Abstract: According to one embodiment, an optical disk device includes a laser light source that emits laser light to be applied to an optical disk, an automatic power control circuit that controls a laser output of the laser light source, and a control processor that performs a setting data transmission process for the automatic power control circuit. The automatic power control circuit includes an operation setting module that makes an operation setting according to setting data obtained in the setting data transmission process of the control processor and a condition determining module that determines whether an operation setting permission condition containing the number of clocks during a transmission period of the setting data is adequate, and inhibits the operation setting of the operation setting module when the operation setting permission condition is not adequate.

Abstract: Recording information is disclosed in which an information recording medium is irradiated with a recording energy beam that is power-modulated into at least a record power level and a record-ready power level lower than the record power level. The information is recorded on the recording medium in the form of length and interval of a mark portion. When forming a mark portion of a predetermined length, the radiation energy of the energy beam is increased as compared with when forming a mark portion of a different length before or after the first pulse of an energy beam pulse train including at least a pulse for forming the mark portion.

Abstract: Recording information is disclosed in which an information recording medium is irradiated with a recording energy beam that is power-modulated into at least a record power level and a record-ready power level lower than the record power level. The information is recorded on the recording medium in the form of length and interval of a mark portion. When forming a mark portion of a predetermined length, the radiation energy of the energy beam is increased as compared with when forming a mark portion of a different length before or after the first pulse of an energy beam pulse train including at least a pulse for forming the mark portion.

Abstract: Recording information is disclosed in which an information recording medium is irradiated with a recording energy beam that is power-modulated into at least a record power level and a record-ready power level lower than the record power level. The information is recorded on the recording medium in the form of length and interval of a mark portion. When forming a mark portion of a predetermined length, the radiation energy of the energy beam is increased as compared with when forming a mark portion of a different length before or after the first pulse of an energy beam pulse train including at least a pulse for forming the mark portion.

Abstract: In a dye-type optical recording medium, a write strategy for use in recording is determined based on recommended write strategy parameters recorded on an optical disk (160) and the characteristics of the optical recording device, and recording is carried out on the optical disk (160) according to the determined write strategy. In a medium of the phase change type, a power ratio and modulation degree for use in recording are determined from a recommended pulse width value in the recommended write strategy parameters recorded in the optical disk (160), the recommended power ratio value, the recommended recording power value, and the characteristics of the optical recording device, and recording is carried out on the optical disk (160) according to the power ratio value and modulation degree value thus determined.

Abstract: An optical disc recorder that records information on an optical disc by means of a laser diode that forms pits in the optical disc through the application of a write pulse of a previously set type, the recorder having a reference power setter that sets a reference power that is the reference value of a drive power of the write pulse, a pulse type checker that checks whether the type of write pulse set consists of a plurality of pulses, which allows the drive power to be set for each pulse of a plurality of pulses, a power corrector for correcting the drive power of at least one pulse of the write pulse by adding a previously set correction power to the reference power, and a drive controller that applies the write pulse, which consists of the pulse with the reference power and the at least one pulse with the drive power corrected.

Abstract: In an information recording/reproducing device, a resting period (tm) is set to be constant regardless of a mark length of a recording mark and regardless of the number of divided recording pulses. Consequently, it is possible to provide an information recording device, an information recording method, and an information recording medium, each allowing formation of a recording mark with a uniform width by use of a low laser power and allowing reduction of the number of parameters for determining a recording waveform, when forming a long recording mark.

Abstract: An equalization filter device includes: an equalization filtering section which has a digital filter and which performs equalization processing on an input signal and updates tap coefficients, which are set for multipliers provided in the digital filter, according to an error between an equalization signal generated by the equalization processing and a target signal; and a tap coefficient holding section which holds the tap coefficients, which are set for the multipliers, in a sequential manner at a necessary timing, wherein the equalization filtering section starts tap coefficient updating calculation processing using the tap coefficients, which are held in the tap coefficient holding section, at an end timing of an abnormal section of the input signal specified on the basis of an abnormal detection result regarding the input signal.

Abstract: A writing current circuit (42) supplies a controlled electrical current to a laser diode (34) for recording data swiftly onto a DVD (16). A plurality of current sources (62) in the writing current circuit (42) supply electrical current directly to the laser diode (34). Each current source (62) respectively receives a single output signal from a current control register (52) included in the writing current circuit (42) which activates or deactivates the current source (62) for supplying a particular quantity of current to the laser diode (34). In one aspect, a pair of current reference signals received by the current source (62) control electrical current supply to the diode (34). Incorporated into these controlling reference signals is a simulation of electrical characteristics of the diode (34). In another aspect, each current source (62) responds to a logical inverse of the output signal from the current control register (52) for controlling overshoot in voltage applied across the diode (34).

