Abstract: A method for determining the completeness of an optical disc and a method for playing the optical disc are provided. The method for playing the optical disc includes: performing focusing on and tracking on the optical disc; detecting whether the optical disc contains any data if the focusing on succeeds while the tracking on fails; if the optical disc contains data, turning on a servo system to perform focusing on and tracking on to the area containing the data and determining whether a file information area contains a file system; if the file information area does not contain any file system, reading the outmost data in a video data area to locate a file allocation data table; and playing the data stored in the video data area according to the file allocation data table.

Abstract: A disk motor which rotationally drives an optical disk; a rotational phase detector which detects a rotational phase thereof; an optical head having a collecting lens which collects an optical bean; a light detector and an LE signal generator which detect a position of the collecting lens in the optical head as a position signal; an LE signal memory recorder and an LE signal memory which store, in synchronization with a rotational phase to be detected by the rotational phase detector, the positional signal from the LE signal generator; an LE signal memory regenerator which outputs as a correction signal, in synchronization with a rotational phase to be detected, the positional signal which has already been detected; a subtractor; an LE signal filter, a drive circuit and a Tk actuator which move the collecting lens using a signal from the subtractor; and a low pass filter which reduces a high-frequency component of the correction signal are provided.

Abstract: A method for rating an information recording medium according to the present invention includes the steps of: receiving a digital read signal, which has been generated based on an analog read signal representing information that has been read from the information recording medium, and shaping the waveform of the digital read signal; subjecting the shaped digital read signal to maximum likelihood decoding, thereby generating a binarized signal showing a result of the maximum likelihood decoding; and calculating the quality of the digital read signal based on the shaped digital read signal and the binarized signal. If the quality of the read signal is calculated by a PRML method in which a number of zero-cross portions are included in a merging path of a minimum difference metric, the quality is calculated by using only a state transition pattern in which only one zero-cross portion is included in a merging path of a non-minimum difference metric.

Abstract: The present invention provides a method for determining what group a given multilayer optical disc belongs to. The disc is one of a number of multilayer optical discs, which are designed so that information stored is retrievable from any of the discs by irradiating the disc with a light beam having the same wavelength and which have been classified into multiple groups. According to this method, performed first is Step (A) of measuring either a distance from a first one of multiple information layers of the given multilayer optical disc to a second one thereof, which is located adjacent to the first information layer, or a distance from the first information layer to the surface of the optical disc. Next, Step (B) of determining, by the distance measured, what group the given multilayer optical disc belongs to is performed.

Abstract: In a write once type optical disc, when ejecting the disc and turning power OFF, it is necessary to update record management data on the disc so that the record management data on the disc coincide with the record management data on the memory. Here, the update of the record management data on the disc requires a certain time. The present invention provides a user-friendly recording/reproduction apparatus including a unit for judging whether the disc record management information can be updated according to the ratio of the recorded capacity with respect to the recording-enabled capacity. Upon completion of the user data recording, the disc record management information is recorded so that the record management data is not updated when power is turned OFF or the disc is ejected, thereby reducing the time required for the power turning OFF and the disc ejection.

Abstract: When a hybrid optical disc is loaded on a player, the next generation DVD layer is reproduced in preference to the DVD layer. Jump to the DVD layer is appropriately performed based on the content of the reproduction list held in the next generation DVD. The jump to the DVD layer is performed based on the command information (jump command) held in the reproduction list of the next generation DVD layer. When reproduction of the title specified by the command information is finished after the jump to the DVD layer, the process returns to the HDDVD layer, and reproduction is performed from the position following the reproducing position at the time of the jump. Thus, the content of the HDDVD layer and the content of the DVD layer are reproduced as one stream.

Abstract: A defect is detected on a storage medium of a disk drive. A location of the defect is determined, within a smallest addressable unit of data stored on the storage medium. An indication of the location is stored in a memory. A location of a sensor of the disk drive relative to the data stored on the storage medium is monitored. A response of at least one of a defect detector of the disk drive, a read channel controller of the disk drive, and a servo controller of the disk drive is changed based on the location of the sensor relative to the data stored on the storage medium and the stored indication of the location of the defect.

