Abstract: A method for detecting an unbalanced optical disc in an optical disc drive. The unbalanced optical disc is detected by a pick-up head of the optical disc drive to obtain a tracking error signal. A first track-across number at which the pick-up head travels on the unbalanced optical disc is determined when the unbalanced optical disc rotates at a first rotational speed. A second track-across number at which the pick-up head travels on the unbalanced optical disc is determined when the unbalanced optical disc rotates at a second rotational speed. The first track-across number and second track-across number are computed to obtain a resulting value. The unbalanced level of the unbalanced optical disc is determined according to the resulting value.

Abstract: An apparatus and method are provided for reproducing replacement data recorded in a spare area of a disc, such as a DVD-RAM. The replacement data is temporarily stored in a memory provided in a disc reading or player apparatus or a RAM provided in a PC connected to the disc reading or player apparatus so that the temporarily stored data can be read without movement of an optical pickup to the spare area during a subsequent data reproducing operation. The replacement data is thereby reproduced along with data recorded in a data area of the disc, in a successive manner. Accordingly, it is possible, for example, to efficiently prevent reproduced pictures from being discontinuously outputted due to a delayed data reading operation caused by a searching operation for the spare area in which the replacement data is recorded.

Abstract: A write once disc, a disc drive therefor, and a method of managing disc defects on the write once disc using the disc drive in consideration of the compatibility of the write once disc with a rewritable disc drive, the write once disc includes a single record layer disc in which a lead-in area, a data area, and a lead-out area are sequentially formed and a first spare area and a second spare area are sequentially formed in the data area. The write once disc includes a defect management area (DMA) formed in at least one of the lead-in area and the lead-out area; a first temporary defect management area (TDMA) formed in at least one of the lead-in area and the lead-out area; and a second TDMA formed between the first spare area and a user data area or between the user data area and the second spare area.

Abstract: An information storage apparatus includes an optical element, a detector, an adjustment mechanism, a memory and a controller. The optical element emits and/or receives a radiation beam along an optical axis. The detector produces a first signal representing a tilt angle of the storage medium with respect to the detector. The adjustment mechanism compensates a tilt angle between the optical axis of the radiation beam and a direction normal to the optical storage medium in response to a second signal. The memory stores calibration data obtained based on relationship information between the first and second signals and tilt-angle information about the deleted tilt angle. The controller generates the second signal referring to the calibration data such that the tilt angle is substantially canceled. The relationship information reflects a deviation of a property of at least one of the detector and the adjustment mechanism measured by an individual test.

Abstract: A method of verifying that a disc recording and reproducing apparatus normally generates or updates defect management area (DMA) information in a supplementary spare area extension mode, and a test apparatus therefore. The method includes extending the supplementary spare area of a test disc in the recording and reproducing apparatus using the test disc with test reference information and generating test information from the test disc; and comparing reference information expected from the test reference information with the test information and providing the result of verification of the test information. Accordingly, a DMA information generation or updating function of the recording and reproducing apparatus upon the extension of the supplementary spare area can be easily verified.

Abstract: A CD-RW resonance removing apparatus comprises a first holding-down plate where at least the driving plate, the sliding rods and the read/write head are mounted; a second holding-down plate to balance the total weight of the first holding-down plate and other components mounted on it; multiple elastic pads attached to the first holding-down plate, called first elastic pads, for connecting the first holding-down plate to the chassis frame; and multiple elastic pads attached to the second holding-down plate, called second elastic pads, connect the second holding-down plate to the first holding-down plate. The first and second elastic pads could be with different K values and damping values. The balancing weight by the second holding-down plate, the absorbing vibration by the second elastic pads, and the isolating vibration function of the first elastic pads, all together, eliminate resonance during operation.

Abstract: If data is recorded using a disc with deviating characteristics and a recorder with deviating characteristics, data will not be appropriately recorded, and errors will occur in the read signal. Standard recording pulse parameters specifying recording pulse positions for plural possible mark length and space length combinations are read from a writable optical disc, these standard recording pulse parameters are then used for test writing, the standard recording pulse parameters are changed uniformly or individually, a best recording pulse parameter is thus obtained, and jitter can be reduced.

Abstract: A repeatable runout compensator that allows a transducer of a servo system in a storage device employing rotating media to follow the eccentricity on the media is disclosed. In exemplary embodiments, the repeatable runout compensator utilizes error values generated by the servo system, which represent the radial and/or axial eccentricity of the media, to generate an output signal having a sinusoidal waveform that is approximately 180 degrees out of phase with the eccentricities and the harmonics of eccentricities on the media.

