JPH05314412A - Magnetic recording/reproducing method - Google Patents

Abstract

PURPOSE:To reproduce a magnetic recording medium without applying a bias magnetic field to an MR head in a magnetic recording/reproducing method for recording the medium by a thin film head and reproducing the medium by the MR head. CONSTITUTION:Binary data is recorded on a magnetic recording medium in a first step 11. One of the binary values is represented by a residual magnetization erase signal and the other is represented by a saturated magnetization signal. An intensity of the residual magnetization from the medium is detected by an MR head 35 in a second step 12. The detected intensity of the residual magnetization is decided by a binary value and reproduced as data in a third step 13. Further, in the first step, the residual magnetization of the medium is previously erased. In the second step, the record signal is formed of a signal which has an intensity responsive to data to be recorded and in which a direction of its magnetic field is inverted, and the data is recorded on the medium. Then, in the third step, at the time of reproducing, a magnitude of the magnetic field of the record signal of the medium is detected. In a fourth step, the magnitude of the magnetic field of the detected record signal is multi-level-judged and converted to a predetermined signal.

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 method, and more particularly to a magnetic recording / reproducing method for recording on a magnetic recording medium with a thin film head and reproducing it with a magnetoresistive (MR) head.

In recent years, miniaturization of magnetic recording / reproducing devices has been demanded. Therefore, it is necessary to record data at high density on a magnetic recording medium such as a magnetic disk and reproduce the data with high accuracy. Therefore, as a reproducing head, it is easy to downsize and has excellent resolution.
A method using a head is known.

In such a magnetic recording / reproducing method, it is necessary to reproduce the residual magnetization recorded on the magnetic recording medium into a predetermined signal without distortion.

[0004]

2. Description of the Related Art Conventionally, as a magnetic recording / reproducing method,
A method is known in which recording is performed by a thin film head configured by winding a coil around a magnetic pole and reproduction is performed by an MR head.

When data is recorded on a magnetic recording medium by this conventional method, the data is first binarized. Then 2
The digitized data is converted into a current of the same magnitude and opposite phase, and the current is passed through the coil of the thin film head.

Therefore, magnetic fields having the same size but opposite directions are generated in the thin film head. Therefore, when this magnetic field is applied to the magnetic recording medium, data can be recorded on the magnetic recording medium as residual magnetization having the same magnitude but opposite directions.

Next, a method of reproducing data by the MR head will be described. The resistance value of the MR head changes when a magnetic field is applied. Therefore, when the MR head moves along the surface of the magnetic recording medium having the remanent magnetization in the vicinity thereof, the resistance value of the MR head changes according to the strength of the magnetic field generated by the remanent magnetization of the magnetic recording medium. To do.

FIG. 8 is a diagram showing magnetoresistive conversion of the MR head. In the figure, as shown by the magnetic field characteristics of the MR head, the resistance value of the MR head has a maximum value when no magnetic field is applied. Further, as shown in the figure, the resistance value of the MR head has a value symmetrical with respect to the direction of the magnetic field.

Further, as described above, binary data is recorded on the magnetic recording medium as remanent magnetization having the same size but opposite directions. Therefore, the resistance value of the MR head with respect to the magnetic field generated by the magnetic recording medium becomes the same value regardless of the data. Further, in the MR head, the smaller the applied magnetic field, the smaller the rate of change in resistance value, and the poorer the linearity with respect to the magnetic field.

Therefore, conventionally, when data is reproduced using the MR head, a method of applying an appropriate bias magnetic field (Hb in the figure) to the MR head has been adopted. This bias magnetic field Hb shifts the magnetoresistive characteristics of the MR head and sets the operating point in the MR head.

As shown in the figure, in the MR head to which the bias magnetic field Hb is applied, when magnetic fields having the same magnitude but opposite directions are externally applied, these can be expressed as a difference in resistance value. Become. Further, the resistance value of this MR head shows a large rate of change with respect to the magnetic field applied from the outside as compared with the case where no bias magnetic field is applied.

Therefore, in the conventional magnetic recording / reproducing method,
An MR head to which a bias magnetic field is applied is generally used as a reproducing head.

