JP3522994B2 - Magnetic recording / reproducing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus, and more particularly to a non-linear magnetization reversal position movement (non-linear
The present invention relates to a technique effectively applied to evaluation of NLTS in a magnetic recording system in which a transition shift: hereinafter abbreviated as NLTS) occurs.

[0002]

2. Description of the Related Art Since the linear recording density in a conventional magnetic recording / reproducing apparatus is lower than the linear recording density required at present, the problem with the magnetization waveform is that the linearity due to waveform interference is rather than the change in the magnetization state. The pattern peak shift was the main. Therefore, there has been adopted a method of operating a linear circuit characteristic as represented by a waveform equalizing circuit or the like to reduce waveform interference.

However, when the linear recording density is increased, a phenomenon called a so-called NLTS in which the magnetization reversal interval changes depending on the magnetization state of adjacent bits occurs, and the NLTS affects the operation margin of the magnetic recording / reproducing apparatus. It has become. Therefore, it is necessary to evaluate such an NLTS and take measures to suppress the NLTS.

In order to take the above means, first, the NLTS
Must be evaluated. As a method for evaluating this NLTS, (1) September 1987, IEE
Published by E, "I-E-E Transactions on Magnetics Vol. 23, No. 5," p23
77-p2379, a method of evaluating NLTS by a 2-bit extraction method using an M-sequence code, (2) September 1991, issued by IEE, "IEE. EE Transactions
On Magnetics Vol.27 No.6 ", p5316-
As described in p5318, two methods have been proposed: a method of observing the fifth harmonic and obtaining the NLTS from the magnitude thereof.

[0005]

However, in the above-mentioned two known methods, the magnetization reversal pattern to be recorded on the medium is defined as an evaluation pattern according to a certain rule, and the evaluation pattern is actually magnetic recording / reproducing. It is out of the range of the recording modulation code used in the device.

For example, when applied to the 8/9 modulation / demodulation PRML system, the magnetization reversal pattern has a run length limited code (hereinafter abbreviated as RLL) (0, 4, 4).
Must match the code. However, (1) above
The known method requires the recording pattern to be an M-sequence code, which cannot be realized within the 8/9 modulation / demodulation rule. Further, in the known method (2), the number of bits that does not cause the magnetization reversal of the magnetization reversal interval is defined and recorded, so that the pattern to be recorded cannot be realized within the 8/9 modulation / demodulation rule.

Therefore, if a dedicated evaluation tester is used, NL
8/9 modulation / demodulation PRML although TS can be measured
A commercially available magnetic recording / reproducing apparatus using a modulator / demodulator according to the method has a drawback that the NLTS cannot be evaluated.

Due to such restrictions, in order to optimize the magnetic recording / reproducing apparatus, the NLTS of the magnetic recording medium is evaluated by a dedicated evaluation tester before incorporating the head medium into the magnetic recording / reproducing apparatus. After incorporating it into the recording / reproducing apparatus, it was inevitable to reset the circuit constants by evaluating the operating margin. Therefore, the NLTS after the magnetic recording medium is installed in the actual magnetic recording / reproducing apparatus
However, there is a problem in that it cannot be directly evaluated using the recording / reproducing system of the magnetic recording / reproducing apparatus, and adjustment to the optimized characteristics of the recording system cannot be performed.

An object of the present invention is to provide a technique capable of directly evaluating an NLTS with an actual magnetic recording / reproducing apparatus.

Another object of the present invention is to provide a technique capable of directly performing the optimization adjustment of the recording timing of the magnetization reversal and the characteristics of the reproducing circuit system in an actual magnetic recording / reproducing apparatus.

Still another object of the present invention is to optimize the recording timing of the magnetization reversal and the characteristics of the reproducing circuit system even after the magnetic recording / reproducing apparatus is shipped so that the state of the magnetic recording / reproducing apparatus can always be kept good. It is to provide the technology that can.

[0012]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

(1) In the magnetic recording / reproducing apparatus of the present invention, a harmonic component of a specific order in the reproduced signal of the evaluation pattern recorded on the magnetic recording medium as the magnetization reversal pattern, and N
By comparing the harmonic components of the orders in a reproduction signal of the reference pattern that does not result in LTS, have NLTS evaluation means for evaluating the NLTS of the magnetic recording medium, evaluation
As a pattern, a series of test signal patterns
A new magnetization reversal of '11', which is an even number of '0'
Use the pattern replaced with "1" under the condition that does not occur in
It is those that.

According to such a magnetic recording and reproducing apparatus, commentary
Value pattern is a series of test signal patterns
A new magnetization reversal of '11', which is an even number of '0'
Use the pattern replaced with "1" under the condition that does not occur in
As described above, as the evaluation pattern (and the reference pattern) , a pattern that matches the channel data after the precoding of the modulation / demodulation method used in the magnetic recording / reproducing apparatus is used. The evaluation pattern and the reference pattern can be generated by using the modulator used in the apparatus, and the NLTS can be evaluated without using a specially designed evaluation apparatus. That is, the NLTS can be directly evaluated by the actual magnetic recording / reproducing apparatus. As a result, even after shipment of the magnetic recording / reproducing apparatus, the recording timing of the magnetization reversal and the optimization adjustment of the reproducing circuit system characteristic can be directly performed in the actual magnetic recording / reproducing apparatus, and the magnetic recording / reproducing apparatus is always in an optimum state. Can be used.

As conditions to be satisfied by the evaluation pattern and the reference pattern, in addition to the condition that they are suitable for the channel data after the precoding of the modulation / demodulation method used in the magnetic recording / reproducing apparatus, the influence of the NLTS is a harmonic of a specific order. There is a necessary condition to be observed as a wave component.
The conditions will be described below.

(A) First, the evaluation pattern is "11 [6
p] 1 [6q] 11 [6p] 1 [6q] ′, which is a modification of the initial pattern,
"1" indicates that there is magnetization reversal, "0" indicates that there is no magnetization reversal, and [6p] is repeated "0" 6 times.
[6q] indicates that the value is '0' repeated 6q times (p and q are natural numbers). ), A second condition that replaces an even number of consecutive '0's in the initial pattern with' 1 'and does not generate new consecutive magnetization reversal' 11 ',
The third (2p + 2q + 1) th order harmonic component cancels out between the reproduced signals of the magnetization reversal added by the replacement.
It is possible to exemplify a case in which both of the above conditions are satisfied and the order is the (2p + 2q + 1) order. For example, when p = q = 1, the pattern can be an NLTS evaluation pattern by measuring the fifth harmonic.

That is, according to the first condition, for example, the NL at the fifth harmonic component in the known example (2).
It is possible to satisfy the condition of the pattern capable of TS evaluation, and it is possible to maintain the polarity of the magnetization reversal of the evaluation pattern by the second condition. In addition, the effect of the magnetization reversal added under the second condition by the third condition is (2
(p + 2q + 1) harmonic components can be prevented from occurring. Furthermore, the evaluation of NLTS is (2p + 2)
By limiting to the q + 1) th harmonic component,
Magnetic recording / reproducing apparatus by replacing an even number of added '1' while maintaining the (2p + 2q + 1) th harmonic component of the NLTS generated from the pattern of p] 1 [6q] 11 [6p] 1 [6q] ' It is possible to adapt to the channel data after the precoding of the modulation / demodulation method used in 1. and eliminate the influence on the (2p + 2q + 1) th order harmonic component due to the replacement of the even number of added '1's.

As an evaluation pattern satisfying such conditions, '11001 when measuring the fifth harmonic component
01010101001100101010101010
0'can be exemplified. As the reference pattern at this time, repetition of '100' can be exemplified.

