Abstract: The present invention provides an apparatus and a method for precisely and adequately evaluating actual quality of reproduced data whenever applying a maximum likelihood decoder for converting signal reproduced from a recording medium into binary signal. Based on data arrays of a pair of binary data outputted from a “Viterbi” decoder, SAM values are secured by selecting any of path-metric differential values (00) and (11) being the difference between a pair of values compared when renewing path-metric values PMM (00) and (11) outputted from the “Viterbi” decoder. The minimum SAM value for an ideally-reproduced signal is outputted from a constant generating circuit. If the SAM values are verified as valid, and yet, if the SAM values coincide with the equation “input SAM values”?“data value outputted from the constant generating circuit”, then squared values outputted from a square circuit are averaged by an averaging circuit. Finally, the average value is outputted as the reproduced signal evaluation.

Abstract: The present invention provides an apparatus and a method for precisely and adequately evaluating actual quality of reproduced data whenever applying a maximum likelihood decoder for converting signal reproduced from a recording medium into binary signal Based on data arrays of a pair of binary data outputted from a “Viterbi” decoder, SAM values are secured by selecting any of path-metric differential values (00) and (11) being the difference between a pair of values compared when renewing path-metric values PMM (00) and (11) outputted from the “Viterbi” decoder. The minimum SAM value for an ideally-reproduced signal is outputted from a constant generating circuit. If the SAM values are verified as valid, and yet, if the SAM values coincide with the equation “input SAM values”?“data value outputted from the constant generating circuit”, then squared values outputted from a square circuit are averaged by an averaging circuit. Finally, the average value is outputted as the reproduced signal evaluation.

Abstract: The present invention provides an optical disk drive and optical disk playback method, with an improved capability of reading address information from an optical disk having address information recorded thereon by wobbling one of side walls of a recording track, with a wider tilt margin.

Abstract: There is disclosed a pulley unit made by interposing a one-way clutch 3 in an annular space between a pulley 1 and an axial body 2, providing a deep groove ball bearing 4 on the base end side of one-way clutch 3, and a roller bearing 5 on the free end side; setting an inner rolling surface of a roller 13 of the one-way clutch 3 to be an outer diameter surface of the axial body 2, and an inner rolling surface of rolling member 22 of the roller bearing 5 to be an outer diameter surface of the axial body 2. The pulley unit permits easy position setting of the pulley 1, so that stabilized lock and free operation can be expected and productivity can be improved.

Abstract: An optical head is used to record and playback information to and from a magneto-optical storage medium having a displacement layer, a disconnecting layer, and a recording layer that are stacked in this order. The displacement layer is defined by a perpendicular magnetic film that is relatively smaller in domain-wall coercivity and that is greater in domain-wall mobility than the recording layer and the disconnecting layer is defined by a magnetic layer that is lower in Curie temperature than the displacement layer and the recording layer. An optimum offset value is set for causing tracking of the optical head to a recording track provided on the magneto-optical storage medium.

Abstract: In reproduction from a magneto-optical recording medium by the domain wall displacement detection method, it is possible to avoid occurrence of ghost signals and to improve dropout, and moreover design of magnetic layers is made easy. A configuration is adopted having at least, in order from the side of incidence of laser light for reproduction, a first magnetic layer 11 constituting a reproduction layer, a second magnetic layer 12 constituting a control layer, a third magnetic layer 13 constituting a blocking layer, and a fourth magnetic layer 14 constituting a recording layer, which if the respective Curie temperatures thereof are TC1, TC2, TC3 and TC4, satisfy the relations TC1>TC3>TC2 and TC4>TC3. At the same time, if the magnetic anisotropy of the second magnetic layer is Ku2 and the magnetic anisotropy of the third magnetic layer is Ku3, the relation Ku3>Ku2 is satisfied.