FIG. 9 shows a perspective view of an example of a conventional reproducing head. As shown in the figure, the reproducing head 1 includes an MR head 2 and a soft magnetic film (S) attached to the MR head 2.
(AL film) 3.

The SAL film 3 is a soft magnetic film that generates a predetermined magnetic field when an electric current is passed through it.
A bias magnetic field is applied to the R head 2. Also, MR
A constant current source 3 is connected to the head 1 in order to detect a change in resistance value as an electric signal.

Therefore, as described above, the reproducing head 1
Converts the data recorded on the magnetic recording medium into a binarized electric signal.

[0016]

However, in the reproducing head 1 used for implementing the above-described conventional magnetic recording / reproducing method, the MR
The strength of the bias magnetic field applied to the head 2 is determined by the thickness of the SAL film 3. Therefore, if the thickness of the SAL film 3 varies due to variations in processing accuracy, the operating point of the MR head 1 varies.

When the operating point of the MR head 1 fluctuates, the resistance value of the MR head 1 with respect to the magnetic field generated by the magnetic recording medium fluctuates, and the reproduced signal is distorted.

In order to prevent this distortion, the SAL film needs to be microfabricated with high precision, and it is difficult to miniaturize the SAL film. Therefore, conventionally, the reproducing head 1 cannot be miniaturized. Therefore, the conventional magnetic recording / reproducing method has a problem that data cannot be recorded at high density on the magnetic recording medium.

The present invention has been made in view of the above points, and an object of the present invention is to provide a magnetic recording / reproducing method capable of reproducing without applying a bias magnetic field to the MR head.

[0020]

In order to solve the above-mentioned problems, the present invention converts the data to be recorded into a recording signal and records it on the magnetic recording medium as a residual magnetization by a thin film head. In a magnetic recording / reproducing method of reproducing data by a magnetoresistive head based on a magnetic field generated by remanent magnetization of a medium, as shown in the principle diagram of FIG.
In step 11, the recording signal is applied to the magnetic recording medium by a first signal for erasing the residual magnetism of the magnetic recording medium,
Data to be recorded is recorded on a magnetic recording medium by forming saturation magnetizations having the same magnitude but opposite directions alternately with second signals, and in the second step 12, the magnetic field is reproduced during reproduction. The presence or absence of remanent magnetization of the recording medium is detected, and the third step 13
Then, the detected residual magnetization is binary-determined and converted into a predetermined reproduction signal, or, as shown in the principle diagram of FIG. Erasure in advance, and in a second step 22, the recording signal is constituted by a signal having an intensity corresponding to the data to be recorded and alternately inverting the direction of the magnetic field, and the data is recorded on the magnetic recording medium. In the third step 23, the magnitude of the magnetic field of the recording signal of the magnetic recording medium is detected during reproduction in the third step 23, and in the fourth step 24, the magnitude of the detected magnetic field of the recording signal is multivalued. It is configured to determine and convert to a predetermined signal.

[0021]

According to the above construction, in the first step 11, the data to be recorded is binarized, and one of the two values is recorded on the magnetic recording medium by the first signal. The other value is recorded in the second signal. Therefore, the magnetic recording medium is divided into a portion having no remanent magnetization and a portion having remanent magnetization of the same size but opposite direction.

The first signal acts to record data on the magnetic recording medium and to demagnetize the recording head that applies the recording signal to the magnetic recording medium. Further, the second signal acts to record data on the magnetic recording medium and to magnetize the recording head alternately in opposite directions. Therefore, the recording head is always demagnetized.

In the second step 12, the intensity of the residual magnetization is detected from the magnetic field generated by the residual magnetization recorded in the magnetic recording medium. Therefore, the remanent magnetization recorded in the magnetic recording medium by the second signal and having the same magnitude but opposite direction is detected as the same remanent magnetization.

Therefore, "no residual magnetization" is detected in the portion recorded with the first signal in the magnetic recording medium,
In the portion recorded with the second signal, "there is residual magnetization"
To detect.

The third step 13 is the second step 1
The residual magnetization detected in 2 is reproduced as binary data.