(B) Next, the evaluation pattern is a repeating pattern having a basic period of 54 bits, which is formed by repeating a 27-bit pattern including an odd number of magnetization reversals ('1') twice. When the NLTS is 0, the signal vectors in the phase plane of the magnetization reversal signal corresponding to the magnetization reversal ('1') of the bits forming the evaluation pattern have a phase difference of 2π / 3 radian with each other. Fifth condition represented as three signal vectors, adjacent to the first magnetization reversal ('1') corresponding to one signal vector among the three signal vectors or adjacent to each other with one bit therebetween. NLT by the second magnetization reversal ('1')
When S occurs, the 2π / of the one signal vector
A case can be exemplified in which the deviation from the phase difference of 3 radians satisfies any of the sixth condition representing the NLTS and the order is the third order or the ninth order.

That is, since the evaluation pattern has 54 bits, as will be described later, when the signal vector of such an evaluation pattern is expressed by the phase plane, when the evaluation order is the third order, π / 9 is obtained. It can be expressed as a combination of vectors of size 1 having a phase difference of radian, and can be expressed as a combination of vectors of size 1 having a phase difference of π / 3 radian with each other when the evaluation order is the ninth order. Further, by leaving three signal vectors having a phase difference of 2π / 3 radians, it is possible to obtain a signal in which NLTS information is added to the third harmonic component or the ninth harmonic component with respect to the fundamental frequency 2π.

Further, since a set of vector signals having a phase difference of π radians cancel each other out in the phase plane and do not affect the power spectrum characteristic, a set of vector signals having a phase difference of π radians is used. Magnetization inversion bits that can be added arbitrarily and that are adjacent to the bits corresponding to the above three signal vectors or that are adjacent to the bits corresponding to the above three signal vectors with one bit apart are generated. It becomes possible to do. That is, it is possible to generate a recording code pattern existing as a recording modulation code used in an actual magnetic recording / reproducing apparatus by adding one or more pairs of two vector pairs having a phase difference of 0 in vector combination. It will be possible.

As an evaluation pattern for evaluating the third harmonic which satisfies the above condition, (i) '11001001
A double repeating pattern of 000100001001000000 ', or (ii)' 0100100100
A double repeating pattern of 001000001000100001 'can be illustrated, and as a reference pattern,' 1000100001001001000001000.
An example of a pattern that repeats 100 'twice can be illustrated. The pattern (i) is a pattern for evaluating the NLTS by the '11' pattern in which the magnetization reversal pattern is continuous, and the pattern (ii) is '101' in which the magnetization reversal pattern is continuous with 1 bit. It is a pattern which evaluates NLTS by a pattern.

Further, as an evaluation pattern for evaluating the ninth harmonic, '00110010000100010001
0001000 'two times repeated pattern,' 0011
00010001000010010001000 'repeated twice pattern,' 00111000100000
10010010000010 'twice repeated pattern,' 0011000000001000100100001
2 repeat pattern of 00010 ', or' 001
100000100010001000100001 '
2 times repeated pattern can be illustrated, and '001001001001001001 is used as a reference pattern.
A two-time repeating pattern of 001001001 ′ can be exemplified. Needless to say, there is a pattern for evaluating the NLTS based on the '101' pattern in the evaluation pattern for evaluating the ninth harmonic.

(C) Further, the reference pattern does not include any pattern of the magnetization reversal continuous pattern ('11') and the magnetization reversal continuous pattern ('101') separated by 1 bit, and the reference pattern is The seventh condition under which the sum of the signal vectors in the phase plane of the magnetization reversal signal corresponding to the magnetization reversal ('1') of the constituent bits is 0.8 or more is the continuous evaluation pattern of the magnetization reversal pattern (' 1
1 ') or a continuous pattern of magnetization reversal separated by 1 bit (' 101 '), or both patterns, and the phase difference in the phase plane becomes 2π / 3 radians when NLTS is 0. It is possible to exemplify the case where any of the eighth condition represented by the signal vector is satisfied.

That is, since the reference pattern does not include a continuous pattern ('11') and a continuous pattern of magnetization reversal separated by 1 bit ('101'), NLTS does not occur, and the sum of signal vectors is Since it is 0.8 or more,
It is possible to generate a harmonic component in the order to be referred to above the noise level, and reduce an error due to the uncertainty of the reference pattern. The reference pattern includes either one or both of a continuous pattern ('11') and a continuous pattern of magnetization reversal ('101') separated by 1 bit, or both patterns, and when the NLTS is 0, the position in the phase plane is increased. Since it is represented by a signal vector with a phase difference of 2π / 3 radians, it is '11' or '101'.
The NLTS can be generated by the magnetization reversal pattern of 1 and the specific harmonic can be affected. It should be noted that such a condition can be considered as another aspect of the condition in the case of the above (b).

(2) The magnetic recording / reproducing apparatus of the present invention is a high-order
The evaluation data and reference data input from the
Conversion pattern and evaluation pattern and reference pattern
The pattern generation means to generate and this pattern generation means
The magnetic reversal pattern converted by
Recording head and the magnetization reversal pattern recorded on the magnetic recording medium.
The playhead that plays the turn and the
Output the generated magnetization reversal pattern to the spectrum analyzer
And means for exerting force. (3) The magnetic recording / reproducing apparatus of the present invention includes a magnetic recording medium on which information is recorded as a magnetization reversal pattern, a modulator for converting data to a magnetization reversal pattern, and a recording signal corresponding to the magnetization reversal pattern. a recording head for recording to, a magnetic recording and reproducing apparatus and a reproducing head for reproducing the magnetization reversal pattern recorded on the magnetic recording medium, evaluation was provided in the magnetic recording and reproducing apparatus in the data generator or higher machine converting the magnetization reversal patterns using the modulator to evaluate data received from the Rupa turn generating means generates an evaluation pattern for evaluating the NLTS, harmonics of a particular order of the reproduction output signal of the evaluation pattern and NLTS evaluating means for calculating the NLTS of the magnetic recording medium using a harmonic component of a particular order of the reproduced output signal component and the reference pattern, even with a It is. Furthermore, (2), (3)
The magnetic recording / reproducing apparatus of this type reduces the NLTS amount of the magnetic recording medium.
The recording signal corresponding to the magnetization reversal pattern
Having a recording timing correction means for adjusting the timing,
This recording timing correction means is recorded with the pattern generation means.
It is provided between the head and the head.

According to the magnetic recording / reproducing apparatus as described in (2) and (3) , the evaluation pattern for evaluating the NLTS is
In order to generate by using the modulator built in and used in the actual magnetic recording / reproducing apparatus, the evaluation pattern and the reference pattern are recorded on the magnetic recording medium by the recording head, and the recorded evaluation pattern and the reference pattern are reproduced. NLTS evaluation means for reproducing by the head, and further calculating the NLTS amount of the magnetic recording medium using the harmonic component of the specific order of the reproduction output signal of the evaluation pattern and the harmonic component of the specific order of the reproduction output signal of the reference pattern. Since it has, it does not require a special evaluator for evaluating the NLTS.

Further, since the recording timing correction means for adjusting the timing of the recording signal is provided so as to reduce the NLTS amount, the timing of the recording signal is adjusted based on the NLTS amount evaluated by the means, and the user data is adjusted. It is possible to improve the reliability of recording and reproducing.

Further, by using the recording / reproducing system of the magnetic recording / reproducing apparatus actually used, the NL in the recording / reproducing system is used.
Since the TS can be evaluated and the timing of the recording signal can be adjusted, the reproduction circuit system can be adjusted while the influence of the NLTS is suppressed to a minimum, and the reproduction circuit system can be optimized. Becomes

The evaluation data or reference data that can be handled by the actual magnetic recording / reproducing apparatus can be supplied from the evaluation data generator or a higher-level device. These evaluation data and the like are input to the modulator. A data selector may be provided in order to arbitrarily select.