Abstract: A method for manufacturing a magneto-optical recording medium in which reading of recorded information is performed through domain wall displacement in a reproduction layer is provided, in which magnetic separation of groove side-wall portions is performed more reliably; as a result a magneto-optical recording medium with satisfactory recording and reproduction characteristics can be provided.

Abstract: A magneto-optical recording medium for recording and reproducing carriers by laser beam irradiation includes a first magnetic layer which is magnetized in the in-plane direction at room temperature and is perpendicularly magnetized at a predetermined temperature T1 or more; a second magnetic layer which is in contact with the first magnetic layer, has a Curie temperature Tc2 higher than the predetermined temperature T1, and has in-plane magnetic anisotropy up to the Curie temperature Tc2; a third magnetic layer which has a Curie temperature Tc3 higher than the predetermined temperature T1 and has perpendicular magnetic anisotropy at least in a predetermined range of a temperature distribution of the magneto-optical recording medium during laser beam irradiation when reproducing; and a rare earth metal layer formed between the third magnetic layer and the second magnetic layer.

Abstract: A laser drive integrated circuit and an optical disk apparatus using the laser drive integrated circuit for forming high-density marks. The optical disk apparatus includes a drive waveform information storage unit for storing at least one information of a drive waveform for driving a laser diode in response to a binary recording signal to be recorded in a recording medium, and a drive waveform decoder for decoding the drive waveform based on the information stored in the drive waveform information storage unit. A recording strategy can be changed in accordance with variations and fluctuations of recording media or characteristics of the recording media, while at the same time reducing a number of signal lines in flexible wiring and alleviating effects of signal distortion in the signal lines.

Abstract: A laser drive circuit includes a first current supply unit which supplies a first drive current to a first laser diode based on a drive waveform signal generated by a drive waveform generating unit, a second current supply unit which supplies a second drive current to a second laser diode based on the drive waveform signal generated by the drive waveform generating unit, and a switching unit which selectively supplies the drive waveform signal generated by the drive waveform generating unit to one of the first current supply unit and the second current supply unit. The drive waveform generating unit may be part of the laser drive circuit, or may be separate from the laser drive circuit, and may include a drive waveform information storage unit which stores a recording strategy according to a type of disk.

Abstract: A magneto-optical recording/reproducing method is disclosed which causes a laser beam to be emitted to a disc recording medium having information recorded thereon earlier by magnetic field modulation, the laser beam causing the disc recording medium to develop a temperature distribution such as to generate a driving force for moving a domain wall of a magnetic domain in the medium so that the magnetic domain smaller in diameter than a spot of the laser beam is expanded sufficiently to let information recorded in the domain be detected. The method comprises the steps of: recording information to the disc recording medium while rotating the medium in a first rotating direction; and reproducing the information that was recorded to the disc recording medium in the recording step while rotating the medium in a second rotating direction reverse to the first rotating direction.

Abstract: In order to improve reproduction characteristics of a magneto-optical recording medium in a case of being subject to a magnetically induced super resolution readout process utilizing a blue-violet laser beam, there is provided a magneto-optical recording medium having a surface roughness of 0.3 nm or less on a surface of a substrate on which recording/reproduction magnetic layers are formed or a surface of a dielectric film formed on the substrate.

Abstract: A laser drive circuit includes a first current supply unit which supplies a first drive current to a first laser diode based on a drive waveform signal generated by a drive waveform generating unit, a second current supply unit which supplies a second drive current to a second laser diode based on the drive waveform signal generated by the drive waveform generating unit, and a switching unit which selectively supplies the drive waveform signal generated by the drive waveform generating unit to one of the first current supply unit and the second current supply unit. The drive waveform generating unit may be part of the laser drive circuit, or may be separate from the laser drive circuit, and may include a drive waveform information storage unit which stores a recording strategy according to a type of disk.

