JPH076447A - Magneto-optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a magneto-optical recording and reproducing device capable of accurately erasing a specified sector in a recording track. CONSTITUTION:While performing tracking with beam spots 201 to 203, information on the sector to be erased is pre-monitored with the beam spot 202. Erasion is performed with the beam spot 24 concerning a magnetization pattern monitored with the beam spot 202.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a magneto-optical recording / reproducing apparatus utilizing the magneto-optical effect.

[0002]

2. Description of the Related Art A magneto-optical recording / reproducing system has attracted attention as a means for recording / reproducing high density information such as video signals.
This system realizes the following characteristics by using an amorphous perpendicular magnetization film of a rare earth-transition metal such as GdCo or TbFe.

(A) High density recording is possible. (B) Not only recording and reproduction but also erasing and re-recording are possible. (C) Polar kerr ef
, the optical system can be simplified.

By the way, it is particularly important that an apparatus adopting such a system is capable of erasing and re-recording as well as recording and reproducing as described above. Therefore, conventionally, the index mark formed on the disk which is the recording medium is used as a reference to detect the sector to be erased in the recording track and to erase the sector.

[0005]

However, according to such a method, if there is uneven rotation of the disk, the access based on the index becomes unstable, so that the sector to be erased in the recording track cannot be detected. There is a problem in that it becomes unstable, and particularly in the case of high density recording, it becomes difficult to accurately erase only a specific sector in a track.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a magneto-optical recording / reproducing apparatus capable of accurately erasing a specific sector in a recording track.

[0007]

According to the present invention, information is recorded or erased in an apparatus for recording / reproducing information on / from a recording medium having a track having a plurality of sectors by utilizing a magneto-optical effect. A first light source for providing a first light beam, a second light source for providing a second light beam for reproducing information, the first light beam and the second light beam on the same recording track of the recording medium. Optical means for directing the second light beam so as to precede the first light beam by a predetermined distance, the first light beam and the second light beam pass in common, and the passing beam is converged. A pickup for detecting the sector to be erased in the recording track prior to the first light beam by the second light beam, and erasing in the recording track by the first light beam. It is configured to perform the cancellation on to the sector.

[0008]

As a result, according to the present invention, the first light beam for recording or erasing information is used as an erasing beam, and the second light beam for reproducing information on the same recording track with respect to this erasing beam. The reproduction beam of 1 is advanced by a predetermined distance, the sector to be erased in the recording track is detected by the reproduction beam, and the erase beam is used to erase the detected sector.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a magnetized state and a beam spot when magneto-optical recording / reproducing is performed while performing tracking on a recording medium having no guide groove for tracking. Considering the case where the recording medium is disc-shaped, the following is required to avoid track interference between adjacent tracks. That is, (1) improving the accuracy of the disc,
(2) To improve track feeding accuracy during recording,
And (3) it is required to make the disk rotation system eccentric.

By the way, when the track pitch is very narrow (about 2 μm) as in the existing optical disc, there arises a problem of track interference. This is because, when recording is performed by changing the disks, a positional deviation of several tens of μm is unavoidable under the present circumstances. Therefore, tracking control becomes necessary.

In FIG. 1, the beam spots 20 _{1 to} 20 ₃ for tracking are imaged on the residual magnetization patterns 10 ₁ to 10 ₃ of the recorded track T10. A beam spot 22 for recording is imaged at a position separated from the beam spot 20 ₂ by the track pitch. With this beam spot 22 having a sufficient power for recording, the magnetization pattern 1 is formed on the track T12 on which recording is currently performed.
2 ₁ is formed. Saturated magnetization as a recording medium
A perpendicular magnetic film such as GdCo or TbFe can be used. In this case, the pattern 10 ₁ to 10 ₃ and 12 ₁ is magnetized perpendicularly to the film plane. The magnetization direction of these patterns is opposite to that of the surrounding magnetic domains. Such magnetization pattern information can be read using the Polarker effect.

The recording track T12 is tracked by using the recorded track T10 as a guide track. This tracking enables recording without track interference. Here, tracking control is performed by the three-beam method. The three-beam method is a well-known technique in the field of optical discs, and therefore its explanation is omitted.

Post-monitoring of recording by the beam spot 22 is performed by using the beam spot 20 ₂ .
The tracking error signal is obtained from the beam spots 20 ₁ and 20 ₃ . Beam spot 22
After has traced the entire recording area, no further recording is possible. Therefore, the beam spot 20 ₂
Playback output from disappears. A recording end signal can be generated from the disappearance of this output, and the light source of the recording beam can be automatically turned off by this recording end signal.