In the recording timing correction means, the state of magnetization reversal 1 bit before or 2 bits before the bit to be corrected is referred to, and depending on the combination of the state of magnetization reversal 1 bit before or 2 bits before. ,
Recording timing correction can be performed so that the magnetization reversal interval is widened. In such a case, the correction of the recording timing can be optimized according to the state of the magnetization reversal, instead of the standardized standard.

Further, the recording timing is corrected by the NLTS
It is also possible to set the recording timing to be delayed by an amount that is 0.6 to 1 times the amount.

Further, it is possible to program the evaluation of the NLTS in the magnetic recording / reproducing apparatus of the present invention to be executed by an evaluation command from a host machine. Needless to say, in the magnetic recording / reproducing apparatus of the present invention. The evaluation of the NLTS can be performed not only before shipping but also after shipping.

Further, the NLTS evaluation means may compare the harmonic component of a specific order between the evaluation pattern and the reference pattern. As the specific harmonic detection means, it corresponds to the radial position of the reproducing head. It is possible to exemplify a spectrum evaluation function circuit that is a combination of a bandpass filter that varies the center frequency of the bandpass filter with a signal and a power measurement circuit. In such a case, it is not necessary to use an FFT circuit or the like having a complicated Fourier transform function, and a simple bandpass filter and a power measuring circuit can inexpensively and easily detect a harmonic component of a signal. . Further, since the center frequency of the bandpass filter is changed by the signal corresponding to the radial position of the reproducing head, it is possible to deal with the change of the order to be evaluated.

(4) The magnetic recording / reproducing apparatus of the present invention includes a magnetic recording medium on which information is recorded as a magnetization reversal pattern,
A modulator for converting data into a magnetization reversal pattern, a recording head for recording a recording signal corresponding to the magnetization reversal pattern on a magnetic recording medium, and a reproducing head for reproducing the magnetization reversal pattern recorded on the magnetic recording medium are provided. a magnetic recording and reproducing apparatus, and spectrum evaluation function circuit for evaluating the harmonic component of the specific order of the output signal of the playback head, NLTS of the magnetic recording medium was evaluated by the scan <br/> spectrum evaluator circuit The storage area that stores
The stored first NLTS amount and the newly evaluated second N
If the second NLTS amount is greater than the LTS amount,
If the first correction value stored in the storage area is positive or
Set the second correction value with the negative variation added, and
To obtain the third NLTS amount, and to obtain the second NLTS
Quantity and the third NLTS quantity are compared, and the smaller value of N
Select the LTS amount and set the correction value corresponding to this NLTS amount.
A recording timing correction circuit for storing in a storage area,
It is those that.

According to such a magnetic recording / reproducing apparatus, it has a recording timing correction circuit, a spectrum evaluation function circuit, and a storage area for the correction value and the NLTS amount.
Since the fourth logic is provided, it is possible to always maintain the optimum recording timing even if the NLTS amount of the magnetic recording medium changes with time. As a result, the reproducing circuit system can always maintain the optimum state, and the reliability of recording / reproducing of the magnetic recording / reproducing apparatus can be improved.

It should be noted that the NLTS amount is a certain value (allowable amount).
The above first to fourth logics are repeated a plurality of times until
Even if the NLTS amount does not fall below a certain value, it is possible to set the maximum number of times of repetition and select the smallest NLTS amount obtained up to the maximum number of times of repetition. In this case, the variation amount added to the correction value can be changed during the repetition. N in this case
The allowable amount of the LTS amount may be 10% of the bit clock cycle, and the maximum number of repeated uses may be 5 times.

If the NLTS amount does not fall below a fixed value even after repeating the first to fourth logics a plurality of times, the NLTS
The first to fourth logics can be terminated even when the change in the TS amount is less than a certain value and is less than the maximum number of times of repeated use. In this case, useless repetition can be omitted. In this case, 1% can be exemplified as the lower limit value of the variation amount of the NLTS amount.

Further, when setting a correction value for a certain NLTS amount, there are a case of NLTS with a '11' pattern in which magnetization reversal occurs continuously, and a case of NLTS with a '101' pattern in which magnetization reversal occurs with one bit separated. The correction value can be set separately for each case, and in addition, '1
N by both 1 'pattern and' 101 'pattern
In the case of LTS, a combination of correction values for each pattern,
That is, the correction value can be set by four combinations. By setting the correction value according to the pattern in which such NLTS occurs, the recording timing can be corrected more precisely.

In the recording timing correction circuit, a pattern and a correction time corresponding to the pattern can be set as the correction value of the recording timing correction circuit, and the recording current of the recording current is changed by the correction time amount in the pattern set in the recording timing correction circuit. It is possible to create a recording current in which the reversal position is shifted.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

(Embodiment 1) FIG. 1 is a flowchart showing an example of an NLTS evaluation procedure used in a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

First, the evaluation pattern of the first embodiment will be described.

The NLTS evaluation pattern of the first embodiment is an evaluation pattern capable of recording the NLTS evaluation pattern by also using a data modulator / demodulator on an actual magnetic recording / reproducing apparatus, and has a basic period of 30 bits. Have, 5th
This is a pattern in which the NLTS affects the second harmonic component.

The evaluation pattern of the first embodiment is
Under a certain condition, the test signal pattern used in the fifth harmonic method of the known example (2) and a plurality of magnetization reversal patterns are fused. A certain condition is that a part of continuous "0" of the test signal pattern used for the fifth harmonic method is "1".
When it is replaced with, the following condition is satisfied (in the following condition, "1" indicates magnetization reversal,
"0" indicates that there is an information bit but no magnetization reversal).

(1) An initial pattern which is a test signal pattern used in the fifth harmonic method, for example, '1100000
Considering 01000000110000001000000 ',' 0 'is replaced by' 1 'while maintaining the polarity of the magnetization reversal of this initial pattern (even number of consecutive' 0 'is replaced by' 1 ').

(2) By adding "1", new continuous magnetization reversal "11" is not generated.

(3) The fifth-order frequency components cancel each other between the reproduced pulses due to the added magnetization reversal.

(4) A pattern that exists as channel data after precoding of the modulation / demodulation method used in the magnetic recording / reproducing apparatus. An 8/9 modulation / demodulation PRML system can be exemplified as a modulation / demodulation system used in the magnetic recording / reproducing apparatus.

As an example of an evaluation pattern satisfying all the above conditions, '11001010101010011001'
0101010100 'can be illustrated. The method of measuring the NLTS from the fifth harmonic using this pattern is hereinafter referred to as the extended fifth harmonic method.

A method of generating a pattern satisfying the above conditions uses a computer to convert a part of "0" to "1".
It is possible to adopt a method of automatically determining whether or not the above conditions are met by performing the operation of replacing with.

Next, referring to FIG. 1, the NL of the first embodiment will be described.
The TS evaluation procedure will be described. The evaluation pattern used for the extended fifth harmonic method is user data '01500A.
80E7 (hex) ', which can be recorded through a data modulator / demodulator.

First, user data '01500A80E
A repeating pattern of 7 (hex) 'is input as evaluation data (step 201).

Next, the user data is converted by the modulator built in the actual magnetic recording / reproducing apparatus to generate an evaluation pattern (step 202). As described above, this evaluation pattern is' 110010101010101001.
It is a repeating pattern of 10010101010100 '.

Next, this evaluation pattern is recorded on the magnetic recording medium (step 203). Here, when the period of the clock for driving the reverse recording current is T, the recording frequency Fw is Fw = 1 / (2T), and recording is performed at such a recording frequency Fw.

Next, the pattern recorded on the magnetic recording medium is reproduced (step 204). An example of this reproduction signal is shown in FIG.

Next, the power spectrum of the reproduced signal is measured (step 205). Power spectrum measurement is
A known FFT analyzer or the like can be used, and an example of the power spectrum is shown in FIG.

