Abstract: A disk drive and an information processing system optimizes the number of rotations of a disk. Data read from a disk and previously-read cache data are temporarily stored in buffer memory. When a total amount of cache data achieved during a given period of time T1 or an average amount of the same is equal to or less than a threshold value X1, a system controller controls the number of rotations in an increasing manner, thereby optimizing the number of rotations. When a total amount of cache data achieved during a given period of time T2 (T1<T2) or an average amount of the same is equal to or greater than a threshold value X2, a system controller controls the number of rotations in an decreasing manner, thereby optimizing the number of rotations.

Abstract: An interference type optical head and an optical disk device that can easily adjust an optical path length difference of a couple of lights, ensure higher signal amplification effect, and are suitable for reduction in size are provided in order to improve a regeneration signal quality with amplification of signal in the case where reflectivity of each layer must be lowered and relative noise for the signal increases because read speed is high in a multilayer optical disk. In view of essentially improving an S/N ratio of the regeneration signal in high-speed rotation of a multilayer disk, a plurality of interference phases are generated and an optical system for differential calculation has been reduced in size with an angular selective polarization conversion element in the optical disk device for amplifying the signal with interference of the light not radiated to the disk with the reflected light from the disk.

Abstract: A holographic information recording and/or reproducing apparatus including: a light source unit emitting reference light and signal light; a first optical path guiding unit guiding the lights to cross; a second optical path guiding unit including a first polarization converter located on an optical path of one of the reference and signal lights, a first polarization beam splitter located at a crossing point of the reference light and the signal light, an optical path converter guiding the reference light and the signal light so that they cross again, a second polarization converter located on an optical path of the signal light before the signal light crosses the reference light, and a second polarization beam splitter uniting the optical paths of the reference light and the signal light; and an objective lens unit illuminating the reference light and the signal light onto one side of a holographic information storage medium.

Abstract: An optical disk device which flexibly and efficiently executes verification of recorded data is provided. A drive controller sets an area to be verified and a mode of verification according to a command which is supplied from a host device. For the area to be verified, the user selects one or a plurality of lead-in, inner, middle, and outer areas. For the verification mode, the user selects one of an immediate execution mode and an in-close-command execution mode. In a duplicator or the like in which same data is recorded on a plurality of optical disks, the user can designate an important data portion and selectively execute verification.

Abstract: Apparatus and method for reading data from or writing data to a stationary optical storage medium. A light beam redirecting mechanism is rotatable about an axis through a stationary dish mirror that faces a stationary optical storage medium from which data may be read or to which data may be written.

Abstract: A servo objective lens and a recording/reproducing objective lens are commonly held on a holder. The servo objective lens and the recording/reproducing objective lens are integrally displaced, thereby pulling servo light onto a servo layer. Upon the pulling, focus positions of recording light and reproducing light follow a focus position of the servo light. As a result, the focus positions of recording light and reproducing light are set close to the servo layer. Thereafter, an optical element for displacing the focus positions of recording light and reproducing light in the optical axis direction is driven to pull the recording light and the reproducing light onto a targeted recording layer.

Abstract: A recording medium, and a method and apparatus for recording and reproducing data to/from the recording medium are disclosed. The recording medium having a data structure for managing a data area of the recording medium includes at least one physical access control (PAC) cluster, the at least one PAC cluster including information for managing logical overwriting to the recording medium, wherein each PAC cluster includes a PAC header, the PAC header being common to each PAC cluster, and a PAC specific information area, the area including information specific to each PAC cluster, wherein the PAC header includes segment information identifying at least one segment area in a user data area of the recording medium.

Abstract: There is provided a type judgment device capable of rapidly and safely identifying the type of an optical disc while preventing unexpected information recording or information erase. An optical beam as parallel light is applied in a circular polarized state to an optical disc having recording tracks and the polarization characteristic in the reflected light is detected. According to the detected polarization characteristic, the type of the disc is judged in accordance with the interval of the adjacent recording tracks.

Abstract: A disk drive controls the rotational speed of a disk to an appropriate value. A system controller of the drive stores data read from a disk and read-ahead data into buffer memory. A time interval ti at which the buffer memory becomes full is measured, and the time interval ti is compared with a predetermined lower limit value t1 and a predetermined upper limit value t2. When a relationship of ti>t2 stands, rotational speed is increased. When a relationship of ti<t1 stands, control is performed in such a way that the rotational speed is decreased so as to achieve t1?ti?t2.

Abstract: A gap pull-in method and an optical disc apparatus. Whether light condensed on a disc as an actuator ascends is near-field light is determined using a gap error signal. The range of an actuator driving voltage value during a section where the decrease rate of the gap error signal is constant is obtained when it is determined that the light condensed on the disc is near-field light. Gap pull-in is performed on the disc during a section where the actuator driving voltage value is within the obtained range.

Abstract: A method for calibrating an SA compensation level of an optical drive is provided. The method includes steps of providing a plurality of SA compensation levels; obtaining a peak-to-peak value of an S curve corresponding to each of the SA compensation levels; selecting a maximum of the peak-to-peak values of the S curves and the SA compensation level corresponding to the maximum; and setting the selected SA compensation level to be an optimal SA compensation level.