Abstract: A light beam is applied to an optical disk through a first hologram and an objective lens. The first hologram has a first region that can diffract light and a second region that can diffract light. The light beam reflected from the optical disk is applied through the objective lens to a second hologram. The second hologram splits the light beam into a first light beam and a second light beam that have passed through the first region and the second region, respectively.

Abstract: An improved writing strategy for constant angular velocity writing of CD-RW (compact disk-rewritable media) uses similar strategy as the constant linear velocity writing mode. The writing strategy includes the steps of dividing the compact disk into annular regions, setting a laser duty ratio for one of the regions, setting a laser write pulse duration to establish the laser duty ratio, and setting the laser duty ratios of the remaining annular regions using the same laser write pulse duration in each region. If the writing strategy results in unacceptable performance, as by laser write jitter being out of tolerance, the laser write pulse duration may be slightly modified in selected areas to acquire the desired performance level.

Abstract: An optical disc recording/reproducing apparatus includes: recording/reproducing means for recording/reproducing information by emitting a light beam onto a disc having a track which wobbles at a predetermined frequency; reflected light detection means for detecting the light beam reflected from the disc; wobble signal detection means for detecting a wobble amplitude signal which represents an amplitude of a signal generated from a component which is extracted from an output of the reflected light detection means and which wobbles at the predetermined frequency; and variation rate detection means for detecting dirt adhered on the disc based on a rate of a variation in the wobble amplitude signal, wherein the variation rate detection means detects the dirt based on the wobble amplitude signal before the recording/reproducing means records/reproduces the information.

Abstract: A recording/playback apparatus for a DVD on which a VOB and a management file of the VOB are recorded. When detecting a failure in the management file, the recording/playback apparatus changes the state of the DVD to: (a) a first state in which reading/writing of the DVD is available; (b) a second state in which reading/writing of the DVD is available but the VOB cannot be played back; or (c) a read only state, in accordance with the detected failure. When the state of the DVD changes to the second state, the recording/playback apparatus writes a new VOB onto the DVD. When the state of the DVD changes to the read only state, the recording/playback apparatus plays back the VOB recorded on the DVD.

Abstract: A method for recording data on an optical disk, capable of detecting an abnormal state which may occur in the middle of data recording, preventing the abnormal state from damaging the optical disk, and recording data continuously from the position wherein the abnormal state happened after the abnormal state terminates. The method of the present invention comprises the steps of (a) examining if an abnormal recording state is encountered while recording data on the optical disk, (b) suspending data recording if an abnormal recording state is detected in step (a), (c) requesting retransmission of the data received in step (a) and receiving said data after said abnormal recording state terminates, and (d) recording said retransmitted data in a selected area on the optical disk.

Abstract: An optical disk drive having a thermal control mechanism on the optical head to control the spacing between the optical head and the surface of the storage medium.

Abstract: A method for controlling the BCA clock in reading BCA data and a circuit of the same are disclosed. A BCA clock extractor is used for read the BCA data correctly. A proper clock modulation is performed through this BCA clock extractor so as to read BCA data correctly.

Abstract: An estimation method produces a reproduction signal while reading from an information recording medium such as an optical disk, and uses an equalizer to produce an equalization signal. The method then synthesizes distribution levels of the equalization signal that range over distributions of (n+1) levels L0, L1, . . . , Ln (in which L0<L1 . . . <Ln and n>2), thereby creating a new distribution. The method then uses the standard deviation of the new distribution as an estimation reference value to estimate the quality of an information reproduction apparatus or the quality of the information recording medium. The quality estimate may be used to adjust a circuit in an information reproduction apparatus that reads the information recording medium.

Abstract: A disk reading apparatus for reading data recorded on a disk medium is disclosed. The disk reading apparatus comprises a motor for rotating the disk medium, a vibration sensor section for detecting vibrations generating inside the disk reading apparatus and for converting the vibrations into a signal, a binarized signal generation section for extracting only a frequency component corresponding to the rotary speed of the disk medium from the signal outputted from the vibration sensor section, and for outputting a signal in which a binaraization is performed, a vibration judgement section for measuring a period of the binarized signal outputted from the binarized signal generation section and for outputting a vibration detection signal when the period of the binarized signal corresponds to the rotary speed of the disk medium, and a rotation control section for lowering the rotary speed of the disk medium when the vibration detection signal is inputted.

Abstract: A method is described for optimizing recording conditions for writing information on an optical record carrier. The information is written on the record carrier in the form of optically detectable marks, each mark being written by a pulse series of radiation. A series of test patterns is written on the record carrier (1) for the optimization. A jitter detector (11) measures both the leading-edge and trailing-edge jitter of the read signal. The leading-edge jitter is used to optimize the value of a parameter influencing only the leading part of a pulse series. The trailing-edge jitter is used to optimize a parameter influencing only the trailing part of the pulse series.