JPH0258683B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a magnetic recording and reproducing device suitable for short wavelength magnetic recording, which records information by magnetizing a magnetic layer in the thickness direction of a magnetic recording medium. It is.

Conventional configurations and their problems Conventionally, in magnetic recording and reproducing devices such as video table recorders, magnetic tape is used as a magnetic recording medium, and the magnetic head or magnetic tape is placed at approximately right angles or several times with respect to the width direction of the magnetic head. By running with an azimuth angle of
Recording or playback is in progress. This type of magnetization in which the medium is magnetized in the direction of motion is called longitudinal magnetization, and in video table recorders, etc., recording demagnetization increases from a recording wavelength of about 1 μm, making recording at shorter wavelengths impractical. It was difficult to adapt.

On the other hand, perpendicular magnetization systems aimed at recording at even shorter wavelengths have been studied, and many proposals for practical use have been made. For example, one example is perpendicular magnetic recording, which includes an auxiliary magnetic pole equipped with a winding for passing a signal current, and a main magnetic pole facing each other and having an end area smaller than the end area of the auxiliary magnetic pole. There is a playback device. This is because when recording and reproducing with the thickness L of the main pole, it is possible to record short wavelengths less than the thickness L, but at the time of reproduction, a loss equivalent to the gear loss in longitudinal recording and reproduction occurs, and the wavelength less than the thickness L The problem was that it was not played back enough.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a magnetic recording/reproducing device which eliminates the above-mentioned conventional drawbacks and enables recording at significantly shorter wavelengths.

Structure of the Invention In order to achieve the above object, the present invention is configured to record information by magnetizing a magnetic layer of a magnetic recording medium in the direction of its thickness, and
comprising a recording/reproducing magnetic pole having a magnetic pole thickness L or a recording magnetic pole and a reproducing magnetic pole having a magnetic pole thickness L, and only in an area where the recording/reproducing magnetic pole or the recording magnetic pole relatively moves at most a distance L on the recording medium. The apparatus is configured to record a signal and then stop recording during a section in which the recording/reproducing magnetic pole or the recording magnetic pole moves relatively at least a distance L on the recording medium.

Furthermore, the present invention includes a reproducing magnetic pole having a magnetic pole thickness L, and the reproducing magnetic pole records the magnetic recording medium in which a section of at most a distance L is recorded, and a subsequent section of at least a distance L is not recorded. It is configured to reproduce and obtain a reproduced signal.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below based on the drawings. Figure 1 shows the main magnetic pole 1, the recording waveform 2, the magnetic tape 3, the tape running direction, the thickness L of the main pole, the auxiliary magnetic pole 4, and the winding 5 of a perpendicular magnetic recording medium. Main pole 1 is magnetic tape 3
magnetize the magnetic layer in the thickness direction. Here, it can be considered that the recording waveform 2 is determined by the recording signal applied when the magnetic tape 3 passes the terminal end g of the main magnetic pole 1, and the wavelength λ of the recording signal has no relation to the thickness L of the main magnetic pole. . That is, it can be seen that it is possible to record a signal having a wavelength shorter than the thickness L of the main pole. This was difficult to achieve with the conventional longitudinal magnetization method due to recording demagnetization.

Next, an example of reproduction of a signal recorded in this manner is shown in FIG. Although it is of course possible to use the main pole described above as the reproducing head, it will be referred to as the reproducing head hereinafter. In this case, the read head width L corresponds to the main pole thickness L mentioned above. FIG. 2a shows a signal that falls within half a wavelength within the width L of the reproducing head, and at this time the reproducing output is at its maximum. This is clear from the fact that when the reproduced output is considered to be a change in magnetic flux passing through the head, the amount of change in magnetic flux becomes maximum when the wavelength λ of the reproduced signal has a relationship of λ=2L with the head width L.

Next, FIG. 2b shows a signal in which one wavelength is included in the head width L. Even if the reproducing head moves at this time, no change in magnetic flux occurs within the reproducing head core, and the reproducing output becomes zero. That is, when the wavelength of the reproduced signal λ=L/n (n is a natural number), the reproduced output becomes 0, which is considered to correspond to the gear loss in conventional longitudinal recording. Note that the auxiliary magnetic pole is omitted in the illustrations from FIG. 2 onwards.