FIG. 2 shows a magnetization state and a beam spot when erasing a specific sector while performing tracking. If the disc rotation accuracy is high and the recording density is not so high, access is performed using the index marks on the disc as a reference to determine the prescribed magnetization pattern (sector).
A method of erasing is also possible. However, in order to accurately erase only a specific sector in a certain track recorded at high density, it is necessary to detect the position of the sector and erase. Such a method not only enables the erasure of high density information, but also relaxes the requirements on the rotational accuracy of the disc. That is, it is possible to accurately erase only a predetermined part of the information recorded at high density even if the rotation accuracy is somewhat poor.

In FIG. 2, tracking beam spots 20 _{1 to} 20 ₃ are imaged on the recorded track T14. An erasing beam spot 24 is imaged between the beam spots 20 ₁ and 20 ₂ . If the beam spot 20 ₁ is separated from the beam spot 20 ₂ by about 4 μm, the beam spots 20 ₁ and 20 ₂ can be easily separated.
A beam spot 24 can be inserted between the two. The tracking drive mechanism of the recording / reproducing pickup is controlled based on the tracking signals obtained from the beam spots 20 ₁ and 20 ₃ . And the beam spot 20 ₂
Therefore, the preceding information of the sector information to be erased is monitored. Magnetization pattern on a specific sector that is monitored by the beam spot 20 ₂ is erased by the beam spot 24, the erased pattern 14 ₁ and comprising (Erased pattern 14 ₁ corresponds to a state before recording actually No specific pattern).

When the light source of the recording beam is composed of a laser diode or the like modulated by the recording information, if the laser diode is not modulated, this light source can be used as the light source of the erasing beam.

When one beam spot is moved between the position of the beam spot 22 of FIG. 1 and the position of the beam spot 24 of FIG. 2, reproduction is performed by one pickup.
It is possible to record and erase. This movement of the beam spot can be performed by changing the deflection amount for the beam. That is, the beam spot is shown in FIG.
It is arranged at the position of reference numeral 24. And at the time of recording,
This beam spot can be moved to the position of reference numeral 22 in FIG. 1 by deflection. In the case of recording and erasing, an external bias magnetic field is applied.

FIG. 3 shows a magnetization state and a beam spot when only reproduction is performed while tracking is performed.
Beam spot 20 ₁ to 20 on the recorded track T16
₃ is imaged. The recording patterns 16 _{1 to} 16 ₃ on the track T16 are reproduced by the beam spot 20 ₂ . In this case, no recording or erasing beam is needed,
The beam source is turned off.

FIG. 4 shows a case where rewriting is performed on an erased sector. In the case of re-recording, recording and reproduction are performed on the same recording track T18. Re-recording is performed by the re-recording beam spot 26 while tracking is performed by the beam spots 20 _{1 to} 20 ₃ .
Pattern 18 ₁ shows the rerecorded magnetization pattern. For re-recording, the beam spot 26 is inserted between the beam spots 20 ₂ and 20 ₃ . By doing so, the re-recorded contents can be immediately after-monitored by the beam spot 20 ₂ . Beam spot 26
Is obtained by moving the beam spot 24 in FIG. This movement can be easily performed by beam deflection using a mirror.

Erasing and subsequent re-recording can be performed as follows. That is, the saturation-magnetized recording medium is erased by the reverse magnetization. Next, this erased portion is heated to a Curie temperature or higher with a laser beam or the like and magnetized in the opposite direction with an external bias magnetic field. Then, the magnetization direction of the heated portion is reversed, and re-recording is performed.

FIG. 5 shows the recording described in FIGS.
1 shows a magneto-optical recording / reproducing apparatus according to an embodiment of the present invention for performing erasing, reproducing and re-recording. The recording laser drive circuit 30 excites and modulates the first laser diode 32 according to the recording signal Er. The presence or absence of modulation by the drive circuit 30 and the presence or absence of laser oscillation are determined by the first mode signal E30. Laser diode 32
Emits a first light beam B32 having a first wavelength.
The beam B32 becomes parallel light through the collimator lens 34 and is incident on the polarization beam splitter 36. The beam B32 transmitted through the beam splitter 36 is ¼
It is converted into circularly polarized light via the wave plate 38. The circularly polarized beam B32 is incident on the optical deflector 40. Optical deflector 4
The deflection amount by 0 is determined by the deflection control signal E42 supplied to the optical deflector drive circuit 42.

