JPH1040655A - Optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand a data recording area, in the data area of the outermost and innermost circumferences of a disk, by recording data with a recording density made slightly lower than that in other data area. SOLUTION: This optical disk is such that a data recording area is divided into multiple zones according to the radial position, in the optical disk equipped with the data recording area consisting of data tracks arranged concentrically or spirally. Then, assuming that (k) is any number between 1 and 50, and that N(k) a sector number per revolution; with (k) in the range from 1 to 3, if (k) is 3, N(k+1)>N(k)+1; if (k)=1 or 2, N(k+1)=N(k)+1. In addition, with (k) in the range from 4 to 47, N(k+1)=N(k)+1; with (k) in the range from 48 to 49, if (k) is 48, N(k+1)<N(k)+1; and if (k) is 49, N(k+1)=N(k)+1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk, and more particularly, to an optical disk with an increased recording capacity.

[0002]

2. Description of the Related Art In a magneto-optical disk, a magneto-optical recording film is formed on a substrate having a groove or the like formed by injection molding from a stamper or the like, and a magnetic recording mark recorded on a land of the magneto-optical recording film, for example, is formed. This is an optical recording medium that is read by laser light.

Generally, a user recording area of a magneto-optical disk is divided into sectors at predetermined intervals in a circumferential direction. Conventionally, a CAV (Constant Angular Velular) that keeps the rotation speed of a magneto-optical disk constant regardless of the inner and outer circumferences of the disk.
ocity) method. In this case, the number of sectors per revolution is constant inside the zone at any radial position on the disk. However, in recent years,
By changing the number of rotations (rotation speed) of the disk for each predetermined zone and thereby changing the number of sectors per rotation for each zone, the number of sectors per rotation is increased toward the outer periphery of the disk. An M (Modified) CAV system with an increased overall recording capacity has been used.

By the way, in general, in a magneto-optical disk,
Oxidation of the edge of the magnetic recording film, large birefringence at the edge of the hole in the substrate due to the process of manufacturing the substrate, large birefringence at the edge of the substrate due to the stress generated when attaching the hub, and during rotation The recording characteristics on the side closest to the outermost or innermost periphery of the magnetic recording film are inferior to the recording characteristics in other parts due to large surface runout or track runout of the substrate at the outermost periphery of the disk. It has been known.

FIGS. 7 and 8 show the relationship between the radial position and the surface deflection acceleration (acceleration in the direction perpendicular to the recording surface) on the rotating optical disk, and the relationship between the radial position and the track deflection acceleration (the acceleration in the direction parallel to the recording surface). ).
As shown in these figures, the radial position 60 of the disk
At a radial position on the outer peripheral side of mm, the accelerations in the direction perpendicular to and parallel to the recording surface increase, causing a focus shift and a track shift of the recording and reproducing spots, which greatly affects the characteristics of magneto-optical recording. is there.

FIG. 9 shows a magneto-optical disk in which the radius of the inner hole of the substrate is 7.5 mm, the radius of the inner peripheral edge of the disk is 12.5 mm, the radius of the outer peripheral edge is 65 m, and the track pitch is 1.0 μm. FIG. 7 is a graph showing an example of a relationship between a radial position and a C / N characteristic (CN ratio: dB) when a mark having a mark length of 0.64 μm is recorded. This shows how the recording characteristics deteriorate at the edge of the magnetic disk. As shown in the figure, the CN ratio is significantly reduced at the inner peripheral position at a radial position of 30 mm or less and at the outer peripheral position at a radial position of 60 mm or more.

For this reason, in the magneto-optical disk, the CA
In either the V or MCAV system, a magneto-optical recording film is generally formed on the substrate in the vicinity of the outermost or innermost circumference of the disk, about 1 to 2 mm from the outermost or innermost circumference. In addition, various measures have been taken such as not to provide a magneto-optical recording area in the magneto-optical recording film within about 1 to 2 mm from the outermost periphery of the magneto-optical recording film.

[0008]

The demand for an increase in the recording capacity of a magneto-optical disk has been increasing with the improvement of the recording capacity of other types of recording media. However, there is a limit to the increase in the recording capacity only by improving the characteristics of the magnetic recording film and the performance of the recording / reproducing apparatus.

In view of the above, it is an object of the present invention to provide an optical disk capable of increasing the recording capacity without depending on the improvement of the characteristics of the magnetic recording film.

