JPH10105969A - Software format device of optical disk and optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce crosstalk and to improve a signal quality further by irradiating an optical disk with laser light from a laser light source for a software format and tracking according to the reflected light. SOLUTION: Laser light modulated by a format signal emitted from a laser light source 2 for a software format signal is made to be a collimated light beam through a first convex lens 3, and passes through a reflection board 4, a half mirror 5, and a focus lens 6 to be emitted onto an optical disk 10. A numerical aperture of the focus lens 6 is set to 0.6. Reflected light from the optical disk 10 passes through the focus lens 6, half mirror 5, and a 2nd convex lens 7 and is made incident on a photodetector 8. The photodetector 8 is connected with a tracking and focusing signal system, and tracking and focusing are performed according to the incident light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft-format device for an optical disk for recording and reproducing information by irradiating a laser beam and an optical disk soft-formatted using the device.

[0002]

2. Description of the Related Art An optical disk for recording and reproducing information by irradiating a laser beam is a recording system having large capacity, high speed access, and medium portability, such as a moving image file, an audio file, and a computer data file. And is expected to continue to develop in the future.

[0003] The principle of the optical disk is that laser light is condensed to the extent of its diffraction limit and irradiated on the surface of the recording medium to form or erase minute recording marks to record information. Reproduction is performed by irradiating with a setting that is low enough not to occur. A groove or wobble pit pattern for tracking guide is provided on the medium surface in order to position a submicron size laser spot on the medium surface with high accuracy. An address signal for specifying a recording / reproducing position of information and a control signal for setting optimum recording / reproducing operation conditions of the medium are provided on the medium surface.

[0004] There are two types of recording methods of the above address signal and control signal, a hard format method and a soft format method. The hard format method is a method in which an address signal and a control signal having a concave and convex shape are recorded in advance on a disk substrate in the same manner as grooves or wobble pits in the process of cutting a master, and is a method that has been practiced on a conventional optical disk. On the other hand, the soft format method is a method of recording an address signal and a control signal on a recording medium film provided on a substrate in the same manner as a data signal, and is in a proposal stage.

[0005] The soft format has a concern that the user side may erroneously erase address information and control information, and has a disadvantage that the S / N ratio of the address signal and the control signal is lower than that of the hard format. On the other hand, the soft format has the advantage that the format efficiency is higher than the hard format, so that the user data capacity can be improved and the master disc cutting process is simplified.

At present, it has been considered to implement a soft format using an actual drive provided to a user. The disk rotation speed during formatting is specified by the recording sensitivity of the medium.However, it is not possible to increase the disk rotation speed because the improvement of the recording sensitivity by the semiconductor laser of the actual drive cannot be expected. Cost. Further, when formatting is performed by an actual drive, the quality of the format signal and the quality of the data signal become equal. For this reason, the error rate increases even though high reliability is required for the format signal. In this case, since it is necessary to increase the redundancy in order to lower the error rate of the format signal, the user data capacity cannot be improved so much and the advantage of the soft format cannot be obtained.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a soft formatting apparatus capable of efficiently formatting an optical disc and improving the reliability of a format signal, and an optical disc formatted soft using this apparatus. To provide.

[0008]

According to the present invention, there is provided an optical disk soft formatting apparatus comprising: a rotation mechanism of an optical disk; a soft formatting laser light source having a higher output than a laser light source used in an actual drive; and a soft formatting laser light source. An optical system for irradiating the optical disk with the laser light to be irradiated and a means for performing tracking based on the reflected light from the optical disk are provided. Examples of the above-mentioned laser light source for soft format include a gas laser.

An optical disk according to the present invention is an optical disk that has been soft-formatted by using the above-mentioned soft format apparatus, wherein the mark property of a format signal is different from the mark property of a data signal to be recorded. It is.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The optical disk to which the present invention is applied may be a phase change optical recording medium or a magneto-optical recording medium. In these optical disks, a recording layer, a protective layer, a reflective layer, and the like are formed on a disk substrate made of, for example, polycarbonate provided with a pregroove by a sputtering method to form a laminated structure.

In the phase change optical recording medium, it is preferable to form a laminated structure suitable for mark length recording and land / groove recording. For example, a laminated structure in which a lower protective layer, a phase change optical recording layer, an upper protective layer, and a translucent layer are formed on a substrate is employed. In this laminated structure, a translucent layer may be provided between the substrate and the lower protective layer.

