JP2890713B2 - Magnetic disk recording device and magnetic disk reproducing device - Google Patents

Description

The present invention relates to a magnetic disk recording device.

B. Summary of the Invention The present invention is directed to a head for recording a signal on a magnetic disk, a head position management means for managing a radial position of the head, and a pattern for detecting a pattern of recording data in which a peak position of a reproduction signal shifts. Detecting means, and a pulse width control means for controlling a pulse width of a recording signal supplied to the head in accordance with the head position information from the head position management means and the pattern information from the pattern detection means, wherein the pulse width control means The change position of the leading end of the pulse of the recording signal is delayed by the first correction amount so that the peak shift amount of the reproduction signal is reduced with respect to the recording data of the pattern in which the peak shift is detected by the pattern detection means. Along with
The subsequent change position is individually controlled so as to be advanced by the second correction amount smaller than the first correction amount, and the pulse width of the recording signal is controlled to be narrowed. The present invention is designed to appropriately suppress the peak shift of the reproduced signal even when the pulse position of the signal changes before and after the change position.

C. Prior Art The so-called RLL (Run Length Limited) in which the maximum inversion interval of a waveform train is finite, which is widely used in magnetic disk devices (magnetic disk recording devices and magnetic disk reproducing devices) and the like.
A code, for example, an RLL2,7 code is a method for converting i bits of input data into 2i bits of recording data, i = 2,3,4
The bit code 0 in the encoded recording data is continuous from a minimum of 2 bits to a maximum of 7 bit information (a so-called minimum run of 0 is 2 and a maximum run is 7). Then, in the magnetic disk device, the recording data includes a so-called NRZI which reverses the direction of the magnetic field of the head when the bit information is 1.
(Non Return to Zero Inverted) modulation is performed to generate a recording signal, and this signal is recorded on a magnetic disk. That is, the magnetization reversal interval formed on the recording medium of the magnetic disk is proportional to the continuous length of the bit information 0 of the recording data, and the pattern of the encoded recording data is “1001” as shown in FIG. It is minimum when the pattern is represented.

When a signal recorded as magnetization reversal of a recording medium of a magnetic disk is reproduced, in a reproduced signal from a head, as shown in FIGS. 6 and 7, for example, the peak position of the reproduced signal moves due to intersymbol interference ( So-called peak shift occurs. As a result, in the adjacent reproduction pulse as shown in FIG. 5, the preceding pulse shifts more forward, the later pulse shifts further backward, and the shift amount is, as shown in FIG. The interval becomes longer as the magnetization reversal interval, that is, the recording data pulse interval is smaller. For example, in a magnetic disk driven to rotate at a constant angular velocity, the relative speed of the head to the recording medium becomes slower toward the inner circumference of the magnetic disk, and the pulse width of the recording signal becomes narrower. This peak shift amount becomes large.

In order to increase the recording density, an area for recording data on the magnetic disk is divided into, for example, an outer peripheral side and an inner peripheral side as shown in FIG. There has been known a magnetic disk drive in which the recording frequency is increased on the inner side and the recording frequency is decreased on the inner peripheral side. In such a magnetic disk drive as well, as shown in FIG. 8, the pulse width of the recording signal is narrower and the peak shift amount is larger as the inner circumference of each area. Also, as shown in FIG. 8, the innermost peak shift amount in the high frequency region where the recording frequency is high is larger than the outermost peak shift amount in the low frequency region.

D. Problems to be Solved by the Invention By the way, conventionally, in order to reduce the peak shift caused by the intersymbol interference as described above, the following peak shift is corrected at the time of recording and reproduction.

At the time of recording, the pattern of the recording data after RLL2,7 encoding is determined, and when a pattern causing a large peak shift, for example, a pattern of “1001” as shown in FIG. The write timing is shifted in a direction to reduce the write timing. During reproduction, for example, a so-called cosine equalizer is used to reduce the peak shift amount by lowering the bottom of the reproduction signal waveform. In other words, the reproduced signal waveform is sharpened to eliminate intersymbol interference.