[0010]

According to a first aspect of the present invention, there is provided an optical disk having a data recording area comprising data tracks arranged concentrically or spirally. The data recording area is divided into a plurality of M zones according to the radial position, and k is an integer from 1 to M and N
(K) is the number of sectors per rotation contained in the k zone, the first k ₁ zone to a predetermined zone near the outermost of the M zone, and, when the L a predetermined positive integer, each The number of sectors per rotation of the zone is represented by k from 1 to k ₁ −
In the range of 1, N (k + 1) = N (k) + L, and in the range of k from k ₁ to M−1, at least one k has N
Provided that (k + 1) <N (k) + L
(K + 1) ≦ N (k) + L.

According to a second aspect of the present invention, in the optical disk of the above-described type, the data recording area is divided into a plurality of M zones according to the radial position, and k is an arbitrary integer from 1 to M. N (k) is the k-th
And the number of sectors per revolution included in the zone
₂ zone innermost first zone or innermost given zone close to the first zone, the first k ₁ zone to a predetermined zone near the outermost of the M zone, and the L predetermined positive When it is an integer, the number of sectors per rotation of each zone is k
Is in the range 1 to k ₂ , at least one k has N
On condition that (k + 1)> N (k) + L, N
(K + 1) ≧ N ( k) + L, the k is the range of k ₂ +1 of k ₁ over 1, N (k + 1) = N (k) + L, and k is k ₁
To M−1, N (k
+1) <N (k) + L, provided that N (k
+1) ≦ N (k) + L.

[0012] In the optical disk of the present invention is preferably the zone of the k ₁ is the outer peripheral edge of the disk to a position within 4 mm, also, the first k ₁ zone within 2mm from the outer peripheral edge portion of the recording film Preferably, it is in position. In this case, good recording characteristics are obtained in each zone, and
A large recording capacity can be obtained. The k ₂ zone within 7.5mm from the inner peripheral edge of the disk, the preferred embodiment of the invention to from the disk substrate hole edges positioned within 22 mm, further, the k ₁ and k _2, k It is also preferable to select ₁ = M−1 and k ₂ = 1.

A control data area and a defect management area for an optical disc can be provided in the outermost Mth zone or the innermost first zone. In this case, highly reliable recording can be performed in these zones. Therefore, it is unlikely that access to data on the entire disk becomes impossible due to indecipherability of control data and defect management information.

In the optical disk of the present invention, by adopting the above configuration, the recording capacity of the disk can be increased without impairing the recording reliability of the entire disk.

[0015]

Embodiments of the present invention will be described with reference to the drawings. FIGS. 1A and 1B are a schematic plan view and a sectional view, respectively, of a magneto-optical disk constituting an optical disk according to an embodiment of the present invention. In FIG. 1, the magneto-optical disk 10 comprises a circular hub portion 11 at the center of the disk and an annular disk portion 12 disposed radially outside the hub portion. The outer radius of the disk portion 12 is, for example, 65.5.
mm, and its inner diameter is, for example, about 25 mm. The hub portion 11 is provided with, for example, about 15
It is bonded to the disk substrate using the inner hole of mm. The disk portion 12 comprises an annular transparent substrate 13 and a magneto-optical recording film 14 and a protective film 15 formed thereon by sputtering and coating, respectively.

The magneto-optical recording film 14 has a radially outer position approximately 9 mm away from the inner peripheral edge of the disk portion 12 as an inner peripheral edge and a radially inner position approximately 2 mm away from the outer peripheral edge of the disk portion 12 as an outer peripheral edge. It is an annular membrane. The magneto-optical recording film 14 is disposed on a user data area (not shown) for recording data desired by the user, and a control data area (not shown) on the outer and / or inner sides thereof for recording physical characteristic information of the disk. Consisting of

Data tracks are previously formed on the magneto-optical recording film 14 at a pitch of 0.85 μm according to the format at the time of manufacturing the magneto-optical disk. The data track has 50 zones (bands) according to its radial position
And magneto-optical recording by the MCAV method is adopted. Each zone has a predetermined number of sectors per one rotation according to the present invention, and mark edge recording is performed in each sector by the user using the (1,7) RLL method.

FIG. 2 shows the number of sectors for each band in the magneto-optical disk of FIG. The data recording area is
The radial position is in the range from 27.00 mm to 63.00 mm, the total number of zones is 50, and the number of sectors per rotation in each zone is 37 at the minimum and 84 at the maximum. The number of sectors per rotation increases monotonically as a whole toward the radially outer circumference, and partial corrections are made at the outermost and innermost circumferences. The recording capacity of each sector is 1410 bytes. Of these, user data is recorded in 1024 bytes.

