JP2723004B2 - Optical recording medium and recording / reproducing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium for recording / reproducing information by a laser beam and a recording / reproducing method thereof, and more particularly, to an additionally recordable (including rewritable) optical recording having information tracks of different heights. The present invention relates to a medium and a method for recording and reproducing the medium.

[0002]

2. Description of the Related Art An optical disk or the like in which information is recorded or reproduced by a laser beam has an excellent feature as a large-capacity storage system because of its high recording density.

In such an optical disk or the like, tracks of about 1 μm are spirally or concentrically provided on an optical recording medium in order to record information at a high density, and recording or reproduction is performed by a narrowly narrowed laser beam. At this time, track servo is performed so that the laser beam does not deviate from a desired track and go to another track. Further, in order to record or reproduce information at a high speed, each track is formed with an irregular preformat for address identification in each unit information section. (For example, JP-A-1-165052 and JP-A-4-172623).

FIG. 7 shows a conventional ISO (International Orga).
nization for Standardization) is a partially enlarged view of an optical disc as a 130 mm magneto-optical type optical recording medium.
(A) is a plan view and (b) is a cross-sectional view.

In FIG. 1, a land portion 101 as an information track 100 is divided by a V-shaped groove portion 102, and a pit 103 which is an unevenness for address identification is formed in the land portion 101 for each unit information section. .

FIGS. 8A and 8B are partially enlarged views of another conventional optical recording medium, wherein FIG. 8A is a plan view and FIG. 8B is a sectional view. In the figure, a land 111 as an information track 110 is separated by a U-shaped groove 112 and
Is formed with a bent portion 113 of a wall surface as unevenness for address identification in each unit information section.

Such irregularities are formed on a transparent substrate, and a recording film is formed on the transparent substrate.

[0008] Generally, a recording film of an optical recording medium such as an optical disk capable of recording is a magneto-optical type film utilizing a magnetic Kerr effect, or a phase change type utilizing a difference in reflectance between crystalline and amorphous. Is used.

A laser beam for recording and reproduction enters through a transparent substrate and has a diameter of about 1.4 μm near the recording film.
Is focused by the focus servo so that As a laser light source, a semiconductor laser having a wavelength of about 6700 to 8300 angstroms is used.

In recording information, a high-power laser beam is irradiated in accordance with the information, so that the recording film absorbs the energy of the laser beam, converts it into thermal energy, and raises the temperature of the recording film. In the magneto-optical type, information is recorded by applying a recording bias magnetic field to a region including this portion so that the magnetization of this portion is oriented in a direction opposite to that of the other portions. The phase change type is
Information recording is performed by rapidly cooling the heated portion by stopping the laser beam irradiation, thereby changing this portion from crystalline to amorphous.

In reading information, a difference in the amount of reflected light due to a difference in the state of the recording film is detected as a signal by irradiating a low-power laser beam along the information track. The magneto-optical type utilizes the fact that when a linearly polarized laser beam is irradiated on a recording film, the polarization direction of reflected light from the recording film rotates according to the magnetization direction of the recording film. The phase change type utilizes the fact that the reflectance in a crystalline state is different from the reflectance in an amorphous state.

Since such a magneto-optical film or a phase change film is easily oxidized, it is generally sandwiched between dielectric films.

Next, a recording / reproducing method for such an optical recording medium will be described.

When recording information or reproducing the information, the information track is irradiated with a low-power laser beam, and the address of the information track is determined from the unevenness for address identification formed in each unit information section of the information track. Is recognized, and the above-described recording and reproduction are performed.

On the other hand, as a method of recording and reproducing at high density,
A method of alternately providing information tracks at different heights has also been proposed (for example, Japanese Patent Laid-Open No. 2-58732).

[0016]

However, the above-mentioned conventional optical recording medium and its recording / reproducing method have a problem that information cannot be recorded at a high density and information recording / reproducing cannot be performed at a high speed. there were.

The present invention has been made in view of the above problems, and has as its object to provide an optical recording medium capable of recording and reproducing information at a high density and at a high speed, and a recording and reproducing method thereof.

[0018]

In the optical recording medium of the present invention, tracks for recording information are alternately provided on the surface of the transparent substrate at different heights . Preformat the track width
In a recordable optical recording medium formed by changing, two adjacent tracks of a low track [or a high track] have the same address in the first block in the unit information section. The low track [or the high track] is arranged so that two tracks adjacent to each other with a shift from the low track [or the high track] have the same address in the second block in the unit information section.

