JPH0714107A - Magnetic disk device and recording current setting method - Google Patents

Abstract

PURPOSE:To automatically set the recording currents of a head at the time of writing data to the in respective devices. CONSTITUTION:Since a disk control part 5 can generate the 1F pattern of a low frequency and the 4F pattern of a high frequency from a pattern generator 17, the 1F pattern is written on places to be measured on a magnetic disk 100 with a head 1 and the 4F pattern is over-written on the places. Thereafter, an over-write modulation is measured by reading-out the places with the head 1, extracting only the 1F pattern with a BPF 7 and by knowing the level via a level holding circuit 9. Subquently in the same way, the disk control part 5 measures cross-talk and resolution by writing the 4F pattern and the 1F pattern on places to be measured and the 1F pattern on adjacent tracks with a prescribed combination and reading-out them. Optimum currents are obtained by performing these measurement while changing recording currents and then data are written on measured places using these recording currents.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device, and more particularly to a method of setting a recording current when writing data on a magnetic disk with a head.

[0002]

2. Description of the Related Art Conventionally, in a magnetic disk device, data is written by overwriting modulation from the already recorded data, but it is necessary to carry out overwriting modulation of an appropriate size.
Crosstalk with adjacent tracks should be minimized. This causes various obstacles during data reproduction when the overwrite modulation and the crosstalk with the adjacent track are large. This is because the S / N (signal / noise ratio) is deteriorated due to the mixing of unnecessary signal components, and a read error is likely to occur. If this read error is likely to occur, the once written data cannot be read, and the reliability and performance of the magnetic disk device itself are degraded, such as a reduction in throughput due to a retry of a read operation.

The overwrite modulation and the crosstalk may be similarly bad in one magnetic disk device as a whole, but may be locally bad due to a defect or deformation of the recording medium and a slight accuracy error at the time of servo writing. There is also. For this reason, when formatting the recording medium (magnetic disk) that is performed at the initial stage, find the part where the above-mentioned overwrite modulation or crosstalk is bad, and mark the very bad part on the recording medium as defective. It is being used for reading and writing. Marking of such a defective portion on the recording medium has been performed by a write / read test at the time of formatting, but such a method may not be able to detect a latent and delicate degree of defective portion. Therefore, in some cases, a defective portion due to overwrite modulation or crosstalk may appear after passing the write / read test.

By the way, since the magnitude of the overwrite modulation and the magnitude of the crosstalk depend on the magnitude of the recording current value at the time of writing data by the head, by setting this recording current value, the reverse current is set. However, the amount of overwrite modulation and crosstalk is decided. Usually, in the recording / reproducing characteristics of the head / recording medium, if the recording current is too small, the existing recording magnetization pattern cannot be completely re-magnetized with a new pattern, and the overwrite modulation inevitably deteriorates. I will end up. However, on the contrary, if the recording current is excessively high, the reproduction output in the high frequency range is lowered and the resolution is relatively lowered.

FIG. 4 shows a typical recording current-reproducing voltage characteristic. The point b indicates that the recording current is large, but the level of the high frequency component during reproduction is lowered, and the resolution is lowered. Therefore, in order to increase the resolution, it is preferable to record the data with the recording current value at the point a where the characteristic B of the low frequency signal and the characteristic B of the high frequency signal are close to each other. However, as described above, the smaller the recording current, the worse the overwrite modulation tends to be. Therefore, the recording current value set at the time of manufacturing the device is eventually set as a compromise between the resolution and the overwrite modulation. . However, since the overwrite modulation is not constant everywhere on the recording medium, if you set the recording current value so that there is enough room for the location where the overwrite modulation is bad,
In a place where overwrite modulation is good, the resolution will be unnecessarily reduced.