Next, the fifth harmonic component of the reproduced signal is measured (step 206). The fifth harmonic component is the fifth harmonic spectrum intensity E5 of the power spectrum, and its unit is dBm. At this time, the recording frequency Fw
Is Fw = 1 / (2T), and since the evaluation pattern is 30 bits / cycle and the fundamental frequency is 1 / (30T), the frequency of the fifth harmonic is Fw (5) = 5 × 1 /
(30T) = 1 / (6T).

On the other hand, the reference data is also input in the same manner as above, and the fifth harmonic component thereof is measured. The reference data is input for reference as a pattern in which the NLTS does not occur, and is for removing influences other than the NLTS, such as harmonic components of the reproduced waveform and reproduced waveform distortion.

First, user data '292929292
A repeating pattern of 9 (hex) 'is input as reference data (step 207).

Next, in the same manner as in step 202, conversion is performed by the modulator to generate a reference pattern (step 20).
8). As described above, this reference pattern is' 100100.
100100100100100100100100 '
Is a repeating pattern.

Next, this reference pattern is used in step 20.
The data is recorded on the magnetic recording medium in the same manner as in No.
9).

Next, the pattern recorded on the magnetic recording medium is reproduced as in step 204 (step 21).
0). An example of this reproduced signal is shown in FIG.

Next, the power spectrum of the reproduced signal is measured in the same manner as in step 205 (step 211). An example of the power spectrum is shown in FIG.

Next, the fifth harmonic component of the reproduced signal is measured in the same manner as in step 206 (step 212). Fifth
The next harmonic component is the spectral intensity X at Fw (5)
5 and the unit is dBm.

Finally, the NLTS is calculated (step 2
13). Since the unit of the observed fifth harmonic component is dBm, it is converted to a linear scale, and in consideration of the fact that it is the fifth harmonic, the coefficient 5 × 3 / π is multiplied and the percentage is displayed. = (10 ^ ((E5-X5) / 2
0)) × (5 × 3 / π) × 100 (%).

According to such a magnetic recording / reproducing apparatus, a pattern that matches the rule of the recording modulation code used in the actual magnetic recording / reproducing apparatus, that is, the rule of the modulator / demodulator for modulating / demodulating data is used as the evaluation pattern, and Since the evaluation pattern used is one that does not generate the fifth harmonic when the NLTS is 0, the NLTS can be directly measured using the recording / reproducing system of the actual magnetic recording / reproducing apparatus. The NLTS can be easily obtained by measuring the fifth harmonic of the reference pattern and the evaluation pattern.

In the first embodiment, "11000000100000" is used as the initial pattern of the evaluation pattern.
0110000001000000 ', that is, '11
The case of p = q = 1 (fifth harmonic evaluation) in [6p] 1 [6q] 11 [6p] 1 [6q] 'is illustrated, but p and q are higher than 2 It goes without saying that this may be the case.

(Second Embodiment) Next, another example of the NLTS evaluation pattern used in the magnetic recording / reproducing apparatus of the present invention will be described.

The evaluation pattern of the second embodiment is 8/9
It is designed to match the modulation code,
The third harmonic component is affected by the NLTS.

First, the general formula of the evaluation pattern is shown in Formula 1 under the condition that the linear superposition of the isolated waveforms is established.

[0072]

[Equation 1]

X is the Fourier transform of the isolated waveform x (t).
The Fourier transform of Equation 1 is represented by Equation 2 as ( ω ).

[0074]

[Equation 2]

Next, if the evaluation pattern is repeated twice with 27 bits, the number of bits becomes 54 bits, and the third bit
When evaluating the third harmonic, the angular frequency of the third harmonic ω = (3 × 2π) / (2 × 27τ) = π / 9τ,
When converted into the expression of the vector phase signal having the magnitude 1, the expression 3 is obtained.

[0076]

[Equation 3]

Here, as a half-period pattern of the NLTS evaluation pattern (shown as a recording code pattern), for example, a = {ak; k = 0 to 26 | '11001001
0000100000100100000 '} is assumed and is substituted into Equation 3 to show in Equation 4.

[0078]

[Equation 4]

Next, consider the vector phase diagram shown in FIG. 3 (a), and substitute Equation 4 in this vector phase diagram. FIG. 3 (b) shows the result obtained by substituting the equation 4.

The entry procedure of FIG. 3B will be briefly described as follows. That is, since the first term of the equation 4 is a vector having a phase angle of 0, the vector A is entered at the position of the phase angle of 0 in FIG. The second term of the equation 4 has a phase angle of −
Although it is π / 9, since the coefficient sign of the second term is negative, it is entered as a vector B having a phase angle of − (π + π / 9).
In the third term, the vector C is entered at the position where the phase difference is -4π / 9. Similarly, the vector D of the fourth term, the vector E of the fifth term, the vector F of the sixth term, and the vector G of the seventh term are entered. Here, the vector A and the vector F, and the vector G and the vector E cancel each other because they have the magnitude 1 and the phases are opposite to each other. Therefore, the evaluation vector signal of the NLTS is composed of the three signal vectors of the vector C, the vector B, and the vector D whose phase angles differ by 2π / 3 radians.

In the case of the evaluation pattern of the second embodiment, N
It is the second bit '1' that the LTS occurs. Therefore, assuming that the second bit, that is, the phase angle of the second term on the right side of Expression 4 rotates by (δ / τ) radian by the NLTS, the vector expression of the evaluation pattern is as shown in Expression 5. Here, δ is a bit shift time by NLTS, and τ is a bit time.

[0082]

[Equation 5]

[0083] assuming the case of an isolated waveform of one bit next to the 2 7 bits, the third harmonic of the third harmonic spectral power E '([omega] 3) and isolated waveform of the evaluation pattern signal including NLTS If the ratio with the spectral power X (ω3) is α, then Equation 6 is obtained.

[0084]

[Equation 6]

[0085] For example other in the following, a = {ak; k = 0~26
｜ '100010000100100100000100
0100 ′} is assumed and the ratio of the third-order harmonic spectrum power X ′ (ω3) of the pattern a to the third-order harmonic spectrum power X (ω3) of the isolated waveform is calculated and shown in Equation 7.

[0086]

[Equation 7]

Therefore, the NLTS δ / τ is given by
By substituting the equation 7 into, the equation 8 is obtained.

[0088]

[Equation 8]

In Expression 8, | E ′ (ω3) | = Es is the value (unit is dBm) of the third harmonic spectrum power of the evaluation pattern measured by the spectrum analyzer, and | X ′ (ω3) | = Xs is a value (unit is dBm) of the third-order harmonic spectrum power of the reference pattern measured by the spectrum analyzer. As described above, N
The LTS can be determined.

The measurement of the third harmonic spectrum power by the spectrum analyzer is the same as the procedure described in the first embodiment, and therefore the description is omitted.

According to such a magnetic recording / reproducing apparatus, since the patterns as described above are used as the evaluation pattern and the reference pattern, the influence of the NLTS occurs only on the third harmonic, and the third harmonic component is generated. The NLTS can be easily evaluated by measuring Also,
Both the evaluation pattern and the reference pattern of the second embodiment are suitable for the pre-coded pattern of the modulation / demodulation method used in the magnetic recording / reproducing apparatus, and therefore the NLTS is directly evaluated using the modulation / demodulation system of the actual magnetic recording / reproducing apparatus. can do.

Although the second embodiment exemplifies the evaluation pattern capable of evaluating the NLTS generated by the '11' pattern, the evaluation pattern capable of evaluating the NLTS generated by the '101' pattern is shown. It may be the NLTS evaluation means used. As such an evaluation pattern, '010010010000100001
A two-time repeating pattern of 000100001 'can be illustrated. That is, the NLTS is composed of the 27th bit, the 1st bit, and the 2nd bit of the '101' pattern.
Is generated. The method of generating such an evaluation pattern is the same as the method described in the second embodiment.

Further, in the second embodiment, the means for evaluating the NLTS by the third harmonic component is exemplified, but the ninth embodiment
It may be a means for evaluating the NLTS based on the second harmonic component. The NLTS evaluation means based on the ninth harmonic component will be described below.