As described above, the peak shift correction performed at the time of recording is performed by using only the pattern information of the recording data, for example, to perform an appropriate correction at the innermost circumference of the magnetic disk. On the outer peripheral side, there has been a problem that peak shift correction is performed excessively, which causes a decrease in phase margin. Also, the peak shift correction in the magnetic disk device using the two recording frequencies by dividing the data area of the magnetic disk as shown in FIG. 8 into an outer circumferential side and an inner circumferential side is performed in the innermost circumference of the high frequency area. Make appropriate corrections. For this reason, on the outer peripheral side of the high frequency region and the inner peripheral side of the low frequency region, there has been a problem that peak shift correction is excessively performed, thereby lowering the phase margin. For waveform equalization performed during reproduction, a method of controlling only the gain of the cosine equalizer in accordance with the recording frequency is used, and the gain of the cosine equalizer is controlled in accordance with the head position, and the head position and recording are controlled. The delay amount of the cosine equalizer is not controlled according to the frequency, and the optimum correction has not been performed.

In addition, due to the effect that the magnetization of the preceding recording medium is partially erased by the subsequent inverted magnetization and the mutual interference effect between the magnetization reactions due to the demagnetization field, as shown in FIG. that peak shift amount P _L of the reproduced signal but is greater than the peak shift amount P _E of the reproduction signal reproduced from the magnetization reversal after, on this point in the conventional magnetic disk apparatus has not been considered at all. That is, as shown in FIG. 9, even if the previous peak shift amount P _L and after the peak shift amount P _E differs significantly, the same amount of correction to the peak shift after the previous peak shift Is performed, the peak shift correction for the previous peak shift becomes insufficient,
The peak shift correction for the subsequent peak shift was excessive, and the effect of reducing the peak shift was not sufficient. In actual experiments, it has been confirmed that errors due to the peak shift are overwhelmingly large.

The present invention has been made in view of such circumstances, and by controlling the pulse width of a recording signal based on a pattern of recording data and a head position, suppresses a peak shift of a reproduction signal during reproduction. It is an object of the present invention to provide a magnetic disk recording device capable of sufficiently securing a phase margin and having a low error rate.

E. Means for Solving the Problems A magnetic disk recording apparatus according to the present invention includes a head for recording a signal on a magnetic disk, a head position managing means for managing a position of the head in a disk radial direction, and a peak position of a reproduced signal. Pattern detecting means for detecting a pattern of print data to be shifted, and a change in a point of a pulse of a recording signal supplied to the head according to head position information from the head position managing means and pattern information from the pattern detecting means. Pulse width control means for individually controlling the position and the subsequent change position to control the pulse width of the recording signal, wherein the pulse width control means generates a peak shift detected by the pattern detection means The change position before the pulse of the recording signal is set to the first position so that the peak shift amount of the reproduction signal is reduced with respect to the recording data of the pattern. In addition to delaying by a correction amount, control is performed to individually narrow the pulse width of the recording signal by individually controlling the subsequent change position to advance by a second correction amount smaller than the first correction amount. I do.

In the magnetic disk recording apparatus according to the present invention, the pulse width control means may determine the first correction amount and the first correction amount as the head position moves toward the inner circumference based on head position information from the head position management means. The second correction amount is increased.

F. Operation In the magnetic disk recording apparatus according to the present invention, the recording signal is controlled by individually controlling the preceding and subsequent changing positions of the recording signal pulse according to the pattern of the recording data after encoding and the head position. , The peak shift of the reproduced signal is suppressed.

G. Embodiment Hereinafter, an embodiment of the magnetic disk recording apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a block circuit diagram of a main part of a magnetic disk drive of a first embodiment to which a magnetic disk recording device according to the present invention is applied. That is, FIG. 1 shows both the recording system and the reproducing system of the magnetic disk drive.

In FIG. 1, a recording system of a magnetic disk drive includes a P / S converter 11 for converting parallel input data input via a data bus 1 into serial data, and converting the serial data into, for example, RLL2,7 codes. An encoder 12 for conversion and the RL
The pattern detector 13 controls the MUX 16 by determining the pattern of the recording data converted to the L2,7 code, and the delay amount connected in series to delay the recording data converted to the RLL2,7 code is variable. Two delay units 14 and 15; and the MUX 16 that selects one data from the data from the encoder 12 and the delay units 14 and 15 and converts the selected data into a recording signal by NRZI modulation, for example. According to the recording signal, the head 2
, And a delay amount controller 17 for controlling the delay amounts of the delay units 14 and 15 based on the head position information from the controller 3.