Further, increasing the recording current tends to improve overwrite modulation, but conversely tends to deteriorate crosstalk. Therefore, this crosstalk must be taken into consideration when setting the recording current value. If the characteristics of overwrite modulation and crosstalk change depending on the position on each magnetic disk device or recording medium, the optimum recording current value described above should also change depending on the position on each device or recording medium. However, in the past, it was only necessary to sample the characteristics of a plurality of magnetic disk devices and set the recording current value at the compromise point, so that the optimum recording current value is not always set for each magnetic recording device. Not happening.
For this reason, the error rate varies between devices, and if the recording current is adjusted appropriately, the performance can be shipped. However, with the conventional recording current value setting method as described above, the performance is poor (can be shipped. There is a drawback that some devices cannot be shipped because they are at the critical point.

[0007]

As described above, in the conventional magnetic disk drive, the write current is set to a value at which the characteristics of these three members can be secured to some extent or more in consideration of overwrite modulation, data resolution and crosstalk. Was set at the time of manufacture. Moreover, since the setting method samples the characteristics of a plurality of magnetic disk devices and sets the characteristics of these devices to values that can be secured to some extent,
Since the performance of each magnetic disk device varies, and some devices do not reach the performance that can be shipped, the yield at the time of manufacturing the device is poor.

In view of the above, the present invention eliminates the above-mentioned drawbacks and allows each device to automatically set the recording current of the head at the time of data writing optimally, thereby maximizing the performance of each device to reduce the error rate. As well as improve
An object of the present invention is to provide a magnetic disk device and a recording current setting method capable of improving the yield of the device during manufacturing.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a pattern generation for generating a low frequency first pattern or a high frequency second pattern in a magnetic disk device in which data is written and read by a head at a predetermined position of a magnetic disk Means and detecting means for detecting the level of the data,
A signal extracting means for passing only the low frequency first pattern component, and a first signal generated by the pattern generating means.
After writing the pattern at the measurement location on the magnetic disk by the head, and then overwriting the second pattern generated by the pattern generating means at the measurement location, the data at the measurement location is read,
From the read data, the first signal is extracted by the signal extracting means.
The pattern component is extracted, the level of the extracted first pattern component is detected by the detecting unit, and the overwrite modulation measuring unit for measuring the value of the overwrite modulation by this level and the pattern generating unit are generated. After writing the second pattern at the measurement point on the magnetic disk by the head, then writing the first pattern generated by the pattern generating means on the tracks on both sides of the measurement point, and then at the measurement point Data is read, the first pattern component is extracted from the read data by the signal extracting means, the level of the extracted first pattern component is detected by the detecting means, and the crosstalk value is measured by this level. Crosstalk measurement means and the pattern generation means After writing the generated second pattern to the measurement location, the level of data obtained by reading the measurement location is detected by the detection means, and then the first pattern generated by the pattern generation means is measured. And a resolution measuring means for detecting the level of data obtained by reading out the measurement location after writing in the location and detecting the resolution from the level ratio between the first pattern and the second pattern detected by the detection means. The overwrite modulation measuring means performs overwrite modulation for each measurement point included in all the recording areas of the magnetic disk by changing the recording current value of the head in a plurality of steps. After obtaining the overwrite modulation value for each recording current value at the measurement point, The crosstalk for each measurement point included in all the recording areas of the magnetic disk is performed by the stalk measuring means by changing the recording current value of the head in a plurality of steps. After the talk value is obtained, the resolution is measured by the resolution measuring means by changing the recording current value of the head in multiple steps for each measurement point included in all the recording areas of the magnetic disk, thereby After obtaining the resolution for each recording current value, the optimum recording current value such that the overwrite modulation, crosstalk, and resolution are all above a predetermined level is obtained for each of the measurement points, and thereafter, this recording current value is used. And a control means for controlling the writing of data to each measurement location on the magnetic disk by the head.

