JP3703292B2 - Information recording medium annealing method and optical information recording / reproducing apparatus using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for annealing an information recording medium and an optical information recording / reproducing apparatus using the method.
[0002]
[Prior art]
In recent years, a magneto-optical information recording / reproducing apparatus using a magneto-optical disk as a recording medium has high expectations because it is portable, has a large storage capacity, and can be erased and rewritten. FIG. 6 shows an optical head of a conventional magneto-optical recording information reproducing apparatus. In FIG. 6, reference numeral 36 denotes a semiconductor laser as a light source. A divergent light beam emitted from the semiconductor laser 36 is collimated by a collimator lens 37 and corrected to a parallel light beam having a circular cross section by a beam shaping prism 38. In this case, the linearly polarized light components orthogonal to each other are P-polarized light and S-polarized light, and this parallel light beam is P-polarized linearly polarized light (in this case, linearly polarized light parallel to the paper surface). This P-polarized light beam is incident on the polarization beam splitter 39. The characteristics of the polarization beam splitter include, for example, a P-polarized light transmittance of 60%, a reflectance of 40%, an S-polarized light transmittance of 0%, and a reflectance of 100%. The P-polarized light beam that has passed through the polarization beam splitter 39 is condensed by the objective lens 40 and irradiated onto the magnetic layer of the magneto-optical disk 41 as a minute light spot. Further, an external magnetic field from the magnetic head 42 is applied to the light spot irradiating portion, and a magnetic domain (mark) is recorded on the magnetic layer.
[0003]
The reflected light from the magneto-optical disk 41 is returned to the polarization beam splitter 39 via the objective lens 40, where a part of the reflected light is separated and brought to the reproducing optical system. In the reproducing optical system, the separated light beam is further separated by a polarization beam splitter 43 prepared separately. As characteristics of the polarization beam splitter 43, for example, the transmittance of P-polarized light is 20%, the reflectance is 80%, the transmittance of S-polarized light is 0%, and the reflectance is 100%. One light beam separated by the polarization beam splitter 43 is guided to a half prism 50 through a condenser lens 49, where it is separated into two, one being a photodetector 51 and the other being a knife edge 52. To the photodetector 53. Then, an error signal for auto-tracking and auto-focusing of the light spot is generated by these control optical systems.
[0004]
The other light beam separated by the polarization beam splitter 43 is separated by a half-wave plate 44 that rotates the polarization direction of the light beam by 45 degrees, a condensing lens 45 that collects the light beam, a polarization beam splitter 46, and a polarization beam splitter 46. The detected light beams are guided to photodetectors 47 and 48 for detecting the light beams, respectively. As the characteristics of the polarization beam splitter 46, the transmittance of P-polarized light is 100%, the reflectance is 0%, the transmittance of S-polarized light is 0%, and the reflectance is 100%. The signals detected by the photodetectors 47 and 48 are differentially detected by a differential amplifier (not shown) to generate a reproduction signal.
[0005]
Incidentally, in the magneto-optical medium, information is recorded by the difference in the direction of perpendicular magnetization as is well known. When linearly polarized light is irradiated onto the magneto-optical medium on which information is recorded due to this difference in magnetization direction, the polarization direction of the reflected light rotates clockwise or counterclockwise depending on the difference in magnetization direction. For example, the polarization direction of the linearly polarized light incident on the magneto-optical medium is the coordinate axis P direction as shown in FIG. 7, the reflected light for the downward magnetization is R + rotated by + θk, and the reflected light for the upward magnetization is R− rotated by −θk. . Therefore, when the analyzer is placed in the direction as shown in FIG. 7, the light transmitted through the analyzer becomes A for R + and B for R−, and if this is detected by the photodetector, the light intensity is detected. Information can be obtained as the difference between In the example of FIG. 6, the polarization beam splitter 46 serves as an analyzer, and the analyzer has a direction of +45 degrees from the P-axis with respect to one separated light beam and −45 degrees from the P-axis with respect to the other light beam. It becomes. That is, the signal components obtained by the photodetectors 47 and 48 are out of phase, so that a reproduced signal with reduced noise can be obtained by differential detection of the individual signals.