Abstract: The invention relates to an optical data system comprising an optical disc drive and a host. The optical disc drive is arranged to receive an optical disc and perform read and write actions with respect to the optical disc. The host is arranged to instruct the optical disc drive to perform a read or write action with respect to the optical disc. The optical disc drive may be arranged to a) the optical disc drive is arranged to perform a quality measurement generating a plurality of quality parameters, b) the optical disc drive is arranged to output the plurality of quality parameters to the host, and c) the host is arranged to decide on a further action based on the received plurality of quality parameters.

Abstract: An optical disk drive for determining a disk characteristic of an optical disk comprising an information layer comprising a substantially circular track is described. The optical disk drive has an optical pickup unit arranged to generate a beam, direct the beam to the optical disk for forming an incident beam, sense a reflected beam produced by the optical disk with a sensor upon receiving the incident beam with the sensor, produce a sensor output signal from sensing the reflected beam; a disk receiving device arranged to receive the optical disk; a motor arranged to provide a transition of the disk receiving device from a first mode to a second mode in at least one transition phase; and a controller arranged to receive the sensor output signal during at least one part of the at least one transition phase and perform at least part of determining the disk characteristic from at least the sensor output signal received during the at least one part of the at least one transition phase.

Abstract: A backup device and a one-key data backup method for the same use a backup device having ability to retrieve a memory card and an optical disc. The backup device is connected to an external computer. A backup application is installed having backup conditions configured in the external computer. When an input unit of the backup device is triggered, the backup device sends a backup request instruction to the external computer. The external computer executes the backup application upon receiving the backup request instruction, and records data of the memory card to an optical disc, or saves the data of the optical disc in the memory card based on configured backup conditions.

Abstract: A disk-shaped rewritable information recording medium having at a first recording layer and a second recording layer is disclosed. The information recording medium includes a first data area situated in the first recording layer, the first data area having a plurality of addresses allocated thereto, the plural addresses continuously increasing in a first direction, a second data area situated in the second recording layer, the second data area having a plurality of addresses allocated thereto, the plural addresses continuously increasing in a second direction opposite to the first direction, and a management information area having an area for recording end recorded area information thereto, the end recorded area information including information for identifying an area in the second data area having data that corresponds to an end position of the second data area.

Abstract: An optical recording and reproducing apparatus which suppresses the generation of a noise component in a servo signal while preventing a deterioration in using efficiency of a light beam is provided. The optical recording and reproducing apparatus has an optical pickup including a liquid crystal correcting element, a liquid crystal element control unit, a memory, and an operation mode control unit. The memory stores a plurality of correction data sets respectively corresponding to a plurality of refractive index distribution to be formed by the liquid crystal correcting element. The liquid crystal element control unit selectively reads out the correction data set corresponding to the operation mode designated by the operation mode control unit from the memory and supplies a driving voltage according to the read-out correction data set to the liquid crystal correcting element.

Abstract: An object of the present invention is to retrieve and process a piece of content to be processed by a simple method at the time of storing content recorded in a CD into an HDD or the like, reading desired content out of the content stored in the HDD from the HDD, and performing a process such as reproduction on the read content. A processor of the invention includes: a storage 1 for storing at least one piece of information so as to be associated with jacket image information of an image related to the content; means for obtaining target medium image data by capturing an image of a jacket of a CD related to the content to be reproduced; means for collating the target medium image data with jacket image information stored in the storage 1 and obtaining the content corresponding to the target medium image data from the storage 1; and means for reproducing the obtained content.

Abstract: According to the present invention, there is provided a method of recording a unique ID to a read-only optical disc based on the 17PP modulation. The read-only optical disc (1) has set thereon a specific physical cluster to which a unique ID is to be recorded. With user data to be recorded to the specific physical cluster being made all zero (0), a pit/land pattern is formed, and a molding machine using a molding die is used to form many optical discs in the common manner. Thereafter, an ID unique to each optical disc is generated, and a land in a predetermined position in the specific physical cluster is transited to a pit by irradiating high-power laser light to the land correspondingly to the bit information, so that the pit/land pattern will comply the 17PP modulation rule even after the transition of the land to the pit.