[0010]

According to the present invention, in the magnetic disk device, the pattern generating means generates the low frequency first pattern or the high frequency second pattern. The detection means detects the level of data. The signal extraction means passes only the low frequency first pattern component. The overwrite modulation measuring means writes the first pattern generated by the pattern generating means at the measurement location on the magnetic disk by the head, and then writes the second pattern generated by the pattern generating means at the measurement location. After overwriting, the data at this measurement point is read out, the first pattern component is extracted from the read out data by the signal extracting means, and the level of the extracted first pattern component is detected by the detecting means. , Measure the value of overwrite modulation by this level. The crosstalk measuring means writes the second pattern generated by the pattern generating means at the measurement location on the magnetic disk by the head, and then writes the first pattern generated by the pattern generating means at the measurement location. After writing to the tracks on both sides, the data at the measurement point is read out, the first pattern component is extracted from the read out data by the signal extracting means, and the extracted first pattern component is extracted.
The level of the pattern component is detected by the detecting means, and the value of crosstalk is measured by this level. The resolution measuring means is the second one generated by the pattern generating means.
After writing the pattern to the measurement location, detecting the level of the data obtained by reading the measurement location by the detection means, and then writing the first pattern generated by the pattern generation means to the measurement location Then, the level of the data obtained by reading this measurement point is detected by the detecting means, and the resolution is measured from the level ratio of the first pattern and the second pattern detected by the detecting means. The control means performs overwrite modulation for each measurement location included in all recording areas of the magnetic disk by the overwrite modulation measuring means by changing the recording current value of the head in a plurality of steps, thereby performing each measurement. After obtaining the overwrite modulation value for each recording current value at each location, the crosstalk measuring means determines the crosstalk at each measurement location included in all the recording areas of the magnetic disk by a plurality of head recording current values. By obtaining the value of the crosstalk for each recording current value of each of the measurement points by performing the step change, the resolution for each measurement point included in all the recording areas of the magnetic disk by the resolution measuring means. By changing the recording current value of the head in multiple steps,
After obtaining the resolution for each recording current value at each measurement point,
The optimum recording current value such that overwrite modulation, crosstalk, and resolution are all above a predetermined level is obtained for each of the measurement points, and thereafter, data is recorded by the head at each measurement point of the magnetic disk by this recording current value. Control writing. As a result, the recording current value is changed at each position on the recording medium in consideration of the variation of each device.
Since the optimum setting is made, the performance of the device can be maximized and the error rate and the like can be reduced. or,
The number of devices that cannot be shipped at the time of manufacturing the device can be reduced, and the yield at the time of manufacturing the device can be improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a magnetic disk device of the present invention. Reference numeral 1 is a head attached to the tip of a carriage mechanism 2 for reading and writing data from and to the magnetic disk 100.
A carriage unit 3 which moves in the radial direction of 00 to be positioned on a target track is amplified by a head amplifier 3 for amplifying data read from the head 1 or for amplifying data written by the head 1, and 4 is amplified by the head amplifier 3. An automatic gain control amplifier (AGC amplifier) for making the level of read data constant, 5 is a disk control unit (HDC) for controlling reading / writing of data from the magnetic disk 100, setting control of an optimum recording current value, and 6 is disk control. A memory for storing various programs and data necessary for the operation of the unit, 7 is a band pass filter (BPF) that passes only the frequency component of the 1F pattern described later, 8 is read data output from the head amplifier 3, and Select either one of the 1F patterns extracted by the bandpass filter 7 Switch, 9 is level-hold circuit for holding the level of a signal input from the switch 8, 10 A / D converter for converting the level, which is held by the level hold circuit 9 into digital data, 1
1 is a low-pass filter (LPF) that removes high-frequency noise components from read data, and 12 is a low-pass filter 11
A pulse generator for generating a pulse in accordance with the data inputted from 13; a PLL circuit 13 for generating a window based on the pulse interval inputted from the pulse generator 12; and 14 a window and a pulse generator inputted from the PLL circuit 13. A data generator that generates data based on pulses input from 12, a decoder that demodulates data input from the data generator 14, a encoder 16 that modulates data input from the disk control unit 5, and a disk 17 A pattern generator that generates a pattern according to an instruction input from the control unit 5, 18 is a D / A converter that digitizes a command input from the disk control unit 5, and 19 is a changeover switch that switches the type of write data. .