As the phase-change optical recording material, a material that reversibly transitions between a crystalline state and an amorphous state by light irradiation and has different optical characteristics between the two states is used. In particular,
GeSbTe, InSbTe, SnSeTe, GeTe
Sn, InSeTlCo and the like. As a material of the lower protective layer and the upper protective layer, an oxide, a nitride, a carbide, a boride, a sulfide, a fluoride, or a mixture thereof can be used. Exemplary materials, and the like _{ZnS-SiO 2, Ta 2 O} 5.
Examples of the translucent layer include those formed using Al, Au, Cu, or an alloy containing AlMo or the like and having a small thickness so as to exhibit light transmittance. Also,
A light-transmitting material such as Si can be used even in a thick film.

Further, as the magneto-optical recording medium, for example, a medium in which a laminated structure of SiN, TbFeCo, SiN and Al is formed on a substrate can be mentioned. The optical disk soft formatting device of the present invention has a configuration similar to that of a real drive, but includes a soft format laser light source, for example, a gas laser, which has a higher output than the laser light source used in the real drive. Further, a laser light source having a shorter wavelength than a laser light source used for an actual drive may be used as a soft format laser light source, or the numerical aperture of an objective lens of a soft format device may be increased. As described above, the laser light source for soft format has a higher output than the laser light source used in the actual drive, so that even if the rotation speed of the optical disk is increased, the format signal can be sufficiently recorded and the formatting can be performed with high efficiency. it can. The recording power at the time of soft formatting by the soft formatting device of the present invention can be freely set.

The optical disc of the present invention is soft-formatted by using the above-mentioned soft format apparatus, and the mark property of the format signal is different from the mark property of the data signal to be recorded. In the present invention, the mark property of a signal means the physical, chemical, and mechanical properties of a mark portion. Specifically, it means a mark size, a crystal state of a mark portion, a chemical bonding state, stress, and the like. In the optical disk of the present invention, the format signal quality is made higher than the data signal quality by differentiating the mark properties between the format section and the data section, thereby achieving the original purpose of the soft format, that is, an increase in user data capacity.

In the present invention, the mark properties of the format signal can be changed by the recording power during soft format. For example, when a permanent soft format mark is formed to prevent the loss of a format signal due to an operation error, the formatting may be performed at a high output that causes an irreversible change in the recording layer. For example, for a phase-change optical recording medium, it is conceivable to change the atomic arrangement irreversibly by high-power laser light. For a magneto-optical recording medium, it is conceivable to crystallize the format signal portion with a high-power laser beam. In the optical disc on which such formatting has been performed, the format signal quality can be made different from the data signal strength, and the format signal quality can be greatly improved by providing the identification function in the actual drive. Also, for example, if the format signal size is smaller than the data signal size using a short wavelength soft format laser light source,
The format signal quality can be further improved by reducing inter-signal interference and crosstalk. On the other hand, if formatting is to be repeatedly performed, the recording power during soft formatting may be reduced to such an extent that irreversible changes do not occur in the recording layer.

[0016]

Embodiments of the present invention will be described below. In this embodiment, a translucent layer made of Au, a first interference layer made of ZnS—SiO ₂ , a recording layer made of GeSbTe, a ZnS—
A phase change optical disk was used in which a second interference layer made of SiO ₂ and a translucent layer made of AlMo were sequentially formed by sputtering.

The phase change optical disk is GeSbT
After the initial crystallization of the recording layer made of e, soft formatting was performed using the soft formatting apparatus shown in FIG. The initialization may be performed simultaneously with the soft format.

FIG. 1 is a diagram showing a configuration of a main part of a soft format apparatus according to the present invention. An optical disk 10 is set on the motor 1 so as to be rotatable. In this apparatus, as a laser light source 2 for soft format, a wavelength of 458 n
m, an argon ion laser with a maximum light source output of 10 W is used. The laser beam modulated by the format signal emitted from the soft format laser light source 2 is converted into a parallel beam by the first convex lens 3,
The light passes through the half mirror 5 and the focusing lens 6 and is irradiated on the optical disk 10. The numerical aperture of the focusing lens 6 is set to 0.6. The reflected light from the optical disk 10 passes through the focus lens 6, the half mirror 5, and the second convex lens 7, and is incident on the photodetector 8. The photodetector 8 is connected to a tracking and focusing signal system, and performs tracking and focusing based on incident light.

First, the optical disk is rotated by the motor 1 for 30 minutes.
High speed rotation was performed at a linear velocity of 〜50 m / s. This linear velocity is several times to about ten times the linear velocity in an actual drive.
Therefore, by using this apparatus, the formatting time can be reduced as compared with the case where soft formatting is performed using an actual drive.