Abstract: The invention relates to the field of optical information recording. In order to prevent abusive or fraudulent use of storage media, the invention provides a process for intentional degradation of information by application of a laser power below the normal power for reading information recorded in super-resolution on the media. This process relies on the surprising observation that a laser power below the super-resolution read power produces an irreversible degradation of the information recorded. This observation has been made with regard to media composed of a three-layer structure comprising an InSb or GaSb layer between two ZnS/SiO2 layers. Application for protecting sensitive data.

Abstract: A method for determining a type of a disk and an optical storage apparatus thereof are provided. The method includes when the disk placed in the optical storage device is not a blank disk, determining whether the phases between a first signal and a second signal of the disk are the same or not; and determining that the disk is a low to high (LTH) data disk or a high to low data disk (HTL) data disk upon whether the phases of the first signal and the second signal are the same or not. Therefore, the reading parameters are correspondingly loaded in the optical storage device according to the type of the disk.

Abstract: An optical pickup has an objective lens drive device which includes a fixed block fixed to a movement base, a movable block having an objective lens and a lens holder that holds the objective lens, a plurality of support springs that couples the fixed block with the movable block, and a focusing magnetic coil that operates the movable block in a focusing direction. A distance between the fixed block and a recording surface of a disk recording medium is larger than a distance between the movable block and the recording surface. The support springs are inclined with respect to the recording surface. The support springs have a longitudinal direction orthogonal to a direction of a thrust generated at the focusing magnetic circuit to the movable block during a focusing operation.

Abstract: An optical recording/reproducing apparatus is arranged so that, upon recording or reproducing a recording medium having a plurality of recording layers, the gap of the lens groups at the time of forming a converged light spot on this first recording layer is DIS (1), the gap of the lens groups at the time of forming the converged light spot on the N-th layer (the furthest layer from the surface of the recording medium) is DIS (N) and the neutral point of the spherical-aberration correcting mechanism is set at a position satisfying the following expression: lens group gap dst (3)=((DIS (1)+DIS (N))/2.

Abstract: The use of a multi-track format in both optical and magnetic data storage applications provides for a number of improvements to system performance including data density and data transfer rates. However, the full advantage in data density can only be achieved through the use of joint equalization and joint detection. The complexity of implementation of these functions arc addressed with a transform domain equalization architecture and a reduced complexity detection method based on a breadth first search of a time-varying trellis. The trellis results from a one dimensional representation of a two dimensional target response, obtained by arranging samples from adjacent tracks in a sequence that respects the original proximity of the samples.

Abstract: A light source emits light with a first wavelength and light with a second wavelength longer than the first wavelength toward an optical disk from adjacent positions. An optical receiver detects light reflected from the optical disk. An astigmatism-generating element generates light used for focus control in a condition where a focusing position on one of two perpendicular cross sections including an optical axis of the light reflected from the optical disk is located ahead of the optical receiver and a focusing position on the other cross section is located behind the optical receiver are included. The astigmatism-generating element is a Fresnel mirror configured to include a plurality of reflecting mirrors. A level difference between the reflecting mirrors adjacent to each other is distributed in a range from a depth of substantially (natural number/2) times the first wavelength to (natural number/2) times the second wavelength.

Abstract: A waveform shaping portion receives a digital reproduced signal generated from an analog reproduced signal reproduced from an information recording medium and shapes the waveform of the digital reproduced signal. A maximum likelihood decoding portion applies maximum likelihood decoding to the digital reproduced signal in the shaped waveform and generates a binarized signal indicating the result of the maximum likelihood decoding. A phase detection portion extracts, during the maximum likelihood decoding, a phase error using state transition patterns having only a single zero cross point among differential metrics at a plurality of merging points at which a set of paths branched from a given state merges. A synchronization detection portion generates a reproduction clock signal using the phase error that has been detected and brings the digital reproduced signal into synchronization with the reproduction clock signal that has been generated.

Abstract: Disclosed is an arrangement that enables to keep a relative positional relation between a beam for servo control and a beam for information recording/reproduction constant concerning focusing control and tracking control, even if the two beams are different from each other. An optical storage medium has a reflection surface for reflecting a first beam having a first wavelength, and reflecting a second beam having a second wavelength different from the first wavelength; and an information storage layer for recording information as an interference pattern by incidence of the first beam, or reproducing the information from a wave surface based on the interference pattern. The reflection surface is formed with plural marks or guide grooves usable in a tracking operation or a focusing operation by irradiation of the second beam.

Abstract: A method for controlling a ball auto-balancing system of an optical disk drive is provided. A rotational member is fixed on a rotating axis of an optical disk drive and rotates synchronously therewith. A spindle motor drives the rotational member to accelerate and decelerate within the rotating speed range at least twice. When the spindle motor accelerates and decelerates for many times, if the measured central error value is greater than the last measured one, the accelerating and decelerating range is adjusted.