In S3, a 6T pattern is followed by a 3bit pattern, 2T, 5T to 8T, and the following bit patterns are prepared, and the WPC 18 setting is written under the condition (ELY ₂ , LTE ₂ ) obtained by the bit shift correction (2). . In the LVM measurement S4, the peak detector 13 (PK-QF
R) slice level control (SLV-CT)
The L), while gradually increasing slice level (SLV) from the minimum value error rate: amplitude margin at E ₁ (LVM): calculating the L _1. LVM standard judgment S5
L ₁ calculated in step ₁ is compared with the LVM standard value (K ₂ ), and L ₁
If is less than or equal to K ₂ , the result is acceptable, and if less than K ₂ , it is unacceptable. In the case of failure, it is judged as a head defect S8 in the retry check S3 three times or more, and the parameter setting operation is ended. In the case of the first time, in another cylinder movement S9, it moves to the cylinder on the outer periphery where the other settings of the R / W channel parameters do not change, and returns to S3. If it passes, the product of the value obtained by subtracting the LVM standard value: K ₂ from the LVM: L ₁ and the value obtained by subtracting the WDM standard value: K ₁ from WDM: W _3x is calculated by the amplitude × window margin product S6. Let the result be LW ₁ . If the amplitude × window margin product: LW ₁ calculated in the next final standard determination S11 is equal to or greater than the final standard value: K ₃ , it passes, and in the level / center calculation S11, LVM:
Calculate the level center at L ₁ and proceed to the next chapter (C6). When LW ₁ is less than K ₃ , the provisional standard determination process is started. First, in the LSI initial setting S12, the filter fc /
Boost is set to the minimum setting. In LVM measurement S13, LVM: L ₂ at error rate: E ₁ is calculated. Amplitude x window margin product S14 LVM: L ₂ to L
VM standard value: A value obtained by subtracting K ₂ , and WDM: W ₃ to WD
M standard value: Calculate the product of the values obtained by subtracting K ₁ and calculate the result as LW ₂
And

In the next standard determination S15, the amplitude / margin calculation result and the window margin calculation result are checked. If both the amplitude and the window margin are less than the standard value, the sign of amplitude × window margin product: LW ₂ is set. Invert in S16. That is, it is a negative number. If either one is greater than or equal to the standard value, the sign of LW ₂ is not inverted. Then filter (FL
T) The fc / Boost maximum check S17 and the addition S18 from the minimum value of fc or Boost are looped to measure WDM: L _{2 in} the fc / Boost setting range and calculate the product of amplitude and window margin: LW ₂ . Extraction of Maximum Value from Calculated LW _{2 In step} S19, the maximum LW _2x is searched for in the entire FLT fc / Boost range. In the standard determination S20, LW _2x is compared with the amplitude × window margin product provisional standard value (K ₄ ) to obtain LW ₂
Is K ₄ or more, it is judged as acceptable and LV at RW ₂ o'clock
M: Calculation of L _C2 at the center value calculation S21 in L _2, WDM:
Calculation of C ₄ at the center value calculation in S22 W _3, fc / Boost setpoint o'clock LW ₂ in FLT selection S23 fc _3, B
Select ST ₃ and go to the next chapter. When LW ₂ is less than K ₄ , the provisional standard is rejected and the process returns to S7.

In the write current setting method C6, GDLY, WPC, FLT (fc / B) is set in the LSI initial setting S2.
boot) and window center are values (G ₁ , ELY ₂ , LTE ₂ , fc ₂ ) calculated and selected in the previous chapter (C5).
・ BST ₂ or fc ₃ · BST ₃ , C ₃ ) is used. In the bit shift worst pattern write S2, the same write pattern as the bit shift correction (1) is prepared, and the WPC 18 is written under the condition (ELY ₂ , LTE ₂ ) obtained in the bit shift correction (2). In window margin (WDM) measurement S3, WDM is performed at an error rate of E ₁ to calculate a margin width W ₄ . WDM in the write current setting range is measured by the write current setting maximum check S5 and the write current increasing S6 loop. When the write current reaches the maximum setting, WDM maximum value extraction S6
Find the value W _4x that maximizes WDM in the write current setting range. Then, at the write current setting condition selection S7 at the time of W _4x , I ₁
Is selected to complete the selection and calculation of each parameter setting value of the R / W channel.