The full width at half maximum of the laser beam for soft formatting by this apparatus on the medium surface is 0.4 μm. On the other hand, in an actual drive, a semiconductor laser light source having a wavelength of 650 nm is used, and a data signal is recorded with a numerical aperture of a focusing lens of 0.6. In this case, the full width at half maximum of the laser beam for recording the data signal on the medium surface is 0.5 μm. As described above, it is preferable that the full width at half maximum of the laser beam for soft format is 80% or less of the full width at half maximum of the laser light for data signal.

FIG. 2 is a plan view of an optical disk on which a format signal by the above-mentioned soft format apparatus and a data signal by an actual drive are recorded. In this figure, land (L), groove (G) and land (L) 3
A recording track of a book is extracted, and a format signal 11 and a data signal 12 recorded thereon are schematically shown. As shown in FIG.
Is smaller than the size of the data signal 12,
Inter-signal interference and crosstalk can be reduced, and the quality of the format signal can be improved.

When the laser output at the time of soft formatting was increased to, for example, 100 mW or more on the medium surface, the format portion was thermally deteriorated and irreversibly phase-separated. In this case, the signal modulation degree of the format part in the phase separation state is higher than the modulation degree of the amorphous mark part of the data signal, so that the signal strength is also excellent.

On the other hand, when the laser output at the time of soft format is set low, an amorphous reversible mark was formed. However, since the size of the format signal 11 is smaller than the size of the data signal 12 as described above, It was confirmed that the interfering interference and crosstalk were reduced, and the format signal had high quality.

The following example can be considered as another embodiment of the present invention. For example, in a phase change optical recording medium,
It has a size almost the same as the size of the data signal mark,
Also, a format signal mark in an amorphous state that is not in an irreversible phase separation state may be formed. In order to form such a format signal mark, the light beam spot diameter by the soft formatting device of the present invention is made to substantially match the light beam spot diameter of the actual drive, and the laser beam is formatted with a laser power that does not induce phase separation during soft formatting. Record. In this case, it seems at first glance that it is difficult to discriminate between the format signal and the data signal. However, as described above, the disk is rotated at a higher speed during the soft format than during the actual drive operation. The cooling rate of the recording layer is higher than that during data signal recording. In amorphous marks formed by melting and rapidly cooling the recording site according to the principle of phase change optical recording, the order at short distances, such as the distance between adjacent atoms, depends on the cooling rate during recording. The higher the speed, the more easily short-range order is lost. Therefore, also in this case, the mark properties are different between the format signal and the data signal. Such a difference in mark properties is caused by, for example, a high resolution T
It can be detected by such means as EM, high-resolution electron diffraction, EXAFS, and the like.

In the magneto-optical recording medium, various modes can be considered in addition to the mode in which the mark size differs between the format signal and the data signal as in the above embodiment. Specifically, (1) an amorphous / rare-earth-transition metal alloy film used in the current magneto-optical recording medium is crystallized by irradiating a high-power laser beam during format recording, and (2) the future In the Co / Pt multilayer film, which is a candidate for a magneto-optical recording medium capable of operating at a short wavelength, alloying is performed by generating interlayer diffusion. Different from
And the like. Such a difference in mark properties can be detected by means such as electron diffraction, MFM, and Lorentz TEM.

In the WORM medium, (1) a hole type, in which the height of the rim of the format signal mark (the bank around the hole) is made different from the height of the rim of the data signal mark due to a difference in cooling rate, 2) Diffusing multilayer film type, in which the phase state of the diffusion alloy mark is changed depending on the cooling rate difference, (3) Dye-based type, in which the degree of progress of the photochemical reaction such as ring opening and ring closing is changed. No.

[0027]

As described in detail above, according to the present invention, the time required for formatting can be greatly reduced, and the quality and reliability of the format signal can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a main part of a soft format device according to the present invention.

FIG. 2 is a plan view showing marks of a format signal and a data signal of an optical disk soft-formatted according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Motor 2 ... Soft format laser light source 3 ... First convex lens 4 ... Reflector 5 ... Half mirror 6 ... Focus lens 7 ... Second convex lens 8 ... Photodetector 10 ... Optical disk 11 ... Format signal 12 ... Data signal

Claims (2)

[Claims] An optical disc rotation mechanism, a soft format laser light source having a higher output than a laser light source used in an actual drive, and an optical system for irradiating the optical disc with laser light emitted from the soft format laser light source And a means for performing tracking based on reflected light from the optical disk. 2. An optical disk which is soft-formatted by using the soft-format apparatus according to claim 1, wherein a mark property of a format signal is different from a mark property of a data signal to be recorded.