Abstract: An aspect of the present invention relates to a method of manufacturing a hexagonal ferrite magnetic powder comprising discharging a melt of a starting material mixture comprising a glass-forming component and a hexagonal ferrite-forming component through an outlet provided in the bottom surface of the melting vat and supplying it between a pair of rotating milling rolls positioned beneath the melting vat; discharging an amorphous material from between the rolls by roll quenching the melt that has been supplied between the milling rolls, wherein at least an outermost layer portion of the milling rolls is comprised of a material with a Young's modulus of 500 GPa or higher and a Rockwell hardness of 85.0 HRA or higher, and the outermost layer portion has a thickness of 5 mm or greater and a surface roughness of 0.5 ?m or less.

Abstract: The optical information recording medium comprises a recording layer on a surface of a support. The surface of the support has pregrooves with a track pitch ranging from 50 to 500 nm, and the recording layer comprises a phthalocyanine derivative denoted by general formula (I) and a compound denoted by general formula (II). In general formula (I), R1 denotes a substituent, n denotes an integer ranging from 1 to 16, and M denotes a metal atom optionally comprising a ligand, a metal oxide, or two hydrogen atoms. In general formula (II), R2 denotes a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms or a substituted or unsubstituted aryl group having 4 to 24 carbon atoms, and m is an integer ranging from 1 to 4.

Abstract: Provided is an optical recording medium having a recording layer, an intermediate layer, an adhesive layer and a cover sheet in this order on a substrate, wherein the thickness t1 of the intermediate layer after a high-temperature high-humidity storage test satisfies the relationship: 0.8t?t1?1.2t wherein t is the thickness of the intermediate layer before the high-temperature high-humidity storage test.

Abstract: An optical information recording medium including a substrate having successively disposed thereon a recording layer, an interlayer, a pressure sensitive adhesive layer and a cover film in which information is recordable and reproducible by irradiating laser light and the pressure sensitive adhesive layer contains a polymer having a glass transition temperature Tg of 0° C. or lower, as well as a method for producing an optical information recording medium including adhering a cover layer to a surface of a recording layer so that a pressure sensitive adhesive layer is abutted on the surface of the recording layer, and an optical information recording medium produced by the method.

Abstract: The present invention provides an optical information recording medium having, a substrate, and on one side of the substrate, in the following order, a recording layer, a first adhesive layer, a first transparent sheet, and a hard coating layer, and on the other side, in the following order, a second adhesive layer, a second transparent sheet, and a label layer, wherein a ratio of the humidity expansion coefficient of layer (b) to that of layer (b) for each of the following (1) to (3) is in a range of 0.8 to 1.2: (1) (a) first adhesive layer, and (b) second adhesive layer; (2) (a) first transparent sheet, and (b) second transparent sheet; and (3) (a) hard coating layer, and (b) label layer.

Abstract: The present invention is an optical information recording medium comprising a substrate having disposed in an order thereon a recording layer, an interlayer, and a cover layer, wherein recording and reproduction are carried out by the irradiation with a laser light having a wavelength in the range of 380 to 500 nm through a lens having a lens numerical aperture NA of 0.7 or more, wherein the recording layer is a layer of an organic substance and the thickness of the interlayer is within a range of 1 nm to 9 nm.

Abstract: A lock-detection circuit that can set an acceptable phase-error range adapted to define a locked state and/or an unlocked state at a constant rate without being affected by a frequency and that can detect the locked state and/or the unlocked state with precision without being affected by various fluctuations and variations, and a PLL circuit including the lock-detection circuit. The range corresponding to a phase difference between first and second output signals is determined to be a locked-state range, where the phase of each of the first and second output signals delays or advances with reference to that of an oscillation-output signal transmitted from a voltage-controlled-oscillation circuit.

Abstract: The present invention provides an optical information medium having a dye recording layer, an adhesive layer and a light transmission layer in this order on a groove provided on a substrate, wherein recording and reproduction are carried out by allowing a laser beam to enter an in-groove portion from the light transmission layer, wherein: D×W is 5,000 nm2 or more wherein the depth of the groove is D (nm) and the width of the groove is W (nm), and the thickness of the dye recording layer in the in-groove portion is 0.7 D to 2.4 D (nm).

Abstract: The present invention provides an optical information recording medium including a substrate with an on-groove and an in-groove, having successively disposed thereon a dye recording layer and a transparent sheet, wherein a width of the on-groove ranges from 50 to 140 nm, and a barrier layer is formed between the recording layer and the transparent sheet. The invention also provides an optical information recording method including irradiating the optical information recording medium with laser light from the side of the medium provided with a cover layer to form a void at a signal pit portion in the dye recording layer and thereby carrying out recording of information as well as an optical information recording medium on which information has been recorded by the method.

