Optical information recording medium, optical information recording/reproducing apparatus, and method of manufacturing optical information recording medium

An optical information recording/reproducing apparatus for recording or reproducing an optical information recording medium which comprises at least two recording layers in which recorded data is formed on a substrate along a spiral or a concentric recording track, wherein in said optical information recording medium data is recorded or reproduced through the substrate, and wherein said optical information recording medium comprising:

• a first recording layer for recording or reproducing data thereon or therefrom using a first laser light at wavelength λ1, focused by an objective lens having a numerical aperture NA1, wherein the shortest pit length P1 of recorded or reproduced data has a value within a predetermined range determined by λ1 and NA1;
• and
• a second recording layer for recording or reproducing data thereon or therefrom using a second laser light at wavelength λ2 that is longer than the wavelength λ1 of the first layer light, said second laser light being focused by an objective lens having a numerical aperture NA2 equal to or smaller than NA1, wherein the shortest pit length P2 of recorded or reproduced data has a value larger than a value determined by λ2 and NA2, said apparatus characterized in that:
• data is recorded or reproduced through the substrate, and
• data on the first recording layer read by the first laser light is reproduced through partial response equalization, and data on the second recording layer read by the second laser light is reproduced through binary equalization.

An optical information recording/reproducing apparatus for recording or reproducing data on or from an optical information recording medium which comprises two recording layers in which recorded data is formed on a substrate along a spiral or a concentric recording track, wherein in said optical information recording medium data is recorded or reproduced through the substrate, and wherein said optical information recording medium comprising:

• a first recording layer for recording or reproducing data thereon or therefrom using a first laser light at wavelength λ1, focused by an objective lens having a numerical aperture NA1, wherein the shortest pit length P1 of recorded or reproduced data satisfies a relationship represented by 0.167×λ1/NA1<P1<0.35×λ1/NA1;
• and
• a second recording layer for recording or reproducing data thereon or therefrom using a second laser light at wavelength λ2 that is longer than the wavelength λ1 of the first layer light, said second laser light being focused by an objective lens having a numerical aperture NA2 equal to or smaller than NA1, wherein the shortest pit length P2 of recorded or reproduced data satisfies a relationship represented by P2>0.35×λ2/NA2, said apparatus characterized in that:
• data is recorded or reproduced through the substrate,
• the wavelength λ1 of the first laser light is in a range of 390 nm to 430 nm, and the wavelength λ2 of the second laser light is in a range of 630 nm to 690 nm, and
• data on the first recording layer is reproduced through partial response equalization, and recorded data on the second recording layer is reproduced through binary equalization.

An optical recording/reproducing apparatus characterized by comprising:

• two laser diodes for emitting laser light at different wavelengths;
• a light path for leading the laser light from said two laser diodes to objective lenses;
• a phase compensation plate disposed immediately before each said objective lens, and exhibiting different phase characteristics depending on the wavelength;
• and
• driving means for driving a lens actuator equipped with said objective lenses in a focusing direction.

A method of manufacturing an optical information recording medium characterized by the steps of:

• forming a first substrate having pre-pits formed in a spiral form on a surface through injection molding;
• forming an Ag film on the pre-pits by a sputtering method to form a first recording layer;
• forming a second substrate having pre-pits formed in a spiral form reverse to those on said first substrate on a surface by injection molding;
• forming an Al—Ti alloy thin film on the pre-pits of said second substrate by a sputtering method to form a second recording layer;
• coating an ultraviolet curable resin on the Ag film on said first substrate by a spin coating method to form an intermediate layer;
• and
• bonding both said substrates such that the Al—Ti thin film side of said second substrate is laid on said first substrate, followed by irradiation by the curing ultraviolet rays from the first substrate side to cure the resin.

A method of manufacturing an optical information recording medium characterized by the steps of:

• forming a first substrate having pre-pits formed in a spiral form on a surface through injection molding;
• forming an Ag film on the pre-pits by a sputtering method to form a first recording layer;
• forming a second substrate having a groove formed in a spiral form reverse to those on said first substrate on a surface by injection molding;
• sequentially laminating a laminate reflective film of Ag and Al—Ti, a ZnS—SiO2 protection film, a GeSbTe phase change recording film, and a ZnS—SiO2 protection film on the groove of said second substrate by a sputtering method to form a second recording layer;
• coating an ultraviolet curable resin on the Ag film of said first substrate by a spin coating method to form an intermediate layer;
• and
• bonding both said substrates such that the protection film side of said second substrate is laid on said first substrate, followed by irradiation by the curing ultraviolet rays from the first substrate side to cure the resin.

A method of manufacturing an optical information recording medium characterized by comprising the steps of:

• forming a first substrate having pre-pits formed in a spiral form on a surface through injection molding;
• forming an Ag film on the pre-pits by a sputtering method to form a first recording layer;
• forming a second substrate having a groove formed in a spiral form reverse to those on said first substrate on a surface by injection molding;
• sequentially laminating an Al—Ti reflective film, a ZnS—SiO2 protection film, a GeTe recording film, and a ZnS—SiO2 protection film on the groove of said second substrate by a sputtering method to form a second recording layer as a Write-Once recording layer;
• coating an ultraviolet curable resin on the Ag film of said first substrate by a spin coating method to form an intermediate layer;
• and
• bonding both said substrates such that the formed recording layer side of said second substrate is laid on said first substrate, followed by irradiation by the curing ultraviolet rays from the first substrate side to cure the ultraviolet curable resin.

A method of manufacturing an optical information recording medium characterized by comprising the steps of:

• forming a first substrate having a groove formed in a spiral form on a surface through injection molding;
• sequentially laminating a ZnS—SiO2 lower protection film, a GeSbTe phase change recording film, a ZnS—SiO2 upper protection film, an Ag reflective film, and a TiO2 interference film on the groove of said first substrate by a sputtering method as a first recording layer;
• forming a second substrate having pre-pits formed in a spiral form reverse to those on said first substrate on a surface by injection molding;
• forming an Al—Ti alloy thin film on the pre-pits by a sputtering method to form a second recording layer;
• coating an ultraviolet curable resin on the TiO2 interference film of said first substrate by a spin coating method to form an intermediate layer;
• and
• bonding both said substrates such that the Al—Ti thin film side of said second substrate is laid on said first substrate, followed by irradiation by the curing ultraviolet rays from the first substrate side to cure the ultraviolet curable resin.