In the optical recording medium of the present invention, at least a first dielectric film, a phase change film, a second dielectric film, and a metal film are laminated on the transparent substrate of the optical recording medium of the first invention. The configuration is as follows.

[0020] The present in the recording and reproducing method of the fifth optical recording medium of the present invention, provided alternately a track for recording information by changing the height on the surface of a transparent substrate, the address identification for each unit information interval to the track Preformat for track width
The optical recording medium is formed by changing the number of tracks, and two adjacent tracks of the low track [or the high track] are arranged so as to have the same address in the first block in the unit information section. Low track [or the high track]
An optical recording medium arranged so that two tracks adjacent to each other and having the same address in the second block in the unit information section is shifted by one and information is recorded in the high track [or the low track]. When recording the information or reproducing the information, the address is recognized from the change in the track width for identifying one of the first block and the second block, and the low-order track [or The high track]
When recording information or playing it back,
The control is performed so as to recognize the address from the change in the track width for the address identification of the first block and the change in the track width for the address identification of the second block.

[0021]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1A and 1B are partially enlarged explanatory views of a preformat of an optical recording medium according to the present invention, wherein FIG. 1A is a plan view and FIG.
FIG. 2 is a schematic flow chart for explaining the address of each track in the recording / reproducing.

On the surface of the transparent substrate 1, high tracks (L2m-1, L2m, etc.) and low tracks (Gn, etc.) are alternately provided as tracks for recording information. Low track
High track while having the same address in the first block of
Is referred to here as an odd track at high altitude,
High track while having the same address in the second block
Is referred to as an even-high track here and will be described below. The addressed portion of each block has a first block and a second block that are contiguous with each other, for example, a first block.
Four bits are recorded in the block, and four bits are recorded in the second block. Each of the first block and the second block is a unit information section of a track, and an address bit of each block exists in the section.

In the low track, addressing is performed using both the first and second tracks, and the addresses 1 and 0 are recorded depending on whether or not wide bends are provided at regular intervals on the track wall. Have been. For example, the address of the low track Gn-1 is (A1, A2, A
3, A4, K1, K2, K3, K4), low track G
The address of n is (A1, A2, A3, A4, B1, B
2, B3, B4) are 8 bits each. The arrangement of the bent portion of the address of the low track has the following conditions. That is, in the first block, the code and position of the address change every two tracks, and in the second block, the code and position of the address change every two tracks, but the change is shifted by one track from the first block.

On the other hand, among the high tracks, odd high tracks (L2m-1, L2m + 1 etc.) are addressed to the first block, and even high tracks (L2m-2, L2m etc.) are addressed to the second block.
Each block is addressed by a code, and the addresses 1 and 0 are recorded depending on whether or not narrow bends are provided at regular intervals on a track wall.
Therefore, the address of each of the even-numbered track and the odd-numbered track is 4 bits. Also, the address of the higher odd track is the same as the address of the first block of the adjacent lower track, and the address of the higher even track is the same as the address of the second block of the adjacent lower track. .

Next, an address detection method will be described with reference to FIG.

First, the distinction between the high track and the low track is determined by the polarity of the push-pull signal obtained from the light receiver when the laser beam crosses the wall surface of the track boundary. Here, when it is determined that the track is a high-altitude track and the laser beam is scanned in the length direction of the track, an address of only 4 bits (for example, A1 to A4 or C1 to C4) is detected in the first block. In some cases, the address is identified as an odd address at a high place, and when an address in which the addresses A1 to A4 and C1 to C4 (or a combination of other addresses) are mixed is detected in the first block and a 4-bit address cannot be detected, No address is detected in the first block as an even track, and a 4-bit address is detected in the second block of the same track. If the track is determined to be a low track after distinguishing between a high track and a low track, an 8-bit address is detected in the first and second blocks.

As described above, an address is detected for each track and an address is detected.

When the address signal is biphase-modulated, the carrier waves of successive high-place odd track numbers are alternately opposite in phase, and the carrier waves of successive high-place even track numbers are also alternately in opposite phases. Since the amplitude of the address identification signal in the first block in the even track is offset and small, it can be immediately determined that the track is an even track.

The roles of the high track and the low track described above may be reversed depending on the method of manufacturing the stamper for forming the preformat, but here, the light of the master exposure machine for manufacturing the stamper is used. The case where the beam is irradiated to a low track is described.