First, assuming an evaluation pattern of a basic period of 54 bits is the same as in the case of the third harmonic. However, the angular frequency of the ninth harmonic ω = (9 × 2π) / (5
4τ) = π / 3τ. Therefore, the different phase angles of the respective signal vectors on the phase plane are π / 3.

The calculation method is omitted since it is the same as the case of the third harmonic, and the expression corresponding to the expression 8 for obtaining the NLTS is shown in the expression 9.

[0096]

[Equation 9]

In Expression 9, | E ′ (ω9) | = Es is the value (unit is dBm) of the ninth harmonic spectrum power of the evaluation pattern measured by the spectrum analyzer, and | X ′ (ω9) | = Xs is a value (unit is dBm) of the ninth-order harmonic spectrum power of the reference pattern measured by a spectrum analyzer. As such an evaluation pattern, '0011001000001000100
010001000 'two times repeated pattern, '00
110001000100001001000100
Two repeated patterns of 0 ',' 0011000100
00010010010000010 'repeated twice pattern,' 0011000001000100100
Two-time repeating pattern of 00100010 ', or' 001100000100010001000100
An example is a pattern in which 001 'is repeated twice, and the reference pattern is' 0010010010010.
A two-time repeating pattern of 01001001001001 'can be illustrated. In addition, even in the evaluation pattern for evaluating the 9th harmonic, N of the '101' pattern is used.
It goes without saying that there are patterns for evaluating LTS.

In this way, N by the ninth harmonic component
The LTS can be obtained in the same manner as in the case of the third order.

It is to be noted that the NLTS is generated by these 9th harmonics.
It is needless to say that the evaluation pattern in the case of evaluating is matched with the recording modulation method used in the actual magnetic recording / reproducing apparatus.

(Third Embodiment) A magnetic recording / reproducing apparatus according to a third embodiment of the present invention realizes each function relating to the evaluation pattern storage location, recording modulation method, evaluation pattern recording area, and NLTS evaluation circuit / measuring device. It is configured by a combination of. The storage location of the evaluation pattern is the first classification,
FIG. 4 shows an example of realization of a magnetic recording / reproducing device by a combination of these classifications, where the recording area of the evaluation pattern is the third classification, the evaluation circuit of the NLTS is the fourth classification, and the recording modulation method is the second classification. .

The first classification relates to the storage location of the evaluation pattern, and can be divided into those to be incorporated as software or hardware and those to which the evaluation pattern is transferred from the host machine.

The second classification relates to a modulator for recording modulation, and also serves as a modulator for all data.

The third classification relates to a method of securing a recording area when performing NLTS evaluation, and it is divided into one that uses a formatted data area and one that has a dedicated area for evaluation. You can

The fourth classification relates to an evaluation circuit and a measuring instrument, which is taken out from the preamplifier output via a jig circuit and then NL is set by an external spectrum analyzer.
The TS evaluation and the preamplifier output are input to the spectrum evaluation function circuit that is already built into the reproduction circuit system.
It can be divided into those for TS evaluation.

Therefore, the magnetic recording / reproducing apparatus for performing the NLTS evaluation and the circuit constant setting can be a combination of the above-mentioned four types of classification.

In the magnetic recording / reproducing apparatus of the present invention, what is particularly intended is that the recording system of the magnetic recording / reproducing apparatus can be realized by using the NLTS evaluation pattern which can be composed of the recording modulation code used in the actual magnetic recording / reproducing apparatus. Combined,
It is to realize a magnetic recording / reproducing apparatus capable of directly performing NLTS evaluation on an actual magnetic recording / reproducing apparatus. Therefore, all the second classification also serves as a modulator for data.

The contents of each classification will be described below with reference to FIGS. 5 to 8 are block diagrams for explaining each function in the magnetic recording / reproducing apparatus according to the embodiment of the present invention.

First, the modulator 101 for performing the second type of recording modulation will be described.

In the magnetic recording / reproducing apparatus 108 which also serves as the data modulator 101, the evaluation pattern for evaluating the NLTS is normally the user data provided from the higher-level machine 113 via the interface 106 as shown in FIG. Similarly to the above, it is input to the modulator 101 and converted into a recording pattern. Then, it is input to the recording timing correction circuit 102, where the recording timing is corrected so that the NLTS is minimized, and the magnetization reversal position of the recording signal is adjusted. The recording information with the adjusted recording timing is converted into a recording current by the recording amplifier 103 and recorded as a magnetization reversal pattern on the medium 105 by the recording head 104. The advantage of this method is that jigs for NLTS evaluation are not particularly required and the cost can be reduced most.

Next, the recording area of the third classification will be described.

The recording area can be divided into a data area of the medium 105 or a dedicated area for NLTS evaluation.

When the NLTS evaluation pattern is recorded in the data area, the NLTS evaluation pattern can be recorded through the completely same process as the case of recording the data. Before shipping the magnetic recording / reproducing apparatus 108, since no information is recorded in the data area, the NL is directly used.
The TS evaluation pattern can be recorded. However, when the NLTS evaluation is performed after shipping, since the user data is recorded in the data area, the following operation is performed to execute the NLTS evaluation.

(1) The user data in the necessary data area for performing the NLTS evaluation is temporarily saved in another storage area.

(2) The NLTS evaluation pattern is recorded in the data area.

(3) After NLTS evaluation, the user data is rerecorded at the original position.

When the NLTS evaluation pattern is recorded in the dedicated area, the NLTS evaluation pattern can be recorded through the same process as in recording data in the data area. When the dedicated area is used, there is an advantage that the NLTS evaluation pattern can be directly recorded without considering the presence or absence of user data. However, it is necessary to increase the recording density because the area that cannot be used by the user, that is, the area related to the system increases.

Next, as the fourth classification, an evaluation circuit or a measuring instrument will be described.

When recording / reproducing is performed using the NLTS evaluation pattern shown in the first or second embodiment, the influence of the NLTS appears in the harmonic spectrum power of a specific order. Therefore, it is possible to exemplify a case where a spectrum analyzer is used as a measuring instrument having a spectrum analysis function and a case where a spectrum evaluation function circuit which is already incorporated in a reproducing circuit system is used.

When using a spectrum analyzer,
As shown in FIG. 6, the magnetization reversal information recorded on the medium 105 is reproduced by the reproducing head 109, the output of the reproduction signal input to the preamplifier 110 is branched, and input to the spectrum analyzer 405 via the jig circuit 406. To do. The spectrum analyzer evaluates the harmonic spectrum power of a specific order.

The advantage of this structure is that the magnetic recording / reproducing apparatus 10 is used.
Since the spectrum analyzer 405 is not provided for each 8 and the spectrum analyzer 405 is shared by a large number of magnetic recording / reproducing devices, it is possible to evaluate any magnetic recording / reproducing device under the same conditions and to reduce the cost. On the other hand, this method has a drawback that it is limited to evaluation before shipment.

When a built-in spectrum evaluation function circuit is provided in the reproduction circuit system, the output of the preamplifier 110 is branched and input to the spectrum evaluation function circuit 407 as shown in FIG. The spectrum evaluation function circuit 407 evaluates the harmonic spectrum power of a specific order and outputs it to the device control unit 107 in the magnetic recording / reproducing device 108.

The advantage of this method is that the NLTS evaluation function can be carried out even after the magnetic recording / reproducing apparatus is shipped since it has a built-in NLTS evaluation function.

Finally, the storage location of the NLTS evaluation pattern of the first classification will be described.

The storage location depends on the functional configuration and usage pattern of NLTS evaluation, and is incorporated as software or hardware, the NLTS evaluation pattern is transferred as one data from the host computer 113 which is the host controller, and NL from the jig via a dedicated interface
The TS evaluation pattern can be divided into three types of input forms.