Abstract: The present invention provides an optical information recording medium that includes a substrate including a groove with a track pitch of 200 to 400 nm and a groove depth of 20 to 150 nm and having successively disposed thereon a light reflecting layer, a recording layer containing a dye in which information is recorded by irradiation with a laser beam having a wavelength of no greater than 450 nm, an adhesive layer, and a cover layer with a thickness of 0.01 to 0.5 mm. A surface of the optical information recording medium on a side disposed with the cover layer has a center surface average roughness (SRa1) of no greater than 3.0 nm when measured over a large surface area and a center surface average roughness (SRa2) of no greater than 3.0 nm when measured over a minute surface area.

Abstract: An optical information recording medium including a substrate, a recording layer formed on the substrate, and a transparent sheet provided on the recording layer via an adhesive layer. The adhesive layer has a peak of loss modulus at a temperature of 0° C. or lower, and exhibits an E1?/E2? ratio of 2.0 or less, wherein E1? and E2? represent storage moduli of the adhesive layer at 25° C. and 80° C., respectively.

Abstract: A lock-detection circuit that can set an acceptable phase-error range adapted to define a locked state and/or an unlocked state at a constant rate without being affected by a frequency and that can detect the locked state and/or the unlocked state with precision without being affected by various fluctuations and variations, and a PLL circuit including the lock-detection circuit. The range corresponding to a phase difference between first and second output signals is determined to be a locked-state range, where the phase of each of the first and second output signals delays or advances with reference to that of an oscillation-output signal transmitted from a voltage-controlled-oscillation circuit.

Abstract: The present invention provides a process for producing an optical information recording medium transparent sheet, including applying a radiation-curable resin coating solution continuously to one surface of a cover film wound in a roll form, followed by continuously irradiating the coat formed in order to cure the coat and thereby form a hard coat layer, forming an adhesive layer continuously onto another surface of the cover film, and winding back into a roll form the cover film on which the hard coat layer and the adhesive layer have been formed; an optical information recording medium transparent sheet produced by this production process, and an optical information recording medium provided with this optical information recording medium transparent sheet.

Abstract: The invention provides an optical information recording medium, for use with a laser irradiating a laser beam having a wavelength of 380 to 500 nm through an objective lens with a numerical aperture of at least 0.7, the optical information recording medium comprising, in the following order: a substrate; a recording layer; a layer of acrylic adhesive; and a cover layer. A light reflecting layer may be provided between the substrate and the recording layer. Also a cover layer formed by an acrylic adhesive material may be provided instead of the layer of the acrylic adhesive material and the cover layer.

Abstract: The invention provides a method for manufacturing an optical information recording medium having a track pitch of 200 to 400 nm and a groove depth of 20 to 150 nm, and being capable of recording and reproducing using a light with a wavelength of 450 nm or less, the method at least comprising: a metal reflective layer forming step for forming a metal reflective layer on a substrate; a recording layer forming step for forming a recording layer of an organic dye type on said metal reflective layer; and a cover layer forming step for forming a cover layer on said recording layer; in this order.

Abstract: Provided are a cover sheet for optical recording media comprising a transparent disk-shaped sheet having a central hole and a hardcoat layer formed thereon wherein the hardcoat layer has a linear crack groove in the circumferential direction in the area close to the outer circumferential edge thereof; and an optical recording medium comprising a disk-shaped substrate having a central hole and at least a recording layer, a transparent sheet, and a hardcoat layer formed in that order thereon wherein the hardcoat layer has a linear crack groove in the circumferential direction in the area close to the outer circumferential edge thereof.

Abstract: The invention provides a method for manufacturing an optical information recording medium having a track pitch of 200 to 400 nm and a groove depth of 20 to 150 nm, and being capable of recording and reproducing using a light with a wavelength of 450 nm or less, the method at least including: a metal reflective layer forming step for forming a metal reflective layer on a substrate; a recording layer forming step for forming a recording layer of an organic dye type on said metal reflective layer; and a cover layer forming step for forming a cover layer on said recording layer; in this order.

Abstract: An optical recording medium includes a substrate having successively disposed thereon a light-reflecting layer, a recording layer and a cover layer, with recording and playback being effected by irradiating the medium with a laser beam having a wavelength of 450 nm or less from the side disposed with the cover layer, wherein a sputter layer having a thickness of 1 to 80 nm is formed between the recording layer and the cover layer, and the sputter layer and the cover layer are adhered with an adhesive. The sputter layer preferably has a thickness within a range from 2 to 50 nm and is preferably formed from a simple substance of Si, Zn, Ag, Al, Ti, Sn or Ge, a compound comprising at least one of the simple substances, or a combination thereof.

Abstract: The present invention provides an optical information recording medium including a substrate and an organic recording layer disposed on the substrate. The organic recording layer has a surface indentation hardness of 0.8 to 3.0 GPa at an indenter submerged depth in a range from 10 to 30 nm.

Abstract: The present invention provides an optical information recording medium which is not adversely affected by temperature and moisture during use and retains stable recording and reproducing properties over the long term. The optical information recording medium comprises a substrate, a recording layer formed on the substrate and a transparent sheet formed on the recording layer through an adhesive layer, wherein a surface of the transparent sheet is provided with a high-molecular compound layer having a saturated water absorption rate of 0.01% or less.