FIG. 3 is a schematic sectional view showing the basic structure of the film structure of an embodiment of the optical recording medium of the present invention.

In the optical recording medium shown in FIG. 3, a first dielectric film 21 is provided on the transparent substrate 1 shown in FIG. 1, a magneto-optical film 22 is provided thereon, and a second dielectric film 21 is provided thereon. The body film 23 is provided in order.

FIG. 4 is a schematic sectional view showing the basic structure of the film structure of another embodiment of the optical recording medium of the present invention.

In the optical recording medium shown in FIG. 4, a first dielectric film 31 is provided on the transparent substrate 1 shown in FIG. 1, a magneto-optical film 32 is provided thereon, and a second dielectric film 31 is provided thereon. A body film 33 is provided, and a metal film 34 is sequentially provided thereon.

FIG. 5 is a schematic sectional view showing the basic structure of the film structure of another embodiment of the optical recording medium of the present invention.

In the optical recording medium shown in FIG. 5, a first dielectric film 41 is provided on the transparent substrate 1 shown in FIG. 1, a phase change film 42 is provided thereon, and a second dielectric film 41 is provided thereon. The body film 43 is provided in order.

FIG. 6 is a schematic sectional view showing the basic structure of the film structure of another embodiment of the optical recording medium of the present invention.

The optical recording medium shown in FIG. 6 has a first dielectric film 51 provided on the transparent substrate 1 shown in FIG. 1, a phase change film 52 provided thereon, and a second dielectric film 52 provided thereon. A body film 53 is provided, and a metal film 54 is sequentially provided thereon.

In these optical recording media, the recording / reproducing of information may be performed by irradiating a laser beam through the transparent substrate 1 with the configuration as shown in FIGS. In some cases, a protective film such as a resin is provided. In some cases, a hot melt agent is applied on a protective film such as a UV curable resin so that the two optical recording media are bonded together such that the transparent substrate faces outward.

Further, when an antireflection film such as SiO2, a hardened transparent organic resin surface hardened film, or a highly conductive transparent film is provided on the transparent substrate 1 opposite to the recording film. There is also.

As the transparent substrate 1, a polycarbonate resin plate, a polyolefin resin plate, an acrylic resin plate,
A glass plate, an acrylic resin plate with a photopolymer, or a glass plate with a photopolymer is used. The preformat described above is formed on the plate itself or on the surface of the photopolymer. The pitch of the information tracks is approximately 0.5 to 1.4 μm.

The material of the first dielectric films 21 and 31 is mainly composed of silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxynitride, silicon hydride carbide, or tantalum oxide. Especially desirable.

The material of the first dielectric films 41 and 51 is a mixture of zinc sulfide and silicon dioxide, silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxynitride, silicon hydride carbide, It is particularly desirable to use tantalum oxide as a main component.

The material of the magneto-optical films 22 and 32 is Tb
Fe, TbFeCo, TbFeTi, TbFeC
oTi, TbFeCr, TbFeCoCr, Tb
FeTa, TbFeCoTa, TbFeNiCr
, TbFeCoNiCr, TbGdFe, TbG
dFeCo, TbGdFeTi, TbGdFeCo
Ti, TbGdFeCr, TbGdFeCoCr
, TbGdFeTa, TbGdFeCoTa, T
bGdFeNiCr, TbGdFeCoNiCr,
TbDyFe, TbDyFeCo, TbDyFeT
i, TbDyFeCoTi, TbDyFeCr,
TbDyFeCoCr, TbDyFeTa, TbD
yFeCoTa, TbDyFeNiCr, TbDy
FeCoNiCr, TbGdNdFe, TbGdN
dFeCo, TbGdNdFeTi, TbGdNd
FeCoTi, TbGdNdFeCr, TbGdN
dFeCoCr, TbGdNdFeTa, TbGd
NdFeCoTa, TbGdNdFeNiCr, T
bGdNdFeCoNiCr, TbGdDyFe,
TbGdDyFeCo, TbGdDyFeTi, T
bGdDyFeCoTi, TbGdDyFeCr,
TbGdDyFeCoCr, TbGdDyFeTa
, TbGdDyFeCoTa, TbGdDyFeN
iCr and TbGdDyFeCoNiCr are particularly desirable. Further, a plurality of other layers may be stacked on these layers.
GdFe, GdFeCo, GdFeTi,
GdFeCoTi, GdFeCr, GdFeCoC
r, GdFeTa, GdFeCoTa, GdFe
NiCr, GdFeCoNiCr, GdNdFe
, GdNdFeCo, GdNdFeTi, GdN
dFeCoTi, GdNdFeCr, GdNdFe
CoCr, GdNdFeTa, GdNdFeCoT
a, GdNdFeNiCr, GdNdFeCoNi
A readout layer of Cr or the like may be overlaid.