Circularly polarized beam B reflected by the optical deflector 40
32 is a dichroic mirror 46 via a lens 44.
Is incident on. The dichroic mirror 46 transmits the laser beam B32 of the first wavelength, but reflects the laser beam of the second wavelength described later. That is, a wavelength that can be separated by the dichroic mirror 46 is selected as the first wavelength and the second wavelength.

The beam B32 transmitted through the dichroic mirror 46 is given to the recording / reproducing pickup 50 via the lens 48. The pickup 50 focuses the first light beam B32 on the recording surface of the recording medium disc 56. The image formation of the beam B32 corresponds to the beam spot 24 of FIG. 2 or the beam spot 26 of FIG. The pickup 50 has a focus servo mechanism and a track servo mechanism. A bias magnetic field generating coil 52 is attached to the pickup 50. The coil 52 is fed by a bias coil drive circuit 54. The drive circuit 54 outputs a drive current 152 having a predetermined magnitude and direction to the coil 52 according to the second mode signal E54.

First light beam B reflected by the disk 56
The reference numeral 32 returns to the quarter wavelength plate 38 via the pickup 50, the lens 48, the dichroic mirror 46, the lens 44 and the optical deflector 40. The polarization direction of the reflected light beam B32 is π / by the quarter-wave plate 38.
It is rotated twice. Then, the reflected light beam B32 becomes linearly polarized light and is reflected by the beam splitter 36. Linearly polarized beam B32 reflected by the beam splitter 36
Enters the photodetector 60 via the cylindrical lens 58. The lens 58 is provided on the light receiving surface of the photodetector 60.
The beam corresponding to the focus error is imaged. The photodetector 60 has, for example, four photodetection units, and two photodetection units facing each other in a diagonal direction form a pair. The outputs of these photodetector pairs are applied to the positive and negative phase inputs of the differential amplifier 62, respectively. Output E6 of amplifier 62
2 indicates a focus error. This output, that is, the focus control signal E62 is fed back to the focus servo section of the pickup 50 for the focus servo operation.

The detection of the focus control signal using the above-mentioned four-division type photodetector 60 is a known technique. For details, see, for example, Journal of Television Engineering, Vol. 32, No. 1 (1978), "Optical Video Disc System", p. Two
0 has specific description.

The reproducing laser drive circuit 70 excites the second laser diode 72 in response to the third mode signal E70. The diode 72 generates a second light beam B20 having a second wavelength. This beam B20 becomes parallel light through the collimator lens 74 and is given to the diffraction grating 76. The diffraction grating 76 splits the parallel beam B20 into three beams B20 _{1 to} B20 ₃ . These three beams are converted into linearly polarized beams B20 _{1 to} B20 by the polarizer 78.
Converted to ₃ . These linearly polarized beams are reflected by the lens 80.
Then, the light passes through the half mirror 82 and enters the dichroic mirror 46. The dichroic mirror 46 3 beams B20 ₁ ~B20 ₃ reflected by the lens 48
An image is formed on the recording surface of the disc 56 via the pickup 50. These three beams B20 ₁ ~B2
The image of 0 ₃ corresponds to the beam spots 20 _{1 to} 20 ₃ shown in FIGS.

Beam B20 ₁ reflected by disk 56
～B20 ₃ the pickup 50 through the lens 48 and the dichroic mirror 46, come back to the half mirror 82. The reflected beams B20 _{1 to} B20 ₃ are reflected by the half mirror 82, and are then split into two by the half mirror 84. Central beam B2 that has passed through the half mirror 85
0 ₂ is incident on the photodetector 88 via the analyzer 86. On the other hand, the central beam B reflected by the half mirror 84
20 ₂ is incident on the photodetector 92 via the analyzer 90. Of the beams reflected by the half mirror 84, the tracking beams B20 ₁ and B20 ₃ are the photodetector 9
It is incident on 4, 96.

The outputs of the photodetectors 88 and 92 are the differential amplifier 9
It is given to the positive phase and negative phase input terminals of 8. The amplifier 98 outputs the reproduction signal E _p according to the difference between the outputs of the photodetectors 88 and 92.
Is output.

The outputs of the photodetectors 94 and 96 are applied to the positive and negative phase input terminals of the differential amplifier 100. Amplifier 100
Outputs the track control signal E100 according to the difference between the outputs of the photodetectors 94 and 96. This signal E100 is
It is returned to the track servo section of the pickup 50 for the track servo operation.

