JP2001084598A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical information recording medium that unnecessitates complex reproducing signal processing and that is free from adverse effect by crosstalk by coping with a situation in which a format such as CAV, ZCAV, CLV, etc., makes the processing of reproducing signals complex and in which a crosstalk from a header information part adversely affects reproduction of a user data part. SOLUTION: Each track is divided into plural sectors by gaps 2, with the width of the gaps 2 formed wider toward the outer circumference, so that the lengths of the sectors are nearly equalized and that the sectors are parallelly arranged between adjacent tracks. In addition, each zone is divided into plural blocks 3 by the gaps 2, with the width of the gaps 2 formed wider toward the outer circumference, so that the lengths of the sectors are nearly equalized within the same block and that the sectors are parallelly arranged between adjacent tracks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc-shaped optical information recording medium capable of recording or reproducing high-density information,
In particular, it relates to the format of a recording medium.

[0002]

2. Description of the Related Art Various types of recording formats for optical information recording media have been proposed, and CLV (constant linear velocity) and CAV (constant angular velocity) methods are known as sector arrangement methods. I have. The CLV method has the advantage that the recording / reproducing conditions can be the same at any position on the disk and that the recording capacity is large, but not all sectors can be arranged in parallel between adjacent tracks.
Therefore, in an optical information recording medium in which a sector includes preformatted header information and a data section for recording user data, the header information section is disposed adjacent to the user data section, and crosstalk from the header information section is generated. However, there is a disadvantage that information reproduction of the user data section is adversely affected.

On the other hand, in the CAV method, the control of the spindle motor for rotating the disk is simple and the access speed can be increased, but the recording capacity is reduced, and information for recording / reproducing information is determined by the radial position on the disk. There is a drawback that the recording / reproducing conditions change because the relative speed between the light beam and the medium changes. Further, as a method improved from the CAV method, the information recording area of a disk-shaped optical information recording medium is divided into a plurality of zones, and more sectors are arranged in one circumference in the outer peripheral zone, so that the recording capacity is small. Is known.
However, even with the ZCAV method, the disadvantage that the recording / reproducing conditions change because the relative speed between the light beam for recording / reproducing information and the medium changes depending on the radial position on the disk has not been improved.

In the conventional optical information recording medium, some optical information recording media capable of super-resolution reproduction have been proposed in order to meet the demand for much larger capacity recording, and some of them have been put to practical use. I have. Here, the optical information recording medium capable of super-resolution reproduction refers to the wavelength of reproduction light and the numerical aperture (N.
A. ) Indicates the optical information recording medium capable of reproducing high-density information exceeding the limit of the reproduction resolution of the signal of the optical memory (the pit period of the detection limit is approximately λ / (2 · NA)). For example, Japanese Patent Application Laid-Open Nos. Hei 3-93058 and Hei 5-
Japanese Patent No. 81717 discloses that the detection limit determined by the wavelength and the numerical aperture of the objective lens is devised so that only a part of the reproduction light beam contributes to the reproduction of the signal by utilizing the temperature rise caused by the irradiation of the reproduction light beam. A super-resolution reproduction technique for improving the reproduction resolution beyond that is disclosed.

Japanese Patent Application Laid-Open No. Hei 6-290496 discloses a technique in which domain walls approaching a reproducing light beam are moved one after another, and the movement of the domain walls is detected to determine the wavelength and the numerical aperture of an objective lens. A technique for improving the reproduction resolution beyond the limit is disclosed. JP-A-8-7350
Japanese Patent Application Laid-Open Publication No. H11-163873 discloses a technique in which a magnetic domain is enlarged during reproduction to improve the reproduction resolution beyond a detection limit determined by the wavelength and the numerical aperture of the objective lens. Further, Japanese Unexamined Patent Publication No.
No. 111330 discloses that, in addition to the recording layer, by providing a layer exhibiting a nonlinear optical effect with respect to the irradiated light,
A medium that enables super-resolution reproduction on an optical disk other than the magneto-optical recording system has been disclosed.