When incorporated as software or hardware, as shown in FIG.
When the NLTS evaluation control signal is output from the device control unit 107 built in 08, the pattern generator 401 outputs the NLTS.
Output the TS evaluation pattern. At the same time, the selector 402 switches the path for outputting the NLTS evaluation pattern to the modulator 101.

The advantage of this method is that the pattern generator 40
Since the NLTS evaluation pattern is registered in 1,
The pattern can be output whenever the NLTS evaluation is performed. Therefore, this method can independently perform NLTS evaluation after shipping.

When the NLTS evaluation pattern is transferred from the host computer 113 as one piece of data, the NLTS evaluation pattern can be set by the host computer 113 because it can be handled in the same manner as general user data. The recording / reproducing device 108 side can handle it without any particular operation.

This method can be used for NLTS evaluation before shipment, and when the host computer 113 has driver software for controlling the magnetic recording / reproducing apparatus 108,
By adding the logic of NLTS evaluation to the driver software, NLTS evaluation after shipment becomes possible.

Next, the magnetic recording / reproducing apparatus 108 having a function corresponding to the case 2 in FIG. 4 will be described.

FIG. 9 is a block diagram showing an example of a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

The magnetic recording / reproducing apparatus 108 incorporates the evaluation data of the NLTS into the magnetic recording / reproducing apparatus 108 as software or hardware, and secures the evaluation data writing area in the data area of the magnetic recording medium. Is evaluated by the spectrum evaluation function circuit incorporated in the reproduction circuit system. The recording / reproducing of the evaluation data also serves as the data recording modulator used in the magnetic recording / reproducing apparatus 108.
8 recording / reproducing system is used. Therefore, the magnetic recording / reproducing apparatus 108 of Case 2 can perform NLTS evaluation before and after shipment.

First, the NLTS evaluation method will be described below.
The NLTS evaluation pattern is generated by the pattern generator 401 and output to the modulator 101 via the selector 402.
Since the NLTS evaluation pattern is composed of the patterns within the modulation rule of the recording modulation method used in the magnetic recording / reproducing apparatus 108, the modulator 101 can perform recording modulation similarly to user data.

After the data is modulated, recording is performed on the medium 105, which is a magnetic recording medium, by the recording head 104 through the recording timing correction circuit 102 and the recording amplifier 103 in the form of magnetization reversal. Since the recording area is secured in the data area, it can be the same as the method of recording user data.

The magnetization reversal information recorded on the medium 105 is
It is reproduced by the reproducing head 109, amplified by the preamplifier 110, and then output to the spectrum evaluation function circuit 407.

The spectrum evaluation function circuit 407 measures the harmonic spectrum power of a specific order and outputs it to the device control section (HDC) 107. Device control unit 107
Then, the magnitude of the NLTS is obtained using the specific order harmonic spectrum power in the case of the evaluation pattern generated by the NLTS and the specific order harmonic spectrum power in the case of the reference pattern in which the NLTS does not occur. N
As the procedure for obtaining the LTS, the procedure described in the first and second embodiments can be used. In addition, the device control unit 10
7 outputs a recording timing correction value control signal corresponding to the obtained NLTS amount to the recording timing correction circuit 102.

In the recording timing correction circuit 102, the NL
When the TS amount is large, the magnetization reversal interval is set to be large. The operation of the recording timing correction circuit 102 is
It is possible to classify by the combination of the magnetization reversal states of 1 bit before and 2 bits before, and the timing correction value can be set for each combination. That is, the correction value corresponding to the '11' pattern in which the magnetization reversal is continuous and the correction value corresponding to the '101' pattern in which the magnetization reversal is continuous can be set independently by one bit. It is possible to set the correction value depending on the combination of.

Furthermore, after setting the correction value of the recording timing, the circuit constant evaluation setting of the reproducing circuit system 111 can be performed. That is, the correction of the recording timing is optimized by the correction value depending only on the NLTS, and the reproducing circuit system 111 can be optimized while the influence of the NLTS is suppressed to the minimum. It is possible to adjust the condition to the best condition.

Note that the actual user data is the host computer 11
3 through the interface 106, selected by the selector 402, converted into a magnetic reversal pattern by the modulator 101, the recording timing is corrected by the optimized recording timing correction circuit, and the recording amplifier 1
The recording signal is amplified by 03 and recorded on the medium 105 by the recording head 104. Further, in reproducing user data, the magnetic reversal pattern recorded on the medium 105 is converted into a signal by the reproducing head 109, amplified by the preamplifier 110, and demodulated by the demodulator 112 via the optimized reproducing circuit system.
Is demodulated by and is transferred to the host computer 113 via the interface 106 in the form of user data.

Next, a case where the NLTS is evaluated after shipping will be described.

After shipping, since the user data is recorded in the data area of the medium 105, the NLTS evaluation pattern cannot be directly recorded. So NLTS
The user data in the data area for recording the evaluation pattern is saved. As the saving method, there are a method of recording in another portion on the medium and a method of temporarily recording in a non-volatile semiconductor memory or the like. It goes without saying that either method may be used.

When the saving of the user data is completed, the NLTS measurement is performed by using the above-mentioned NLTS evaluation method, and the recording timing correction control of the recording timing correction circuit 102 is performed. Then, the circuit constant evaluation setting of the reproduction circuit system 111 is performed.

When the setting of the reproduction circuit system 111 is completed, the user data in the temporarily saved state is re-recorded at the original position. In this case, since the correction value of the recording timing correction circuit 102 has been changed, it is preferable to re-record other user data.

However, due to the frequency of use of the magnetic recording / reproducing apparatus 108, it may not be possible to re-record other user data. In consideration of this case, the magnetic recording / reproducing device 108 is provided with the correction values and circuit constants of the reproducing circuit system 111 up to several times before.
A memory area provided inside, for example, a device management area on the medium 105, the interface 106, or the device control unit 107.
Can be recorded in the memory area of. That is, as one method of retry when a reproduction error occurs,
It can be used to set the circuit constants up to several times before and to reproduce.

Regarding the timing of performing the NLTS evaluation after shipment, (1) when the number of retries increases due to an increase in reproduction errors, and (2) when the usage environment of the magnetic recording / reproducing device 108 changes, is exemplified. be able to.

When the number of reproduction errors increases, the device control section 107 can issue an NLTS evaluation command signal to perform NLTS evaluation. When the usage environment of the magnetic recording / reproducing apparatus 108 is changed, the magnetic recording / reproducing apparatus 108 itself cannot tell if there is no symptom such as an increase in reproduction errors. Therefore, the NLTS evaluation can be performed when a command such as a circuit constant reset command is received from the host computer 113.

Next, a method of performing NLTS evaluation and setting the correction value of the recording timing correction circuit will be described with reference to FIG.

A trigger for correcting the recording timing,
For example, the correction value setting routine of the recording timing correction circuit 102 is started when the magnetic recording / reproducing apparatus 108 is turned on or at a certain fixed time, or in response to an NLTS evaluation command from the host computer 113 (step 301). This routine is composed of software or firmware and can be incorporated in the magnetic recording / reproducing device 108 or the host computer 113.

When the routine is started, first, the NLTS is measured using the current correction value (WPC0) of the recording timing correction circuit 102 (step 302). The method described above can be used as the method for measuring NLTS. The NLTS amount at this time is NLTS1.

Next, assuming that the NLTS amount before shipment of the magnetic recording / reproducing apparatus 108 or the previous setting of the correction value of the recording timing correction circuit 102 is NLTS0, NLTS
1 and NLTS0 are compared in size (step 30).
3). NLTS if NLTS1 is smaller than NLTS0
1 is substituted into NLTS0 (step 304), and NLTS
A value of 0 is recorded (step 305) and this routine ends.

On the other hand, when NLTS1 is larger than NLTS0, the correction value WPC of the recording timing correction circuit 102
2 = WPC0-α is set (step 306).