FIG. 2 is a schematic diagram showing each functional system of the magnetic disk device shown in FIG. A is a waveform amplitude measurement system,
1. The changeover switch 8 is switched to the terminal b side in FIG. 1, a level hold circuit 9 and an A / D converter 10,
4F pattern read from the magnetic disk 100 and 1
The waveform amplitude of the F pattern is measured and these data are supplied to the disk control unit 5. B is a measurement system for overwrite modulation and crosstalk, which includes an AGC amplifier 4,
It is composed of a BPF 7, a changeover switch 8 switched to the terminal a side, a level hold circuit 9 and an A / D converter 10, and measures the magnitude of overwrite modulation and crosstalk and supplies it to the disk controller 5. C
Is a data read system, and includes an AGC amplifier 4, LPF 11,
It is composed of a pulse generator 12, a PLL circuit 13, a data generation 14 and a decoder 15. The data read from the magnetic disk 100 is processed and demodulated, and this is supplied to the disk controller 5. D is a data write system, and includes a pattern generator 17 or an encoder 16
And a changeover switch 19, which modulates data input from the disk control unit 5 into write data or generates a measurement pattern corresponding to a command from the disk control unit 5 to generate a magnetic disk. The write data for measurement is supplied to 100. E is a recording current control system, which is composed of a D / A converter 18, which converts a control signal input from the disk control unit 5 into an analog signal and outputs the analog signal to the head amplifier 3, thereby recording the head. Control the current.

Next, the operation of this embodiment will be described. When the power is turned on, the device shown in FIG. 1 performs an operation of setting the optimum recording current value of the head during data recording. This time,
The changeover switch 19 is switched to the terminal a side by the disk control unit 5. At the time of setting the optimum recording current, the disk control unit 5 generates a code pattern for measurement described below from the pattern generator 17 to measure overwrite modulation, crosstalk and resolution.
There are usually several types of such code patterns, for example in the case of (1, 7) RLL code: (1) Amplitude worst pattern 100000001010
100000001010100000001, (2) 1F pattern
100000001000000001000000100000001, (3) 4F pattern 101010101010101010101010101010101 The above (1) amplitude worst pattern and (2) 1F pattern give a low signal frequency, and (3) 4F pattern gives a high signal frequency. Signal frequencies with lower overwrite modulation and crosstalk have a greater effect, so
This is used for measurement. When the overwrite modulation is measured, after the head 1 is positioned at the position (track or sector) to be measured, the disk controller 5 operates the pattern generator 17 to first perform the 1F pattern (or worst amplitude pattern). ) Is sent to the head 3 via the changeover switch 19 and the head amplifier 3, and this 1F pattern is written in the measurement portion of the magnetic disk 100. At this time, the disk control unit 5 operates the head 1
The head amplifier 3 is controlled via the D / A converter 18 so that the recording current of (1) becomes a specific value. Next, the disk controller 5 causes the pattern generator 17 to generate a 4F pattern, and overwrites the 4F pattern on the measurement point where the 1F pattern is written. After that, the disk controller 5
After the changeover switch 8 is set to the terminal a side, the head 1 reads the measurement point of the magnetic disk 100, and the overwrite modulation and the crosstalk component are measured as described below.

That is, the level of the data read by the head 1 is made constant by the AGC amplifier 4, and then BP is set.
It is input to F7 and LPF11. The BPF 7 extracts the 1F pattern from the read data and outputs it to the level hold circuit 9 via the changeover switch 8.
By the way, the frequency characteristic of the read data is shown in FIG.
It is thought that it is as shown in. Here, since the low frequency component a corresponds to the 1F pattern, the level hold circuit 9 holds the peak level of the low frequency component a in FIG. The A / D converter 10 digitizes the peak level and transfers it to the disk controller 5. The disk controller 5 evaluates the magnitude of overwrite modulation from the magnitude of the peak level input from the A / D converter 10, and stores it in the memory 6. The disk control unit 5 performs the above-described overwrite modulation measurement several times by changing the recording current value at some points, and stores the overwrite modulation value at each time in the memory 6.