[0006]

However, these optical information recording media capable of super-resolution reproduction require a conventional optical information recording system in which the intensity of a reproducing light beam is not super-resolution reproduced in order to reproduce a signal. It needs to be controlled more precisely than the recording medium.
Therefore, in order to use an optical information recording medium capable of super-resolution reproduction in a CAV format or ZCAV format in which recording and reproduction conditions change depending on a radial position on a disk, a complicated light beam intensity control device is required. Met. Also, C
In the AV format or ZCAV format, since the physical length of a recording mark recorded on a disc changes depending on the radial position, the frequency characteristic of the reproduced signal also changes depending on the radial position, and the processing circuit for the reproduced signal is complicated. Processing was required. On the other hand, in the CLV method, as described above, the preformatted header information section is disposed adjacent to the user data section, so that it is difficult to reproduce the information in the user data section due to crosstalk from the header information section. There was a disadvantage of becoming.

The present invention has been made in order to solve the above-mentioned conventional disadvantages, and does not require complicated reproduction signal processing.
It is still another object of the present invention to provide an optical information recording medium free from adverse effects due to crosstalk.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a disk-shaped optical information recording medium having a plurality of tracks formed in a spiral or concentric shape, wherein each track is divided into a plurality of sectors by gaps, This is achieved by an optical information recording medium characterized in that the width of the gap is made wider toward the outer periphery, so that the lengths of the sectors are substantially the same and the sectors are arranged in parallel between adjacent tracks. .

It is another object of the present invention to provide a disk-shaped optical information recording medium in which a plurality of tracks are formed in a spiral or concentric shape and an information recording area is divided into a plurality of zones in a radial direction. Is divided into a plurality of blocks by a gap, and the width of the gap is formed to be wider toward the outer periphery, so that the sector length is substantially the same in the same block, and the sectors are arranged in parallel between adjacent tracks. This is achieved by an optical information recording medium characterized in that:

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view showing the configuration of one embodiment of the optical information recording medium of the present invention. In FIG. 1, an optical information recording medium 1 has a disk shape, and a number of tracks are formed in a spiral (or concentric) shape. The optical information recording medium 1 is divided into a plurality of zones in the radial direction, and in FIG.
1, Z2, Z3, Z4...
Each zone is divided into a plurality of blocks 3 at substantially equal intervals by a gap 2, and within the block 3 divided by the gap 2, the length of the sector is the same.
In the same block, sectors are arranged in parallel between adjacent tracks.

FIG. 2 is a diagram showing one block 3 in an enlarged manner. In FIG. 2, reference numeral 4 denotes a spiral (or concentric) track. Each zone is composed of a plurality of tracks 4 and is divided by gaps 2. The gap 2 is wider in the outer periphery in the same block 3, and in the same block, the length of the sector does not change between the inner peripheral portion and the outer peripheral portion, and has the same length. Each sector comprises a preformatted header information section 5 and a user data section 6 for recording / reproducing data. Each sector is arranged in parallel between adjacent tracks as described above. In the header information section 5, header information and the like for identifying sectors are recorded by pits.

In this embodiment, since the adjacent sectors are arranged in parallel, the preformatted header information section 5 is provided at least except for the zone boundary.
Does not leak into the user data section 6, and does not adversely affect the reproduction of information in the user data section 6. Further, the width of the gap 2 between the sectors is increased toward the outer periphery so that the length of the sector is not changed between the inner periphery and the outer periphery. The physical length of the mark becomes constant irrespective of the radius, and as a result, the reproduction signal processing can be easily performed without changing the frequency characteristics of the reproduction signal.