The innermost first band has a radial position of 27.0.
It starts at 0 mm and ends at a radial position of 27.72 mm. The minimum number of sectors per rotation of the first band is 37. The second band starts at a radial position of 27.72 mm and is 2
Ends at 8.84mm. The number of sectors per rotation of the second band is 38, which is one more than the number of sectors of the first band.
Hereinafter, the outermost 50th band has a radial position of 62.28 mm.
And ends at 63.0mm. The number of sectors per one rotation on the outermost circumference is 84. The data recording capacity of the magneto-optical disk of this embodiment is 2.705 gigabytes (GB) in total.

Most zones have one more sector per revolution than the adjacent zone radially inward of the zone, and
The recording density in each zone is set to be substantially the same. This means that the minimum mark length of the marks recorded in each zone is 0.528 μm to 0.53 μm.
1 μm and the maximum mark length is 0.1 μm.
It is also indicated by being in the range from 555 μm to 0.538 μm.

However, in the forty-eighth zone closest to the outermost circumference and the forty-ninth zone on the outer circumference side adjacent thereto, the number of sectors per rotation is the same as each other.
The number of sectors per unit area in the zone near the outermost periphery including the zone and the 50th zone is smaller than that in the zone inside in the radial direction. As a result, the recording density of the zone near the outermost periphery is set low. In addition, the difference between the number of sectors per revolution between the third zone and the fourth zone near the innermost circumference is set to 2. Therefore, in the zone near the innermost circumference from the third zone to the first zone, the other zone is different. The number of sectors per unit area is smaller than that of the section. As a result, the recording density is set low even in the zone near the innermost circumference.

In this embodiment, in the configuration of the present invention,
This is an example in which k ₁ = 48 and k ₂ = 3. In this embodiment, k is an arbitrary number from 1 to 50, and N (k) is the number of sectors per rotation.
Is 3, N (k + 1)> N (k) +1, and k
For = 1 or 2, N (k + 1) = N (k) +1. When k is in the range of 4 to 47, N (k + 1) =
N (k) +1, where k is 48 to 49, when k is 48, N (k + 1) <N (k) +1, and when k is 49, N (k + 1) = N (k) As +1.

As described above, in the zones near the outermost circumference and the innermost circumference, the number of sectors per rotation is reduced and the recording density is set low, so that the properties of the recording film are deteriorated at the outermost circumference and the innermost circumference. Good recording characteristics can be obtained even in the zone near the periphery. By making these data recording areas, the recording area on the magneto-optical disk can be expanded.

As a modification of this embodiment, the zones 48 and 49 having the same number of sectors per rotation may be handled as one zone, and may be handled as a zone configuration as shown in FIG. In particular, when the sum of the widths of the two zones is smaller than twice the width of the other zones, the change in the recording / reproducing characteristics in the two zones is small, and therefore it is preferable to treat them as one zone.

FIGS. 3 and 4 are views similar to FIG. 2 of the magneto-optical disks of Comparative Examples 1 and 2, respectively, for comparison with the zone configuration of the magneto-optical disk of the above embodiment. .

Comparative Example 1 of the configuration shown in FIG. 3 has a configuration similar to the zone configuration employed in a conventional commercially available magneto-optical disk, for example, and has magneto-optical recording characteristics lower than those of other portions. No data recording area is provided near the outermost and innermost circumferences of the film. Therefore, the data recording area is
Radial positions are set from 30.0 mm to 60.01 mm, so that the total number of zones remains at 42. The number of sectors per rotation in each zone monotonically increases toward the outer periphery of the disk, and each time the zone number increases by one, the number of sectors per rotation increases by one. The number of sectors per rotation is 4 in the innermost zone.
2. 83 in the outermost zone. In Comparative Example 1, the minimum mark length of the recording mark is 0.530 μm, and the maximum mark length is in the range from 0.537 μm to 0.543 μm. The shortest recording mark length is fixed at 0.53 μm in consideration of recording characteristics. The recording capacity of the comparative example 1 is 2.259 GB, which is about 83% of the above embodiment.
It is. That is, according to the above embodiment, the recording capacity is increased by about 20% as compared with the conventional magneto-optical disk.

In the comparative example 2 shown in FIG. 4, the zone configuration is the same as the zone configuration of the magneto-optical disk of the above embodiment, and a data area is provided in a range from a radial position of 27.00 mm to 63.00 mm. ing. However, as in Comparative Example 1 shown in FIG. 3, the number of sectors in each zone monotonically increases toward the outer periphery of the disk. With such a configuration, the recording mark has a minimum mark length in a range from 0.527 μm to 0.531 μm and a maximum mark length in a range from 0.538 μm to 0.542 μm. The recording capacity of Comparative Example 2 having the above configuration is 2.7.
This is 11 GB, which is only a slight difference of about 0.2% as compared with the recording capacity of the embodiment.