[0006]
Recently, there is an increasing demand for increasing the recording density of this magneto-optical medium. In general, the recording density of an optical disk such as a magneto-optical medium depends on the laser wavelength of the reproducing optical system and the NA (numerical aperture) of the objective lens. That is, since the diameter of the light spot is determined when the laser wavelength λ of the reproducing optical system and the NA of the objective lens are determined, the size of the reproducible magnetic domain is limited to about λ / 2NA. Therefore, in order to realize high density in the conventional optical disk, it is necessary to shorten the laser wavelength of the reproducing optical system or increase the NA of the objective lens. However, since there is a limit to the improvement of the laser wavelength and the NA of the objective lens, a technique for improving the recording density by devising the configuration of the recording medium and the reading method has been developed.
[0007]
For example, the applicant of the present application scans a track on a magneto-optical medium formed by laminating a plurality of magnetic layers in Japanese Patent Application Laid-Open No. Hei 6-290495 with a light spot, thereby causing perpendicular magnetization in the first magnetic layer. The recorded magnetic domains (marks) are transferred to a third magnetic layer disposed with the second magnetic layer for adjusting the exchange coupling force interposed therebetween, and the domain walls of the magnetic domains transferred to the third magnetic layer are transferred. A domain wall moving reproduction method has been proposed in which a reproduction signal is obtained after the magnetic field is moved to make it larger than the magnetic domain recorded in the first magnetic layer.
[0008]
The domain wall motion reproduction method will be described with reference to FIGS. FIG. 8 is a diagram for explaining the principle of the domain wall motion reproducing method. (A) is sectional drawing which shows the structure of a magnetic layer, (b) is the top view seen from the side in which a light spot injects. In the figure, reference numeral 54 denotes a magneto-optical disk as a magneto-optical medium, which is composed of three magnetic layers. First, reference numeral 55 denotes a first magnetic layer, which is a recording layer for recording information as magnetic domains (hereinafter referred to as a recording layer). Reference numeral 56 denotes a second magnetic layer, which is an adjustment layer for adjusting the exchange coupling force between the first magnetic layer 55 and the third magnetic layer 57 (hereinafter referred to as an adjustment layer). The third magnetic layer 57 transfers the magnetic domain recorded in the recording layer 55 by using the function of the adjustment layer 56 and the heat distribution by the light spot, and further moves the domain wall of the transferred magnetic domain, thereby recording the magnetic domain. The reproducing layer is made larger than the size of the magnetic domain recorded in the layer 55 (hereinafter referred to as a reproducing layer). 58 represents a reproducing light spot, and 59 represents a desired track to be reproduced on the magneto-optical disk 54. An arrow in each of the recording layer 55, the adjustment layer 56, and the reproducing layer 57 represents the direction of atomic spin, and a domain wall 60 is formed in a region where the directions of spin are opposite to each other. Reference numeral 61 denotes a domain wall on which the magnetic domain transferred to the reproducing layer 57 is about to move.
[0009]
FIG. 8C is a graph showing the temperature distribution formed on the magneto-optical disk 54. In principle, the domain wall motion reproduction can be performed by using one light spot or two light spots, but here, for the sake of simplicity of explanation, a method of performing reproduction using two light spots. Will be explained. FIG. 8 shows only light spots that contribute to the reproduction signal. A second light spot (not shown) is irradiated to form the temperature distribution of (c). Now, it is assumed that the temperature on the optical disc 54 is Ts near the Curie temperature of the adjustment layer 56 at the position Xs. A hatched portion indicated by 62 in (a) indicates a portion that is equal to or higher than the Curie temperature.
[0010]
FIG. 8D is a graph showing the distribution of the domain wall energy density σ1 of the reproducing layer 57 corresponding to the temperature distribution shown in FIG. When there is a gradient of the domain wall energy density σ1 in the X direction in this way, the force F1 shown in the figure acts on the domain wall of each layer existing at the position X. This F1 acts to move the domain wall to the lower domain wall energy. Since the reproducing layer 57 has a small domain wall coercive force and a large domain wall mobility, the domain wall easily moves by this force F1 alone. However, in the region before the position Xs (right side in the figure), the temperature of the magneto-optical disk 54 is still lower than Ts, and is exchanged with the recording layer 55 having a large domain wall coercive force, so that the domain wall position in the recording layer 55 is The domain wall in the reproducing layer 57 is also fixed at the corresponding position.