Abstract: A driver includes a parameter generation module configured to generate timing parameters based upon a received bit stream. A timing encoding module is configured to determine a plurality of pulse defining parameters based on the timing parameters. A pulse generation module is configured to determine a plurality of generic pulses based on the plurality of pulse defining parameters. The pulse generation module is configured to combine the plurality of generic pulses into a plurality of enable signals. The pulse generation module is configured to selectively invert a first enable signal of the plurality of enable signals. The pulse generation module is configured to output the plurality of enable signals including the first enable signal to a laser driver.

Abstract: Provided herein are hybrid laser diode drivers (LDDs) that drive a laser diode in response to receiving enable signals from a controller. In accordance with specific embodiments, a hybrid LDD includes a read channel to selectively output a read current, one or more write channel each to selectively output a write current, and an oscillator channel to selectively output an oscillator current. Additionally, in specific embodiments the hybrid LDD includes a decoder that receives the enable signals from the controller, and based on the enable signals, controls timing of the currents output by the read, write and oscillator channels.

Abstract: The present invention provides a method of recording control information in a recordable optical disc including at least one recording layer. In recording control information within a management area of an optical disc including at least one or more recording layers, the present invention includes providing the control information to each of the at least one or more recording layers per recording velocity, recording an information identifying a type of the corresponding control information within the control information, and recording a write strategy (WS) interworking with the type of the control information. In recording a write strategy (WS) within disc information, CLV and CAV are separately recorded, whereby it is able to efficiently cope with the record/playback of the optical disc.

Abstract: A method and recording device for recording marks in a phase-change type record carrier uses increased cooling period between pulses in a sequence of write pulses by applying m write pulses, where m is depended on n/? (? being an integer larger than 1). The number of write pulses m may be set to the integer value closest to n/?.

Abstract: An information readout method for an optical information medium comprising an information recording layer having pits or recorded marks representative of information data involves the step of irradiating a laser beam to the information recording layer through an objective lens for providing readings of the pits or recorded marks. When the laser beam has a wavelength ? of 400 to 410 nm, the objective lens has a numerical aperture NA of 0.70 to 0.85, and the pits or recorded marks have a minimum size PL of up to 0.36?/NA, readout is carried out at a power Pr of at least 0.4 mW for the laser beam. When the laser beam has a wavelength ? of 630 to 670 nm, the objective lens has a numerical aperture NA of 0.60 to 0.65, and the pits or recorded marks have a minimum size PL of up to 0.36?/NA, readout is carried out at a power Pr of at least 1.0 mW for the laser beam. Pits or recorded marks of a size approximate to the resolution limit determined by diffraction can be read out at a high C/N.

Abstract: A laser power controller includes a loop control section to control a laser light output level of an optical head that applies laser light onto a disk for recording data to be a prescribed value, a DAC control section to hold as a previous level a laser control level preceding switching of a laser output level upon track change between a groove track and a land track during recording, and an analog SW to select the DAC control section to control the laser light output level by the previous level for a certain time period from the track change and to select the loop control section after the certain time period.

Abstract: A digital signal reproducing apparatus includes an analog to digital converter for sampling and quantizing a signal read from an optical recording medium in accordance with a reproduced clock having a frequency which is one-half of a channel bit frequency and outputting an obtained digital RF signal, an offset compensation circuit for reducing an offset component in an amplitude direction from the digital RF signal, and a simplified interpolation filter for reconstructing a signal indicating a predetermined pattern recorded in the optical recording medium from the output signal of the offset compensation circuit and outputting the reconstructed signal. A control operation is performed to reduce the magnitudes of respective values shown by first phase error information on a section with the predetermined pattern and by second phase error information on a section other than the section with the predetermined pattern.

Abstract: Recording information is disclosed in which an information recording medium is irradiated with a recording energy beam that is power-modulated into at least a record power level and a record-ready power level lower than the record power level. The information is recorded on the recording medium in the form of length and interval of a mark portion. When forming a mark portion of a predetermined length, the radiation energy of the energy beam is increased as compared with when forming a mark portion of a different length before or after the first pulse of an energy beam pulse train including at least a pulse for forming the mark portion.