The crosstalk measurement is only slightly different from the overwrite modulation measurement described above.
The disk control unit 5 starts from the pattern generator 17 to 4F.
A pattern is generated, and the pattern is written from the head 1 to the measurement location on the magnetic disk 100 via the changeover switch 19 and the head amplifier 3. At this time, the disk controller 5 controls the head amplifier 3 via the D / A converter 18 so that the recording current of the head 1 becomes a specific value. continue,
The disk control unit 5 seeks the head 1 to the adjacent track and performs the 1F pattern (or the worst amplitude pattern) in the same procedure.
Is written in the adjacent track of the measurement point, and similarly, the 1F pattern is also written in the adjacent track on the opposite side. After that, the disk control unit 5 reads the measurement location where the 4F pattern is written by the head 1. The data read by the head 1 is input to the AGC amplifier 47 via the head amplifier 3, where the level is made constant, and then the BPF is set.
7 and LPF11. The BPF 7 passes only the frequency component of the 1F pattern (or the worst amplitude pattern) and outputs it to the level hold circuit 9 via the changeover switch 8.

The level hold circuit 9 holds the peak value of the passing frequency component, and the peak value is digitized by the A / D converter 10 and then input to the disk control section 5. Here, the crosstalk from the adjacent track is 1F written on both adjacent tracks when the head 1 traces the measurement location where the 4F pattern is written.
Since the amount of pattern data can be measured, the level of the 1F pattern held by the level hold circuit 9 can be evaluated to measure the magnitude of crosstalk. Therefore, the disk controller 5 evaluates the magnitude of crosstalk from the magnitude of the peak level input from the A / D converter 10 and stores it in the memory 6. The disk control unit 5 performs the above crosstalk measurement several times by changing the recording current value at some points, and stores the crosstalk value at each time in the memory 6
Remember.

When measuring the next resolution, the disk control unit 5 first generates a 4F pattern from the pattern generator 17 and supplies it to the head 1 through the changeover switch 19 and the head amplifier 3, so that the magnetic field is generated by the head 1. The 4F pattern is written at the measurement location on the disk 100. At this time, the disk controller 5 controls the head amplifier 3 via the D / A converter 18 so that the recording current value of the head 1 becomes a specific value. Next, the disk controller 5 reads out the measurement location where the 4F pattern is written by the head 1. As a result, 4F read by the head 1
The pattern is input to the level hold circuit 9 via the head amplifier 3 and the changeover switch 8. Since the level hold circuit 9 holds the peak value of the input 4F pattern waveform, the A / D converter 10 digitizes the peak value and then outputs it to the disk controller 5. The disk controller 5 stores the peak value held by the level hold circuit 9 in a predetermined area of the memory 6. The peak value corresponds to the amplitude value of the 4F pattern read by the head 1.

Next, the disk control unit 5 causes the pattern generator 17 to generate a 1F pattern, writes the 1F pattern on the measurement portion of the magnetic disk 100 by the head 1, and then writes the 1F pattern on the head. By reading at 1, the peak value of the waveform of the 1F pattern is held in the level hold circuit 9 and input to the disk controller 5 by the same procedure as above. The disk controller 5 stores the peak value of the input 1F pattern in the memory 6
Stored in a predetermined area of. By the way, the resolution can be obtained as (amplitude of 4F pattern) / (amplitude of 1F pattern), and the disk control unit 5 obtains the resolution at the time of data reading from the both peak values stored in the memory 6, and calculates this. It is stored in a predetermined area of the memory 6. The disk controller 5 also switches the recording current value in a plurality of steps to measure the resolution, and stores the resolution for each recording current value in the memory 6.

In the above operation, the changeover switch 19 is used instead of giving the measurement pattern from the pattern generator 17.
May be switched to the b side, and the disk controller 5 may create the pattern, modulate it by the encoder 16 and output it to the head 1. In this case, the pattern generator 17 and the changeover switch 19 are not necessary. .