Abstract: An optical disc includes a reflective film formed on concave and convex marks after the concave and convex marks are synchronized with the integral multiple of a channel bit length and formed in accordance with modulated main information. Thereafter, continuous or intermittent laser light synchronized with the integral multiple of the channel bit length is irradiated at intervals longer than the longest one of the concave and convex marks in accordance with a spiral track formed in a circumferential direction of the concave and convex marks, whereby an optical characteristic of the reflective film is changed to form a recordable mark and sub-information necessary to reproduce the main information is recorded in a superimposition manner.

Abstract: An optical disk processing system having a recording unit and a printing unit is provided. The optical disk processing system comprises a printing unit and a recording unit. A drive controller of the recording unit rotationally drives a loaded optical disk (D) and detects whether or not a rotational speed is reduced during acceleration. When the rotational speed is reduced, it is judged that a stick-slip has occurred and loading of a plurality of the optical disks (D) is detected.

Abstract: This optical disk device includes an examination means which examines a first physical characteristic of an optical disk, and a servo means which starts servo control based upon that first physical characteristic. This optical disk device includes a read means which incorporates the examination means, and which reads type information from the optical disk under that servo control based upon the first physical characteristic. This optical disk device includes a control means which decides whether or not a second physical characteristic of the optical disk, which is determined as a standard for the type of type information read, and the first physical characteristic, agree with one another. And, if the control means has decided that these two physical characteristics do not agree with one another, it commands the read means to read replay data from the optical disk, under that servo control based upon the first physical characteristic.

Abstract: An optical disk drive according to the present invention has the ability to read data from multiple types of optical disks, each of which includes at least one information storage layer. The drive includes: a driving mechanism 120, which is loaded with a selected one of the optical disks of the multiple types and which rotates the optical disk 102; an optical pickup 30 for irradiating the optical disk 102, which has been loaded into the driving mechanism 120, with a converged light beam, thereby generating an electrical signal based on light that has been reflected from the optical disk 102; and a control section (ODC 50) for controlling operations of the driving mechanism 120 and the optical pickup 30. The control section 50 includes a right/wrong side determining section for determining, by reference to the electrical signal generated by the optical pickup 30, whether or not the optical disk 102 has been loaded into the driving mechanism 120 with the other surface opposed to the optical pickup 30.

Abstract: In order to record an interference fringe pattern in a recording layer of a medium, a plurality of laser beams are caused to interfere so as to form interference fringes in the recording layer; and during a time period over which the plurality of laser beams are caused to interfere, the following steps are continuously performed: (1) producing a signal varying according to a shift of a specific position in the recording layer; and (2) shifting a fringe-forming position in the recording layer by changing a phase of at least one of the laser beams or moving the recording layer based upon the signal produced in the step (1).

Abstract: An apparatus for converting a groove/land polarity on an optical medium, comprises a physical identification (PID) detector for detecting a first PID value from a first sector, a sector information unit for providing an information which includes a second PID value indicative of either a second sector or at least one reference groove/land changing point, a sector counter for counting a first value whose an initiation is set by the sector information unit based on the information and/or by the PID detector based on the first PID value, and a comparing unit for determining at least one oncoming groove/land changing points, when the first value approaches a second value predetermined in or generated by the sector information unit according to the information.

Abstract: A method of recording data, as embodied, includes creating and temporarily storing first management information for the data recorded before a recording failure occurs, when the recording failure occurs during recording of the data on a recording medium; continuously recording the data starting from a subsequent available recording location; and creating second management information for the data recorded after the occurrence of the recording failure, and recording the second management information on the recording medium in connection with the temporarily stored first management information when recording is completed.

Abstract: An optical disc apparatus of the present invention records and/or reproduces data to/from an optical disc where data is recorded on one of a groove track and a land track. The optical disc apparatus includes an identification section for identifying the type of the optical disc as being either an optical disc where data is recorded or reproduced to/from a groove track or an optical disc where data is recorded or reproduced to/from a land track. The identification section identifies the type of the optical disc while in a state where a focus control is being performed and a tracking control is not being performed.

Abstract: A disc discriminating method for use in an optical disc drive includes the following steps. Firstly, an optical pickup head of the optical disc drive is controlled to move in a first direction when the optical pickup head is in a track-unlocked state. Then, a tracking error signal and a radio frequency signal are generated. According to the tracking error signal, a tracking error zero crossing signal is obtained. According to the radio frequency signal, a radio frequency zero crossing signal is obtained. According to a phase relation between the tracking error zero crossing signal and the radio frequency zero crossing signal, the disc is discriminated as an on-groove recording disc or an in-groove recording disc.