Further, according to the structure in which the magnetic recording / reproducing is performed in the first step 21 to the fourth step 24, the magnetic recording medium is demagnetized in the first step 21. Therefore, after this step, the recording signal existing on the magnetic recording medium is only the recording signal recorded on the magnetic recording medium in the subsequent steps.

In the second step 22, the recording signal having the intensity corresponding to the data to be recorded is recorded on the magnetic recording medium. Further, the recording signal in the second step 22 magnetizes the recording head for applying the recording signal to the magnetic recording medium alternately in opposite directions. Therefore, the recording head is always demagnetized.

In the third step 23, the intensity of the recording signal is detected from the intensity of the magnetic field generated by the magnetic recording medium and converted into a predetermined signal. ..

In the fourth step 24, data is reproduced from the signal converted in the third step 23.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 is a block diagram of a first embodiment of a magnetic recording / reproducing method according to the present invention. In the figure, parts corresponding to those in FIG. 1 are designated by the same reference numerals.

In the figure, 31 indicates a pre-encoder. The pre-encoder 31 uses an NRZ (Non Ret).
If there is no change in data, such as a urn to zero) signal, a signal in which a direct current signal is continuous is modulated into a binary signal suitable for magnetic recording and reproduction, and the binary signal is output.

The output of the pre-encoder 31 is connected to the 1/2 counter 32 and the selector 33. The 1/2 counter 32 is a synchronous counter which is composed of a flip-flop 32a and which is inverted once while the data output from the pre-encoder 31 is inverted twice.

An erase clock, which has a higher frequency than the data to be recorded, is further input to the selector 33. The selector 33 switches and outputs a positive or negative DC signal and a high frequency signal having the same cycle as the erase clock, according to the data input from the pre-encoder 31.

The output of the selector 33 is the amplifier 34.
Connected to. The amplifier 34 amplifies the signal input from the selector 33 and outputs an alternating current or a direct current.

The output of the amplifier 34 is connected to the coil 36 of the thin film head 35 which is a recording head. Therefore, a current corresponding to the output signal of the selector 33 flows through the coil 36.

The thin film head 35 has a magnetic pole 37 for propagating the magnetic field generated in the coil 36. Therefore, when the selector 33 outputs a DC signal, a stationary magnetic field is generated in the magnetic pole 37, and when the polarity of the DC signal is reversed, the direction of the stationary magnetic field is also reversed. When the selector 33 outputs a high frequency signal, an AC magnetic field having the same frequency as the high frequency signal is generated in the magnetic pole 37.

It is generally known that the magnetic recording medium can be demagnetized by applying an alternating magnetic field to the magnetic recording medium.
Therefore, when data is recorded on the magnetic recording medium using the thin film head 35, two types of magnetization states having the same size but opposite directions and demagnetization without residual magnetization are recorded on the magnetic recording medium. You can create a state.

Therefore, with the above configuration, the first step 11, that is, the recording of data can be performed. An alternating magnetic field is generated in the thin film head 35 of this embodiment, and a stationary magnetic field whose direction is alternately inverted is further generated. Therefore, the thin film head 35 is always kept in a demagnetized state, and a magnetic field with good reproducibility can be applied to the magnetic recording medium.

Next, the detection of the residual magnetization corresponding to the second step 12 will be described. In the figure, 38 is M
The R head is a reproducing head for detecting the magnetic field generated by the residual magnetization of the magnetic recording medium.

In the figure, 39 is a constant current source, which is MR
The head 38 is driven by direct current. When the magnetic field is applied from the outside, the resistance value of the MR head 38 changes according to the strength of the magnetic field. Therefore, the magnetic field applied to the MR head 38 can be detected by detecting the potential difference between both ends of the MR head 38.

Next, the binary determination corresponding to the third step 13 will be described. In the figure, reference numeral 42 denotes an amplifier, which is connected to the MR head 38 via capacitors 40 and 41. The capacitors 40 and 41 are coupling capacitors, and remove unnecessary components from the output of the MR head 38.

The output of the amplifier 42 is connected to the waveform shaping circuit 43. The waveform shaping circuit 43 shapes the input signal waveform and outputs it to the binary determination circuit 44. The binary decision circuit 44 binary-decides the input signal and performs a predetermined conversion to reproduce the signal read from the magnetic recording medium as the same data as the recorded data.