The disk control unit 5 measures the above-mentioned overwrite modulation, crosstalk, and resolution by switching the recording current value in a plurality of steps. A value is determined, and this value is stored in the memory 6 as the optimum recording current value at the measurement location of the magnetic disk 100 on which the above-described measurement is performed.
The disk control unit 5 performs the above-described measurement and determination of the optimum recording current for the measured locations for all the measured locations of the magnetic disk 100, and stores the obtained data in the memory 6 for each measured location. . Here, as the measurement location, for example, a sector, a track, or an area in which several tracks are collected can be applied.

When writing data supplied from a host computer or the like, the disk control unit 5 checks which measurement location the sector on the magnetic disk 100 to which this data is written belongs to, and determines the optimum recording current value at this measurement location. Is read from the memory 6 and a control signal is sent from the D / A converter 18 to the head amplifier 3 so as to obtain the optimum recording current value.
Then, the recording current of the head 1 is controlled. After that, when the head 1 is positioned at the designated sector portion, the disk controller 5 modulates the write data by the encoder 16 and then supplies it to the head 1 from the head amplifier 3 via the changeover switch 19. To do. As a result, the head 1 writes the write data in the designated sector at the optimum recording current value. However, the changeover switch 19 is switched to the terminal b side by the disk control unit 5 at the time of writing.

When formatting the data area, the overwrite modulation and crosstalk are obtained for each track / sector on the medium by the above-mentioned procedure in advance, and if these values are set to a predetermined standard. If it exceeds the value, the defective track / defective sector is clearly indicated, and marking for disabling the subsequent use is performed on the measured sector so that the sector is not used for data recording. If the result of the above measurement indicates that there are too many unusable regions, this lot is removed as a defective product during manufacturing.

According to the present embodiment, when the data area is formatted, the device measures the overwrite modulation and crosstalk for each sector of the magnetic disk 100, and the optimum recording current for each sector of this device. In order to set, the characteristics of multiple conventional magnetic disk devices are sampled, and compared with the case where the recording current value is set at the compromise point, the overwrite modulation or crosstalk is used without reaching a predetermined level. The disabled area can be reduced, the yield of products can be improved, and the unusable area can be reduced to contribute to high density recording. Further, when actually writing data, overwrite modulation, crosstalk, and resolution are measured for each sector of the magnetic disk 100 (when the above-described measurement location is used as a sector unit), for example, at power-on. Since it is possible to set the optimum recording current value that takes into consideration the unevenness of the recording medium of each sector and the eccentricity of the track, etc. The performance of the device can be maximized in accordance with the variation in the characteristics of each device. Incidentally, dividing the magnetic disk 100 into a plurality of areas and setting the optimum recording current value in one area to be the same for simplification also has a sufficient practical advantage. At this time, the disk controller 5 obtains optimum recording current values for all the sectors in the one area, and stores the most severe optimum recording current value in the memory 4 as the optimum recording current of this area. become.

[0024]

As described above, according to the magnetic disk device and the recording current setting method of the present invention, the recording current of the head at the time of writing data can be automatically and optimally set in each device so that each device can be set automatically. By maximizing the performance, the error rate can be improved and the yield of the device at the time of manufacturing can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetic disk device of the present invention.

FIG. 2 is a schematic diagram showing each functional system of the magnetic disk device shown in FIG.

FIG. 3 is a diagram showing a typical recording current-reproduction voltage characteristic.

FIG. 4 is a diagram showing frequency characteristics of a read signal which is affected by overwrite modulation and crosstalk.