Abstract: According to one embodiment, a reproduction apparatus includes an execution unit configured to execute an advanced application, a detection unit configured to detect a series of keys which are operated by a user while the advanced application is executed, a recording unit configured to record key macro information formed of the detected series of keys and operation timings of the series of keys, and a key event generating unit configured to read the key macro information recorded by the recording unit and to generate a series of key events corresponding to the series of keys at the operation timings.

Abstract: A method of recognizing a track pitch of an optical disk, adapted for an optical disk player, is provided. The method includes the steps of driving an optical pickup head to a predetermined position, so that the optical pickup head and the spindle motor are a predetermined distance apart, reading a data sector address, and recognizing the magnitude of the track pitch of the optical disk according to the value of the data sector address.

Abstract: A recording medium on which a recording/reproducing unit block is recorded, an apparatus to record and/or reproduce data on/from the recording medium, and a method of recording/reproducing the data on/from the recording medium. The recording/reproducing unit block comprises invalid data used in disc certification, and an identifier to indicate that the invalid data is included in the recording/reproducing unit block, the invalid data being used during the disc certification on a portion of the recording medium or the entire recording medium.

Abstract: An information recording medium, recording and/or reproducing apparatuses, and recording and/or reproducing methods which enable effective management of a last data recording address of a data area of the information recording medium. The information recording medium includes a data area for recording user data, temporary recording management information for managing a data recording status of the data area and temporary disc management information for managing the information recording medium, wherein the temporary disc management information includes first information regarding a last recorded location of data in the data area and second information regarding whether the information regarding the last recorded location is consistent with an actual last recorded location of the data area.

Abstract: An optical disc verification method according to the present invention includes the steps of: writing data on first, second and third radial locations on an optical disc at a writing speed V1 and reading the data written there, thereby measuring read signal quality index values A, B and C, where the second radial location is inside of the first radial location and the third radial location is inside of the second radial location; writing data on the first and second radial locations at a writing speed V2, which is higher than V1, and reading the data written there, thereby measuring read signal quality index values D and E; and correcting the signal quality index value C with the difference between the signal quality index values B and E, thereby calculating a signal quality index value F that would be obtained if data is written on, and then read from, the third radial location at the speed V2.

Abstract: Optical disc recording processing of recording data to be recorded on an optical disc having a plurality of recording layers at a recording velocity depending on the radial position includes use pattern selection processing of selecting a use pattern in which given recordable regions included in a data zone of the optical disc are used for recording of the data to be recorded in given use order, among a plurality of use patterns different in the number of recording layers used, so that the total recording time is shortened, based on given conditions including at least the capacity of the data to be recorded, the recording velocities of use regions in the use pattern, and the number of interlayer shifts in the use pattern. The data to be recorded is recorded according to the use pattern selected in the use pattern selection processing.

Abstract: A portable data storage assembly, comprising a holographic data storage layer, and an optical tracking layer comprising addressing information for the holographic data storage layer, wherein that addressing information defines a first storage band comprising a first plurality of storage addresses and a second storage band comprising a second plurality of storage addresses, wherein said second plurality of storage addresses is greater than said first plurality of storage addresses.

Abstract: Provided is an optical disk device installed in a personal computer, including: an information creation unit that creates identification information for identifying the type of the personal computer based on a command transmitted from the personal computer; and a parameter selection unit that conducts switching, for parameter selection, concerning a parameter indicating an amount of unbalance of an optical disk, which has previously been determined depending on the type of the personal computer, in accordance with the identification information created by the information creation unit.

Abstract: A method of recording read/write compatibility information on an optical disc and a recording medium employing the method. Extended part version information, latest part version having recording capability, and latest part version having reproducing capability are stored in n.xy form on 6 bytes of a reserved zone of a physical format information zone of the optical disc. A recording/reproducing apparatus to record extended part version information on a reserved zone of a physical format information zone of a recording medium. The recording/reproducing apparatus has a base part version and a comparing unit to determine recording/reproducing compatibility with a recording medium having a detailed extended part version stored in a reserved zone of a physical format information zone.