Abstract: A method for setting recording power of recording light, capable of an appropriate setting for a multilayer optical recording medium. The recording power of the recording light for an information recording layer of the multilayer optical recording medium to be irradiated with, is set by: evaluating an information recording layer to be evaluated for recording power when all the information recording layer(s) lying closer to a light incident surface than the information recording layer to be evaluated does is/are in a low transmittance state; evaluating the information recording layer to be evaluated for recording power when all the information recording layer(s) lying closer to the light incident surface than the information recording layer to be evaluated does is/are in a high transmittance state; and determining ground information for setting recording power, based on these values of the recording power.

Abstract: A write strategy setting apparatus applied in an optical disc drive includes a storage unit, an error calculator, and a write strategy controller. The storage unit stores an initial write strategy including a plurality of write strategy parameter sets corresponding to a plurality of data set types; the error calculator calculates an error value set for each data set type generated by the optical disc drive utilizing a corresponding write strategy parameter set in the initial write strategy, and stores the calculated error value set into the storage unit to thereby overwrite the write strategy parameter set; and the write strategy controller determines a modified write strategy by referring to a plurality of error value sets stored in the storage unit and the initial write strategy, and then storing the modified write strategy into the storage unit.

Abstract: Recording devices and methods are provided for recording marks on an information layer of a record carrier using a 2T write strategy, which enable recordation of marks on the information layer when no write parameter settings specifically tuned for the record carrier are available for use in the 2T write strategy.

Abstract: There is provided an optical information recording/reproducing apparatus capable of obtaining a high super-resolution effect using an optical information recording medium in which a super-resolution thin film is formed. An optical information recording medium 1 having a super-resolution layer is irradiated with a laser light in a light emission pattern such that a bias light emission portion that does not cause the super-resolution layer to be in the state of super-resolution and a pulse light emission portion that causes the super-resolution layer to be in the state of super-resolution alternatively appear, and reflected light is detected. A reproduction signal based on the pulse light emission portion and a reproduction signal based on the bias light emission portion are acquired.

Abstract: A media ID recording apparatus has an optical pickup 20 for forming an elongated optical spot on a recording surface of an optical disk DK; and a support table 32 for fixedly supporting the optical pickup 20. The optical pickup 20 is fixed to the support table 32 via a wedge-like spacer 33 as tilted toward the radial direction of the optical disk DK. The focal position of the elongated optical spot at the rear side in the moving direction is matched to the recording surface of the optical disk DK and the focal position of the optical spot at the front side in the moving direction is shifted from the recording surface of the optical disk DK, whereby the light intensity of the optical spot at the front side in the moving direction becomes smaller than the light intensity of the optical spot at the rear side in the moving direction. A media ID is recorded on the optical disk DK by using the optical spot thus set.

Abstract: A record carrier including a data area for storing data in the form of marks, in which the data is encoded by means of a channel code, wherein a parameter of the channel code is controlled so as to introduce a predetermined run length distribution in the marks on the record carrier, thereby introducing first information relating to a watermark, and a non-data area comprising second information relating to a watermark, the first and the second information forming the watermark. This watermark, extending over the data-area and the inner-ring area and/or the outer-ring area, can be used for checking the authenticity of the record carrier and/or the recordings made on this record carrier.

Abstract: The present invention provides a method of recording control information in a recordable optical disc including at least one recording layer. In recording control information within a management area of an optical disc including at least one or more recording layers, the present invention includes providing the control information to each of the at least one or more recording layers per recording velocity, recording an information identifying a type of the corresponding control information within the control information, and recording a write strategy (WS) interworking with the type of the control information. In recording a write strategy (WS) within disc information, CLV and CAV are separately recorded, whereby it is able to efficiently cope with the record/playback of the optical disc.

Abstract: The present invention provides an optical information recording apparatus and method capable of effectively determining appropriate recording parameters in a short time with favorable efficiency, when recording information onto an optical disk having different information recording conditions and information recording characteristics. An information recording condition or an information recording characteristic of an optical disk 1 is identified, and a recording pulse position is corrected at a correction accuracy according to the identifies information recording condition or information recording characteristic, such that a recording mark is formed in a predetermined position.