The material of the phase change films 42 and 52 is preferably a chalcogen element compound, and particularly preferably GeSbTe. Elements such as nitrogen may be added to the phase change films 42 and 52 in a small amount.

The material of the second dielectric films 23 and 33 is mainly composed of silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxynitride, silicon hydride carbide, or tantalum oxide. Especially desirable.

The material of the second dielectric films 43 and 53 is a mixture of zinc sulfide and silicon dioxide, silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxynitride, silicon hydride carbide, It is particularly desirable to use tantalum oxide as a main component.

The material of the metal films 34 and 54 is preferably an aluminum alloy. As additional elements, Ti, C
r, Ta, Ni, and NiCr are particularly desirable.

A laser beam for recording and reproduction enters through the transparent substrate 1 and is approximately φ1.0 to φ
The light is focused by a focusing servo so as to have a thickness of 1.4 μm. Wavelength 6500-830 for laser light source
A semiconductor laser of about 0 Å or the like is used.

[0050]

The optical recording medium and the recording / reproducing method of the present invention have an effect that information can be recorded / reproduced at high density and at high speed.

[Brief description of the drawings]

FIG. 1 is a partially enlarged explanatory view of a preformat of an optical recording medium according to the present invention;

FIG. 2 is a flowchart showing a method for recording and reproducing addresses on an optical recording medium according to the present invention.

FIG. 3 is a plan view showing a basic structure of an optical recording medium according to one embodiment of the present invention;

FIG. 4 is a plan view showing a basic structure of an optical recording medium according to another embodiment of the present invention;

FIG. 5 is a plan view showing a basic structure of an optical recording medium according to another embodiment of the present invention;

FIG. 6 is a plan view showing a basic structure of an optical recording medium according to another embodiment of the present invention;

FIG. 7 is a partially enlarged explanatory view of a preformat of a conventional optical recording medium;

FIG. 8 is a partially enlarged explanatory view of a preformat of a conventional optical recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 21, 31, 41, 51 First dielectric film 22, 32 Magneto-optical film 23, 33, 43, 53 Second dielectric film 34, 54 Metal film 100, 110 Information track 101, 111 Land portion 102 V-shaped groove portion 103 Pit 112 U-shaped groove portion 113 Wall bent portion

Claims (6)

(57) [Claims] 1. Tracks for recording information are alternately provided on the surface of a transparent substrate at different heights, and the tracks are provided with a preformat for address identification for each unit information section.
A recordable optical recording medium formed by changing the width of a track, wherein two adjacent tracks of a low track [or a high track] have the same address in a first block in a unit information section. And two tracks adjacent to the low track [or the high track] one by one and having the same address in the second block in the unit information section. An optical recording medium characterized by the above-mentioned. 2. The optical recording medium according to claim 1, wherein at least a first dielectric film, a magneto-optical film, and a second dielectric film are laminated on the transparent substrate. 3. The optical recording apparatus according to claim 1, wherein at least a first dielectric film, a magneto-optical film, a second dielectric film, and a metal film are laminated on the transparent substrate. Medium. 4. The optical recording medium according to claim 1, wherein at least a first dielectric film, a phase change film, and a second dielectric film are laminated on the transparent substrate. 5. The light according to claim 1, wherein at least a first dielectric film, a phase change film, a second dielectric film, and a metal film are laminated on the transparent substrate. recoding media. 6. Tracks for recording information are alternately provided on the surface of a transparent substrate at different heights, and a preformat for address identification is recorded on each track in each unit information section.
An optical recording medium formed by changing the width of a track, wherein two adjacent tracks of a low track [or a high track] have the same address in the first block in the unit information section. And using an optical recording medium in which two tracks adjacent to the low track [or the high track] are arranged so as to have the same address in the second block in the unit information section. When information is recorded or reproduced on the high track [or the low track], a track width change for address identification of one of the first block and the second block is performed. When the information of the low track [or the high track] is recorded or the information is reproduced, the track width change for the address identification of the first block and the address of the low track are used. 2 Method of recording and reproducing control optical recording medium to recognize its address from the Tsu track width change for the address identification of click.