Next, in FIG. 2b, consider the reproduction output when only one wavelength is recorded. In Fig. 3, t ₁ is a diagram showing the moment when the leading edge S ₁ of the recording signal coincides with the leading edge h ₁ of the reproducing head and reproduction begins, and t ₂ is a diagram showing a state in which one wavelength is included in the head width L. t ₃ shows the diagram at the moment the playback ends. From the state of t ₁ above
FIG. 4 shows the magnetic flux φ passing through the read head core from the state t ₂ to the state t ₃ and the differential dφ/dt of the magnetic flux φ. Here, dφ/dt indicates the reproduction output.

During reproduction, the signal passing between the head tip _h1 and the head rear end _h2 shown in FIG. 3 does not contribute to the change in the magnetic flux φ passing through the head core (dφ/ dt=0), it does not appear in the playback output. In other words, in the reproduced output dφ/dt in Fig. 4, the interval t ₁ to _{t 2} is considered to be the reproduced waveform at the head tip h ₁ , and the interval t ₂ to t ₃ is considered to be the reproduced waveform at the rear end h ₂ of the head. .

In this way, the wavelength λ=L/n (L: head width,
When reproducing a signal where n is a natural number, it is not possible to obtain a reproduction output with continuous waves as shown in Figure 2b, but reproduction is possible by recording in burst form as shown in Figure 3. .

As the reproduction output, the waveform obtained between t ₁ and _{t 2} in FIG. 4 may be used, the waveform obtained between t ₂ and _{t 3} may be used, or both waveforms may be synthesized. You can also do it. An example of this synthesis method will be briefly described.

In Figure 5, a is the reproduced waveform, b is the signal waveform reproduced at the tip of the head, c is the waveform obtained by delaying b by the time Tl during which the reproducing head moves a distance L relative to the tape, and d is the phase of c. Inverted waveform, and e
shows the waveform obtained by superimposing the remolded waveform and the waveform of d, and it is clear that the S/N ratio is
Improved by 6dB.

FIG. 6 shows a circuit block diagram for realizing this synthesis method. The circuit is composed of an amplifier 8, analog switches SW1 and SW2, a delay circuit 5, a phase inversion circuit 6, and a mixer circuit 7. Switch SW2 is ON between t ₁ and _{t 2} shown in Fig. 4, and from t ₂ to t 2
Switch SW1 is ON during _t3 . Switch SW2
The signal passed through, that is, the signal detected at the tip of the head, is delayed by the time Tl in the delay circuit 9, phase inverted in the phase inversion circuit 6, and then sent to the mixer circuit 7. In this mix circuit 7, the above signal and the signal passing through switch SW1 have the same waveform, and by adding them together, the S/N is reduced by 6 dB.
can be improved.

Here, in the above-mentioned recording and reproducing method, short wavelength recording and reproducing is possible because conventional recording demagnetization in the longitudinal direction and gear loss during reproduction do not occur.

Next, an example of short wavelength recording and reproduction will be shown. FIG. 7 shows an example of recording and reproducing at a wavelength of 1 μm with the head width L=5 μm. a shows the recording state, b shows the playback state, c shows the playback waveform, and d shows the output waveform when the S/N is improved using the mix circuit. That is, it can be seen that short wavelength recording and reproduction is possible by recording in burst form, regardless of the head width.

Here, the recording section is determined by the reproduction head width L and has no relation to the recording head width, so the recording head width does not need to be L. Alternatively, a recording/reproducing head having a head width L may be used.

In this way, in the conventional perpendicular magnetic recording system, it was not possible to reproduce a signal with a wavelength of λ = L/n (n is a natural number), where the width of the reproducing head is L. Record only while moving a distance L at most on the recording medium,
By recording in a so-called burst, in which recording is stopped while moving at least a distance L,
A flat frequency characteristic can be reproduced up to the short wavelength region, and good short wavelength recording and reproduction is possible.