The recording signal Er is temporarily stored in the buffer memory 102. The contents stored in this memory 102 are
It is read as recorded information E102. On the other hand, the reproduction signal E _p is amplified by the reproduction amplifier 104 and becomes monitor information E104. The monitor information E104 corresponds to the recording information for one rotation of the disc 56 (recording information for one track before). The recording information E102 and the monitor information E104 are compared by the comparator 106. This comparison is based on the recording information E1 read as serial data, for example.
02 and the monitor information E104, which is also serial data, are sequentially compared. As a result of this successive comparison, a check signal E106 is output. The check signal E106 causes a logic level change, for example, when there is a mismatch between the information E102 and E104. By using the check signal E106, it is possible to confirm the information recording state of one track before.

FIG. 6 shows a specific example of the optical deflector 40 schematically shown in FIG. The input light beam B32 is transmitted through the first mirror 40
₁ , reflected by the second mirror 40 ₂ and the third mirror 40 ₃ . Of these mirrors, the first mirror 40 ₁
The second mirror 40 ₂ is rotationally driven by the optical deflector drive circuit 42. The rotation direction and the rotation amount of the mirrors 40 ₁ and 40 ₂ are determined by the deflection control signal E42. The mirror 40 ₁ swings the beam B32 left and right. As a result, the spot of the beam B32 is moved in the circumferential tangential direction (track direction) of the disc 56. The mirror 40 ₂ swings the beam B32 up and down. As a result, the spot of the beam B32 is moved in the radial direction of the disc 56. By combining the rotations of the mirrors 40 ₁ and 40 ₂ with each other, the spot of the beam B 32 can be moved to an arbitrary position on the disk 56. That is, the beam spot 24 shown in FIG. 2 is replaced by the spot 22 shown in FIG.
Position or the position of the spot 26 shown in FIG. 4 or the like.

The optical deflector 40 may be a so-called electro-optical element. Recording by the apparatus of FIG. 5 is performed as follows. Now, it is assumed that the recording on the track T10 in FIG. 1 is completed and the information corresponding to the recording pattern 10 ₂ is stored in the buffer memory 102. The first mode signal E30, the second mode signal E54, and the third mode signal E70 each specify a recording mode. Further, the deflection control signal E42 specifies that the recording beam should be shifted by one track pitch. In this case, the first laser diode 32 and the second laser diode 72 are both excited, and the coil 52 generates a bias magnetic field for recording.

First, the beam spots 20 ₁ and 20 ₃
With the tracking control is performed using the signal E _p indicating the recording pattern 10 ₂ is played. This pattern
The recording state of 10 ₂ is checked in the comparator 106. When it is confirmed that the beam spots 20 _{1 to} 20 ₃ correctly trace the track T10, recording by the beam spot 22 is performed on the track T12. When one of the rotation of the recording disk 56 is completed, turn the track T12 is traced by the beam spot 20 ₁ to 20 _3, recording by spot 22 is performed on the next track.

Erasing by the device shown in FIG. 5 is performed as follows. In this case, mode signals E30, E54 and E70 specify the erase mode. In addition, the control signal E
42 designates that the erasing beam is inserted between the tracking beams. This designation places the beam spot 24 between the spots 20 ₁ and 20 ₂ as shown in FIG. The first laser diode 32 oscillates laser light unmodulated, and the coil 52 generates an erasing bias magnetic field. Second laser diode 7
2 also performs laser oscillation.

First, the beam spots 20 ₁ and 20 ₃
The tracking control is performed and the reproduction by the beam spot 20 ₂ is performed. Then, the sector to be erased is detected by the beam spot 20 ₂ , and the beam spot ₂ is detected.
Erasure by 4 is performed.

At the time of reproduction, the mode signals E30, E54 and E70 specify the reproduction mode. Control signal E4
2 designates the same state as the erase mode, for example.
When the reproduction mode is designated, the first laser diode 32
Is not excited, and only the second laser diode 72 is oscillating. Further, the coil 52 does not generate a bias magnetic field. During playback, as shown in FIG. 3, the beam spot 20 ₁ and 20 and tracking of the track T16 by _3, the beam spot 20 ₂ by the pattern 16 ₂
Is played.

Re-recording is performed as follows. In this case, the mode signals E30, E54 and E70 specify the re-recording mode. Further, the control signal E42 specifies that the re-recording beam should be inserted between the tracking beams. This designation places the beam spot 26 between the spots 20 ₂ and 20 ₃ as shown in FIG. First, the beam spots 20 ₁ and 20 ₃
Tracking is performed, and the beam spot 20 ₂ searches for a portion to be re-recorded. When the re-recorded portion is found, a re-recording bias magnetic field is generated from the coil 52, and re-recording is performed by the beam spot 26. The recording result by the beam spot 26 is the same as the beam spot 2
0 ₂ , immediately monitored.