Next, the operation of each part will be described with reference to FIGS. 4 and 5. FIG. 4 is a diagram showing an example of data output by the pre-encoder 31 and a recording signal output by the selector 33. In FIG. 3B, the period and the signal shown in the period are high frequency signals having the same period as the erase clock.

As shown in the figure, in this embodiment,
When the data value "0" is input from the pre-encoder 31 (period, in the figure), the selector 33 outputs a positive or negative DC signal (the same figure (B)), and the data value "
When 1 "(period in the figure) is input, a high frequency signal is output.

On the other hand, the output signal of the 1/2 counter 32 is input to the selector 33. Based on the output signal of the 1/2 counter 32, the selector 33 alternately receives a positive DC signal (period in the figure) and a negative DC signal when the data value “0” is input from the pre-encoder 31. A DC signal (period in the figure) is output.

Therefore, a magnetic field synchronized with the recording signal shown in FIG. 6B is applied to the magnetic recording medium via the thin film head 35. Therefore, in the magnetic recording medium, demagnetization,
Data is recorded with saturation magnetization in opposite directions.

FIG. 5 is a diagram showing magnetoresistive conversion of the MR head 38 of this embodiment. As shown in FIG.
The R head 38 exhibits a maximum resistance value when no magnetic field is applied. Further, it exhibits a symmetrical characteristic with respect to the direction of the applied magnetic field.

FIG. 6B shows the residual magnetization when data is recorded on the magnetic recording medium by the above method. Further, FIG. 9C shows that the residual magnetization of FIG.
Shows the resistance value of the MR head 38 when applied to the MR head 38.

As shown in FIGS. 7B and 7C, when the magnetic recording medium is demagnetized (in the same figure (B), period,
), The resistance value of the MR head 38 shows the maximum value (in FIG. 7C, period,). Further, when the magnetic recording medium is magnetized positively or negatively (in the same figure (B), period,
,), And the resistance value of the MR head 38 is the same regardless of the direction of magnetization (in the figure (C), period ,,,
).

As described above, the data recorded on the magnetic recording medium by the above method can be easily reproduced by the MR head 35. Further, according to the method of this embodiment, the bias magnetic field, which was conventionally required when reproducing data from the magnetic recording medium using the MR head, is unnecessary.

Therefore, the reproducing head can be composed of the MR head 38 alone, and the reproducing head can be miniaturized. Therefore, the data density of the magnetic recording medium can be increased as compared with the conventional one, and high density recording of data becomes possible.

As described above, according to the magnetic recording / reproducing method of this embodiment, the reproduced signal is not distorted when the data is reproduced from the magnetic recording medium. Therefore, the reliability of data management is improved. Further, the method of this embodiment can be carried out by a reproducing head having a simple structure as compared with the conventional method.

FIG. 6 is a block diagram of the second embodiment of the magnetic recording / reproducing method according to the present invention. 2 and 3 in FIG.
The same parts as those of are denoted by the same reference numerals, and the description thereof will be omitted.

In the figure, 51 is an erase signal circuit, which is a circuit for outputting the same signal as the high frequency signal output by the selector 33 in the first embodiment. The output signal of the erase signal circuit 51 is supplied to the thin film head 52.
The thin film head 52 has the same structure as the thin film head 35 of the first embodiment.

The thin film head 52 is used in the magnetic recording medium 60.
By applying a high-frequency signal to the surface of the magnetic recording medium, the magnetic recording medium corresponding to the first step 21 can be erased.

In the figure, 53 is a D / A converter which converts digital data into analog signals. D
The analog output signal of the / A converter 53 is supplied to the data inverting circuit 54.

The data inversion circuit 54 inverts the polarity of the input signal periodically or irregularly and outputs it.
The output of the data inversion circuit 54 is connected to a thin film head 55 having the same structure as the thin film head 35 of the first embodiment.

Therefore, the strength of the thin film head 55 is D
A magnetic field that changes similarly to the change of the analog signal output from the / A converter 53 is generated. Further, the polarity of this magnetic field is regularly or irregularly reversed.