[Explanation of symbols]

1 ... Head 2 ... Carriage part 3 ... Head amplifier 4 ... AGC amplifier 5 ... Disk control part 6 ... Memory 7 ... Band pass filter 8, 19 ... Changeover switch 9 ... Level hold circuit 10 ... A / D converter 11 ... Low pass Filter 12 Pulse generator 13 PLL circuit 14 Data generator 15 Decoder 16 Encoder 17 Pattern generator 18 D / A converter 100 Magnetic disk

Claims (9)

[Claims] 1. In a magnetic disk device for writing and reading data by overwriting on a predetermined portion of a magnetic disk by a head, pattern generating means for generating a low frequency first pattern or a high frequency second pattern and data level are set. After writing the detecting means for detecting, the signal extracting means for passing only the low frequency first pattern component, and the first pattern generated by the pattern generating means to the measurement location on the magnetic disk by the head, Furthermore, after writing the second pattern generated by the pattern generating means to the same measurement location by overwriting, the data of this measurement location is read out, and the first pattern component is extracted from the read data by the signal extraction means,
An overwrite modulation measuring means for detecting the level of the extracted first pattern component by the detecting means, and measuring the value of the overwrite modulation by the level.
A magnetic disk device, wherein when the value of overwrite modulation at the measurement point measured by the modulation measuring means is worse than a predetermined value, the measurement point is excluded from the data recording area. 2. In a magnetic disk drive for writing and reading data by overwriting on a predetermined portion of a magnetic disk by a head, a pattern generating means for generating a low frequency first pattern or a high frequency second pattern and a data level are set. After the detecting means for detecting, the signal extracting means for passing only the low frequency first pattern component, and the second pattern generated by the pattern generating means are written by the head to the measurement location on the magnetic disk, Next, after writing the first pattern generated by the pattern generating means to the tracks on both sides of the measuring point, the data at the measuring point is read out, and the first pattern component is extracted from the read-out data by the signal extracting means. The level of the extracted first pattern component is detected by the detecting means, Crosstalk measuring means for measuring the value of the crosstalk according to the level of, and if the crosstalk value of the measurement point measured by the crosstalk measuring means is worse than a predetermined value, A magnetic disk device characterized by being excluded from the recording area. 3. In a magnetic disk drive for writing and reading data to and from a predetermined location on a magnetic disk by a head, the pattern generating means for generating a low frequency first pattern or a high frequency second pattern and a data level are set. After writing the detecting means for detecting, the signal extracting means for passing only the low frequency first pattern component, and the first pattern generated by the pattern generating means to the measurement location on the magnetic disk by the head, Furthermore, after writing the second pattern generated by the pattern generating means to the same measurement location by overwriting, the data of this measurement location is read out, and the first pattern component is extracted from the read data by the signal extraction means,
The level of the extracted first pattern component is detected by the detecting means, and the overwrite modulation measuring means for measuring the value of the overwrite modulation by this level, and the second pattern generated by the pattern generating means are described above. After writing to the measurement location on the magnetic disk by the head, then writing the first pattern generated by the pattern generating means to the tracks on both sides of the measurement location, the data at the measurement location is read out, and The signal extraction means extracts a first pattern component from the read data, and the level of the extracted first pattern component is detected by the detection means,
Crosstalk measuring means for measuring the value of crosstalk according to this level, and the overwrite modulation measuring means of the head modulates overwrite modulation for each measurement point included in all recording areas of the magnetic disk. By changing the recording current value in a plurality of steps to obtain an overwrite modulation value for each recording current value at each of the measurement points, the crosstalk measuring means is included in all recording areas of the magnetic disk. By performing crosstalk at each measurement point by changing the recording current value of the head in multiple steps, after obtaining the crosstalk value for each recording current value at each measurement point, overwrite modulation and cross Optimal recording current value so that both talks are above a certain level The seeking for each measurement point, since the recording current magnetic disk apparatus characterized by comprising a control means for controlling to write data to the respective measuring points of the magnetic disk by the head by. 4. In a magnetic disk drive for writing and reading data to and from a predetermined location of a magnetic disk by a head and reading the data, a pattern generating means for generating a low frequency first pattern or a high frequency second pattern and a data level are set. After writing the detecting means for detecting, the signal extracting means for passing only the low frequency first pattern component, and the first pattern generated by the pattern generating means to the measurement location on the magnetic disk by the head, Furthermore, after writing the second pattern generated by the pattern generation means to the measurement location by overwriting, the data at the measurement location is read out, and the first pattern component is extracted from the read data by the signal extraction means,