Abstract: Provided herein are hybrid laser diode drivers (LDDs) that drive a laser diode in response to receiving enable signals from a controller. In accordance with specific embodiments, a hybrid LDD includes a read channel to selectively output a read current, one or more write channel each to selectively output a write current, and an oscillator channel to selectively output an oscillator current. Additionally, in specific embodiments the hybrid LDD includes a decoder that receives the enable signals from the controller, and based on the enable signals, controls timing of the currents output by the read, write and oscillator channels.

Abstract: Provided herein are hybrid laser diode drivers (LDDs) that drive a laser diode in response to receiving enable signals from a controller. In accordance with specific embodiments, a hybrid LDD includes a read channel to selectively output a read current, one or more write channel each to selectively output a write current, and an oscillator channel to selectively output an oscillator current. Additionally, in specific embodiments the hybrid LDD includes a state machine that receives the enable signals from the controller, and based on the enable signals, controls timing of the currents output by the read, write and oscillator channels.

Abstract: The present invention provides a polycarbonate resin produced by the continuous interfacial process characterized in that after alkaline hydrolysis with sodium hydroxide, the polycarbonate resin contains an amount of 0.01 to 150 ppm of carbamate compounds according to formula (1) said amount measured by high pressure liquid chromatography, wherein R1 and R2 independently of one another denote hydrogen or C1-C12-alkyl, or together denote C4-C12-alkylidene, and R3 and R4 independently of one another denote hydrogen. C1-C12-alkyl or phenyl, or together with the carbon atom to which they are bonded form cyclohexyl or trimethylcyclohexyl, the process comprising phosgene reacting with at least one bisphenol at 8 to 17% molar excess of phosgene relative to the bisphenol.

Abstract: In an optical recording method and apparatus of the present invention, a driving power is applied to a light source to control emission of a light beam to a recording layer of an optical storage medium, the driving power including a sequence of mark and space portions, each mark portion having a pulse width that corresponds to a multiple of a period T of a write clock. A multi-pulse waveform of each mark portion of the driving power includes a front-end portion, a multi-pulse portion and a tail-end portion, the front-end portion having a first pulse width t1 with a high-power write level Pw and starting from a middle-power erase level Pe, the multi-pulse portion including write pulses each having a second pulse width t2 with the write level Pw and a third pulse width t3 with a low-power base level Pb, the multi-pulse portion having a duty ratio z=t2/(t2+t3), and the tail-end portion having a fourth pulse width t4 with the base level Pb and ending at the erase level Pe.

Abstract: An optical storage system modulates a laser beam based on a high frequency modulation (HFM) signal and a pattern to be recorded on an optical storage medium. At least one of an amplitude and a frequency of the HFM signal is adjusted when using the light beam to record the pattern on the optical storage medium or read data from the medium.

Abstract: A method for optimizing write parameters using two-stage adjustment is provided. A first kind of write strategy parameters optimization procedure for adjusting at least one static write strategy parameter of a write strategy is performed. A second kind of write strategy parameters optimization procedure for adjusting at least one dynamic write strategy parameter of the write strategy is performed after performing the first kind of write strategy parameters optimization procedure. The static write strategy parameter corresponds to a signal length of a pit on an optical disk and the dynamic write strategy parameter is utilized to overcome heat interference when forming the pit.

Abstract: A method for tuning a plurality of write strategy parameters of an optical storage device includes detecting a plurality of lengths, each length corresponding to a pit or a land on an optical storage medium accessed by the optical storage device, performing calculations corresponding to a plurality of data set types and generating a plurality of data-to-clock edge deviations respectively corresponding to the data set types, and utilizing the data-to-clock edge deviations for tuning the write strategy parameters corresponding to the data set types respectively.

Abstract: An optical recording method for recording information by irradiating an optical disc medium with a modulated write pulse train of laser light variable over a plurality of power levels such that a plurality of marks are formed on the optical disc medium, edge positions of each of the marks and a space between adjacent two of the marks being utilized for recording of the information.

Abstract: An optical disk driving unit includes a pickup configured to supply a drive current to a laser unit, and to irradiate a laser beam to an optical disk. A plurality of signal lines are configured to transmit control information of the drive current to the pickup. A pickup controller is configured to control operation of the pickup by transferring control data to the pickup via the signal lines when the drive current is a constant value.

Abstract: The objects of the present invention are to facilitate the driving of the recording energy source, and to secure sufficient cooling time of the recording medium to promote the high-speed formation of high-precision marks and to provide high-speed and large-capacity information recording apparatuses at a low cost. To achieve the above objects, at the time of information recording, p is chosen as the integer constant for marks natural number k times long of the detection window width by referring to the mark length in the recording data sequence, the recording data sequence is discriminated according to the quotient obtained by and the remainder remaining after dividing k+p by two or more integer constants, and the energy generating means is driven according to different procedures based on the result of discrimination obtained thereby.