The reproducing system of the magnetic disk drive includes a reproducing amplifier 21 for amplifying a signal from the head 2, an equalizer 22 having a variable equalization characteristic for waveform equalizing the reproduced signal from the reproducing amplifier 21, A shaper 23 for shaping the equalized waveform to generate a detection pulse representing the presence or absence of a signal; a discriminator 24 for discriminating the detection pulse to generate a reproduction pulse; and decoding the reproduction pulse to generate serial reproduction data. , An S / P converter 26 for converting the serial reproduced data into parallel data, and an equalizing characteristic of the equalizer 22 to the controller 3.
And an equalization characteristic controller 27 for controlling based on the head position information from the controller.

The controller 3 controls the actuator to which the head 2 is attached by an actuator servo 4.
And a function of driving the head 2 in the radial direction of the magnetic disk. That is, the controller 3 manages the head position information and controls the driving of the head 2, and supplies the head position information to the delay amount controller 17 and the equalization characteristic controller 27.

Next, the operation will be described. Parallel input data is supplied to the P / S converter 11 via the data bus 1. This P / S converter 11 converts parallel input data into serial data. The encoder 12 performs, for example, PLL 2,7 code conversion, and generates a recording data sequence from the input data sequence. That is,
The pattern of the recording data is a pattern in which bit information 0 is continuous from a minimum of two pieces to a maximum of seven pieces. This recording data is supplied to the pattern detector 13 and the delay unit 14.

The delay amount controller 17 controls the delay amounts of the delay units 14 and 15 based on the head position information and the recording frequency from the controller 3. For example, the delay amount of the delay units 14 and 15 is
As shown in the figure, control is performed so that the delay amount is such that the peak shift amount WC according to the head position is corrected. That is, in the high frequency region and the low frequency region of the recording frequency, the delay
Control is performed so that the delay amounts of 14 and 15 are increased.

The pattern detector 13 controls the MUX 16 by determining the pattern of the recording data. For example, when detecting a pattern "1001" in which two zeros at which the peak shift occurs most greatly are detected, the output of the delay unit 15 is selected according to the first bit information 1 of the pattern "1001", and The MUX 16 is controlled so that the output of the delay unit 14 is selected in response to one bit information 0 and the output of the encoder 12 is selected in response to the subsequent bit information 1. In addition, the pattern “100
When a pattern other than "1" is detected, the MUX 16 is controlled so as to select the output of the delay unit 14.

The MUX 16 performs, for example, NRZI modulation on the data selected as described above to generate a recording signal, and supplies the recording signal to the drive amplifier 18. The drive amplifier 18 modulates the direction of the magnetic field of the head 2 based on the recording signal, and records this signal on a magnetic disk. That is, the information is recorded by inverting the magnetization of the recording medium of the magnetic disk in accordance with the bit information 1 of the recording data.

That is, as the head 2 is positioned further inward of the magnetic disk, the delay amounts of the delay units 14 and 15 are increased, and a pattern in which the interval between the bit information 1 of the recording data where the peak shift is large occurs is detected. When encoder 12, delay device
By selecting the recording data from 14 and 15 as described above, the pulse width of the recording signal is narrowed, and the peak shift amount of the reproduction signal due to the intersymbol interference is reduced.

As described above, in the recording system of the magnetic disk device, the peak shift of the reproduction signal can be suppressed by controlling the pulse width of the recording signal of the magnetic disk based on the head position information and the pattern of the recording data. That is,
It is possible to perform peak shift correction corresponding to the head position and the pattern of the recording data. As a result, the peak shift amount can be greatly reduced to increase the phase margin, and the error rate of the magnetic disk drive can be reduced.

 Next, the reproducing system of the magnetic disk drive will be described.

The head 2 reproduces a signal recorded as magnetization reversal of the recording medium of the magnetic disk. The reproduction amplifier 21 amplifies the signal from the head 2 and supplies the amplified reproduction signal to the equalizer 22.

The equalizer 22 is an equalizer whose equalization characteristic is variable as described above, and is, for example, a cosine type of a transversal filter having a waveform equalization characteristic as shown in FIG. It is an equalizer. Assuming that a single input pulse is f (t), the output g (t) is represented by g (t) = f (t) −k [f, using a gain coefficient k and a delay time τ. (t + τ) + f (t−τ)], and the gain coefficient k and the delay time τ are controlled by the head position. That is, the head position information is supplied from the controller 3 to the equalization characteristic controller 27, and the equalization characteristic controller 27 controls the gain coefficient k and the delay time τ based on the head position information. For example, control is performed so that the delay time τ is increased as the width of the solitary wave in the reproduction signal is increased. That is, the gain coefficient k and the delay time τ are changed based on the change in the pulse interval depending on the head position. Specifically, as shown in FIG.
Is controlled so that the gain and the delay time are adjusted to correct the peak shift amount RC corresponding to the head position.

