Abstract: A multi-layer information medium which is less likely to be deflected and twisted is provided. Such medium is also provided at low cost. The optical information medium comprises a substrate or a pair of substrates, and at least two information-storing layers for storing recorded information and/or tracking servo information disposed on said substrate or between said pair of substrates, and at least one information-storing layer is recorded or read by the recording beam or the reading beam which has passed through other information-storing layer(s). In this medium, the medium has at least one cured intermediate layer comprising an active energy radiation-curable resin, and at least one of said cured intermediate layer(s) has a tensile elongation at break of 15 to 200% and a tensile modulus of 20 to 1,000 MPa.

Abstract: In an optical information medium comprising a supporting substrate, an information recording layer thereon, and a light-transmitting layer wherein a recording/reading laser beam enters the recording layer through the light-transmitting layer, the light-transmitting layer is formed of a resin and has a tensile strength at break of 5-40 MPa, a tensile elongation at break of 15-100%, and a tensile modulus of 40-1,000 MPa. The medium has improved recording/reading characteristics when a laser beam defines a beam spot having a small diameter of up to 300 &mgr;m and the medium is rotated at a high linear velocity of at least 8 m/s.

Abstract: A method and apparatus is provided for preparing an optical information medium comprising a disk-shaped substrate having a center hole, an information recording layer thereon, and a resin-based light-transmitting layer thereon by which recording/reading laser beam is transmitted. The apparatus includes a rotating table (2) for holding and rotating the substrate (100) having the information recording layer borne thereon, a plug means (3) including a disk member (31) for closing the center hole (101) and an integral support shaft (32), and a nozzle (4) for feeding a coating fluid containing the resin to the outer periphery of the support shaft (32), wherein the coating fluid is flowed from the support shaft to the disk member, then over the substrate, thereby forming the light-transmitting layer having a minimized thickness variation.

Abstract: An optical information medium comprising a supporting substrate, an information recording area on the supporting substrate, and a light-transmitting layer covering at least the information recording area, wherein the information recording area is irradiated with the recording/reading laser beam through the light-transmitting layer, and wherein the light-transmitting layer is highly scratch resistant upon contact with the optical pickup is provided. Also provided is an optical information medium which has a scratch-resistant light transmitting layer, and which experiences reduced vibration in high-speed rotation without suffering from problems in focus servo and tracking servo. In such optical information medium, the surface of the medium on the side of the laser beam incidence at least in the part above the information recording area has a dynamic coefficient of friction of up to 0.4.

Abstract: In an optical information medium comprising a supporting substrate, an information recording layer thereon, and a light-transmitting layer wherein a recording/reading laser beam enters the recording layer through the light-transmitting layer, the light-transmitting layer is formed of a resin and has a tensile strength at break of 5-40 MPa, a tensile elongation at break of 15-100%, and a tensile modulus of 40≧1,000 MPa. The medium has improved recording/reading characteristics when a laser beam defines a beam spot having a small diameter of up to 300 &mgr;m and the medium is rotated at a high linear velocity of at least 8 m/s.

Abstract: An optical information medium is provided which has a light-transmitting substrate which exhibits excellent light transmittance when a laser beam of blue/violet region or ultraviolet region is used as the recording and/or reading beam; whose light transmittance is not substantially affected by the variation or fluctuation of the oscillation wavelength of the laser beam source; which has a long-term weatherability; and which exhibits sufficient protective effects against exterior impacts. The optical information medium includes an information recording layer and a light-transmitting substrate, and the medium is used such that the recording and/or reading laser beam reaches the information-recording layer through the light-transmitting substrate. The light-transmitting substrate has a light transmittance T and difference &Dgr;T between the maximum value and the minimum value of the light transmittance T in arbitrary wavelength range of 10 nm which satisfies the relations: T≧0.8 and &Dgr;T≦0.

