JPH11203608A - Recording equalizer and magnetic recording and reproducing device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a recording correcting system and to allow it to have high accuracy by controlling the pattern of a recording current as desired at the time of recording magnetization information. SOLUTION: A current from a constant current power source 22 to be driven with a high voltage power source 24 is directed to a recording head via a switching circuit 21. The switching circuit 21 inverts the polarity of the current according to outputs A(n) from a data butter. Outputs i(n) from a current value calculating circuit are inputted to a current bypassing circuit 23 to make a prescribed current so as to flow through the circuit 21 by branching one part of the current from the constant current circuit 22. Here, the circuit 23 digitally control a reference potential by the outputs i(n) from the current value calculating circuit while using a current mirroring circuit. Then, the far the recording head is separated from the rotary shaft, the faster the rising time of the recording current is made by changing the voltage of the power source driving the constant current power source 22 with a digital circuit while using the control signal of an actuator driving the recording head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording equalizer for correcting interference between adjacent codes generated when magnetic information is recorded on a magnetic recording device or the like, and a magnetic recording / reproducing device using the same.

[0002]

2. Description of the Related Art With the progress of the information-oriented society, there is an increasing demand for high density and high storage capacity of magnetic disk devices used as external storage devices of computers. The recording density of the magnetic disk device is currently increasing at an annual rate of 40 to 60%. Such rapid densification is supported not only by the development of a low-noise medium, but also by the adoption of new technologies such as an MR head and a PRML (Partial Response Maximum Likelihood) system.

In the PRML system, the conventional 1-7 / PD
(Peak Detection) method, the same linear recording density (BP
In the case of I), recording is performed on the medium with a 1.5 times magnetization reversal density (FCI). Therefore, it is necessary to take countermeasures against various phenomena which occur in a high magnetization reversal density and a high frequency region, which have not existed conventionally. One of them is Non-Linear Transition Shift;
Non-linear phenomena during recording typified by NLTS). In particular, in the PRML system, the linearity of the recording / reproducing channel is required to exhibit its performance sufficiently.

In the PRML channel, since the determination is made using the amplitude value obtained by sampling the reproduced waveform, sampling at the correct timing and equalization to the correct waveform position are essential. For this purpose, it is required to accurately control the magnetization reversal position written on the medium by the magnetic head. However, if there is a demagnetizing field in the medium, the head magnetic field is modulated, causing a shift in the magnetization reversal position to be written. The phenomenon that the magnetization reversal position shifts from the reversal position expected from the reversal timing of the recording current is NLTS.

The influence of the NLTS is greatest one bit before, and the magnetization reversal position to be written (magnetization reversal position expected from the reversal timing of the head magnetic field)
Is shifted in the direction opposite to the traveling direction of the recording head viewed from the recording medium. Conventionally, in order to correct such a shift in the recording position, a method (recording correction) of shifting the reversal timing of the head magnetic field according to the recording pattern and controlling the magnetization reversal position to a normal position on the medium has been adopted. I have.

When recording and correcting NLTS, usually 1
In consideration of the magnetic field from the magnetization transition one bit before or one bit before, the reversal timing is delayed from the timing of the basic clock by the time corresponding to the above shift ((IEE Transactions on Magnetics (IEEE Trans. Vol. 26, No.
5, p2298).

[0007]

The above-mentioned method of controlling the reversal timing of the head magnetic field to correct the recording of the NLTS is not suitable for a magnetic recording apparatus realizing a recording density of 2 gigabits per square inch or more. Is complicated.

An object of the present invention is to simplify a recording correction method,
It is an object of the present invention to provide a recording equalizer suitable for high-density recording by increasing the precision and a magnetic recording apparatus that realizes a recording density of 2.5 gigabits or more per square inch using the same.

[0009]

In the present invention, the above object is achieved by controlling the magnitude of the recording current and the rise time according to the recording conditions to correct the NLTS recording. The recording conditions include factors that change the flying conditions, such as temperature, air pressure, and abrasion state of the slider, and the medium characteristics, in addition to the recording pattern and the relative speed between the medium and the recording head.

First, as a means for correcting the recording of the NLTS, a method of adjusting the above-mentioned conventional inversion timing was examined.
In this method, the recording correction amount varies depending on recording conditions such as a recording pattern and a difference in inner and outer peripheral conditions of a disk with the increase in recording density, so that there is a problem that a recording equalizer becomes complicated and costs increase. For this reason, as a result of further study on the recording equalization method, it was found that the recording position was moved by a slight change in the magnitude of the recording current. Then, when recording was performed by precisely controlling the magnitude of the recording current, the magnetization transition was formed at the correct position, and it was found that recording correction by controlling the magnitude of the recording current was effective. Was.