The NLTS at the correction value of the recording timing correction circuit 102 is measured and set as NLTS2 (step 307).

NLTS2 and NLTS0 are compared (step 308). If NLTS2 is smaller than NLTS0, NLTS2 is substituted for NLTS0 (step 309).
Further, WPC2 is substituted for WPC0 (step 31)
0). Then, WPC0 is set to the recording timing correction circuit 102.
(Step 311). Then, NLTS0 is recorded (step 305).

When NLTS2 is larger than NLTS0, the correction value WP of the recording timing correction circuit 102 is set.
C3 = WPC0 + α is set (step 312). The NLTS is measured in the state of the correction value WPC3 of the recording timing correction circuit 102 (step 313). The NLTS at this time is referred to as NLTS3.

NLTS3 and NLTS0 are compared (step 314). If NLTS3 is smaller than NLTS0, NLTS3 is substituted into NLTS0 (step 31).
5) and WPC3 is substituted for WPC0 (step 3)
16). Recording timing correction circuit 1 using WPC0
Set the timing correction amount to 02 (step 31
1). Then, record NLTS0 (step 30).
5).

When NLTS3 becomes larger than NLTS0, NLTS3 and NLTS2 are compared (step 317). If NLTS3 is small, NLTS0 is set.
NLTS3 and WPC3 are respectively substituted into WPC0 and WPC0 (steps 315 and 316). And WPC0
Is substituted into the recording timing correction circuit 102 (step 311), and NLTS0 is recorded (step 30).
5).

When NLTS2 is small, NLTS2 is substituted for NLTS0 (step 309), and WPC is further set.
WPC2 is substituted for 0 (step 310). Then, WPC0 is set in the recording timing correction circuit 102 (step 311). Then, NLTS0 is recorded (step 305).

The NLTS correction amount can be set as described above.

According to such a magnetic recording / reproducing apparatus 108, the previous correction value and the NLTS amount are stored to store the current N value.
Since the amount can be compared with the LTS amount, the magnetic recording / reproducing device 108 can always be maintained in the optimum state, and the reliability of the recording / reproducing of the magnetic recording / reproducing device 108 can be improved. As a result, the number of retries is reduced, and the responsiveness of the magnetic recording / reproducing device 108 can be improved.

It should be noted that the NLTS amount is a constant value, for example, 10%.
The correction value setting routine of the recording timing correction circuit 102 is repeatedly used a plurality of times until
If the S amount does not fall below 10%, the correction value can be set in the recording timing correction circuit 102 when the NLTS amount becomes the smallest during the maximum number of times the correction value setting routine is repeated, for example, up to 5. In such a case, it is possible to prevent the routine from being repeated more than necessary, and it is possible to eliminate the adverse effect that the routine is repeated indefinitely.

When the correction value setting routine of the recording timing correction circuit 102 is repeatedly used a plurality of times, if the NLTS amount does not fall below a certain value, or if the change in the NLTS amount falls below a certain value, such as 1%, the maximum value is repeated. The correction value setting routine can be ended even if the number of times of use is less than the number of times of use. In such a case, useless repetition of the routine can be prevented.

Further, a continuous pattern of magnetization reversal ('1
1), the correction value of the recording timing correction circuit 102 is set for the '11' pattern, and the recording timing is specified for the '101' pattern. The correction value of the correction circuit 102 can be set for the '101' pattern. Further, when the NLTS amounts in both the '11' and '101' patterns are specified, the correction value of the recording timing correction circuit 102 is set for the '11' pattern and '101'.
Combinations with the settings for the patterns, that is, four settings can be made. In such a case, NL
The optimum correction value can be set according to the pattern that causes TS, and the correction of the recording timing correction circuit 102 can be performed more precisely.

In the recording timing correction circuit 102, a pattern and a correction time corresponding thereto can be set as a correction value. Then, in the pattern set in the recording timing correction circuit 102, the recording current is generated by shifting the reversal position of the recording current by the correction time amount, and the medium 10 is generated.
It is possible to record to 5. Thereby, the shift of the magnetization reversal position due to the influence of the NLTS can be alleviated.

The magnetic recording / reproducing apparatus 108 of Case 1, Case 3 to Case 5 based on the combination of the functional classifications shown in FIG. 4 can be obtained by replacing the functional parts of Case 2 described above. The features of each case will be described below in comparison with case 2.

The case 1 has the same recording system as the case 2, but the spectrum evaluation function circuit 407 is not mounted in the reproducing system. Therefore, in order to perform spectrum evaluation, an external spectrum analyzer 40 via a jig circuit is used.
5 is used. Therefore, in case 1, only the evaluation adjustment before shipment is possible.

Case 3 has the same recording / reproducing circuit system as Case 2. Therefore, NLTS evaluation after shipping is possible. Furthermore, since it has a dedicated area as a recording area for NLTS evaluation, it is not necessary to perform a high-risk process of temporarily saving user data, and therefore the processing method becomes simple. However, in order to secure the dedicated area, the magnetic recording / reproducing device 108 must have an increased capacity for the dedicated area. That is, the recording density must be increased by the capacity corresponding to the dedicated area.

Case 4 is a method in which the NLTS evaluation pattern is treated in the same manner as general user data, and the evaluation pattern is transferred from the host computer 113. However, as compared with Case 2, the spectrum evaluation function circuit 407 is not mounted in the reproduction system. Therefore, in order to perform spectrum evaluation, an external spectrum analyzer 4 via a jig circuit is used.
05 is used. Therefore, in case 4, only the evaluation adjustment before shipment becomes possible.

In addition to the circuit system of case 4, case 5 includes
The reproduction system is equipped with a spectrum evaluation function circuit 407. The NLTS evaluation method is the same as in Case 4. In this case 5, by incorporating the NLTS evaluation command in the driver software of the host computer 113, the NLTS evaluation after shipment becomes possible.

The following example of the configuration of the spectrum evaluation function circuit 407 can be shown.
In the NLTS evaluation pattern shown in the first to third embodiments,
Since it is designed so that the influence of NLTS appears on the harmonic spectrum power of a specific order, it becomes possible by measuring the output through a bandpass filter having a narrow bandwidth. In the current disk device, the recording frequency is set so that the recording density is almost the same in all zones. Therefore, the recording frequency is different for each zone. Therefore, the center frequency of the bandpass filter is switched for each zone. Therefore, it is possible to detect the signal of only the specific frequency by utilizing the change of the center frequency for each zone.

Although the invention made by the present inventor has been specifically described based on the embodiments of the present invention, the present invention is not limited to the above embodiments and various modifications can be made without departing from the scope of the invention. It goes without saying that it can be changed.

For example, in the first to third embodiments, the 8/9 modulation / demodulation method is exemplified as the modulation / demodulation method of the magnetic recording / reproducing apparatus 108, but the modulation / demodulation method is not limited to this, and a modulation / demodulation method which may be defined in the future is used. It includes.

The reproducing head is not limited to the magnetically reading type, but may be an optically reading type. That is, the present invention may be applied to a magneto-optical recording system.

[0172]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) The NLTS can be directly evaluated by an actual magnetic recording / reproducing apparatus. As a result, circuit constants such as recording timing correction are directly obtained, and the cost can be reduced by shortening the adjustment time and man-hours.

(2) It is possible to directly perform the optimization adjustment of the recording timing of the magnetization reversal and the characteristics of the reproducing circuit system in the actual magnetic recording / reproducing apparatus.

(3) Even after the magnetic recording / reproducing apparatus is shipped, the recording timing of the magnetization reversal and the characteristics of the reproducing circuit system are optimized so that the magnetic recording / reproducing apparatus can always be kept in the optimum state and the performance can be maintained. .

[Brief description of drawings]

FIG. 1 is an NL used in a magnetic recording / reproducing apparatus according to a first embodiment.
9 is a flowchart showing an example of a TS evaluation procedure.