Therefore, the thin film head 55 applies a magnetic field to the magnetic recording medium, the polarity of which is periodically or irregularly reversed according to the strength of the analog signal output from the D / A converter 53, In the magnetic recording medium, the second step 2
Data corresponding to 2 can be recorded.

As shown in the figure, the thin film heads 52 and 55 of this embodiment are arranged in parallel to face the surface of the magnetic recording medium 60. Therefore, the magnetic recording medium 60
By recording the data while moving in a predetermined direction, the thin film head 55 can sequentially record the data in the portion where the residual magnetization is erased by the thin film head 52.

Therefore, the residual magnetization can be erased and the data can be recorded almost at the same time. Further, since the data is recorded with the intensity of remanent magnetization, it has a feature that the density of information is higher than that in the case of recording with or without remanent magnetization.

Similar to the case of the first embodiment, the MR head 38 detects the residual magnetization corresponding to the third step 23.
Using. The signal detected by the MR head 38 is input to the multilevel determination circuit 57 via the waveform shaping / amplification circuit 56. The waveform shaping / amplifying circuit 56 is a circuit corresponding to the capacitors 40 and 41, the amplifier 42, and the waveform shaping circuit 43 of the first embodiment.

Further, the MR head 38 detects only the strength of the magnetic field as described above. Therefore, the recording signal detected by the MR head 38 becomes an analog signal according to the magnetization intensity of the magnetic recording medium.

In the multi-value determination circuit 57, the multi-value determination which is the fourth step 24 is performed. The multi-level determination circuit 57 is a circuit for performing multi-level determination of an analog signal, and multi-level determination of the magnetization intensity signal converted into the analog signal by the MR head 38 is performed and reproduced as data.

As described above, according to the magnetic recording / reproducing method of the present embodiment, the data can be reproduced without distortion and the reproducing head can be realized with a simple structure as in the case of the first embodiment. .. Further, as described above, the method of the present embodiment has a high information density of data and is more advantageous for high-density recording of data.

Further, in the present embodiment, the thin film head 5
2, the demagnetization signal is always generated, and the thin film head 55
, Alternately, data recording signals composed of magnetic fields having opposite directions are generated. Therefore, both thin film heads 5
For both 2 and 55, regardless of their own hysteresis characteristics,
It can be supplied to a magnetic recording medium having a stable magnetic field without being magnetized.

FIG. 7 is a block diagram of the third embodiment of the magnetic recording / reproducing method according to the present invention. 2 and 3 in FIG.
The same parts as those in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted.

In the figure, reference numeral 58 is a thin film head,
It has the same structure as the thin film head 35 of the embodiment. The thin film head 58 has a changeover switch 61 at its input terminal. The changeover switch 61 includes an output terminal of the erase circuit 51 and an output terminal of the inverting circuit 54, and the thin film head 5.
This is a switch for switching the connection of the eight input terminals.

A D / A converter 53 is connected to the inverting circuit 54 as in the second embodiment. Therefore, the thin-film head 58 can be switched and supplied with a high-frequency signal for erasing the residual magnetic field and an analog signal for recording data, the polarity of which is regularly or irregularly inverted.

Therefore, in the method of this embodiment, first, a high frequency signal is supplied to the thin film head 58 to erase the residual magnetization of the magnetic recording medium, which corresponds to the first step 21. Then, the changeover switch 61 is changed over, and a magnetization signal for data recording is applied to the erased portion to record data corresponding to the second step.

As a result, the same residual magnetization as that of the second embodiment can be recorded on the magnetic recording medium. Therefore, the recorded data can be reproduced by the same method as in the second embodiment.

As described above, the method of this embodiment is suitable for high density recording as in the second embodiment. Further, since the same thin film head 58 erases the residual magnetization of the magnetic recording medium and records the data, only one recording head is required. Therefore, it has a feature that the device configuration for carrying out the method of the present embodiment is simplified.

In the thin film head 58 of this embodiment, a degaussing signal and a recording signal composed of a magnetic field whose direction is alternately inverted are generated. Therefore, like the other embodiments described above,
The thin film head 58 is always in a demagnetized state and can supply a stable recording signal to the magnetic recording medium.