The magneto-optical disk of the embodiment and Comparative Example 2
These were actually manufactured for the magneto-optical disk of
The densest pattern, which is a repetition of the shortest mark / shortest space in each zone, was recorded on these, and their characteristics were compared.
The recording of the densest pattern was performed on the land of the magneto-optical recording film, and the polarization direction of the laser was parallel to the groove. In comparison of the recording characteristics, the reproduction laser wavelength to be evaluated was set to 680 n.
m, the numerical aperture of the objective lens of the evaluator was 0.55, the linear velocity of the disc was 9.42 m / s, and the magnetic field strength during recording was 23.
9 kA / m (= 300 Oe (Oe)), the duty ratio of the laser power at the time of recording is 37.5%, the laser power at the time of erasing is 7.0 mW, the bottom output of the laser power at the time of recording is 1.0 mW, and The laser output at the time of reproduction was 1.5 mW, and the recording power was CN at each radial position.
The power that maximizes the ratio was selected.

In the comparative example, the characteristics are measured by sampling a part of the entire area of the disk. In the embodiment, the number of sectors per rotation differs from the number of sectors per rotation in the comparative example. Near the first to third
The band and the 48th to 50th bands were measured. The results are shown in FIGS. FIG. 5 shows data obtained by measuring the carrier level CL and the noise level NL. FIG. 6 shows the CN ratio (C / N) obtained based on the data.
Is a comparison result. Generally, when the CN ratio is lower than 45 dB, a reproduction error occurs. Therefore, a CN ratio of 45 dB or more is required.

In FIG. 5, the carrier level CL has a relatively large value in the embodiment on both the inner side and the outer side of the disk, and the noise level NL is
On the inner peripheral side, almost the same value was obtained, and on the outer peripheral side, a smaller value was obtained in the embodiment. Thus, as shown in FIG. 6, in the magneto-optical disk of the embodiment, the CN ratio sufficiently satisfies the required 45 dB or more even in the zone of the outer peripheral portion and the inner peripheral portion. , And the CN ratio was lower than 45 dB in a part of the outer peripheral part, and lower than that of the embodiment in the inner peripheral part.

When recording / reproducing a conventional magneto-optical disk having a track pitch of 0.85 μm with an evaluator having a wavelength of 680 nm and a numerical aperture of an objective lens of 0.55, if the recording mark length becomes shorter than 0.6 μm. In the middle area of the disk, the CN ratio is lower than 47 dB, and at the inner hole edge of the disk substrate, the inner edge and the outer edge of the disk, the CN ratio is further lower by 1 to 2 dB, and therefore, 45 dB or less. Could be. Therefore, the present invention is particularly effective for an optical disk having a minimum mark length of 0.6 μm or less.

The crosstalk amount from the adjacent track is -30 dB or more when the track pitch is 0.9 μm or less, and − when the track pitch is 0.85 μm.
25 dB. When the crosstalk amount is -30 dB or more, the recording data becomes susceptible to the recording data of the adjacent track, and the margin of the recording characteristics is reduced. Therefore, the present invention is particularly effective for an optical disk having a track pitch of 0.9 μm or less.

In general, in an optical disc, a defect management area for recording replacement information of defective sectors on the disc is often recorded on an outer peripheral portion and / or an inner peripheral portion of the disk due to restrictions on its arrangement. In this case, if the defect management information recorded on the outer peripheral portion or the like cannot be decoded, it is impossible to access the entire area of the disc. That is, in the magneto-optical disk of Comparative Example 2, if the outer peripheral portion is used as a defect management area, data on the entire disk may not be deciphered due to a low CN ratio in the outer peripheral portion.

As described above, in the magneto-optical disk according to the embodiment, unlike the conventional ZCAV recording method, the outermost and innermost data areas of the disk record data more than the other data areas. A configuration is employed in which data is recorded at a slightly lower density, and the outermost and innermost portions are used as data areas. By adopting such a configuration, the data recording area is expanded as compared with the conventional magneto-optical disk, and the deterioration of the recording characteristics in these portions, which has been a concern in the past, is prevented. Is obtained.

Although the present invention has been described based on the preferred embodiment, the optical disk of the present invention is not limited to the configuration of the above embodiment, and various modifications and changes can be made from the configuration of the above embodiment. Modified optical disks are also included in the scope of the present invention.