The level of the extracted first pattern component is detected by the detecting means, and the overwrite modulation measuring means for measuring the value of the overwrite modulation by this level, and the second pattern generated by the pattern generating means are described above. After writing to the measurement point on the magnetic disk by the head, then writing the first pattern generated by the pattern generating means to the tracks on both sides of the measurement point, and reading the data at this measurement point, The signal extraction means extracts a first pattern component from the read data, and the level of the extracted first pattern component is detected by the detection means,
The crosstalk measuring means for measuring the value of the crosstalk by this level and the second pattern generated by the pattern generating means are written in the measurement point, and then the level of the data obtained by reading the measurement point is detected. After the first pattern generated by the pattern generating means is written in the measurement location, the level of the data obtained by reading the measurement location is detected by the detection means, and then detected by the detection means. Resolution measurement means for measuring the resolution from the detected level ratio of the first pattern and the second pattern, and the overwrite modulation measurement means is used to detect over-measurement at each measurement location included in all recording areas of the magnetic disk. Write modulation is performed by changing the recording current value of the head in multiple steps. After obtaining the overwrite modulation value for each recording current value at each measurement point by the crosstalk measuring means, the crosstalk for each measurement point included in all the recording areas of the magnetic disk is measured by the crosstalk measuring means. After obtaining the crosstalk value for each recording current value at each of the measurement points by changing the recording current value in a plurality of steps, each resolution contained in all the recording areas of the magnetic disk by the resolution measuring means. By changing the recording current value of the head in multiple steps at each measurement point, the resolution for each recording current value at each measurement point is obtained, and then overwrite modulation, crosstalk, and resolution are both at a predetermined level. Obtaining the optimum recording current value as described above for each of the measurement points,
Thereafter, the magnetic disk device is provided with a control means for controlling the writing of data to each measurement position of the magnetic disk by the head according to the recording current value. 5. An area including a plurality of measurement points of the magnetic disk is set, and as an optimum recording current value of this area, the most severe optimum recording current value among the optimum recording current values of the measurement points included in this area. 5. The magnetic disk drive according to claim 1, wherein a current value is selected and used. 6. A method for setting a recording current of a head of a magnetic disk device, wherein the head writes a data to a predetermined portion of a magnetic disk by overwriting and reads the data, wherein overwrite modulation of an arbitrary recording portion of the magnetic disk is performed. After measuring, and measuring the resolution at the same location, obtain the optimum recording current value so that both the overwrite modulation and the resolution are above a predetermined level, and then the data is recorded at this location by the head with this recording current value. A write current setting method characterized by performing write control. 7. A method for setting a recording current of a head of a magnetic disk device, wherein data is written and read by a head to a predetermined portion of a magnetic disk by overwriting, wherein overwrite modulation of an arbitrary recording portion of the magnetic disk is performed. After the measurement and the crosstalk at the same location, the optimum recording current value such that both the overwrite modulation and the crosstalk are above a predetermined level is obtained, and thereafter, the data is recorded at this recording current value by the head. A write current setting method characterized by performing write control to a location. 8. A method for setting a recording current of the head of a magnetic disk device, wherein data is written to and read from a predetermined portion of the magnetic disk by a head, wherein overwrite modulation of an arbitrary recording portion of the magnetic disk is performed. After the measurement and the crosstalk at the same location, the optimum recording current value such that both the overwrite modulation and the crosstalk are above a predetermined level is obtained, and thereafter, the data is recorded at this recording current value by the head. Recording current setting method characterized by performing write control to a location 9. A method for setting a recording current of a head of a magnetic disk device, wherein data is written to and read from a predetermined portion of a magnetic disk by a head, wherein overwrite modulation of an arbitrary recording portion of the magnetic disk is performed. After measuring, and measuring the resolution at the same location, and measuring the crosstalk at the same location, find the optimum recording current value such that both overwrite modulation and resolution and crosstalk are above a certain level. A recording current setting method, characterized in that data is written to the location by the head at the recording current value.