[0074]

As described above, according to the present invention, the reproduced signal waveform is not distorted even if the bias magnetic field is not applied to the reproducing head, and the reliability of data management is improved. Further, since the structure of the reproducing head is simple and the miniaturization is easy, the data can be reproduced with the residual magnetic field in a smaller area than the conventional one. Therefore, it becomes possible to record data on the magnetic recording medium with high density.

Further, according to the present invention, the recording head is not magnetized regardless of its own hysteresis characteristic. Therefore, the magnetic field strength applied to the magnetic recording medium becomes stable, and the magnetization strength of the magnetic recording medium becomes stable. Therefore, the reproduction of the data is facilitated and the reproduction accuracy is improved.

[Brief description of drawings]

FIG. 1 is a principle diagram (1) of the present invention.

FIG. 2 is a principle diagram (2) of the present invention.

FIG. 3 is a configuration diagram of a first embodiment of a magnetic recording / reproducing method according to the present invention.

FIG. 4 is a diagram showing an example of a recording signal of the first embodiment of the magnetic recording / reproducing method according to the present invention.

FIG. 5 is a diagram showing magnetoresistive conversion of the magnetoresistive head of the first embodiment of the magnetic recording / reproducing method according to the present invention.

FIG. 6 is a configuration diagram of a second embodiment of the magnetic recording / reproducing method according to the present invention.

FIG. 7 is a configuration diagram of a third embodiment of a magnetic recording / reproducing method according to the present invention.

FIG. 8 is a diagram showing magnetoresistive conversion of a magnetoresistive head according to a conventional magnetic recording / reproducing method.

FIG. 9 is a perspective view of an example of a conventional reproducing head.

[Explanation of symbols]

 38 magnetoresistive (MR) head 11, 21 first step 12, 22 second step 13, 23 third step 24 fourth step 32 1/2 counter 33 selector 35, 52, 55, 58 thin film head 36 Coil 37 Magnetic pole 44 Binary judgment circuit 51 Erase signal circuit 53 D / A converter 54 Inversion circuit 57 Multi-value judgment circuit 60 Magnetic recording medium 61 Changeover switch

Claims (4)

[Claims] 1. Data to be recorded is converted into a recording signal and recorded on a magnetic recording medium as a residual magnetization by a thin film head, and based on a magnetic field generated by the residual magnetization of the magnetic recording medium, the data is recorded by a magnetoresistive head. In the magnetic recording / reproducing method for reproducing, a first signal for erasing the residual magnetism of the magnetic recording medium and a saturation magnetization of the same magnitude but opposite direction are alternately arranged on the magnetic recording medium. And a second signal given to the magnetic recording medium to record data to be recorded on the magnetic recording medium (11), and at the time of reproduction, the presence or absence of residual magnetization of the magnetic recording medium is detected (12). Is binary-coded and converted into a predetermined reproduction signal (13). 2. A magnetic recording / reproducing method for converting data to be recorded into a recording signal, recording as residual magnetization on a magnetic recording medium, and reproducing the data based on a magnetic field generated by the magnetic recording medium. The residual magnetization of the magnetic recording medium is erased in advance (21), and the recording signal is constituted by a signal having an intensity corresponding to the data to be recorded and alternately inverting the direction of the magnetic field, and the data is recorded in the magnetic field. Recording on a recording medium (22), at the time of reproduction, the magnitude of the magnetic field of the recording signal of the magnetic recording medium is detected (24), and the magnitude of the detected magnetic field of the recording signal is multivalued,
A magnetic recording / reproducing method characterized by converting (24) to a predetermined signal. 3. A method of erasing a residual magnetization of a predetermined portion of the magnetic recording medium (21), and sequentially recording data (22) in a portion of the predetermined portion where the residual magnetization has been erased. The magnetic recording / reproducing method according to claim 2, which is characterized in that: 4. The residual magnetization of a predetermined portion of the magnetic recording medium is erased (21), and after the residual magnetization of the predetermined portion is erased, data is recorded in the predetermined portion (24). The magnetic recording / reproducing method according to claim 2.