Abstract: An optical axis shift correcting device is provided in an optical information device including an irradiation element for applying a laser, an optical system for guiding a laser applied to an optical disc having a recording track, and a light reception element for receiving the light from the optical disc generated by the guided laser via the optical system. The optical axis shift correcting device includes a jitter acquisition element, an optical axis modification element modifying the direction of the optical axis with respect to the light reception element, and a control element controlling the optical axis modification element to reduce the shift when the acquired jitter amount exceeds a predetermined threshold value. The optical axis shift correcting device thus corrects the optical axis light shift on the surface of the light reception element with respect to the radial direction of the optical disc set in the optical information device.

Abstract: An optical information medium measurement method of the present invention, for measuring a degree of modulation in an optical information medium of a multilayered structure having a plurality of information layers, includes a first step of measuring the modulation degree of each layer of the optical information medium, by use of a measurement optical system, a second step of obtaining a thickness between layers of the optical information medium, a third step of obtaining a reflectance of each layer of the optical information medium, and a fourth step of converting the modulation degree of each layer, the modulation degree being measured in the first step, into a modulation degree at a reference optical system differing from the measurement optical system, based on a value indicative of the thickness between layers, the thickness being obtained in the second step, and a value indicative of the reflectance of each layer, the reflectance being obtained in the third step.

Abstract: Provided is a digital broadcast receiver capable of displaying a message, a list of titles of contents or the like together with a viewing screen without interrupting viewing of contents. The digital broadcast receiver includes a controller 25 configured to determine whether an optical disc inserted into the receiver is a read-only optical disc or a recordable optical disc and also to control a display screen. Upon insertion of an optical disc, the controller 25 causes a display screen including a first display area and a second display area to be displayed, the first display area displaying digital broadcast or external input contents, the second display area displaying a message indicating that the optical disc is being prepared. In a case where the optical disc is a read-only optical disc, the controller 25 causes only a playback screen of contents recorded in the optical disc to be displayed upon completion of the preparation of the optical disc.

Abstract: The effect of detection errors when detecting if a disc recording medium is in a disc drive is eliminated. A control unit 17 detects if an optical disc 11 was supplied to an optical disc drive 13 based on the operation of the transportation unit 16, causes the optical disc drive 13 to detect if an optical disc 11 is inside the disc drive, and compares the results of these detection operations. If the results do not match, the control unit 17 causes the optical disc drive 13 to repeat the operation discharging and loading the optical disc 11, and causes the optical disc drive 13 to again detect if an optical disc 11 is present after the discharge and loading operation. The control unit 17 then determines if the new detection result from the optical disc drive 13 and the detection result related to supplying the optical disc 11 to the optical disc drive 13 match, and based on the result of this evaluation detects an optical disc drive 13 operating error.

Abstract: An optical disc apparatus includes: a defect detecting section 124 for detecting, based on a light detection signal and with respect to a preset detection reference level, a fingerprint or a bubble on the disc 102 as a defect to output a defect detection signal; and a waveform shaping section 126 to output a hold signal that holds, in response to the defect detection signal, a signal from a tracking control section 109 at a level just before the defect has occurred. The apparatus is initially operated not to hold the signal from the tracking control section 109 even if there is a defect. But once a tracking failure has occurred during a read operation, settings are changed to hold the signal from the tracking control section 109 against the defect while the read operation is retried.

Abstract: Novel evaluation indexes are introduced to allow both a total evaluation of data recording and an evaluation of individual detection patterns. A data recording evaluation method includes a step of reproducing a result of data recording performed on an optical disk and identifying a predetermined detection pattern in a reproduction signal, a step of detecting a signal state of the reproduction signal associated with the predetermined detection pattern, and a first calculation step for calculating a first evaluation index value based on the detected signal state and a reference state identified from the predetermined detection pattern. When there is a plurality of predetermined detection patterns as described above, a second calculation step is further provided for calculating a second recording state evaluation index value using the first evaluation index value calculated from each of the predetermined detection patterns.

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: Disclosed herein are aspects of optical tape technology, tape manufacturing, and tape usage.