The shaper 23 shapes the waveform after the equalization, detects a peak position, for example, and generates a detection pulse indicating the presence or absence of a signal.
The discriminator 24 reproduces a reproduction pulse from a detection pulse using, for example, a clock from a so-called synchronization signal generator. Decoder
Reference numeral 25 decodes the RLL 2,7 code and reproduces serial reproduction data. The S / P converter 26 converts the serial reproduced data into parallel data and outputs it to the data bus 1.

As described above, in the reproducing system of the magnetic disk device, it is possible to perform the peak shift correction corresponding to the head position by controlling the equalization characteristics of the equalizer using the pulse interval, that is, the head position information. Become. As a result, the peak shift amount can be greatly reduced to increase the phase margin, and the error rate of the magnetic disk drive can be reduced.

Next, a description will be given of a second embodiment of the magnetic disk recording apparatus according to the present invention. FIG. 4 is a block circuit diagram of a recording system of a magnetic disk drive to which the present invention is applied.

In FIG. 4, the recording system of the magnetic disk drive includes a P / S converter 31 that converts parallel input data input via the data bus 5 into serial data, and converts the serial data into, for example, RLL2,7 codes. An encoder 32 for conversion and the RL
A pattern detector 33 that determines the pattern of the recording data converted to the L2,7 code and controls the MUX 36, and a delay amount connected in series to delay the recording data converted to the RLL2,7 code are variable. Two free delay units 34a and 35a,
One of the data from the encoder 32 and the delay units 34a and 35a is selected, and the selected data is subjected to, for example, NRZI modulation to form a recording signal, and the MUX 36 to drive the head 6 by the recording signal. An amplifier 38 and the delay units 34a and 3
A delay amount controller 37 that controls each delay amount of 5a based on the head position information from the controller 7, and each set value of the delay amount individually set from the delay amount controller 37, the delay unit 34a, It comprises registers 34b and 35b which are stored to supply to 35a.

The controller 7 controls the actuator to which the head 6 is attached by an actuator servo 8.
And has a function of driving the head 6 in the radial direction of the magnetic disk. That is, the controller 7 manages the head position information and controls the driving of the head 6, and supplies the head position information to the delay amount controller 37.

Next, the operation will be described. Parallel input data is supplied to the P / S converter 31 via the data bus 5. This P / S converter 31 converts parallel input data into serial data. The encoder 32 performs, for example, a PLL 2,7 code conversion, and generates a recording data sequence from the input data sequence. That is,
The pattern of the recording data is a pattern in which bit information 0 is continuous from a minimum of two pieces to a maximum of seven pieces. This recording data is supplied to the pattern detector 33 and the delay unit 34a.

The delay amount controller 37 controls the delay amounts of the delay units 34a and 35a via the registers 34b and 35b, respectively, based on the head position information and the recording frequency from the controller 7. For example, the total delay amount of the delay units 34a and 35a is controlled so as to be a delay amount that corrects the peak shift amount WC according to the head position shown in FIG. That is, in the high frequency region and the low frequency region of the recording frequency, control is performed so that the total delay amount of the delay units 34a and 35a is increased as the head position is located on the more inner side. Specifically, the delay amount of the delay circuit 34a, and a value for correcting the peak shift amount P _L shown in FIG. 9 described above, the delay circuit 35a in the delay amount of peak shift amount P _E
To the value to be corrected.

The pattern detector 32 controls the MUX 36 by determining the pattern of the recording data. For example, when detecting a pattern “1001” in which two zeros at which the peak shift occurs most greatly are detected, the output of the delay unit 35a is selected corresponding to the first bit information 1 of the pattern “1001”, and The MUX3 selects the output of the delay unit 34a in response to one bit information 0 and selects the output of the encoder 32 in response to the subsequent bit information 1.
Control 6 Note that the pattern "1
When a pattern other than "001" is detected, the MUX 36 is controlled so as to select the output of the delay unit 34a.

The MUX 36 performs, for example, NRZI modulation on the data selected as described above to generate a recording signal, and supplies the recording signal to the drive amplifier 38. The drive amplifier 38 modulates the direction of the magnetic field of the head 6 based on the recording signal, and records this signal on the magnetic disk. That is, the information is recorded by inverting the magnetization of the recording medium of the magnetic disk in accordance with the bit information 1 of the recording data.