Here, the fact that the physical length of the recording mark is constant irrespective of the radius means, for example, that the physical length of the recording mark is 2
This means that the length of the T mark is the same as the length of the 2T mark in the outer peripheral portion, and it goes without saying that the physical lengths of the 2T mark and the 4T mark, which are originally different in time length, are different. . In particular, when the PRML method is used for reproduction signal processing in order to achieve a higher density as a medium capable of super-resolution reproduction of each sector, or a domain wall movement detection method described in JP-A-6-290496. In the case of super-resolution reproduction, the quality of the reproduction signal changes depending on the relative relationship between the spot diameter of the reproduction light beam and the length of the recording mark, so that the physical length of the recording mark depends on the radius. That is, the reproduction signal quality does not change depending on the recording position, and the reproduction signal processing can be easily performed.

In this embodiment, as shown in FIG. 1, since the arrangement of the blocks is shifted between the zones, the crosstalk signal from the header information section 5 preformatted at the zone boundary is used for the user data section. 6 may leak. However, since the sector in which this phenomenon occurs is only a small part when viewed from the whole, it may be used as it is by allowing some sectors with low reliability, or if more reliability is required, A buffer track not used for recording information may be provided at the zone boundary. Further, if there is a sector in which the crosstalk signal from the header information section 5 does not leak into the user data section 6 even at the boundary of the zone depending on the arrangement of the sectors, only that sector may be used.

Next, an optical information recording medium having the above-described format was manufactured, and recording and reproduction experiments were attempted. Hereinafter, the results will be described.

(Embodiment 1) FIG. 3 is a view showing a photoresist master exposure apparatus used for manufacturing an optical information recording medium master. First, an Ar laser oscillating device 7 having a wavelength of 442 nm is used as a light source, and a laser beam emitted from the device is guided to a beam splitter 9 by a mirror 8 and split into two laser beams. One of the split laser beams is guided to the acousto-optic modulator 10, and the other laser beam is guided to the acousto-optic modulator 12 via the mirror 11. Here, the pit signal from the formatter 13 to the acousto-optic modulator 10 and the acousto-optic modulator 12
The acousto-optic modulators 10 and 12 modulate the laser light according to the pit signal and the groove signal, respectively.

The modulated laser light from the acousto-optic modulator 10 passes through the beam splitter 14 and is guided to the recording lens 15, and is condensed by the recording lens 15 so that header information is formed on the photoresist master 16 in the form of pits. Be recorded. At the same time, the laser light emitted from the acousto-optic modulator 12 is guided to the recording lens 15 via the mirror 17 and the beam splitter 14, and is condensed by the recording lens 15 to form a tracking guide groove on the photoresist master 16. It is formed. The photoresist master 16 is rotating at a constant speed, and by simultaneously irradiating the pit signal and the laser beam of the guide groove by the same operation, the photoresist master 16 is rotated.
The header information and the guide groove are formed from the innermost circumference to the outermost circumference.

FIG. 4 shows the structure of a sector. Each sector is composed of a header information section having a length of 71 bytes in which header information is recorded by pits, and a user data section of 9960 bytes for a user to record data. The modulation code of 1-7 RLL is used for both the header information section and the user data section. These sectors are formed continuously on the disk in a spiral manner with a gap therebetween, and only the guide groove for tracking is formed in the gap. The track pitch is, for example, 0.9 μm.

As shown in Table 1, the used area of the disk is divided into zone 11 from zone 0 to zone 10, and 15 sectors are arranged in one zone in zone 0 at the innermost periphery.
The outermost zone 10 has 25 sectors per round. Within each zone, the sector length is the same,
The arrangement of the sectors is adjusted such that the width of the gap between the sectors is increased toward the outer periphery and the sectors are arranged in parallel between adjacent tracks. The linear recording density of the user data section is four times the linear recording density of the header information section. Further, Table 1 shows the radial position of each zone, the number of sectors per round, the length of the sector of each zone, the length of the gap between the sectors of each zone, the linear recording density of the header information section, and the line of the user data section. This shows the recording density.