[0036]

As described above, according to the optical disc of the present invention, the recording capacity of the disc is increased by enlarging the recording area, and the recording reliability in the enlarged recording area is the same as that of the other recording areas. Therefore, the present invention has a remarkable effect of providing an optical disk having high reliability and a large recording capacity.

[Brief description of the drawings]

FIGS. 1A and 1B are a plan view and a sectional view, respectively, of a magneto-optical disk constituting an optical disk according to an embodiment of the present invention.

FIG. 2 is a graph showing a zone configuration in the magneto-optical disk according to the embodiment shown in FIG. 1;

FIG. 3 is a graph similar to FIG. 2 for the magneto-optical disk of Comparative Example 1.

FIG. 4 is a graph similar to FIG. 2 for the magneto-optical disk of Comparative Example 2.

FIG. 5 is a graph showing the measurement results of the carrier level and the noise level of each of the magneto-optical disks of the embodiment and Comparative Example 2.

FIG. 6 shows the CN of the magneto-optical disk according to the embodiment and the comparative example 2.
5 is a graph showing a comparison of ratios.

FIG. 7 is a graph showing surface runout acceleration at each radial position of a general optical disc.

FIG. 8 is a graph showing track deflection acceleration at each radial position of a general optical disc.

FIG. 9 shows C at each radial position of a conventional magneto-optical disk.
9 is a graph showing an N ratio.

10 is a graph showing a zone configuration of an example in which the zone 48 and the zone 49 having the same number of sectors per rotation are treated as one zone in the magneto-optical disk of the embodiment of FIG.

[Explanation of symbols]

 Reference Signs List 10 optical disk 11 hub part 12 disk part 13 substrate 14 magneto-optical recording film 15 protective film

Claims (14)

[Claims] 1. An optical disc having a data recording area composed of data tracks arranged concentrically or spirally on a recording layer, wherein the data recording area is divided into M zones according to a radial position, k is an arbitrary integer from 1 to M, N (k) is the number of sectors per rotation included in the k-th zone, k ₁ zone is a predetermined zone close to the outermost M-th zone, and When L is a predetermined positive integer, the number of sectors per rotation of each zone is represented by N (k + 1) = N when k ranges from 1 to k ₁ -1.
(K) + L, and the k is the range of k ₁ of M-1, on condition that at least one of k in N (k + 1) is <N (k) + L, N (k + 1) ≦ N (k) + L An optical disc characterized by comprising: 2. An optical disc having a data recording area composed of data tracks arranged concentrically or spirally on a recording layer, wherein the data recording area is divided into a plurality of M zones according to a radial position, the N (k) as any integer from 1 to M k and the number of sectors per rotation contained in the zone of the k, close the first k ₂ zone to the first zone or the first zone of the innermost given zone, the predetermined zone near the first k ₁ zone outermost of the M zone, and, when the L a predetermined positive integer, the number of sectors per rotation in each zone, from k 1 In the range of k ₂ , at least one k has N
On condition that (k + 1)> N (k) + L, N
(K + 1) ≧ N (k) + L, where k is in the range of k ₂ +1 to k ₁ −1, N (k + 1) = N
(K) + L and k is in the range of k ₁ to M−1, provided that N (k + 1) <N (k) + L for at least one k, N (k + 1) ≦ N (k) + L An optical disc characterized by comprising: 3. The optical disk according to claim 1, wherein the k ₁ -th zone is located at a position within about 4 mm from the outer peripheral edge of the disk. 4. A first k ₁ zone is positioned within about 2mm from the outer peripheral edge portion of the recording film, an optical disk according to claim 1 or 2. 5. in the k ₂ zone is located within about 15mm from the inner peripheral edge of the disk, an optical disk according to claim 2. 6. The k ₂ zone is at a position within about 22mm from the inner hole edge of the disk substrate, optical disk according to claim 2. 7. The optical disc according to claim 1, wherein k ₁ = M−1. 8. The optical disk according to claim 2, wherein k ₂ = 1. 9. The optical disc according to claim 1, wherein a defect management area is provided in the M-th zone. 10. A defect management area provided in a first zone,
An optical disc according to claim 2. 11. The optical disc according to claim 1, wherein the shortest mark length is 0.6 μm or less. 12. The optical disc according to claim 1, wherein the track pitch is 0.9 μm or less. 13. The optical disk according to claim 1, wherein each zone width of the data recording area is substantially the same. 14. The optical disc according to claim 1, wherein two adjacent zones having the same number of sectors per rotation are treated as one zone.