The present invention has been made based on such studies, and it is intended to correct recording by controlling a recording current pattern when recording magnetic information on a magnetic recording medium using a magnetic recording head. Features.

The recording correction utilizes the fact that when the recording current is small, the recording position moves in the head traveling direction as viewed from the medium. If there is a transition one bit before a certain transition, there is a large NLTS in the direction opposite to the head running direction, so the recording current is reduced to correct this. The size of the NLTS is
Since it depends on the length between adjacent magnetization transitions recorded on the medium and becomes shorter as it becomes shorter, the recording current needs to be made smaller.

The current value is controlled by a method of dividing the reference potential of the constant current power supply by a digital circuit, a current mirror circuit, or the like.

The magnitude of the recording current for recording a certain transition is
After the polarity of the current is changed, the current gradually increases. However, when three or more bits have passed, the value becomes almost constant, and is considered as a steady value.

When recording dibits or the like at a high recording density, if the rise time of the recording current is long, the recording current is inverted before the recording current becomes sufficiently large. Therefore, the effective recording current of the first bit of the dibit decreases, and the recording position moves in the head traveling direction. To correct this, it is necessary to shorten the rise time of the recording current.

To speed up the rise time of the recording current,
A method of increasing the set current of the recording current and a method of increasing the voltage of the power supply for driving the constant current power supply can be considered. further,
By providing a voltage bypass circuit in parallel with the constant current power supply and supplying current to the switch circuit directly from the high voltage power supply,
The rise time of the recording current can be shortened. The voltage bypass circuit is turned on for a short time at the beginning of the rise of the recording current.

The recording equalizer is usually integrated on one chip, and is located near the recording head. In this case, since the constant current power supply is placed at a remote position, it receives the output from the current value calculation circuit in the recording equalizer and changes the current value of the constant current power supply and the power supply voltage of the constant current power supply. It becomes difficult to do. By providing the bypass circuit in the chip, the current value and the voltage can be appropriately changed according to the recording conditions.

The current flowing in the current bypass circuit provided in parallel with the switch circuit can be controlled by switching the reference potential by a digital circuit using a current mirror circuit.

Since the recording medium is disk-shaped and rotates at a constant speed around the center, the relative speed between the recording medium and the recording head increases as the recording head moves away from the rotation axis.
In the conventional magnetic recording / reproducing apparatus, since the rising time of the recording current is constant, the rising of the recording head magnetic field viewed from the medium becomes slower as the distance from the rotation axis increases. Therefore, the recording density must be reduced as the distance from the rotation axis increases. By increasing the rise time of the recording current as the recording head moves away from the rotation axis,
The recording density at the outer peripheral portion can be improved. The voltage of the power supply for driving the constant current power supply is changed by a digital circuit using a control signal of an actuator for driving the recording head.

The recording equalizer of the present invention includes a write head for recording magnetization information on a magnetic recording medium by an output from the recording equalizer, a read head for reading magnetization information recorded on the magnetic recording medium, and a read head for reading data. By incorporating it in a magnetic recording / reproducing apparatus having decoding means for decoding an output signal, a highly reliable magnetic recording / reproducing apparatus realizing a recording density of 2.5 gigabits per square inch or more can be obtained.

[0021]

FIG. 1 shows a basic configuration of a recording equalizer 1 which is a main part of the present invention.
Is composed of at least a data buffer 2, a recording current calculation circuit 5, and a recording current driver circuit 6.

The recording data A (... n ...) is input to the data buffer 2. Suppose now that the target of recording is A
Assuming that (n), the data buffer 2 has A
In addition to (n), reference bits A (n−2) and A (n−1) and a rear bit A (n + 1) that are necessary for calculating the nonlinear shift amount are referred to.
Is stored. The data buffer 2 has a function of transmitting such information as needed to the recording current calculation circuit 5 and the recording current driver 6 located at the subsequent stage.