Abstract: In the multi-layer information medium having a plurality of information-storing layers according to the present invention, distance between the adjacent information-storing layers is reduced with no increase in cross talk between these layers. The optical information medium has at least two information-storing layers each storing recorded information and/or servo information, and at least one of the information-storing layers is recorded or read by the recording beam or the reading beam which has passed through other information-storing layer(s). The medium has a filter layer between the adjacent information-storing layers, and in the spectral absorption characteristics in the wavelength range of 300 to 1000 nm of this filter layer, a wavelength range exhibiting an absorption of 80% or higher and a wavelength range exhibiting an absorption of 20% or lower are present.

Abstract: In the multi-layer information medium having a plurality of information-storing layers according to the present invention, all of the information-storing layers exhibits excellent reading properties. The multi-layer information medium also exhibits good mechanical precision. The optical information medium has at least two annular information-storing layers each storing recorded information and/or servo information on a disk-shaped substrate formed with a center hole or between a pair of disk-shaped substrates each formed with a center hole, and at least one of the information-storing layers is recorded or read by the recording beam or the reading beam which has passed through other information-storing layer(s).

Abstract: There are provided a composition for coating which can form an ink receiving layer having excellent adhesion with hydrophobic substrates, water-resistance and printing stability, and an optical recording medium having an ink receiving layer formed from this composition. The composition contains a radiation-curable compound (A) composed of 50 to 90% by weight of a monofunctional (meth) acrylic monomer and 10 to 50% by weight of a multifunctional (meth) acrylic monomer, a water-absorbing organic filler (C) in an amount of 10 to 60% by weight relative to (A), and a water-absorbing inorganic filler (D) in an amount of 1 to 20% by weight relative to (A). This composition is applied on a protecting film (6) and cured to form an ink receiving layer (7), to obtain an optical disk (1).

Abstract: An optical information medium is provided. The medium comprises a supporting substrate, an information recording layer thereon, and a light-transmitting layer thereon and a recording or reading laser beam enters the recording layer through the light-transmitting layer, and in such medium, recording/reading characteristics are improved when the beam spot of a laser beam has a small diameter and the linear velocity is high with the function of the light-transmitting layer to protect the information recording layer maintained at a sufficient level. Also provided is a medium wherein storage stability is improved.

Abstract: The invention provides an optical recording medium preventing deterioration of an organic dye, having improved durability and being highly reliable, as well as a process for producing the same. The recording layer (3) including an organic dye as the main component, and the reflective layer (4) comprising a metal selected from Cu, Ag and Au or an alloy containing at least one of these metals, are formed in this order on substrate (2). An ultraviolet-curable material is laminated on the reflective layer (4) and cured by irradiation with UV rays at 200 to 1000 mJ/cm2 in such a manner that a cure shrinkage factor is not more than 10% by volume to form the protective layer (5) so that the organic acid content in the resulting ultraviolet-cured resin is not more than 10 ppm by weight, whereby the optical disk (1) is obtained. The dye is preferably a cyanine type dye, and the reflective layer is preferably Cu, Ag or an alloy containing at least one of these metals.

Abstract: An optical information medium is provided which has a light-transmitting substrate which exhibits excellent light transmittance when a laser beam of blue/violet region or ultraviolet region is used as the recording and/or reading beam; whose light transmittance is not substantially affected by the variation or fluctuation of the oscillation wavelength of the laser beam source; which has a long-term weatherability; and which exhibits sufficient protective effects against exterior impacts. The optical information medium comprises an information recording layer and a light-transmitting substrate, and the medium is used such that the recording and/or reading laser beam reaches said information-recording layer through said light-transmitting substrate. The light-transmitting substrate has a light transmittance T and difference &Dgr;T between the maximum value and the minimum value of the light transmittance T in arbitrary wavelength range of 10 nm which satisfies the relations: T≧0.8 and &Dgr;T≦0.

Abstract: A multi-layer information medium which is less likely to be deflected and twisted is provided. Such medium is also provided at low cost. The optical information medium comprises a substrate or a pair of substrates, and at least two information-storing layers for storing recorded information and/or tracking servo information disposed on said substrate or between said pair of substrates, and at least one information-storing layer is recorded or read by the recording beam or the reading beam which has passed through other information-storing layer(s). In this medium, the medium has at least one cured intermediate layer comprising an active energy radiation-curable resin, and at least one of said cured intermediate layer(s) has a tensile elongation at break of 15 to 200% and a tensile modulus of 20 to 1,000 MPa.