FIG. 2 is a graph showing a signal waveform and a power spectrum observed in the NLTS evaluation procedure of the first embodiment, where (a) is a reproduced signal waveform of an evaluation pattern, (b) is a power spectrum of (a), and 3C shows a reproduced signal waveform of the reference pattern, and FIG. 3D shows the power spectrum of FIG.

3A is a vector phase diagram for explaining an evaluation pattern according to the second embodiment, and FIG. 3B is a vector phase diagram in which a signal vector corresponding to each magnetization reversal of the evaluation pattern is written. Indicates.

FIG. 4 is a function classification diagram showing classification and combination of functions of the magnetic recording / reproducing apparatus according to the embodiment of the present invention.

FIG. 5 is a block diagram for explaining functions in the magnetic recording / reproducing apparatus according to the embodiment of the present invention.

FIG. 6 is a block diagram for explaining functions in the magnetic recording / reproducing apparatus according to the embodiment of the present invention.

FIG. 7 is a block diagram for explaining functions in the magnetic recording / reproducing apparatus according to the embodiment of the present invention.

FIG. 8 is a block diagram for explaining functions in the magnetic recording / reproducing apparatus according to the embodiment of the present invention.

FIG. 9 is a block diagram showing an example of a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 10 is a flowchart showing an example of a recording timing correction procedure in the magnetic recording / reproducing apparatus according to the embodiment of the present invention.

[Explanation of symbols]

101 ... Modulator, 102 ... Recording timing correction circuit, 1
03 ... recording amplifier, 104 ... recording head, 105 ... medium, 106 ... interface, 107 ... device control unit, 1
08 ... Magnetic recording / reproducing apparatus, 109 ... Reproducing head, 110
... Preamplifier, 111 ... Reproducing circuit system, 112 ... Demodulator,
113 ... Higher-level machine, 401 ... Pattern generator, 402 ... Selector, 405 ... Spectrum analyzer, 406 ... Jig circuit, 407 ... Spectrum evaluation function circuit, 410 ...
Pattern generator, A, B, C, D, E, F, G ... Vector.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuto Ishida 2880, Kozu, Odawara-shi, Kanagawa Hitachi, Ltd. Storage Systems Business Department (72) Inventor, Rinjiro Tsuchiya 2880, Kozu, Odawara, Kanagawa Hitachi, Ltd. Manufacturing system storage system business department (56) Reference JP-A-7-57227 (JP, A) JP-A-9-44806 (JP, A) JP-A-4-295670 (JP, A) US Pat. No. 5493454 (US, A) US Pat. No. 5,068,754 (US, A) Xiaodong Che et. a. , A Generalized Frequency Domain Non linearity Measure method, IEEE Transactions on Magnetics, USA, 1994, Vol. 30, No. 6, pp. 4236-4238 (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 5/00-5/024 G11B 5/09

Claims (5)

(57) [Claims] 1. A non-linear magnetization reversal position shift (NLTS) and a harmonic component of a specific order in a reproduction signal of an evaluation pattern recorded on a magnetic recording medium as a magnetization reversal pattern.
Wherein by comparing the orders of the harmonic components, a magnetic recording and reproducing apparatus having the NLTS evaluation means for evaluating the NLTS of the magnetic recording medium in the reproduction signal of the reference pattern does not produce, as the evaluation pattern, ' 11 [6p] 1 [6q] 1
1 [6p] 1 [6q] '(' 1 'has magnetization reversal,
'0' has no magnetization reversal, [6p] is '0' 6p (p is
[6q] is '0' 6q (q is a natural number)
Test signal satisfying (representing a natural number) times)
This is a modification of the pattern, and the magnetization reversal is “11” in which an even number of the consecutive “0” in the test signal pattern is continued.
It is replaced with '1' under the condition that does not newly generated, the replacement
'1' signals of the harmonic components of the order
A magnetic recording / reproducing apparatus characterized by using a pattern satisfying a requirement of erasing each other . 2. A pattern generating means for converting evaluation data and reference data input from a higher-level machine into a magnetization reversal pattern to generate an evaluation pattern and a reference pattern, and the magnetization reversal pattern converted by the pattern generating means. A recording head for recording on the magnetic recording medium; a reproducing head for reproducing the magnetization reversal pattern recorded on the magnetic recording medium; and means for outputting the magnetization reversal pattern reproduced by the reproducing head to a spectrum analyzer , The pattern generation means outputs the evaluation data to the magnetization reversal.
When converting the evaluation data into the
[6p] 1 [6q] 11 [6p] 1 [6q] '(' 1 '
Indicates magnetization reversal, '0' indicates no magnetization reversal, and [6p] indicates
Repeated 6p (p is a natural number) times of '0', [6q] is
6q of q (q is a natural number) repeated)
It is a modification of the evaluation data to be added,
Magnetization reversal that continues even number of consecutive '0's' 1
Replace it with '1' under the condition that 1'is not newly generated.
'1' signals of the converted harmonic components cancel each other
A magnetic recording / reproducing apparatus, characterized in that the magnetic reversal pattern is converted to match each other . 3. A magnetic recording medium on which information is recorded as a magnetization reversal pattern, a modulator for converting data into the magnetization reversal pattern, and a recording for recording a recording signal corresponding to the magnetization reversal pattern on the magnetic recording medium. A magnetic recording / reproducing apparatus comprising a head and a reproducing head for reproducing a magnetization reversal pattern recorded on the magnetic recording medium, the evaluation data generator being provided in the magnetic recording / reproducing apparatus or a high-level device. Pattern generation means for converting the obtained evaluation data into the magnetization reversal pattern using the modulator and generating an evaluation pattern for evaluating the NLTS; and a harmonic component of a specific order of a reproduction output signal of the evaluation pattern, An NLTS evaluation method for calculating the NLTS amount of the magnetic recording medium using the harmonic component of a specific order of the reproduction output signal of the reference pattern. If, have a, the pattern generating means, the magnetization anti the evaluation data
When converting the evaluation data into the
[6p] 1 [6q] 11 [6p] 1 [6q] '(' 1 '
Indicates magnetization reversal, '0' indicates no magnetization reversal, and [6p] indicates
Repeated 6p (p is a natural number) times of '0', [6q] is
6q of q (q is a natural number) repeated)
It is a modification of the evaluation data to be added,
Magnetization reversal that continues even number of consecutive '0's' 1
Replace it with '1' under the condition that 1'is not newly generated.
'1' signals of the converted harmonic components cancel each other
A magnetic recording / reproducing apparatus, characterized in that the magnetization reversal pattern is converted into a mutually compatible pattern . 4. A magnetic recording / reproducing apparatus according to claim 2 or 3.
In the above arrangement, there is provided recording timing correction means for adjusting the timing of the recording signal corresponding to the magnetization reversal pattern so as to reduce the NLTS amount of the magnetic recording medium, and the recording timing correction means is used for the pattern generation means and the recording. magnetic recording and reproducing apparatus characterized in that it comprises between the head. 5. A magnetic recording / reproducing apparatus according to claim 2 or 3.
And a storage area for storing a NLTS amount of the magnetic recording medium evaluated by the spectrum evaluation function circuit, the spectrum evaluation function circuit for evaluating a harmonic component of a specific order of the output signal of the reproducing head, The first NLTS amount stored in the area is compared with the newly evaluated second NLTS amount, and the second NLTS is compared.
When the TS amount is larger, a second correction value obtained by adding a positive or negative variation to the first correction value stored in the storage area is set, and the NLTS is evaluated again to determine the third correction value. NLTS amount is acquired, and the second NLTS amount and the third NLTS amount are acquired.
The smaller amount of NLTS and select the smaller NLTS amount,
A magnetic recording / reproducing apparatus, comprising: a recording timing correction circuit that stores a correction value corresponding to the NLTS amount in the storage area.