[0020]

[Table 1]

Next, after developing the photoresist master 16 thus formatted, a Ni film is formed on the photoresist layer by sputtering, and the Ni film is plated with Ni by an electroforming method. The stamper was created by processing the diameter. Subsequently, the stamper was mounted on a mold of an injection molding machine, and a polycarbonate resin was injection molded to have a diameter of 90 m.
m, an inner diameter of 15 mm, and a board thickness of 1.2 mm were duplicated.
An 80 nm-thick SiN layer was formed as a light interference layer on this substrate by a sputtering method, and subsequently, a GdF layer was formed as a first magnetic layer.
The eCo layer is 30 nm, the DyFe layer is 10 nm as the second magnetic layer, and the TbFeCo layer is 80 n as the third magnetic layer.
m, a 50 nm SiN film was sequentially formed as a protective layer, and finally an ultraviolet curable resin was applied as a protective film by spin coating, and then cured by irradiating ultraviolet rays to produce an optical information recording medium. This recording medium is disclosed in Japanese Patent Application Laid-Open No. 6-29049.
No. 6 discloses a domain wall motion type magneto-optical medium.

Next, using the recording / reproducing apparatus shown in FIG.
Recording and reproduction of signals were performed on the optical information recording medium manufactured as described above, and an experiment for confirming recording and reproduction was performed. In FIG. 5, reference numeral 501 denotes an optical information recording medium manufactured by the above manufacturing method. Reference numeral 502 denotes an optical pickup for recording / reproducing a magneto-optical signal, reference numeral 503 denotes a signal reproducing circuit for reproducing data from a reproduction signal detected by the optical pickup 502, and reference numeral 520 denotes an optical information recording medium 501 by a magnetic field modulation method.
A recording magnetic field generator 522 for recording information on a laser drive circuit 522 for driving a recording / reproducing laser.
Is a CPU for controlling the system.

The optical pickup 502 includes a recording / reproducing laser light source 504, a collimating lens 505, a beam splitter 506 with a beam shaping unit, an objective lens 507, an actuator 508, a beam splitter 509, and a convex lens 5.
10, cylindrical lens 511, servo sensor 51
2. It is composed of a birefringent crystal 513, a convex lens 514, and an RF sensor 515. In a servo control circuit (not shown), a focus error signal and a tracking error signal are generated based on the output signal of the servo sensor 512, and the actuator 508 is controlled based on the focus error signal and the tracking error signal, thereby controlling the recording layer of the rotating optical information recording medium 501. So that the light beam from the laser light source 504 is focused on
Focus control and tracking control are performed so as to follow the track of the recording medium 501. The output signal of the RF sensor 515 is supplied to the signal reproducing circuit 503, and the recorded information is reproduced by performing predetermined signal processing in the signal reproducing circuit 503 as described later.

Here, a recording light beam is emitted from the optical pickup 502 while the recording medium 501 is rotated at a constant linear velocity of 2 m / s by driving a spindle motor (not shown), and at the same time, recording is performed from the recording magnetic field generator 520. By applying a magnetic field modulated according to a signal, information was recorded by a magnetic field modulation method. That is, the CPU 52
3 controls the laser drive circuit 522 to
04 irradiates a recording light beam from the CPU 523 with predetermined recording data from the 1-7 RLL encoder 521.
Then, a predetermined magnetic field was applied by driving the recording magnetic field generator 520 with the modulation signal, thereby recording predetermined information. The recording laser power was 5 mW, and the recording magnetic field strength was 200 Oe. Further, as shown in Table 1, recording was performed in all areas from the innermost zone to the outermost zone.

Next, the information thus recorded was reproduced. At the time of reproducing information, reproduction by domain wall motion as described in JP-A-6-290496 is performed.
The output of the F sensor 515 is differentially detected by the amplifier 516 in the signal reproducing circuit 503 to obtain a reproduced signal having a sharp rise and fall, and the reproduced signal is equalized by the equalizer 517, and the comparator 518
, And demodulated by a 1-7 RLL decoder 519 to generate reproduced data. The reproduction power was 2.0 mW. As a result of performing recording and reproduction in this manner, the innermost recording radius position of the recording medium 501 is 23.72.
mm, the recording laser power, recording magnetic field intensity, reproduction laser power, characteristics of the equalizer 517, etc. can be satisfactorily recorded and reproduced in all regions from the outermost recording radius position 41.00 mm without any change. .

