JPH05101540A - Optical disk - Google Patents

Abstract

PURPOSE:To record with high density and to obtain interchangeability with a conventional disk by forming tracks with different pitchs in the range of the end part of a track area and in an other radius range. CONSTITUTION:An area 3 forming the track of an optical disk is divided to a user recording area 1 and a part 2 basing on a format standard. The part 2 complies with the conventional ISO format standard, and the track pitch of the part 2 is made 1.6mum, and a read-in track and a control track area, etc., are provided in the part 2. Then, the track pitch of the user area 1 is made 1.0mum, and the number of a sector is made 40 sectors per 1 track. Thus, the data of 320MB are stored in one disk (86mm diameter). Further, since the information of the user area is read based on the conventional format standard by a drive and recorded and reproduced similarly with the conventional format, the interchangeability of the disk is held.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc medium used in an optical recording / reproducing apparatus.

[0002]

2. Description of the Related Art A thin film made of a light-sensitive material is formed on a disk-shaped substrate, the disk is rotated, and light such as a laser is condensed and irradiated on the disk to make the light-sensitive material uneven. , Signals are recorded at high density by causing changes in the direction of magnetization, reflectance, and the like.

Specifically, as a write-once optical disc capable of recording only once, a recording film made of a metal having a low melting point or an organic dye having a high reflectance is used to form pits by laser light; As an optical disk capable of recording data as many times as possible, a magnetic metal thin film having perpendicular magnetic anisotropy is used as a recording film, and recording is performed by changing the direction of magnetization by laser light and an external magnetic field. The magneto-optical disk is used for reproduction by utilizing the change in the polarization direction of the laser light due to the effect, and recording is performed by causing the change of crystal-amorphous by the heating by the laser light, and the change in the reflectance is used. A phase-change type optical disc and the like for reproducing by reproducing have been developed and put into practical use.

As an optical recording system using these optical disks, various attempts have been made in order to secure a larger storage capacity. As one of the methods, it is considered to reduce the beam spot diameter on the surface of the recording film by shortening the wavelength of the laser beam to perform high density recording, and a recording film suitable for this method was developed. There is. When such a method is used, not only the length of the recording mark in the recording direction is shortened but also the width in the direction perpendicular to the recording mark is reduced. Therefore, the track pitch is reduced within a range in which crosstalk can be avoided, and the recording surface is reduced. It is possible to improve the density. That is, according to the current ISO format standard of the write-once and rewritable optical discs, the track interval is 1.6 μm in the continuous servo system and 1.5 μm in the sample servo system, but the short wavelength as described above When a drive having a laser light source is used, the track pitch of the optical disk can be made smaller than the above and the recording density can be increased.

[0005]

Generally, the seek operation of an optical disk drive is usually performed by a combination of a coarse seek operation by a coarse motion motor system and a fine seek operation by an actuator in an optical pickup. The rough seek operation is generally performed by detecting the optical pickup position with a position detector such as a linear encoder. Therefore, when the track pitch is narrowed for the above-mentioned purpose, the relationship between the track address and the radial position is different from that of the disk according to the conventional format standard, so that there is a problem in detecting the track address during rough seek of the drive.
That is, the compatibility of the drive with the conventional disc cannot be ensured.

The problem to be solved by the present invention is to provide an optical disk capable of high recording density and having compatibility with a disk according to a conventional format standard for one drive. .

[0007]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, have determined that a predetermined radius range corresponding to the end of the area having the track of the disk and another radius range. It was found that it would be better to form tracks with different pitches.