The recording current calculation circuit 5 first calculates a recording correction amount of a target bit to be recorded based on an output result from the data buffer 2. This calculation refers to the length of one bit to be recorded on the magnetic recording medium determined from the fundamental frequency (recording frequency: recording PLL circuit frequency) determined by the relative speed between the medium heads and the closest recording density.
The calculation principle of the recording correction amount will be described later. Also,
A bit determination circuit may be inserted between the data buffer 2 and the recording current value calculation circuit 5, and the recording correction amount in the recording current value calculation circuit 5 may be referred to from a table calculated in advance.

Next, the obtained recording correction amount is converted into a recording current value i (n) according to a conversion formula or table obtained in advance. The principle of converting the recording correction amount into a recording current value will be described later.

After calculating the recording current value, the calculation result i (n)
To the recording current driver 6. In the current driver 6, A
(n) a function of inverting the current polarity in accordance with the information; In the present invention, the magnitude of the recording current after the reversal at this time is defined as the calculated recording current value. The feature of the present invention is that the structure can be simplified because the inversion timing does not need to be changed unlike the conventional method.

The principle of converting the recording correction amount into a recording current value will be described with reference to FIG. The figure shows a gap recording on a magnetic recording medium having a thickness of 30 nm and a coercive force of 2400 Oersted.
This shows the measurement results when recording was performed at a relative speed between head media of 16 m / s using a 200 nm inductive head. FIG. 2A shows an example of a change in the recording position with respect to the magnitude of the recording current, where the head traveling direction is positive. In the measurement, following the isolated transition recorded at a recording current of 43 mA, the current is inverted and recorded at a predetermined current value after 100 ns, the transition interval is calculated from the reproduction output obtained by the MR head, and the recording current is 43 mA. This is a comparison with the recording position in the case of. FIG. 2B shows the recording current dependence of the transition width measured simultaneously at this time.

FIG. 2A shows that the smaller the recording current, the more the recording position is shifted to 3 to 4 nm / m in the positive direction (head running direction).
Move at the rate of A. Therefore, when there is a large NLTS in the direction opposite to the head traveling direction as in the second transition of the dibit, writing to the correct position can be performed by reducing the recording current by an amount corresponding to this. Similarly, when the recording position moves in the head running direction as in the first transition of the dibit, the recording current may be increased by a corresponding amount.

The transition width is shown in FIG.
It takes the minimum value at mA and increases slowly when the current is greater, whereas it increases rapidly when the current is small.

If the transition width is large, partial extinction of the recorded magnetization is likely to occur due to inter-transition interference. Therefore, the current value at which high-density recording of about 250 kFCI (bit length 100 nm) needs to be in the range of 30 to 70 mA. is there. Therefore, the shift amount at which the recording position can be controlled by the current value is estimated to be a maximum of about 130 nm from FIG. The NLTS for the combination of the media heads used is 250 kFCI, about -20 nm for the second transition of the dibit and 7 nm for the first transition of the dibit, as described later.
Therefore, recording correction can be performed in an extremely favorable state. The NLTS of the first transition of the dibit becomes larger when the rise time of the recording current is late. This is because the recording current is reversed before the recording current becomes large enough,
This is probably because the effective recording current has decreased. When recording is performed on the outer peripheral portion of the medium disk, the rise of the recording head magnetic field viewed from the medium is slow, and the NLTS of the first transition of the dibit is large.

Here, the initial setting of the recording current will be described. Before actually performing recording, it is necessary to determine a recording current value of an isolated transition which is a reference for correction. This is because the transition width in the recording current value for correcting the expected NLTS is
Decide to be as small as possible.

More specifically, for the dibit having the largest NLTS among various recording patterns, the NLTS is measured over the entire recording area, and the maximum value (first transition of the dibit) and the minimum value (first transition of the dibit) are measured. Second transition of dibit). Then, the correction amount of the isolated transition is set to 0, and the recording current value of the isolated transition is determined so that the transition width in the recording current value for correcting the obtained maximum value and the minimum value becomes substantially equal. At this time, the recording current values for correcting the maximum value and the minimum value are on opposite sides of the current value at which the transition width is minimum. In FIG. 2, when the current value of the isolated transition is set to 41 mA, the recording current value for correcting the maximum value is 43 mA, and the recording current value for correcting the minimum value is 35 mA, and the transition width is small in these current ranges. The value is kept. When the bit lengths are the same, the first transition of the dibit under the disk outer circumference condition takes the maximum value, and the second transition of the dibit under the disk inner circumference condition takes the minimum value, so that the measurement over the entire recording area may be omitted. Instead of reducing the transition width, the recording current value of the isolated transition may be set so that the overwrite S / N ratio is maximized.