Abstract: This invention provides a multi-layer information medium wherein layer-specific information unique to the particular layer has been adequately recorded, and delay in the access to the recorded data associated with reading of the layer-specific information is suppressed. Such multi-layer information medium is also provided at low cost. The optical information medium has at least two information-storing layers each storing recorded information and/or tracking servo information, and at least one of the information-storing layers is a data layer storing recorded information, and at least one of said information-storing layers is recorded or read by the recording beam or the reading beam which has passed through other information-storing layer(s), and in this medium, the data layer has layer-specific information unique to the particular data layer recorded therein.

Abstract: An optical information medium comprising a supporting substrate, an information recording area on the supporting substrate, and a light-transmitting layer covering at least the information recording area, wherein the information recording area is irradiated with the recording/reading laser beam through the light-transmitting layer, and wherein the light-transmitting layer is highly scratch resistant upon contact with the optical pickup is provided. Also provided is an optical information medium which has a scratch-resistant light transmitting layer, and which experiences reduced vibration in high-speed rotation without suffering from problems in focus servo and tracking servo. In such optical information medium, the surface of the medium on the side of the laser beam incidence at least in the part above the information recording area has a dynamic coefficient of friction of up to 0.4.

Abstract: In an optical information medium comprising a supporting substrate, an information recording layer thereon, and a light-transmitting layer wherein a recording/reading laser beam enters the recording layer through the light-transmitting layer, the light-transmitting layer is formed of a resin and has a tensile strength at break of 5-40 MPa, a tensile elongation at break of 15-100%, and a tensile modulus of 40-1,000 MPa. The medium has improved recording/reading characteristics when a laser beam defines a beam spot having a small diameter of up to 300 &mgr;m and the medium is rotated at a high linear velocity of at least 8 m/s.

Abstract: In the multi-layer information medium having a plurality of information-storing layers according to the present invention, distance between the adjacent information-storing layers is reduced with no increase in cross talk between these layers. The optical information medium has at least two information-storing layers each storing recorded information and/or servo information, and at least one of the information-storing layers is recorded or read by the recording beam or the reading beam which has passed through other information-storing layer(s). The medium has a filter layer between the adjacent information-storing layers, and in the spectral absorption characteristics in the wavelength range of 300 to 1000 nm of this filter layer, a wavelength range exhibiting an absorption of 80% or higher and a wavelength range exhibiting an absorption of 20% or lower are present.

Abstract: In the multi-layer information medium having a plurality of information-storing layers according to the present invention, all of the information-storing layers exhibits excellent reading properties. The multi-layer information medium also exhibits good mechanical precision. The optical information medium has at least two annular information storing layers each storing recorded information and/or servo information on a disk-shaped substrate formed with a center hole or between a pair of disk-shaped substrates each formed with a center hole, and at least one of the information-storing layers is recorded or read by the recording beam or the reading beam which has passed through other information-storing layer(s).

Abstract: An optical information medium includes a disk-shaped substrate (100) having a center hole (101), an annular information recording area thereon, and an annular resin-based light-transmitting layer (102) thereon by which recording/reading laser beam is transmitted to the information recording area. The light-transmitting layer (102) terminates at a radially inner periphery which forms an annular raised rim (6). The rim is effective for protecting the light-transmitting layer from damages and dust adhesion, and when a plurality of such media are stacked, preventing the media from intimate contact.

Abstract: A method and apparatus is provided for preparing an optical information medium comprising a disk-shaped substrate having a center hole, an information recording layer thereon, and a resin-based light-transmitting layer thereon by which recording/reading laser beam is transmitted. The apparatus includes a rotating table (2) for holding and rotating the substrate (100) having the information recording layer borne thereon, a plug means (3) including a disk member (31) for closing the center hole (101) and an integral support shaft (32), and a nozzle (4) for feeding a coating fluid containing the resin to the outer periphery of the support shaft (32), wherein the coating fluid is flowed from the support shaft to the disk member, then over the substrate, thereby forming the light-transmitting layer having a minimized thickness variation.