Further, as the reproduction output, a reproduction signal from the leading end of the reproduction head, that is, information obtained while the reproduction head moves relatively at most a distance L over the recording medium after the signal starts to be reproduced may be used. The reproduction signal from the rear end portion of the reproduction head, that is, the information obtained after the reproduction head has moved at least a distance L relative to the recording medium after the signal starts to be reproduced may be used, and as described in this embodiment. It can also be obtained by combining both of the above information.

Furthermore, in the above explanation, an example of recording and reproducing an analog signal was shown, but in principle, the present invention is suitable for digital recording and reproducing, and in that case, it is considered that the 2-bit length of the digital signal corresponds to one wavelength as described in this explanation. It's fine.

Effects of the Invention As is clear from the above explanation, according to the present invention, since these are perpendicular magnetic recording, recording demagnetization does not occur during recording, and short wavelength reproduction is possible during reproduction. Therefore, the recording and reproducing density is dramatically improved.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the perpendicular recording system, Figure 2 is a diagram showing reproduction in the perpendicular recording system, Figure 3 is a diagram showing reproduction in the present invention, and Figure 4 is a diagram showing the head core in reproduction in the present invention. Figure 5 is a diagram for explaining the reproduction method of the present invention, Figure 6 is a block diagram showing an example of the reproduction method, and Figure 7 shows high-density recording and reproduction. This is a diagram. 1... Main magnetic pole, 2... Recording waveform, 3... Magnetic tape, 4... Auxiliary magnetic pole, 5... Winding wire, 6... Inverting circuit, 7... Mixing circuit, 9... Delay circuit.

Claims (1)

[Claims] 1. A recording/reproducing magnetic pole or a recording magnetic pole configured to record information by magnetizing the magnetic layer of a magnetic recording medium in its thickness direction, and having a magnetic pole thickness L. A reproducing magnetic pole having a magnetic pole thickness L is provided, the recording/reproducing magnetic pole or the recording magnetic pole records a signal only in a section in which the recording/reproducing magnetic pole or the recording magnetic pole moves relatively at most a distance L on the recording medium, and then the recording/reproducing magnetic pole or the recording magnetic pole 1. A magnetic recording and reproducing apparatus, characterized in that recording is stopped during a section in which the object moves relatively at least a distance L on a recording medium. 2. The magnetic recording/reproducing apparatus according to claim 1, wherein the wavelength or 2-bit length of the recording signal is shorter than the thickness L of the recording/reproducing magnetic pole or the reproducing magnetic pole. 3 The magnetic layer of the magnetic recording medium is configured to record information by magnetizing it in the thickness direction, and is equipped with a reproducing magnetic pole having a magnetic pole thickness L, and only in an area of a distance L at most. A magnetic recording and reproducing apparatus characterized in that a reproduced signal is obtained by reproducing the magnetic recording medium, which has been recorded and in which no data is recorded in the next section of at least a distance L, by means of the reproducing magnetic pole. 4. The reproduction signal is obtained only from the output of the reproduction magnetic pole obtained during a period in which the reproduction magnetic pole moves relatively at most a distance L on the recording medium after the reproduction magnetic pole starts reproducing the signal recorded on the recording medium. A magnetic recording and reproducing apparatus according to claim 3. 5. The reproduced signal is obtained in the interval from when the reproducing magnetic pole starts reproducing the signal recorded on the recording medium to the point where the reproducing magnetic pole has moved a relative distance L further on the recording medium. 4. The magnetic recording/reproducing apparatus according to claim 3, wherein the magnetic recording/reproducing apparatus obtains only the output from the reproduced magnetic pole. 6. The reproduction signal consists of a first signal obtained during a period in which the reproduction magnetic pole starts reproducing the signal recorded on the recording medium and then moves relatively at most a distance L on the recording medium, and then further A second signal obtained in a section where the second signal moves a distance L is used as information, and the first signal is delayed for a predetermined time and then synthesized with the second signal. The magnetic recording and reproducing device according to scope 3.