Once the initial setting of the recording current is performed,
All recording currents are calculated based on the recording current of the isolated transition. At this time, the [recording position] on the vertical axis may be moved in parallel so that the recording correction amount becomes 0 at the determined recording current.

When the current is adjusted by a bypass circuit provided in parallel with the switch circuit for inverting the current polarity of the recording head, a current value larger than an expected maximum value of the recording current value is set to a constant current source. Assuming current value, temperature, pressure,
It is possible to cope with fluctuations in factors that affect the flying conditions such as the wear state of the slider and the medium characteristics.

When recording correction is performed on actual data, the recording correction amount of a recording target bit, which will be described in detail below, is converted into a recording current using FIG. Figure 2 shows the conversion.
-A may be approximated to a simple second-order or third-order equation.

The principle of calculating the recording correction amount will be described with reference to FIG. FIG. 3 shows a magnetic recording medium having a film thickness of 30 nm and a coercive force of 2400 Oersteds with a gap interval of 200 nm.
With a recording current of 40 mA using an inductive head of
FIG. 9 shows the measurement results of the first transition shift (S1) and the second transition shift (S2) when several dibits are recorded. In the figure, the horizontal axis indicates the bit length of the dibit [nanometers], and the vertical axis indicates the shift of each transition position from the magnetization reversal position to be written (expected from the reversal timing of the head magnetic field).
On the vertical axis, the traveling direction of the recording head viewed from the recording medium is positive.

It can be seen from the figure that the magnitude of the shift (S1, S2) increases as the bit length L decreases. For example, S2 is 9 nanometers at a bit length of 150 nanometers and 20 nanometers at a bit length of 100 nanometers, and is shifted in the direction opposite to the running direction of the recording head. S1 is the bit length of each,
The size shifts in the opposite direction (running direction of the recording head) at about 1/3 of S2.

The calculation of the recording correction amount is performed by using FIG. 3 or FIG.
The approximate expression obtained from the above is used. The recording correction amount of the recording target bit is determined when there is a transition two bits before the recording target bit from the length of one bit recorded on the magnetic recording medium (S
2) The shift amount and the case where there is a transition one bit before (S
2) The shift amount and the case where there is a transition after one bit (S
It is obtained as a total value with the shift amount of 1). It should be noted here that if there is a transition one bit before, the shift amount of the transition two bits before must be summed as a positive value by changing the S2 code. One bit length L
Is given by Equation 1 where f is the recording basic clock frequency, S is the number of rotations of the disk per minute, and r is the distance from the disk rotation axis to the recording head position.

[0038]

L = 2 × 3.14 × r × S / (60 × f) [m] (1) The head position is determined by using a control signal of the actuator for driving the head or by setting the head position in advance at the head of the sector of the medium. It may be written.

To determine the recording correction amount, the shift of the transition with respect to the required bit length may be stored in advance as a table.

In the present embodiment, the information up to two bits before is used for calculating the recording correction amount.
In order to achieve higher density by using information up to one bit before, it is necessary to further use information up to one bit before.
Up to a recording density of about 150 kFCI,
Up to a bit before is sufficient, and if it exceeds 300 kFCI, it is necessary to use information up to 3 bits before. 1
The influence of the transition after the bit is greatly related to the rise time of the recording current, and need not be considered when the rise time is sufficiently fast and the transition width is short.

In this embodiment, when there is a transition after one bit, the rise time of the recording current of the recording target bit is set to one when there is no transition after one bit in order to prevent the effective recording current from decreasing. 10% faster than the rise time. The means for increasing the rise time of the recording current is automatically incorporated into the measurement of FIG.
To further increase the rise time, a method of increasing the voltage of the power supply for driving the constant current power supply, or a method of providing a voltage bypass circuit and supplying a current directly from the high voltage power supply to the switch circuit may be used.

FIG. 4 is a block diagram showing an example of a signal processing circuit of the magnetic recording apparatus according to the present invention. The recording information (data) first enters the modulator 7. The modulator 7 processes the original data according to a predetermined fixed rule so that the "0" information does not exist more than a predetermined number. The output of the modulator 7 is sent to a precoder 8. The precoder 8 processes the data into codes having strong interference between adjacent signals. For example, "001
00 ”is equalized to become“ 001100. ”The output signal from the precoder 8 is A (n) here.
Call. The A (n) signal is sent to the recording equalizer 1 shown in FIG. The processing in the recording equalizer 1 is as described above.