Abstract: A driver control module comprises a parameter generation module, a timing encoding module, and a pulse generation module. The parameter generation module receives a bit stream and generates a set of timing parameters based upon contents of the bit stream. The timing encoding module receives the set of timing parameters from the parameter generation module and creates N sets of pulse defining parameters, wherein N is an integer greater than one. The pulse generation module creates N generic pulses using the sets of pulse defining parameters, combines the generic pulses into P enable signals, and outputs the enable signals to a laser driver, wherein P is an integer greater than one.

Abstract: A method for tuning a plurality of write strategy parameters of an optical storage device includes detecting a plurality of lengths, each length corresponding to a pit or a land on an optical storage medium accessed by the optical storage device, performing calculations corresponding to a plurality of data set types and generating a plurality of data-to-clock edge deviations respectively corresponding to the data set types, and utilizing the data-to-clock edge deviations for tuning the write strategy parameters corresponding to the data set types respectively.

Abstract: The present invention relates to an recording method for a multi-layered optical recording medium including M phase change recording layers, with M?2. The method comprises recording a mark in a Kth one of said recording layers by using a laser to irradiate the Kth recording layer using a recording pulse train including a plurality of laser beam pulses. The recording pulse train for the Kth recording layer has a cycle of t(K)[T], the 1st recording layer is the recording layer closest the laser beam, and the Mth recording layer is the recording layer furthest from the laser beam, T is a clock cycle. The following relationship is satisfied: t(1)<t(M), and the cycle of recording pulse train does not decrease from one recording layer to the next recording layer in the direction in which the laser beam irradiates.

Abstract: An information recording method and device for recording information by irradiating an optical information recording medium with an energy beam includes forming a first recording mark by irradiation of a monopulse-shaped energy beam having at least a first power level and a second power level that is higher than the first power level, and forming a space succeeding the first recording mark with a write strategy having a downward pulse of a third power level that is lower than the first power level on a backside of a midpoint of the space.

Abstract: An optical disc apparatus having a construction that lowers a peak value of a laser beam applied to an optical disc and controls a current supplied to the laser. Provisions are made to prevent recorded marks on the optical disc from degrading by utilizing the laser beam radiated onto the optical disc. Provisions are also made to minimize gradual deterioration of the laser itself that would otherwise be caused by the emission of laser beam, to minimize unwanted radio waves that would otherwise be produced from the optical disc apparatus by the emission of laser beam, and to prevent the responsiveness of the optical disc apparatus from being impaired.

Abstract: A method and apparatus for writing data to an optical storage medium are disclosed. A write signal indicating power levels of a laser diode is generated by encoding and decoding codewords. The codewords are generated and decoded according to a Successive State Change Criterion (SSCC) or SSCC II proposed by the present invention. By doing so, toggling (i.e. state changing) times occurring in channels transferring the codewords can be significantly reduced to avoid the problems of pulse distortion and disappearance in high frequency transmission. Alternatively, toggles appearing in the respective channels can be spread to avoid interference between the channels. Further, a phase adjustment device for adjusting a phase of each codeword is disclosed.

Abstract: An optical information recording reproduction device is disclosed, in which aberration detection is stably performed, so that an excellent record grade can be achieved. An RF signal is subjected to differential operation along a time axis of the signal, the RF signal being obtained from reflected light including primary light situated in the periphery of a primary dark ring enclosing zero-order light in a central portion of a beam spot formed on a pit; pulse signal waveforms are represented in an absolute value form, the pulse signal waveforms being generated in correspondence with front and rear ends of the beam spot on the time axis; the pulse signal waveforms represented in the absolute value form are stored into a storage medium; the stored, two pulse signal waveforms are combined to generate a beam profile of the beam spot formed on an optical recording medium; and a beam spot diameter, spherical aberration, and coma aberration of a record laser beam are adjusted based on the beam profile.