Abstract: A laser drive integrated circuit and an optical disk apparatus using the laser drive integrated circuit for forming high-density marks. The optical disk apparatus has a drive waveform information storage unit for storing at least one information of the drive waveform for driving a laser diode in response to a binary recording signal recorded in a recording medium and a drive waveform decoder for decoding the drive waveform based on the information stored in the drive waveform information storage unit. The recording strategy can be changed in accordance with the variations and fluctuations of recording media or the characteristics of the recording media, while at the same time reducing the number of signal lines of flexible wiring and alleviating the effect of the signal distortion.

Abstract: The present invention provides an apparatus and a method for precisely and adequately evaluating actual quality of reproduced data whenever applying a maximum likelihood decoder for converting signal reproduced from a recording medium into binary signal. Based on data arrays of a pair of binary data outputted from a “Viterbi” decoder, SAM values are secured by selecting any of path-metric differential values (00) and (11) being the difference between a pair of values compared when renewing path-metric values PMM (00) and (11) outputted from the “Viterbi” decoder. The minimum SAM value for an ideally-reproduced signal is outputted from a constant generating circuit. If the SAM values are verified as valid, and yet, if the SAM values coincide with the equation “input SAM values”≦“data value outputted from the constant generating circuit”, then squared values outputted from a square circuit are averaged by an averaging circuit.

Abstract: A laser drive integrated circuit and an optical disk apparatus using the laser drive integrated circuit for forming high-density marks. The optical disk apparatus includes a drive waveform information storage unit for storing at least one information of a drive waveform for driving a laser diode in response to a binary recording signal to be recorded in a recording medium, and a drive waveform decoder for decoding the drive waveform based on the information stored in the drive waveform information storage unit. A recording strategy can be changed in accordance with variations and fluctuations of recording media or characteristics of the recording media, while at the same time reducing a number of signal lines in flexible wiring and alleviating effects of signal distortion in the signal lines.

Abstract: There is disclosed a pulley unit made by interposing a one-way clutch 3 in an annular space between a pulley 1 and an axial body 2, providing a deep groove ball bearing 4 on the base end side of one-way clutch 3, and a roller bearing 5 on the free end side; setting an inner rolling surface of a roller 13 of the one-way clutch 3 to be an outer diameter surface of the axial body 2, and an inner rolling surface of rolling member 22 of the roller bearing 5 to be an outer diameter surface of the axial body 2. The pulley unit permits easy position setting of the pulley 1, so that stabilized lock and free operation can be expected and productivity can be improved.

Abstract: Aqueous protein-containing solutions, in which a protein is dissolved at a high concentration at a pH near the isoelectric point of the protein by adding an anionic polymer or a salt thereof to the solution. Pharmaceutical formulations using a physiologically active protein are prepared using this technique.

Abstract: A pulley unit A includes two, inner and outer ring bodies 1, 2 disposed concentrically, a one-way clutch 3 interposed in an annular space between both ring bodies 1,2, and rolling bearings provided on both sides of the one-way clutch 3 in the annular space, wherein a recessed part 10b provided on a member 10 where a cam face 10a for forming a wedge space for storing a roller 13 of the one-way clutch 3 is formed and a projecting part 12c provided on the axial one end of a cage 12 of the one-way clutch 3 are fitted to each other in the axial direction to prohibit the circumferential movement of the cage 12, and the projecting part 12c is physically checked from slipping off the recessed part 10b to prohibit the axial movement of the cage 12.

Abstract: A magneto-optical information recording/reproducing apparatus in which a magneto-optical information recording medium at least including a first magnetic film having perpendicular magnetic anisotropy, and a second magnetic film to which information recorded on the first magnetic film is transferred by irradiation of a laser beam, is used so that a readout laser beam is irradiated onto the second magnetic film to thereby readout the information transferred to the second magnetic film. The apparatus includes a 2-split detection circuit for receiving the readout laser beam reflected from the second magnetic film of the recording medium, and a subtraction circuit in which output signals of the two detection elements of the 2-split detection circuit are subtracted from each other to generate a differential signal.