The output from the recording equalizer 1 is defined as i (n) A (n). Here, i (n) represents a recording current value. The recording current value i (n) is calculated by the recording equalizer 1 as described above,
And controlled. An output from a recording current driver (see FIG. 1) provided at the last stage of the recording equalizer 1 is supplied to a recording head 15.
Sent to Here, the recording medium 17
Is recorded as magnetic information.

At the time of reading, the read head 16 converts the magnetic information into an electric signal again using the electromagnetic conversion. The reading head 16 may be used also as the recording head 15. When the read head 16 and the recording head 15 are separated from each other, if a magneto-resistive (MR) element or a giant magneto-resistive (GMR) element is used as the read head 16, the sensitivity is high and suitable for high-density recording. I have. Since the electric signal here is weak, it enters the preamplifier circuit 10 first. After that, it enters the PR equalizer 11 and the ML decoder 12.

The PR equalization circuit 11 performs a conversion reverse to the processing in the precoder 8. For example, the information “00110”
0 is inversely converted to “00100.” In this case, the reproduced waveform is compared with a learning waveform incorporating intersymbol interference in advance to convert the reproduced waveform into “1” and “0” information. In the ML decoding circuit 12, for the reproduced information,
Decoding is performed according to rules previously given to the modulator output based on several bits of information before and after.

The PR equalizer 11 and the ML decoder 1
In 2, it is necessary to perform the operation at a certain timing. It is easily understood that if this goes wrong, the wrong information will be decoded. For this reason, the PR equalization circuit 11 and the ML decoding circuit 12 obtain the timing of operating using the output of the common VCO (voltage controlled oscillator) 13. Finally, the information is sequentially input to the demodulation circuit 14 and inversely converted to the form of the first record information (the form including the continuation of "0").

The basics of the flow shown in FIG. 4 are the same as those of the PRML signal processing device disclosed so far.
By changing only the recording equalizer 1 part, high-density recording becomes possible, so that the cost is suppressed.

FIG. 5 shows a recording current pulse waveform before correction,
FIG. 4 is an explanatory diagram showing a recording current pulse waveform after correction, and a relationship between a recording current and a recording correction amount. FIGS. 5 (a) and 5 (b)
The waveform of the current pulse before correction for writing information A (-2) to A (5) and the profile of the recorded magnetization state in the head traveling direction are shown. FIGS. 5C and 5D show the profile of the recording current pattern and the recorded magnetization state in the head running direction according to the conventional recording correction method. FIG. 5 (e),
(f) shows a profile of a recording current pattern and a recorded magnetization state according to the recording correction method of the present invention.

Here, as an example, a case where "001001100" is recorded on a medium with a bit length of 100 nm as shown in FIG. 5A will be described. In this information, A (0) is an isolated transition, and A (3) and A (4) are dibits. When the recording current is constant and recording is performed as it is, the transition position is as shown in FIG.
A (4) shifts in the direction in which the phase advances by about 20 nm (FIG. 5).
(b)). To correct this, it is necessary to adjust the recording current value so that the phase of A (3) is advanced by 7 nm and the phase of A (4) is delayed by 20 nm.

FIG. 5C shows the IEEE Trans. Magn.
26, No. 5, p. 2298 is an example of a recording current pattern in which the reversal timing is adjusted so that the phase of A (4) is delayed by 20 nm according to the recording correction method described in Vol. In this method, the leading bit of the dibit (A
The recording correction of (3)) is not performed. Therefore, as shown in FIG. 5D, A (3) cannot be written in the correct position.
It is difficult to configure a magnetic recording device that achieves a recording density of 1.5 gigabits per square inch or more. To correct this, it is necessary to adjust the inversion timing in a direction opposite to the conventional method. To adjust the inversion timing,
Intuitively, it is easy to understand the recording correction, but to realize it, the circuit becomes complicated and the cost increases.

FIG. 5E shows that A (4) is shifted by 2 nm so that the phase of A (3) is advanced by 7 nm using the recording equalizer according to the present invention.
It is an example of a recording current pattern in which the recording current value is adjusted so that the phase is delayed by 0 nm. Since the rise time of the current is slow, the recording current of the preceding bit (A (3)) of the dibit is set to -43 mA, but the current polarity is inverted before reaching the set value (at about -41 mA). Recorded in the correct position. In the profile of the magnetization state in the head traveling direction recorded according to the present invention, as shown in FIG. 5F, all transitions of A (0), A (3), and A (4) are recorded at correct positions. I was able to. The method according to the present invention for adjusting the recording current value can simplify the circuit and reduce the cost.