Finally, R / W channel parameter setting C
In step 7, all the setting / calculation values obtained in each chapter (C1 to C6) are stored in the control register 11 (CTL-REG), and the setting is completed. This is performed for each head and for each divided data cylinder area (zone).

By the above method, the parameters of the R / W channel LSI (fc of FLT, Boost, GDLY, W
ELY and LTE of PC, window center, level
By searching and setting (center, write current), the window margin and level
A wide margin result can be obtained.

[0040]

As described above, the method of setting the R / W channel parameter of the magnetic disk device of the present invention is an active filter (cutoff frequency, boost) for performing waveform equalization, which is a parameter relating to recording and reproduction. , Delay), slice level in the peak detector, window shift in the data synchronizer, write pre-compensation to control the timing of the write pulse, and the set value of the write current in the selected cylinder area.
Depending on the head address, the window margin (WD
M) or the amplitude margin (WDM) can be set to an optimum value, and the read error rate of the device can be reduced and the probability of occurrence of a defect can be suppressed to a low level, thus improving the reliability and stability. . Further, variations in characteristics of the disk medium, the magnetic head, the recording / reproducing LSI, etc. can be carried out in units of device, head, and zone (cylinder), which has an effect of improving yield.

[Brief description of the drawings]

1 is a flowchart showing an outline of an RWC parameter that is a part of an operation sequence and a write current setting method in a microprocessor (MPU) that sets an RWC and a write current in the hardware configuration of FIG. 1;

FIG. 2 is a block diagram showing an example of a hardware configuration of a magnetic disk device necessary for expressing each parameter of an R / W channel (RWC) and a method of setting a write current according to the present invention.

FIG. 3 is a flowchart for implementing string shift correction.

FIG. 4 is a flowchart for performing string shift correction.

5 is a diagram showing a change order of variable registers in FIGS.

FIG. 6 is a flowchart for implementing bit shift correction (1).

FIG. 7 is a flowchart for implementing bit shift correction (1).

FIG. 8 is a diagram showing a changing order of the variable registers in FIGS.

FIG. 9 is a flowchart for implementing a bit shift correction (2).

FIG. 10 is a flowchart for implementing a bit shift correction (2).

FIG. 11 is a diagram showing the changing order of the variable registers in FIGS.

FIG. 12 is a flowchart for performing amplitude / margin measurement.

FIG. 13 is a flowchart for performing amplitude / margin measurement.

FIG. 14 is a flowchart for performing amplitude / margin measurement.

FIG. 15 is a diagram showing the changing order of the variable registers in FIGS. 12, 13 and 14;

FIG. 16 is a flowchart for implementing write current setting.

FIG. 17 is a diagram showing a change order of the write current in FIG.

[Explanation of symbols]

10 R / W channel LSI (RWC) 11 Control register (CTL-REG) inside LSI 12 Filter (FLT) 13 Peak detector (PK-QFR) 14 Data synchronizer (DT-SYC) 16 Encoder (ENC) 17 Decoder (Decoder) DEC 18 write precompensation (WPC) 19 servo demodulator (SV-DM) 20 automatic gain control (AGC) 30 write current control circuit (WC-CTL) 40 recording / reproducing chip (R / W IC) 50 micro Processor (MPU) 60 Disk controller (HDC) 70 Servo control circuit (SPM / SEEK CTL) 80 Disk medium 90 Magnetic head Chapter 1 (C1) Analog ETF implementation routine Chapter 2 (C2) String shift correction routine Chapter 3 ( C3) Bit shift correction (1) routine Chapter 4 (C4) Bit shift correction (2) routine Chapter 5 (C5) Amplitude margin measurement routine Chapter 6 (C6) Write current optimization routine Chapter 7 (C7) R / W Channel parameter setting routine

Claims (9)