That is, the track pitch in the radius range corresponding to the end of the area having the track is set to I of the optical disk.
1.6 in continuous servo system according to SO format standard
.mu.m, 1.5 .mu.m in the sample servo system, and in a range other than this, that is, in the user area, the track pitch in this area is reduced according to the beam spot diameter as described above, and information on the track pitch in this user area is set. Is recorded as data in the control track portion included in the radius range corresponding to the end portion of the area having the above-mentioned track, thereby having a higher recording density than before and complying with the conventional ISO format standard. Compatibility with the disc can be ensured. Also,
When a laser with a short wavelength is used, the diameter of the recording marks can be reduced, the distance between the marks can be shortened, and high-density recording can be performed. In response to this, the number of sectors per track is increased. Although it is possible to increase the recording density, the number of sectors only in the user area is increased like the track pitch, and the number of sectors in the radius range corresponding to the above-mentioned end is obtained according to the ISO format standard. By describing the same in the control track section, it is possible to ensure compatibility with conventional optical disks.

[0009]

EXAMPLES Specific examples of the present invention will be described below.

FIG. 1 shows an example of an embodiment of the optical disc of the present invention.
It was shown to. The diameter of the optical disk substrate used in this embodiment is 8
6mm, track radius is 23mm at the innermost circumference and 4 at the outermost circumference
It is 1 mm. In this disk substrate, the track pitch in the range of radius 23 mm to 24 mm is 1.6 μm, and in this range, the format standard of 90 mm rewritable optical disk (ISO / SC23 / WG2CD10090)
In accordance with the above, a lead-in track, a control track area, etc. were provided. Here, information that the track pitch of the user area is 1.0 μm and the number of sectors is 40 sectors per track is recorded in the control track area according to the above format standard. Next, in the subsequent user area, the track pitch was 1.0 μm, the track address was 0 to 15999, and the number of sectors was 40 sectors per track. Furthermore, the area outside this (radius 40 mm to 41 mm, track address 1600
0 to), the track pitch was again set to 1.6 μm, and the number of tracks, radius range, etc., in accordance with the format standard, were the same as the radius range from 23 mm to 24 mm except for the track address.

A magneto-optical recording film having a general structure is formed on an optical disk substrate on which the above preformat is recorded to obtain a magneto-optical disk medium.

A semiconductor laser of a pickup of an optical disk drive for recording / reproducing this disk has a wavelength of 67.
The rotation speed was 0 nm and the rotation speed was 3600 rpm.

Next, a method of positioning the pickup of the optical disk drive on the target track when the above-mentioned magneto-optical disk is used will be described.

When the optical disk cartridge is inserted into the drive, the pickup first accesses an area having a track pitch of 1.6 μm on the inner peripheral portion of the disk. In this area, since the track pitch and the number of sectors per track are the same as those of the conventional disc according to the format standard, the reproduction can be performed similarly to the conventional disc. Next, the drive reads the control track portion in this area and determines the number of tracks (track pitch) in the user area and the number of sectors per track. The relationship between the radial position of the disc and the track address is calculated from this track pitch information, and the coarse pickup motor can move the optical pickup to the vicinity of the target track during the rough seek. The inter-mark modulation method was used as the recording method, and the mark detection window width was switched based on the information on the number of sectors per track in the control track area.

By the above method, the data storage capacity of the user area of one disk is 320 MB,
Larger capacity was achieved. In addition, the above-mentioned optical disc drive is a system in which the information in the user area is once read in the control track area based on the conventional format standard, and the track pitch and the number of sectors are judged and switched based on this information. Similarly, recording / reproducing can be performed on a disc based on, and the compatibility of the disc can be maintained.

[0016]

The optical disk of the present invention is capable of high-density recording and has compatibility with a disk according to the conventional format standard for one drive.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

[Explanation of symbols]

 1 User recording area 2 Part conforming to the format standard 3 Area where tracks are formed

Claims (4)

[Claims] 1. An optical disc in which tracks are formed in advance, and a track interval is different between a predetermined radius range corresponding to an end of an area having a track of the disc and another radius range. 2. The optical disk according to claim 1, wherein a track interval in a radius range other than the predetermined radius range corresponding to the end of the area having the tracks is narrower than a track interval at the end. 3. The optical disk according to claim 1, wherein a radius range other than the predetermined radius range corresponding to the end of the area having tracks is the user recording area. 4. The optical disk according to claim 1, wherein the number of sectors is different between the predetermined radius range corresponding to the end of the area having tracks and the other radius ranges.