Accordingly, in this way, the first light beam is used as the erasing beam spot 24, and the magnetization pattern (sector) to be erased by the beam spot 20 ₂ of the second light beam preceding this beam spot 24. Since the monitored magnetization pattern is erased by the beam spot 24 in advance, and the magnetization pattern to be erased can be determined immediately before the erasing beam spot 24, some rotation irregularity occurs in the rotation of the disk. Even if it occurs, the magnetization pattern to be erased can be stably detected without being affected by the rotational unevenness of the disk, and the magnetization pattern recorded at high density can be erased accurately. The embodiments shown in the drawings described in this document do not limit the present invention in any way.
Various modifications can be made within the spirit and scope of the invention. For example, although the reflection reading method is shown in FIG. 5, the present invention can also be applied to the transparent reading method using the Faraday effect.

[0039]

As described above, according to the present invention, the first light beam for recording or erasing information is used as an erasing beam, and information is reproduced on the same recording track for this erasing beam. The reproduction beam of the second light beam to be performed is advanced by a predetermined distance, the sector to be erased in the recording track is detected by the reproduction beam, and this sector is erased by the erase beam. Sectors to be erased can be detected stably without being affected. This not only enables reliable erasure of high-density information, but also relaxes the requirement for the rotation accuracy of the disc. That is, even if the rotation accuracy is somewhat poor, it is possible to accurately erase a predetermined sector recorded at high density.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a case where magneto-optical recording / reproduction is performed while tracking is performed by a device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a case where recorded information is erased while performing tracking by the apparatus according to an embodiment.

FIG. 3 is a diagram illustrating a case where recorded information is reproduced while tracking is performed by the apparatus according to an embodiment.

FIG. 4 is a diagram illustrating a case where re-recording is performed while performing tracking by the apparatus according to an embodiment.

5 is a block diagram showing a schematic configuration of a magneto-optical recording / reproducing device that performs the operation described in FIGS. 1 to 4. FIG.

6 is a perspective view showing a specific example of the optical deflector shown in FIG.

[Explanation of symbols]

T10, T14, T16 ... Recorded tracks, 10 ₁ to 1
0 ₃ , 12 ₁ , 14 ₂ , 16 _{1 to} 16 ₃ ... Remanent magnetization pattern (recording pattern), 20 _{1 to} 20 ₃ ... Tracking beam spot (20 ₂ ... Reproducing beam spot),
22 ... beam spot for recording, T12 ... recording track,
24 ... erasing beam spot, 14 ₁ ... erased pattern, T18 ... recording track, 18 ₁ ... re-recording pattern,
26 ... Re-recording beam spot, 30 ... Recording laser drive circuit, Er ... Recording signal, 32 ... First laser diode (first light source), E30 ... First mode signal, B32 ... First
Light beams, 34, 74 ... Collimator lens, 36 ... Polarization beam splitter, 38 ... Quarter wave plate, 40 ... Optical deflector, 42 ... Optical deflector drive circuit, E42 ... Deflection control signal,
44, 48, 80 ... Lens, 46 ... Dichroic mirror, 50 ... Recording / reproducing pickup (pickup means), 52 ... Bias magnetic field generating coil, 54 ... Bias coil drive circuit, E54 ... Second mode signal, I52 ... Drive current, 56 ... Recording medium disk, 58 ... Cylindrical lens, 60, 88, 92, 94, 96 ... Photodetector,
62, 98, 100 ... Differential amplifier, E62 ... Focus control signal, E70 ... Third mode signal, 76 ... Diffraction grating,
78 ... Polarizer, 82, 84 ... Half mirror, 86, 90
... analyzer, E _p ... reproduction signal, E100 ... track control signal, 102 ... buffer memory, E102 ... recording information, 1
04 ... Regenerative amplifier, E104 ... Monitor information, 106 ... Comparator, E106 ... Check signal, 40 ₁ ... First mirror,
40 ₂ ... 2nd mirror, 40 ₃ ... 3rd mirror.

Claims (1)

[Claims] 1. A first light source for providing a first light beam for recording or erasing information in an apparatus for recording / reproducing information on / from a recording medium having a track having a plurality of sectors by utilizing a magneto-optical effect. A second light source for providing a second light beam for reproducing information, the first light beam and the second light beam on the same recording track of the recording medium, and the second light beam for the first light beam. An optical unit for directing the beam so as to precede the beam by a predetermined distance; and a pickup for passing the first light beam and the second light beam in common and converging the passing beam. The beam detects the sector to be erased in the recording track prior to the first light beam,
The magneto-optical recording / reproducing apparatus is characterized in that a sector to be erased in the recording track is erased by the first light beam.