The recording current driver 6 (see FIG. 1) used in this embodiment will be described with reference to FIG. High voltage power supply 24
The current from the constant current power supply 22 driven by the switch is directed to the recording head via the switch circuit 21 (i (n) A
(n)). The switch circuit 21 has a function of inverting the polarity according to the output A (n) from the data buffer. On the other hand, the output i (n) from the current value calculation circuit enters the current bypass circuit 23, functions so that a part of the current from the constant current power supply 22 is branched, and a predetermined current flows to the switch circuit 21. The current bypass circuit 23 uses a current mirror circuit and digitally controls the reference potential based on the output i (n) from the current value calculation circuit. When the voltage bypass circuit 25 is used, the rise time of the recording current can be shortened. The voltage bypass circuit 25 is turned on for a short time at the beginning of the rise of the recording current.

By separating the high voltage power supply 24 and the constant current power supply 22, the main part of the recording current driver 6 can be integrated on one chip of the recording equalizer, and the current value and voltage can be appropriately adjusted according to the recording conditions. It can be changed.

The recording medium of this embodiment is disk-shaped and rotates at a constant speed around the center, and the relative speed between the recording medium and the recording head increases as the recording head moves away from the rotation axis. The voltage of the power supply for driving the constant current power supply was changed by a digital circuit using the control signal of the actuator for driving the recording head, and the rising time of the recording current was increased as the recording head was further away from the rotation axis. As a result, the rise of the recording head magnetic field as viewed from the medium does not become too slow even in the outer peripheral portion, so that the recording density in the outer peripheral portion is improved.

According to the present invention, since the magnetization area (interval between magnetization transitions) recorded on the recording medium is controlled to be an integral multiple of the length of one bit, the rotation of the disk is time-dependent. Must be stable. In the recording equalizer 1, the above-described control is performed with high accuracy by synchronizing operations such as the timing of newly storing information in the data buffer 2 and the timing of reversing the recording current with the same recording basic clock. be able to.

As a result of applying the recording equalizer according to the present invention to a magnetic disk drive having the signal processing circuit shown in FIG. 4, a high recording density exceeding 2.5 gigabits per square inch could be realized. . In this recording equalizer,
The recording current is adjusted to correct the bit shift. Therefore, there is no need to change the recording timing as in the related art. As a result, it was possible to reduce the number of parts, reduce the cost, and increase the speed of the device. Further, by combining the recording equalizer of the present invention, an MR or GMR magnetic head with high reproduction sensitivity and a decoding technique such as PRML,
Recording and reproduction can be performed even at a high recording density of 3 gigabits per square inch or more.

Further, using the recording equalizer according to the present invention,
By combining with a perpendicular magnetic recording medium, it is possible to provide a magnetic recording device that realizes a recording density of 5 gigabits per square inch or more.

[0058]

According to the present invention, it is possible to obtain a highly reliable magnetic recording apparatus capable of realizing a recording density of 2.5 gigabits per square inch or more. Further, by using the recording equalizer of the present invention, the bit shift can be finely corrected from a simple sequence under any peripheral speed condition. Also, compared to conventional recording equalizers, fewer parts
Low price and high speed can be realized.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a recording equalizer constituting a main part of the present invention.

FIG. 2 is a diagram showing a relationship between a recording current and a recording position.

FIG. 3 is a diagram illustrating a relationship between a bit length to be written and a recording correction amount.

FIG. 4 is a block diagram of a signal processing circuit of the magnetic recording device according to the present invention.

FIG. 5 is a comparison between a recording current pulse waveform of the present invention and a conventional waveform.

FIG. 6 is a block diagram of a recording current driver of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording equalizer, 2 ... Data buffer, 5 ... Current value calculation circuit, 6 ... Recording current driver, 7 ... Modulation circuit, 8 ... Precoder, 9 ... Magnetic head, 10 ... Preamplifier, 11 ... Equalizer, 12 ML decoder, 13 VCO (voltage / frequency converter), 14 demodulator, 15 recording head, 16 reading head, 17 magnetic recording medium, 21 switching circuit, 22 constant current power supply, 23 Current bypass circuit,
24: High voltage power supply, 25: Voltage bypass circuit.