Abstract: The present techniques provide methods and systems reading a data bit of interest on an optical data disc with a reduced error rate. The data bit estimation may be improved by reducing deterministic noise resulting from an optical reader system and/or the optical data disc. The reader may adjust the position of a detector to detect light scattered from the disc based on parameters of known noise sources. In one embodiment, the detector may be moved vertically in relation to the data bit of interest on the optical disc. In another embodiment, more than one detector may be used to detect light scattered from a data bit of interest. In embodiments, the positioning of the detector(s) may be based on system or disc parameters, and the detected scatterings may provide a data reading, improved for an optical return from a present micro-hologram.

Abstract: When a medium selection button 101 is operated, an optical disc reproduction apparatus 1 recognizes which medium is selected according to inputted medium selection information, and then opens a tray 104. Next, when a medium selection button 101 is operated, the optical disc reproduction apparatus 1 determines the inputted medium selection information and closes the tray 104. Next, the optical disc reproduction apparatus 1 acquires a priority list 16 and modifies the priority list 16 such that the order of the selected medium in the priority list 16 is a first priority and the remaining orders of the other media are successively lowered. The optical disc reproduction apparatus 1 performs a medium check for each of the media in accordance with the orders of the modified priority list 16.

Abstract: A method of detection is described to be used in file system-based player devices to determine the type of compact disk that has been inserted into a player. The method automatically distinguishes between the DTS-CD format and standard audio CDs. The method allows the operating system or CPU software to take appropriate action to decode and playback the audio stream once the a decision between standard audio CD or DTS-CD is made.

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 method of controlling recording of an optical disc device and an optical disc device using the method. The optical disc device performs recording of data on a labeled surface of the optical disc. The device includes a buffer memory, a record unit and a controller. The buffer memory stores data and the record unit records data on the labeled surface of the optical disc from the buffer memory. The controller controls the record unit such that when a recording error occurs, the recording is stopped and when the error is corrected, data is recorded from a stopped position.

Abstract: The present invention relates to a method for recording an AV file using an information recording disk in which data is recorded/reproduced by sectors. The recording method includes the steps of determining whether or not input data is AV data; detecting a defective sector existing in an assigned data recording area; when the input data is AV data while a defective sector is detected in the data recording area, allocating a defective extent including the defective sector; recording AV data in continuous sectors while skipping the defective extent; and allocating an area of continuous sectors where on the AV data is recorded as one AV extent.

Abstract: A random access control method is provided, implemented in an optical disc drive for recording data to an optical disc. In the optical disc drive, a buffer stores a plurality of write commands each associated with a data block bound to a destination address. A processor controls the buffer to build a disc write task from the write commands in which addresses are organized in order. A drive unit is controlled by the processor, performing a recording operation to record the data blocks to the optical disc according to the disc write task; wherein the processor further controls the drive unit to verify the recorded data blocks after completing the recording operation.

Abstract: According to one embodiment, there is provided an optical disk apparatus including a recording unit which irradiates an optical disk with a laser beam to record information in a first format and a second format, a generation unit which generates warning information to an optical disk apparatus capable of performing a read process in the second format while being not capable of performing the read process in the first format, the warning information warning that information is recorded in the first format in the optical disk, and a control unit which controls the recording unit to record the warning information in the second format in the optical disk apparatus when the information is recorded in the first format in the optical disk.

Abstract: A method of identifying a type of a disc includes steps of: obtaining a first address of a first position on the disc; moving a pick-up unit to a second position of the disc; obtaining a second address of the second position; calculating a difference between the first address and the second address; and identifying the type of the disc by comparing the difference with a predetermined value.

Abstract: In a super-resolution optical disk for the purpose of achieving an increase in the density of recording data by reproducing a recording mark smaller than optical resolution, the optimum reproduction power needs to be determined since the quality of a super-resolution reproduced signal strongly depends on the reproduction laser power. However, since the track error signal required for tracking servo also depends on the reproduction power, there is a need for a method for determining the reproduction power taking into account both the stabilization of tracking servo and a quality improvement of the reproduction signal. The reproduction power is changed under conditions with focusing servo applied but without application of tracking servo. Thereby, a cross track signal is detected to identify a reproduction power region that leads to quality improvement of both a reproduction signal and a track error signal.