(Embodiment 2) Next, only a guide groove for tracking is formed at the boundary of each zone, one buffer track in which no sector is arranged is provided, and other optical information is the same as in Embodiment 1. A recording medium was produced. When a signal was recorded and reproduced on this recording medium using the recording / reproducing apparatus shown in FIG. 5, the recording laser power, the recording magnetic field intensity, the reproducing laser power, the characteristics of the equalizer 517, etc. were similarly changed without any change. , Medium radius 23.72mm
It was confirmed that information could be recorded / reproduced satisfactorily in all the regions from a radius of 41.00 mm. Further, Example 1
On the other hand, in the case of the medium, there were two tracks at the boundary of each zone where crosstalk from pits recorded in the header information section adversely affected the signal reproduction of the user data section. In the medium of Example 2, the crosstalk from the pits recorded in the header information section adversely affects the signal reproduction of the user data section in only one track of the buffer track. Can be improved.

Example 3 Next, a polycarbonate substrate having the same format as in Example 1 was manufactured. FIG. 4 shows the structure of a sector. Each sector is composed of a header information section having a length of 71 bytes in which header information is recorded by pits, and a user data section of 4980 bytes for a user to record data. For the header information section and the user data section, 1-7 RLL is used for the modulation code. These sectors were formed on the disk continuously in a spiral shape with the gap interposed, and only the guide groove for tracking was formed in the gap.

The track pitch was 0.9 μm. Also, as shown in Table 2, the disk divides the used area into 11 zones of zone 0 to zone 10, and arranges 15 sectors per circumference in zone 0 at the innermost periphery and zone 10 at the outermost periphery. Has 25 sectors per round. In each zone, the length of the sector is the same, the width of the gap between the sectors is increased toward the outer periphery, and the arrangement of the sectors is adjusted so that the sectors are arranged in parallel between adjacent tracks. The linear recording density of the user data section is four times the linear recording density of the header information section. Further, Table 2 shows the radial position of each zone, the number of sectors per round, the length of the sector of each zone, the length of the gap between the sectors of each zone,
It shows the linear recording density of the header information section and the linear recording density of the user data section.

[0029]

[Table 2]

As described in Japanese Patent Application Laid-Open No. 5-81717, the magnetization of the reproducing layer shifts from in-plane magnetization to perpendicular magnetization only in a region where the temperature becomes higher than a certain temperature due to laser beam irradiation during reproduction. Only in the portion where the perpendicular magnetization has been transferred, the signal recorded in the recording holding layer in advance is transferred to the reproducing layer, and in a region below a certain temperature, the reproducing layer having in-plane magnetization functions equivalently to an equivalent mask, A magneto-optical recording film capable of super-resolution reproduction was laminated. In addition, a light transmitting layer, a reproducing layer, a recording layer, and a protective layer are sequentially laminated on a transparent substrate made of polycarbonate, and finally, an ultraviolet curable resin is applied as a protective layer by spin coating and then irradiated with ultraviolet light to cure. An optical information recording medium of Example 3 was manufactured.

The reproducing layer has a high Curie temperature, has a compensation temperature between room temperature and the Curie temperature, and exhibits in-plane magnetization at room temperature, but shifts vertically when the temperature rises to a predetermined temperature or more by light beam irradiation. GdFeCo (film thickness 4)
0 nm). The compensation temperature of the reproducing layer was 100 ° C., and the Curie temperature was 300 ° C. or higher. Since the recording layer has a large perpendicular magnetic anisotropy and it is necessary to stably maintain minute magnetic domains, it is formed of TbFeCo (film thickness: 80 nm), the Curie temperature is 230 ° C., and the coercive force is 15 kOe or more. . The light transmitting layer and the protective layer were formed of SiN.