Claims (15)

[Claims] In a recording equalizer used for recording magnetization information on a magnetic recording medium using a magnetic recording head, the magnitude of a steady value of a recording current is appropriately changed according to recording conditions. And a record equalizer. 2. When recording two transitions separated by 3 bits or more, a second transition from the first transition is recorded depending on whether or not a transition one bit before the first transition is recorded. 2. The recording equalizer according to claim 1, wherein the maximum value of the recording current before the recording is different. 3. A dibit is recorded when an isolated transition that is at least 3 bits away from a certain transition, a dibit that is at least 3 bits away from the isolated transition, and a transition that is at least 3 bits away from the dibit are recorded. The maximum value of the recording current before the next transition is recorded is the maximum value of the recording current before the dibit is recorded after the previous transition of the dibit is recorded. 2. The method as claimed in claim 1, wherein the distance is smaller.
Or the recording equalizer according to 2. 4. A maximum value of the magnitude of a recording current from when a dibit is recorded to before a subsequent transition is recorded is set according to a length between adjacent magnetization transitions recorded on a medium. The recording equalizer according to any one of claims 1, 2, and 3, wherein: 5. A recording equalizer used for recording magnetization information on a magnetic recording medium using a magnetic recording head, wherein a rise time of a recording current is appropriately changed according to recording conditions. Chemist. 6. When a dibit is recorded at least 3 bits or more away from a previous transition and at least 2 bits away from a subsequent transition, the rising time of the recording current of the first bit is equal to the rising time of the recording current of the second bit. 1 compared to time
The recording equalizer according to claim 5, wherein the recording equalizer is faster than 0%. 7. When the time interval between the recording timing of one transition and the next transition is less than 1.5 times the rise time of the recording current, the time from the recording of the first transition to the recording of the next transition is recorded. When the maximum value of the recording current is Id, and the maximum value of the recording current of the isolated transition recorded at least 3 bits or more from the previous transition and at least 3 bits from the subsequent transition is Is, Id 7. The recording equalizer according to claim 1, wherein is equal to or larger than Is. 8. The magnetic recording medium according to claim 1, wherein the magnetic recording medium has a disk shape and can be rotated about a center, and a rise time of a recording current is changed according to a distance from the rotation axis to a magnetic recording head. 6. The recording equalizer according to 5. 9. A recording equalizer used when recording magnetization information on a magnetic recording medium using a magnetic recording head, is supplied from a constant current power supply to invert the polarity of a current flowing through the recording head. A recording equalizer using a recording current driver of a method of switching a current by using a switch circuit, and appropriately changing a current value supplied from a constant current power supply according to recording conditions. 10. A recording equalizer used when recording magnetization information on a magnetic recording medium using a magnetic recording head, is supplied from a constant current power supply to invert the polarity of a current flowing through the recording head. Using a recording current driver that switches a current using a switch circuit, providing a current bypass circuit in parallel with the switch circuit, branching the current supplied from the constant current power supply, and controlling the current flowing through the current bypass circuit. Wherein the current flowing through the switch circuit is appropriately changed according to recording conditions. 11. The recording equalizer according to claim 10, wherein said switch circuit and said current bypass circuit are formed in the same integrated circuit. 12. A recording equalizer used when recording magnetization information on a magnetic recording medium using a magnetic recording head, is supplied from a constant current power supply to invert the polarity of a current flowing through the recording head. A recording equalizer characterized by using a recording current driver of a method of switching a current using a switch circuit and appropriately changing a power supply voltage for driving a constant current power supply according to recording conditions. 13. A recording equalizer used when recording magnetization information on a magnetic recording medium using a magnetic recording head, is supplied from a constant current power supply to invert the polarity of a current flowing through the recording head. Using a recording current driver that switches the current using a switch circuit, a voltage bypass circuit is provided in parallel with the constant current power supply, and according to the recording conditions,
A recording equalizer characterized by supplying a current directly to a switch circuit from a high voltage power supply. 14. The recording equalizer according to claim 10, wherein said switch circuit, said current bypass circuit, and said voltage bypass circuit are formed in the same integrated circuit. 15. A recording equalizer according to any one of claims 1 to 14, a write head for recording magnetization information on a magnetic recording medium by an output from said recording equalizer, and A magnetic recording / reproducing apparatus comprising: a read head for reading recorded magnetization information; and decoding means for decoding an output signal from the read head.