[Claims] 1. A cutoff frequency (fc), a boost (Boost), and a delay amount (DLY), which are parameters for controlling characteristics of an active filter for performing waveform equalization on a signal read from a disk medium, are set. Means for setting the slice level (SLV) in the peak detector, and window shift (WS) in the data synchronizer.
F) setting means, write precompensation (WPC) setting means for writing pulse timing, and write current (Ic) setting means in the magnetic disk device, wherein the window shift setting is performed. , The error rate is measured according to the frequency of bit mismatch between the read signal and the write signal, the window margin at a predetermined error rate is calculated, and the setting of the slice level (SLV) is changed to change the predetermined value. Calculating an amplitude margin (LVM) at each error rate, and setting each parameter (fc, Boost, DL) of the filter.
Y) when changing window margin (WDM)
Is determined by searching for fc, Boost, and DLY for which WDM is optimal, and WPC for which WDM is optimal when the WPC is changed.
The setting value is searched and determined, the Ic setting value for which WDM is optimum when Ic is changed is searched and determined, and the Ic setting value is calculated from the filter parameter (fc, Boost) and the optimum WDM. An R / W channel parameter setting method for a magnetic disk device, characterized in that the optimum set values of fc and Boost are searched and determined from the SLV from the window center. 2. A worst-case repetitive pattern is written, then the group delay is set to a certain initial value, the window margin at a constant error rate is measured, and then the set value is changed in the + direction, Repeat the measurement of the window margin, return to the first set value after the group delay reaches the + direction maximum set value, change the set value in the − direction, and then move the window until the − direction maximum set value is reached.・ Repeat margin measurement,
A R / W channel parameter setting method for a magnetic disk device, characterized in that a group delay value and a window center when the window margin takes a maximum value are selected from among these. 3. The group delay set in claim 2 is used to measure the window margin by changing the early side while keeping the rate side value of the write precompensation amount at 0, and then With the early side set to 0, the window center obtained by changing the late side is measured, and the window center selected in claim 2 is most selected when the early side is moved or the late side is moved. 3. The R / W of the magnetic disk drive according to claim 2, wherein a close window margin is selected, and the value of write precompensation at this time is set as a temporary setting value.
Channel parameter setting method. 4. The values on the early side and the late side of the pre-compensation temporarily set in claim 3 are used as initial values, and both the early direction and the late direction are equally added and changed.
For each precompensation value, fc and Boost of the filter are changed to
It is characterized by measuring the margin and window center, and setting the value as the write precompensation amount when the write precompensation amount when the window margin takes the maximum value meets the standard. The R / W channel parameter setting method of the magnetic disk device according to claim 3. 5. When the product of the difference between the measured amplitude margin value and its preset standard value and the difference between the measured window margin value and its preset standard value is larger than a certain standard value. Determines that the amplitude margin is the final pass,
A method for setting an R / W channel parameter of a magnetic disk device, characterized in that a level center at that time is calculated and set as a slice level. 6. When the product according to claim 5 is smaller than a certain standard value, the values of fc and Boost of the filter are sequentially changed starting from a minimum set value, and the measured amplitude margin value in each state is set in advance. If the product of the difference between the standard value and the measured window margin value and the preset standard value is less than a certain standard value, the amplitude margin is judged to be provisionally acceptable, and F of the filter
A method for setting an R / W channel parameter of a magnetic disk device, characterized in that c and Boost are set values and a level center is calculated and a slice level is set. 7. In a device to be used, a repetitive pattern of the worst condition is written, then a window margin at a constant error rate is measured with the write current having a certain initial value, and then the set value of the write current is set. It is characterized in that the window margin is repeatedly measured until the write current reaches the maximum set value by sequentially adding and increasing, and the write current when the window margin takes the maximum value is set as the set value. R / W of magnetic disk device
Channel parameter setting method. 8. In the device used, the group delay amount is set by the method according to claim 2, and the value of write precompensation is set by the method according to claim 3. Fc, Boost and light
A pre-compensation value is set, a slice level is set by the method according to claim 5, and a slice level, fc and B are set by the method according to claim 6.
9. A method for setting an R / W channel parameter of a magnetic disk device, wherein the write current value is set by the method according to claim 7 by setting oost. 9. The magnetic according to claim 8, wherein the value of each parameter can be set to be optimized for each device, each head, each cylinder or zone, that is, each aggregate of adjacent cylinders. A method for setting R / W channel parameters of a disk device.