Next, signals were recorded and reproduced on the magneto-optical information recording medium of Example 3 using the recording and reproducing apparatus shown in FIG. At this time, while the optical information recording medium was rotated at a constant linear speed of 4 m / s by a spindle motor, information was recorded by a magnetic field modulation method, and then the recorded signal was reproduced. The recording laser power during recording was 7 mW, the recording magnetic field strength was 250 Oersted, and the reproduction laser power during reproduction was 2.5 mW. Also in this case, it was confirmed that information could be recorded and reproduced well in all regions from a radius of 23.72 mm to a radius of 41.00 mm without changing the recording laser power, recording magnetic field intensity, reproducing laser power, and the characteristics of the equalizer. did it.

FIG. 7 is a plan view showing another embodiment of the optical information recording medium of the present invention. In FIG. 7, the entire recording area of the recording medium 1 is defined as one zone, and a gap 2 is defined at the boundary of each zone.
Is provided. The recording medium 1 is divided into a plurality of blocks 3 by the gap 2. The width of the gap 2 becomes wider toward the outer periphery. In each of the blocks 3 sandwiched by the gap 2, the sector length is the same, and the sectors are arranged in parallel between adjacent tracks.

The structure of the block 3 sandwiched between the gaps 2 is the same as that of FIG. 2; a header information section 5 is provided at the head position of each sector, and a user data section 6 for recording and reproducing data subsequently. Is provided. Even with such a configuration, although the recording capacity is reduced, the sector length is the same and the sectors are arranged in parallel between adjacent tracks. It does not leak into the part. Further, since the length of the sector is substantially the same at the inner and outer peripheral portions, the length of the recording mark is constant regardless of the radial position,
Playback signal processing can be easily performed.

[0035]

As described above, according to the present invention, the length of the sector is made substantially the same regardless of the radial position of the recording medium,
In addition, since the sectors are arranged in parallel between adjacent tracks, the frequency characteristics of the reproduced signal do not change depending on the radial position of the recording medium, and the circuit for processing the reproduced signal can be simplified. Further, information can be accurately reproduced without crosstalk from the header information part leaking into the user data part. Furthermore, when used for a medium capable of super-resolution reproduction, complicated control of the light beam intensity is not required, and the medium can be suitably used for a super-resolution reproduction medium.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of an optical information recording medium of the present invention.

FIG. 2 is an enlarged view showing a part of the recording medium of FIG. 1;

FIG. 3 is a view showing a photoresist master exposure apparatus used to manufacture the recording medium of FIG. 1;

FIG. 4 is a diagram showing an example of a sector structure.

FIG. 5 is a block diagram showing an example of a recording / reproducing apparatus for recording / reproducing information on / from the recording medium of FIG.

FIG. 6 is a diagram showing another example of a sector structure.

FIG. 7 is a plan view showing another embodiment of the optical information recording medium of the present invention.

[Explanation of symbols]

 Reference Signs List 1 optical information recording medium 2 gap 3 block 4 track 5 header information section 6 user data section

Claims (5)

[Claims] 1. In a disk-shaped optical information recording medium in which a plurality of tracks are formed in a spiral or concentric shape, each track is divided into a plurality of sectors by a gap, and the width of the gap is formed wider toward the outer periphery. An optical information recording medium characterized in that the sectors have substantially the same length, and the sectors are arranged in parallel between adjacent tracks. 2. A disk-shaped optical information recording medium in which a plurality of tracks are formed in a spiral or concentric shape, and an information recording area is divided into a plurality of zones in a radial direction.
Each zone is divided into a plurality of blocks by a gap, and the width of the gap is made wider toward the outer periphery, so that the sector length is substantially the same in the same block, and the sectors are arranged in parallel between adjacent tracks. An optical information recording medium, wherein: 3. The optical information recording medium according to claim 2, wherein a buffer track is provided between said zones. 4. The optical information recording medium according to claim 1, wherein header information for identifying the sector is recorded in a pit at a head position of the sector. 5. The optical information recording medium according to claim 1, wherein the area for recording the information of the sector comprises a recording layer capable of super-resolution reproduction.