Abstract: To provide a recording and reproducing method for dye-based recordable DVD media, including: recording a mark of the shortest length on a dye-containing recording layer of a dye-based recordable DVD medium using single pulse whose front edge is energized; recording marks other than the shortest thereon using single pulse whose front and rear edges are energized for a given duration, the power of the front edge of pulse being equal to that of the front edge of pulse for the shortest mark, the power of the rear edge of pulse being equal to that of the rear edge of pulse for the shortest mark; and reproducing recorded information using a reproduction beam, wherein the irradiation intensity of cooling pulse provided after the rear edge of pulse upon mark recording is 0.1 mW or less for a given duration, and the recording linear velocity is 42 m/s or more.

Abstract: The invention relates to a method for determining write strategy parameter values for writing data on an optical disk from a group of optical disks of different types using an optical disk drive, in particular to different types of BD disks. The method includes identifying the type of optical disk, the type of optical disk being associated with a standard write strategy with standard write strategy parameters; determining a cluster write strategy with cluster write strategy parameters, the number of cluster write strategy parameters being smaller than the number of standard write strategy parameters; initializing the cluster write strategy parameters with initial cluster write strategy parameter values; and optimizing cluster write strategy parameter values for at least a subset of the cluster write strategy parameters. The optimizing is preferably performed on optimization sets of cluster write strategy parameters in a pre-determined optimization order.

Abstract: A test-write method for accurately and quickly determining recording conditions, and an apparatus suitable therefor. In a 2T-based strategy, recording pulse conditions are determined by separately test-writing an even-number length mark and an odd-number length mark, and then the relative positions of the even-number length mark and the odd-number length mark at the recording pulse start time are adjusted.

Abstract: An information recording method includes the steps of recording test data with changing a top pulse width Ton and monitoring reflected light intensity; determining an optimum top pulse width from the monitoring result; determining respective optimum off pulse widths according to multilevel data from a monitoring result of the determined optimum top pulse width; recording test data with changing recording power in sequence with the use of the optimum top pulse width and the optimum off pulse width determined, monitoring reflected light intensity, and thus determining optimum recording power.

Abstract: A method of recording data on a double-layer optical recording medium having a recording layer with high light transmittance is provided. A laser beam is modulated to emit a pulse series of laser including a write pulse of a write power and a cooling pulse of a bottom power, so as to encode and write data to be recorded as recording marks of a length nT along a track of the recording layer, where n is an integer and T is one clock cycle. An nT recording mark is formed using (n?1) write pulse(s), and when forming a recording mark of 4 T or longer, a cooling pulse with a pulse width of 0.8 T to 2 T is inserted before the last write pulse. Recording marks are thereby accurately formed without heat interference between consecutive recording marks and cross erase between recording marks of adjacent tracks.

Abstract: An optical recording and reproducing apparatus includes a recording-pulse-shift setting unit that shifts a front edge and a rear edge of a recording pulse and sets a write strategy of the recording pulse, an mark-edge-position evaluating unit that detects a front edge and a rear edge of a mark formed and detects a front mark edge position error and a rear mark edge position error, an assuming unit that assumes that the front mark edge position error is represented by a first linear function and assumes that the rear mark edge position error is represented by a second linear function, a sensitivity calculating unit that executes test recording and calculates sensitivities, and a write-strategy calculating unit that calculates a write strategy of the recording pulse on the basis of the sensitivities.

Abstract: It is an object of certain inventive aspects to provide a recording condition closer to an optimum even for a medium unknown to a drive, and more particularly, to provide means for obtaining a preferable recording condition even for a high-speed recording in which conducting a test recording is difficult. In order to accomplish the object, a power and a phase of a recording pulse are simultaneously corrected at predetermined timing, depending on a recording speed or a recording position such as an inner or outer circumference. For instance, a phase shift ?Phase generated due to a continuing recording from an inner circumference to an outer circumference at ×2 speed is corrected simultaneously with a correction of a power shift at the timing when a recording speed is changed from ×2 to ×4. For the other recording speed, in the same manner as above, a power and a phase shift are simultaneously corrected at every time when a recording speed is changed.

Abstract: In an optical disk drive that is equipped with a binarization circuit by the PRML method and carries out record/reproduction at a speed higher than a standard speed, to realize reproduction compatibility between the drive and another optical disk drive by the ordinarily adopted direct slice method. It can be realized by applying verification judgment equivalent to reproduction at a standard speed in accordance with a reproduction speed. More specifically, it is realized by counting 2 T data number by the direct slice method, using a Viterbi decoder that validates a run length shorter than the minimum run length, and adopting other measures. A higher record/reproduction speed is realized while reproduction compatibility, which is an important original function of an interchangeable optical disk, is secured.