[0011]
Here, it is assumed that the domain wall 61 is at the position Xs of the medium as shown in FIG. Further, it is assumed that the temperature of the magneto-optical disk 54 rises to Ts near the Curie temperature of the adjustment layer 56 at the position Xs and the exchange coupling between the reproducing layer 57 and the recording layer 55 is broken. As a result, the domain wall 61 in the reproducing layer 57 instantaneously moves to a region where the temperature is higher and the domain wall energy density is smaller as indicated by the arrow B. Therefore, when the reproducing light spot 58 passes, the atomic spins of the reproducing layer 57 in the spot are all aligned in one direction as shown in FIG. As the medium moves, the domain wall 61 (or 60, etc.) instantaneously moves, the direction of atomic spin in the light spot is reversed, and all are aligned in one direction. The reflected light from the magneto-optical disk 54 is detected by the conventional optical head shown in FIG. 6, and a reproduction signal is obtained by performing similar differential detection. According to such a domain wall motion reproduction system, the signal reproduced by the light spot always has a constant amplitude regardless of the size of the magnetic domain recorded in the recording layer 55, and the waveform interference caused by the optical diffraction limit. Freed from problems. That is, if domain wall motion reproduction is used, a magnetic domain smaller than about the resolution limit λ / 2NA determined by the laser wavelength λ and the NA of the objective lens can be reproduced, and a submicron linear density can be reproduced.
[0012]
FIG. 9 is a diagram illustrating an example of an optical head when two light spots are used. Reference numeral 63 denotes a recording / reproducing semiconductor laser having a wavelength of, for example, 780 nm. Reference numeral 64 denotes a heating semiconductor laser having a wavelength of, for example, 1.3 μm. Both are arranged to be incident on the recording medium with P-polarized light. The laser beams emitted from the semiconductor lasers 63 and 64 are made into a substantially luminous flux by collimator lenses 65 and 66 after being made into a substantially circular shape by beam forming means (not shown). Reference numeral 67 denotes a dichroic mirror that transmits 100% of light at 780 nm and reflects 100% of light at 1.3 μm. Reference numeral 68 denotes a polarizing beam splitter, which transmits 70 to 80% of the P-polarized light and reflects almost 100% of the S-polarized light of the vertical component.
[0013]
The parallel light flux converted by the collimator lenses 65 and 66 enters the objective lens 69 through the dichroic mirror 67 and the polarization beam splitter 68. At this time, the light beam of 780 nm is made larger with respect to the size of the opening of the objective lens 69, and the light beam of 1.3 μm is made smaller than the size of the opening of the objective lens 69. Therefore, even if the same objective lens 69 is used, the lens NA acts on a 1.3 μm light beam, and the size of the light spot on the recording medium 70 becomes larger than that on the recording medium 70. The reflected light from the recording medium 70 passes through the objective lens 69 again to become a parallel light beam, is reflected by the polarization beam splitter 68, and is obtained as a light beam 71. After the light beam 71 is subjected to wavelength separation or the like by an optical system (not shown), a servo error signal and an information reproduction signal are obtained in the same manner as in the conventional method.
[0014]
FIG. 10 is a diagram showing the relationship between the recording / reproducing light spot and the heating light spot on the recording medium. First, in FIG. 10A, 72 is a recording / reproducing light spot having a wavelength of 780 nm, and 73 is a heating light spot having a wavelength of 1.3 μm. 74 is a domain wall of a magnetic domain recorded in 75 lands, and 76 is a groove. Reference numeral 77 denotes a region where the temperature is increased by the heating light spot 73. Thus, on the land 75 between the grooves 76, the recording / reproducing light spot 72 and the heating light spot 73 are combined. As a result, a temperature gradient as shown in FIG. 10B can be formed on the moving recording medium. The relationship between the temperature gradient and the recording / reproducing light spot 72 is the same as that shown in FIG. 8, thereby enabling domain wall motion reproduction.
[0015]
On the other hand, in an MD (mini disc) or the like, the width of a track is wobbled, and information such as a track number is added to the change in wobbling. These wobblings are created by modulating the power of a light spot that cuts a track when creating a master disk substrate.
[0016]
[Problems to be solved by the invention]
In the above-described recording medium of the domain wall motion reproduction system, it is necessary to block the feature of the medium between adjacent tracks, that is, magnetism, in order to enable the domain wall of the reproduction layer to move. Conventionally, by irradiating a high-temperature light spot with a constant power to anneal between adjacent tracks, the magnetism is lost, and the continuity of the characteristics of the medium between adjacent tracks is interrupted. On the other hand, in the domain wall motion reproduction method, the linear density is as high as submicron. However, if information such as the track number by the prepit is recorded, the prepit is limited by the limit of the optical system, so that it is significantly lower than the linear density in the domain wall moving reproduction method, and the recording capacity is impaired. There was a problem.
[0017]
In view of the above-described conventional problems, the present invention provides an information recording medium annealing method and an optical information recording / reproducing apparatus using the same, which can greatly increase the recording density without impairing the recording capacity. For the purpose.
[0018]
[Means for Solving the Problems]
An object of the present invention is to provide information between information tracks on an information recording medium. The High heat light spot so By scanning Forming an annealed region extending along the information track; And modulating the light intensity of the light spot scanned between the information tracks according to predetermined information, The elongated annealed region This is achieved by an annealing method for an information recording medium, wherein predetermined information is recorded between the information tracks by changing the width of the information recording medium.
[0019]
Another object of the present invention is to provide an optical information recording / reproducing apparatus for recording information by irradiating a light beam onto an information track of an information recording medium from the optical head or reproducing the recorded information. Means for driving a light source that emits a light beam to emit a hot spot for annealing; By scanning between the information tracks of the information recording medium with the light spot for annealing, an annealed region extending along the information track is formed, and the light intensity of the light spot scanned between the information tracks is set to a predetermined value. By changing the width of the elongated annealed region by modulating according to the information of It is achieved by an optical information recording / reproducing apparatus comprising: means for recording predetermined information between the information tracks.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of an embodiment of the optical information recording / reproducing apparatus of the present invention. In FIG. 1, 1 is an optical information recording / reproducing apparatus, and 2 is a control circuit for controlling the information recording / reproducing apparatus 1 as a whole. The control circuit 2 controls transmission / reception of information to / from an information processing apparatus such as an external computer, controls information recording / reproduction with respect to the magneto-optical disk, and controls other operating units. Reference numeral 3 denotes a spindle motor for rotationally driving the magneto-optical disk 4 and is controlled by a spindle motor controller 10. The magneto-optical disk 4 is inserted into or ejected from the information recording / reproducing apparatus 1 by a mechanism (not shown). Reference numeral 5 denotes an optical head that optically records and reproduces information on the magneto-optical disk 4, and 6 denotes a magnetic head that is located on the opposite side of the optical head 5 with respect to the magneto-optical disk 4 and applies a magnetic field when recording information. As the optical head 5, one equivalent to the one-beam optical head shown in FIG. 6 can be used. Reference numeral 7 denotes an optical head and magnetic head control circuit for controlling the position of the optical spot of the optical head 5 and the position of the magnetic head 6. The control circuit 7 performs auto tracking control, seek operation control, and auto focusing control. 8 is an information recording circuit for recording information, and 9 is an information reproducing circuit for reproducing information.
[0021]
As the magneto-optical disk 4, the one shown in FIG. 8 or the like is used. That is, it includes at least three magnetic layers including a recording layer (first magnetic layer), an adjustment layer (second magnetic layer), and a reproducing layer (third magnetic layer). The function is the same as in the description of the prior art. That is, the recording layer records information as a magnetic domain, the adjustment layer adjusts the exchange coupling force between the recording layer and the reproduction layer, and the reproduction layer uses the magnetic domain recorded in the recording layer as a function of the adjustment layer and the light spot. The size of the magnetic domain recorded on the recording layer is made larger by transferring using the heat distribution due to, and moving the domain wall of the transferred magnetic domain.
[0022]
As a specific material of each layer of the magnetic layer group, an amorphous alloy composed of a combination of one or more transition metals and rare earth metals can be used. For example, transition metals mainly include Fe, Co, Ni, and rare earth metals mainly include Gd, Tb, Dy, Ho, Nd, and Sm. Typical combinations include TbFeCo, GdTbFe, GdFeCo, GdTbFeCo, GdDyFeCo, and the like. Further, a small amount of Cr, Mn, Cu, Ti, Al, Si, Pt, In, or the like may be added to improve the corrosion resistance. Furthermore, a metal layer such as Al, AlTa, AlTi, AlCr, or Cu may be added to these layer structures to adjust the thermal characteristics.
[0023]
FIG. 2 is an enlarged view showing the configuration of the optical head 5 and a part of the magneto-optical disk 4. With reference to FIG. 2, a method of performing an annealing process for interrupting the continuity of the medium characteristics between adjacent tracks of the magneto-optical disk 4 will be described. In FIG. 2, 12 is a semiconductor laser as a light source, and 13 is a collimator lens that converts laser light emitted from the semiconductor laser 12 into parallel light. The parallel light converted by the collimator lens 13 enters the objective lens 15 via the polarization beam splitter 14, and the light spot 16 is condensed on the magnetic layer of the magneto-optical disk 4 by the objective lens 15. The reflected light from the magneto-optical disk 21 passes through the objective lens 15 again and enters the polarization beam splitter 14 and is reflected by the beam splitter 14 to become 17 light beams. As described with reference to FIG. 6, the control signal for auto-tracking and auto-focusing of the optical head and the detection of the magneto-optical reproduction signal are performed from the light flux 17 by an optical system (not shown).
[0024]
The magneto-optical disk 4 is a groove recording medium, and information is recorded in the groove portion. Reference numerals 22a to 22e denote land portions, and 23a to 23d denote groove portions. It is assumed that the magneto-optical disk 4 rotates in the direction of the arrow. Reference numeral 18 denotes a driving circuit for the semiconductor laser 12, 19 denotes an optical head control circuit, and 20 denotes a detection circuit for detecting reflected light from the disk 4. Here, in this embodiment, when the magneto-optical disk 4 is inserted into the information recording / reproducing apparatus for the first time, in order to enable the domain wall to move in the reproducing layer, the magnetic field of the land portion 22 is measured. Is lost, and the continuity of the media characteristics between adjacent tracks is interrupted. As a result, the magnetic domain recorded in the groove portion does not have a domain wall in the lateral direction (parallel to the track), and the domain wall having the meaning of information (the domain wall described with reference to FIG. 8) can be moved.
[0025]
When performing the annealing process, first, the optical head 5 is moved to the outermost periphery or the innermost periphery of the magneto-optical disk 4. Next, a light spot is irradiated from the optical head 5 to the disk 4, and a control signal for auto-focusing is detected from the reflected light by the detection circuit 20, and focusing control is performed by a mechanism (not shown). Next, an auto-tracking control signal is detected by the detection circuit 20. At this time, an offset is given to the auto-tracking control signal, and the light spot 16 is controlled to scan on the land portion 22 to be annealed. The light intensity of the light spot 16 of the optical head 5 is set to an intensity of high heat power that causes the magnetism of the land portion to disappear.
[0026]
For example, the control circuit 19 performs the annealing process continuously while controlling the semiconductor laser driving circuit 18 from one end of the disk 4 to the other end on the land portion 22a of FIG. In this case, the semiconductor laser drive circuit 18 modulates the drive current of the semiconductor laser 12 to modulate the light intensity of the light spot. Specifically, the light intensity of the light spot is modulated in accordance with information to be recorded as a pre-pit signal on the disk 4, for example, information such as track number, sector number, and clock pit for synchronization, and the information is recorded on the land 22a. ing. The change in the annealing width indicated by the oblique lines of the land 22a in FIG. 2 indicates the information recorded by the modulation of the light spot. Further, as information at this time, the left and right grooves of the land portion 22a in FIG. 2 are regarded as one track, and information on the left and right tracks is recorded. For example, when recording track numbers, one track number of the left and right grooves is recorded in the land portion 22a. Discrimination between the left and right groove tracks is performed during reproduction as will be described later.
[0027]
When the annealing process for the land portion 22a is completed, the annealing process for the next land portion 22b is performed. Also in this case, the light spot 16 is scanned on the land portion 22b of the disk 4, and the land portion 22b is annealed. However, in this case, the light spot is not modulated, the light spot 16 having a constant power is scanned, and the land portion 22b is annealed with a constant power as shown by the oblique lines in FIG. Next, as shown in FIG. 2, the light spot 16 is moved to the land portion 22c and the land 22c is annealed. In this case, the intensity of the light spot 16 is changed to the track number or the like as in the land portion 22a. Modulation is performed according to the information, and information such as the track number is recorded at the same time as the land portion 22c is annealed. The next land 22d is annealed with a constant power, and the next land 22e is annealed by modulating the light spot. As described above, the annealing process using the modulation power and the annealing process using the constant power are alternately performed in the land portion (between tracks).
[0028]
FIG. 4 shows this state. Similarly, the magneto-optical disk 4 is a groove recording medium, 28 is a groove portion, and 29 and 30 on both sides thereof are land portions. The land portion 29 is indicated by a thin line, and the land portion 30 is indicated by a thick line. For example, 29 indicates a land portion annealed with a constant power, and 30 indicates a land portion annealed with a modulation power.
[0029]
Next, when recording or reproducing information on the magneto-optical disk 4 subjected to the annealing process in this way, the offset of the auto tracking control signal is restored and control is performed so that the light spot 16 scans the groove portion. To do. The light intensity of the light spot is set to an appropriate value according to recording and reproduction. Since the annealed region has lost its magnetism, the magneto-optical effect does not occur and the magneto-optical reproduction signal is not parasitic. Here, in this embodiment, the reflected light from the medium of the light spot is detected by a sensor (not shown) in the optical head 5 at the time of recording or reproducing, and is recorded on the land portion simultaneously with annealing by the detection circuit 20. Play information such as track numbers. In this case, the signal obtained from the reflected light of the light spot includes a component due to the modulation of the light spot as shown in FIG. 2, and an envelope of the magneto-optical signal corresponding to the change in the annealing width is obtained. Therefore, information such as the track number currently being scanned is obtained based on the envelope signal. However, as described above, one track number (sector number) indicating the left and right groove portions is recorded on the land portion, but the reflected light from the medium is detected by a two-divided photodetector (not shown), Since the left and right groove portions are modulated by the output, the currently scanned groove portion of the two groove portions can be determined. In the case of a land recording medium, annealing by modulation and annealing by constant power are alternately performed for each groove portion.
[0030]
FIG. 3 shows a land / groove recording medium. As in FIG. 2, when this medium is inserted into the information recording / reproducing apparatus for the first time, annealing is performed to enable the domain wall to move in the reproducing layer. The annealing process is basically the same as in the case of FIG. In the disk 4, 25a to 25d are land portions, and 26a to 26d are groove portions. The optical head 5 and its periphery are the same as in FIG. When the annealing process is performed, the optical head 5 is similarly moved to the outermost periphery or the innermost periphery of the magneto-optical disk 4. Next, an auto-focusing control signal is detected from the reflected light of the disk 4 by the detection circuit 20, and focusing control is performed by a mechanism not shown.
[0031]
In addition, the auto-tracking control signal is detected by the detection circuit 20, and at this time, an offset is given to the auto-tracking control signal. In this case, first, the light spot 16 is formed at the center of one boundary between the land portion and the groove portion. The scanning is performed so as to come, and the annealing process is continuously performed at a constant power while controlling the semiconductor laser driving circuit 18 by the control circuit 19 from one end of the track of the magneto-optical disk 4 to the other end. . Next, the optical head 5 is returned to the other end of the track, and scanning is performed so that the light spot 16 comes to the center of the other boundary between the land portion and the groove portion, and from one end of the magneto-optical disk 4 to the other end. Until the control circuit 19 controls the semiconductor laser drive circuit 18, the power is modulated in accordance with information such as the track number as in FIG.
[0032]
FIG. 5 shows this state. The magneto-optical disk 4 is a land / groove recording medium, 32 is a land portion, and 33 is a groove portion. For example, first, annealing is performed on the thin line 34 from the end of the magneto-optical disk to the other end with a constant power, and then the power is modulated on the thick line 35 to anneal from the end of the magneto-optical disk to the other end. Process.
[0033]
When recording and reproducing information on the magneto-optical disk thus annealed, the offset of the auto-tracking control signal is restored and the light spot 16 is controlled to scan on the land or the groove. . Also in this medium, since the magnetism has disappeared in the annealed region (shaded area in the figure), the magneto-optical effect does not occur and does not contribute to the magneto-optical reproduction signal. At the time of recording and reproducing information, the modulated information in the annealing region can be detected by obtaining the envelope of the magneto-optical reproduction signal by the detection circuit 20 in exactly the same manner as described in FIG. Information such as numbers can be obtained. Further, for example, the same envelope is obtained in the land portions 25b and 26b, but by detecting the polarity of tracking, it is possible to determine whether the land portion is being scanned or the groove portion is being scanned. And 26b can be recognized.
[0034]
In the above embodiment, the magneto-optical disk is annealed by the information recording / reproducing apparatus. However, means for irradiating the light spot when manufacturing the information recording medium, means for modulating the light intensity of the light spot, etc. are used. It may be performed at a factory.
[0035]
【The invention's effect】
As described above, according to the present invention, annealing is performed using a high heat light spot and the power of the light spot is modulated in order to block the continuity of the characteristics of the medium between adjacent information tracks. Since the predetermined information is recorded between the tracks by changing the annealing width, the predetermined information such as the track number can be recorded without losing the recording capacity, and the recording density can be greatly increased. In particular, in the case of the domain wall motion reproduction method, the recording density can be greatly increased as compared with the information recording by prepits.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an embodiment of an optical information recording / reproducing apparatus of the present invention.
FIG. 2 is a diagram for explaining an annealing method in the case of a groove recording medium.
FIG. 3 is a diagram for explaining an annealing method in the case of a land groove recording medium.
FIG. 4 is a diagram illustrating a state where a groove recording medium is subjected to an annealing process.
FIG. 5 is a diagram illustrating a state where the land groove recording medium is subjected to an annealing process.
FIG. 6 is a diagram showing a head used in a conventional magneto-optical recording / reproducing apparatus.
FIG. 7 is a diagram for explaining the principle of reproducing a magneto-optical signal.
FIG. 8 is a diagram for explaining a domain wall motion reproduction method.
FIG. 9 is a diagram showing an example of an optical head used for domain wall motion reproduction by two beams.
10 is a diagram showing two beams and a temperature distribution on a recording medium by the optical head of FIG.
[Explanation of symbols]
1. Optical information recording / reproducing device
2 Control circuit
4 magneto-optical disk
5 Optical head
6 Magnetic head
7 Optical head and magnetic head control circuit
8 Information recording circuit
9 Information reproduction circuit
12 Semiconductor laser
15 Objective lens
16 light spots
18 Laser drive circuit
19 Optical head control circuit
20 Detection circuit

Claims (7)

The information between information tracks of the recording medium to form an annealed region which extends along the information track by scanning a light spot of high heat, and the information track predetermined information light intensity of the light spot that scans across A method for annealing an information recording medium, wherein predetermined information is recorded between the information tracks by changing the width of the extended annealed region according to modulation in response.   2. The method for annealing an information recording medium according to claim 1, wherein the predetermined information is a track number, a sector number, or a clock pit for synchronization.   2. The method of annealing an information recording medium according to claim 1, wherein annealing by modulating the light intensity of the light spot and annealing at a constant power are alternately performed for each information track. In an optical information recording / reproducing apparatus for recording information by irradiating a light beam onto an information track of an information recording medium from an optical head or reproducing recorded information, a light source for emitting the light beam in the optical head is used for annealing. And an annealing process region extending along the information track by scanning between the information tracks of the information recording medium with the light spot for annealing, Means for modulating the light intensity of a light spot scanned between the information tracks according to predetermined information, and recording predetermined information between the information tracks by changing the width of the elongated annealed region. An optical information recording / reproducing apparatus.   5. The optical information recording / reproducing apparatus according to claim 4, wherein the predetermined information is a track number, a sector number, or a clock pit for synchronization.   5. The optical information recording / reproducing apparatus according to claim 4, wherein the recording unit alternately performs annealing by modulating the light intensity of the light spot and annealing by a constant power for each information track.   An envelope signal indicating predetermined information recorded between the information tracks is detected from an output of an optical sensor that detects reflected light from the recording medium at the time of recording or reproducing information, and based on the detected envelope signal 5. The optical information recording / reproducing apparatus according to claim 4, further comprising means for reproducing predetermined information.

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