That is, as the head 6 is located further inside the magnetic disk, the delay amounts of the delay units 34a and 35a are increased, and the delay amount of the delay unit 35a is made larger than the delay amount of the delay unit 34a. When a pattern in which the interval between the bit information 1 of the recording data in which the shift occurs greatly is detected, the recording data from the encoder 32 and the delay units 34a and 35a is selected as described above, whereby the pulse width of the recording signal is obtained. To reduce the peak shift amount of the reproduction signal due to the intersymbol interference, and to cope with the difference in the peak shift amount between the earlier change position and the later change position of the pulse of the recording signal.

As described above, in this embodiment, the pulse width of the recording signal of the magnetic disk is controlled by the head position information and the pattern of the recording data, and the peak shift amount at the position where the pulse of the recording signal changes before and after the pulse is changed. By responding to the difference, the peak shift of the reproduction signal can be more appropriately suppressed. That is, the head position,
It becomes possible to perform peak shift correction corresponding to the difference in the amount of peak shift between the previous change position and the subsequent change position of the recording data pattern and the recording signal pulse. As a result, the peak shift amount can be appropriately reduced to increase the phase margin, and the error rate of the magnetic disk drive can be further reduced.

Note that the present invention is not limited to the above-described embodiment, and a magnetic disk recording device and a magnetic disk reproducing device in which a recording system and a reproducing system of a magnetic disk device are respectively different devices also have a peak according to a head position and the like. Each shift may be corrected. Further, the coding rules used for the magnetic disk device are not limited to the above-mentioned RLL2,7 code.

H. Effects of the Invention As is clear from the above description, in the magnetic disk recording apparatus according to the present invention, based on the head position and the pattern of the recording data, the change position of the leading end of the pulse of the recording signal is recorded on the magnetic disk. The peak shift amount of the reproduced signal caused by intersymbol interference is controlled by individually delaying the correction position by one correction amount and advancing the subsequent change position by a second correction amount smaller than the first correction amount. Can be reduced, and proper peak shift correction can be performed in accordance with the difference in the peak shift amount between the earlier change position and the later change position of the pulse of the recording signal.

Therefore, according to the present invention, it is possible to suppress the peak shift of the reproduction signal, secure a sufficient phase margin, and provide a magnetic disk recording device with a low error rate.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a main part of a magnetic disk drive of a first embodiment to which a magnetic disk recording apparatus according to the present invention is applied, and FIG. 2 is a diagram showing a relationship between a head position and a peak shift correction amount. FIG. 3 is a waveform diagram for explaining the principle of the equalizer, and FIG. 4 is a diagram showing the recording system of the magnetic disk drive of the second embodiment to which the magnetic disk recording apparatus according to the present invention is applied. FIG. 5 is a block circuit diagram of a main part, FIG. 5 is a diagram showing a relationship between recording data and a reproduction pulse, and FIGS. 6 and 7 are diagrams showing a relationship between a pulse interval and a peak shift; FIG. 9 is a diagram showing a relationship between a head position and a peak shift, and FIG. 9 is a diagram showing a difference in a peak shift amount between a preceding change position and a subsequent change position of a pulse of a recording signal. 2, 3, head 3, 7, controller 12, 32 encoder 13, 33 pattern detector 14, 15, 34a, 35a delay 16, 16, MUX 17, 37 delay Quantity controller 22 …… Equalizer 25 …… Decoder 27 …… Equalization characteristic controller

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 5/09

Claims (2)

(57) [Claims] A head for recording a signal on a magnetic disk;
Head position management means for managing the position of the head in the disk radial direction; pattern detection means for detecting a pattern of recording data in which the peak position of the reproduction signal shifts; head position information and the pattern detection from the head position management means Pulse width control means for individually controlling a preceding change position and a subsequent change position of a pulse of a recording signal supplied to the head in accordance with pattern information from the means, and controlling a pulse width of the recording signal. The pulse width control means includes means for changing a point of a pulse of the recording signal so that a peak shift amount of a reproduction signal is reduced with respect to recording data of a pattern in which a peak shift is detected by the pattern detection means. The position is delayed by the first correction amount, and the subsequent change position is individually advanced by the second correction amount smaller than the first correction amount. Controlling a magnetic disk recording device and performing control to narrow the pulse width of the recording signal. 2. The pulse width control means increases the first correction amount and the second correction amount as the head position moves toward the inner circumference based on head position information from the head position management means. 2. The magnetic disk recording apparatus according to claim 1, wherein: