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: Provided is a recording adjustment method capable of controlling an edge position of a mark with high accuracy. Based on the acquired read-out signal waveform, a starting position of a last pulse is adjusted such that a so-called L-SEAT shift value for an end edge of the mark becomes minimum.

Abstract: In one embodiment the present invention includes a circuit comprising a switch and a switch driver. The switch is configured to provide synchronous rectification switching of a back-EMF voltage. The synchronous rectification switching produces a source voltage. The switch driver is configured to receive the back-EMF voltage and the source voltage. The switch driver provides a control signal to a control terminal of the switch. The control signal has a frequency. The frequency is used to control an amount of the synchronous rectification switching. Accordingly, the frequency reduces a dissipated power associated with the synchronous rectification switching.

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 asynchronous timing detector 3 detects and measures a specific pattern (sync pattern) of audio and video reproduced signals having a digital value form an A/D converter 2 and its appearance interval based on an asynchronous clock generated by an asynchronous clock generator 4, and calculates a cycle ratio of the measured sync pattern appearance interval (the number of clock pulses of the asynchronous clock) to a normal value (the number of clock pulses of a synchronous clock obtained by measuring a sync pattern appearance interval using the synchronous clock). A pseudo-synchronous clock generator 7 thins the asynchronous clock based on the cycle ratio to generate a pseudo-synchronous clock which is pseudo-synchronous with channel data. Therefore, even when an initial frequency error is large, frequency and phase pull-in is relatively quickly performed until a timing recovery operation becomes stable.

Abstract: A calibration circuit and a calibration method thereof for data recovery are provided. The calibration circuit includes an amplitude detector, a period detector, and a compensation circuit. The amplitude detector samples amplitudes of a data signal according to a zero-crossing signal and outputs an amplitude signal accordingly. The period detector counts a clock signal according to the zero-crossing signal and outputs a period signal accordingly. The compensation circuit receives the amplitude signal, the period signal, and the data signal. The compensation circuit adjusts a phase of the data signal by calculating differences between a reference signal and the amplitude signal and between the reference signal and the period signal and outputs a calibrated data signal accordingly. Accordingly, a better recognition performance on the data signal is achieved by calibrating the data signal in real-time.

Abstract: An information recording device, an information reproducing device, and an information recording medium securely protect copyright of main information, and prevent illegal access to the recorded main information. The information recording device includes a medium unique information generating section that generates second sub information by data-converting stamper unique information based on disc identification information that differs for each optical disc after transferring main information and first sub information from a stamper having the main information and the first sub information recorded thereon onto an optical disc, and a medium unique information recording section that records the second sub information on the optical disc having recorded thereon in advance the main information and the first sub information in a form different from the forms of the main information and the first sub information.

Abstract: There is provided an optical disc having preformed thereon a spiral wobbled track as a grove and/or land along with data is to be recorded. The track is wobbled for a series of predetermined signal units each composed of an FSK information bit part based on a waveform resulted from FSK modulation of information bit and a singe-frequency part based on a waveform of a single frequency. The FSK modulation uses two different frequencies of which the one is the same as the single frequency and the other is different from the single frequency. These different frequencies are in such a relation that each of them has an even number of wobbles and an odd number of wobbles alternately in a predetermined cycle.

Abstract: Provided is an optical disc having main information to be decrypted using sub information recorded thereon by arranging concave or convex recording marks in a spiral track wherein a reflective film is formed on the recording marks. First sub information is recorded and superimposed on the main information by shifting/deforming the recording marks or altering a pattern of the recording marks. Second sub information is recorded and superimposed on the main information by changing a reflectivity of the reflective film. The first and second sub information are recorded in an area from which the first and second sub information are to be read simultaneously. The second sub information is recorded in a manner to be associated with the first sub information. The first and second sub information are associated with each other and are recorded in the same area.

Abstract: A system including a demodulator module, a timing module, and a writing module. The demodulator module demodulates a wobble signal having a first period using timing signals having a second period and generates a phase error signal based on the wobble signal. The wobble signal is generated based on wobble information stored on an optical medium. The first period is a first multiple of a channel bit period of the optical medium. The second period is a second multiple of the channel bit period. The timing module generates a clock signal based on the phase error signal. The writing module writes, based on the clock signal, a predetermined number of bits on the optical medium during the first period. The predetermined number of bits written during the first period is based on the second multiple in response to the second multiple being greater than the first multiple.

Abstract: An apparatus for accessing data from a disc with a linking area comprises a pick up head, a servo, a processing unit, a position predictor, and a control signal generator. The pick up head reads data from the disc and generates a read signal. The servo controls the pick up head. The processing unit processes the read signal and controls the servo according to a plurality of control signals. The position predictor tracks time position on the disc and generates position information. The control signal generator receives the position information and generates the control signals according to the position information.

Abstract: Various embodiments of the present invention provide systems, methods and media formats for processing user data derived from a storage medium. As an example, a system is described that includes a storage medium with a series of data. The series of data includes a servo data and a user data region. The user data region includes a first synchronization pattern and a second synchronization pattern located a distance from the first synchronization pattern. A storage buffer is provided that is operable to receive at least a portion of the series of data. A retiming circuit calculates an initial phase offset and frequency offset for a defined bit within the storage buffer using a first location of the first synchronization pattern and a second location of the second synchronization pattern. An error correction loop circuit re-samples the series of data from the storage buffer based at least in part on the initial phase offset and a frequency offset.

Abstract: A tracking signal generating apparatus includes a phase detector and a digital phase controller. The phase detector generates an up signal and a down signal which contain information regarding a phase difference between a plurality of square wave signals that have been generated from an optical signal. The digital phase controller generates an up limit signal or a down limit signal whose logic levels are controlled so that a phase difference between the up limit signal and the down limit signal is reduced.

Abstract: An electron beam irradiating apparatus according to an embodiment includes: a deflector configured to perform blanking or deflecting of the electron beam emitted from an electron gun, the blanking being performed based on a blanking control signal, the deflecting being performed based on a deflection control signal, or blanking and deflecting being performed based on the blanking control signal and the deflection control signal; a first clock signal generation circuit configured to generate a first reference clock signal having cycles which vary with a drawing radial position on the stage; a second clock signal generation circuit configured to generate a second reference clock signal having cycles which are independent of the first reference clock signal; and a control signal generation circuit configured to generate a first control signal that is at least one of the blanking control signal and the deflection control signal, based on the first reference clock signal and the second reference clock signal.

Abstract: An apparatus includes a recorder having at least two optical pickup heads for simultaneously recording at least two bit streams on respective layers of recordable media in one of an opposite track path and a parallel track path.

Abstract: A recording apparatus, which records information in an optical recording medium, includes: a mode-lock laser unit including a saturable absorber section that applies a bias voltage, a gain section that feeds a gain current, a semiconductor laser that emits laser light used to record the information on the optical recording medium, and an external resonator; an optical modulation unit performing amplification modulation on the laser light emitted from the mode-lock laser unit; a reference signal generation unit generating a master clock signal and supplying a signal synchronized with the master clock signal to the gain section of the semiconductor laser; a recording signal generation unit generating a recoding signal based on the master clock signal; and a driving circuit generating a driving pulse used to drive the optical modulation unit based on the recording signal.

Abstract: An optical disk drive device has an RF equalizer configured to generate an equalized RF signal by controlling a frequency characteristic of a delay time of an RF signal read out from an optical disk based on a control input signal, a playback clock extractor configured to extract a playback clock for reproducing data recorded on the optical disk from the equalized RF signal, and an RF rate controller configured to generate the control input signal inputted to the RF equalizer, wherein the control input signal is a signal for correcting waveform distortion of the RF signal by controlling the delay time of the RF signal dependent on a frequency of the playback clock.

Abstract: A first optical receiver circuit in an optical receiver IC, which composes an optical disk device, generates a first voltage signal VS1 indicating an amount of light of a laser beam oscillated in a multimode. A second optical receiver circuit generates a second voltage signal VS2 indicating an amount of light of an optical feedback from an optical disk. A binarization circuit extracts a band component corresponding to a predetermined frequency in VS1, and binarizes the band component, thereby obtaining a digital signal. A delay element delays a phase of the digital signal by time equivalent to a phase difference between VS1 and VS2, and outputs the phase delayed signal as a timing signal. A sample hold circuit (S/H) samples and holds the VS2 in synchronization with the timing signal. Further, A LPF eliminates a band component corresponding to the frequency from an output signal of the S/H.

Abstract: An A/D converter samples a read signal in synchrony with a system clock sclk having a fixed frequency, to perform an A/D conversion. A fluctuation compensator is configured as an internal-feedback-type compensation filter, and suppresses fluctuation of a digital signal output from the A/D converter. A digital PLL uses an interpolator to generate, by interpolation, a sampled value of the read signal at a timing in synchrony with a channel frequency, and uses NCO to generate a synchronizing clock and an interpolated-phase signal that is fed back to the interpolator. A binarization circuit binarizes the read signal based on the interpolated value output from the interpolator. The frequency characteristic of the fluctuation compensator is controlled based on the frequency value output from the loop filter.

Abstract: When a multilayered optical disc is used, the signal-to-noise ratio of a read signal is decreased as effective reflectance is extremely low due to the influence of reflection and absorption by front recording layers. Further, when a high-frequency modulation technology is used to suppress returned light noise of a laser, the erasure of recorded information is likely to occur on certain types of discs, making it difficult to simultaneously achieve the suppression of returned light noise of a laser and the prevention of the erasure of recorded information. To address the above problems, the present invention includes a section that performs a read by executing a multi-tone demodulation. The present invention also includes a section that controls the position and shape of a read light pulse to be radiated on a recording layer.

Abstract: To provide an optical disk device, an optical disk control method and an integrated circuit, which are capable of writing a recordable mark by changing the reflectance ratio of a reflective film formed on concave-convex pits without using an industrial special device or a high-power laser light source. A data reproduction controller (103) sets a first rotation speed in a disk rotation speed switching unit (108) and a first laser power in a laser power switching unit (107) when reproducing the concave-convex pits. When writing the recordable mark, a mark recording controller (104) sets in the disk rotation speed switching unit (108) a second rotation speed that is slower than the first rotation speed and the lowest rotation speed at which the concave-convex pits can be reproduced, and sets a second laser power greater than the first laser power in the laser power switching unit (107) in accordance with the emission timing.

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: Aspects of the disclosure provide an apparatus. The apparatus includes a pick-up unit, such as an optical pick-up unit, a wobble channel and a defect detector. The pick-up unit generates a push-pull signal corresponding to a wobbled track of a storage medium. The wobble channel includes circuits to receive the push-pull signal, obtain a wobble signal from the push-pull signal, and calculate a wobble amplitude metric based on the wobble signal. The defect detector compares the wobble amplitude metric to a threshold to detect wobble defects.

Abstract: A recording method is provided, which comprises the steps of (a) generating a plurality of pulse sequences corresponding to a plurality of linear velocities, (b) while rotating a recording medium with a linear velocity selected from the plurality of linear velocities, forming at least one of a recording mark and a space by irradiating the recording medium with a pulse sequence selected from the plurality of pulse sequences, the pulse corresponding to the linear velocity. The step (a) comprises the steps of (a-1) measuring at least one first recording parameter corresponding to at least one linear velocity selected from the plurality of linear velocities, (a-2) determining a second recording parameter corresponding to the plurality of linear velocities based on the at least one first recording parameter measured, and (a-3) generating the plurality of pulse sequences corresponding to the plurality of linear velocities based on the second recording parameter measured.

Abstract: According to a method of the present invention for recording data on an optical disk, a recording pulse corresponding to a long mark includes a combination of a leading pulse and a subsequent intermediate pulse. Further, a level of the leading pulse indicates a first recording power, and a level of the intermediate pulse indicates a second recording power. When an optical disk includes a plurality of recording layers, a ratio of the second recording power to the first recording power is determined for each recording layer. When the recording speed is variable, the ratio of the second recording power to the first recording power is determined for each recording speed.

Abstract: Aspects of the disclosure provide a signal processing circuit that has fast response time to sudden profile changes in an electrical signal. The signal processing circuit includes a processing path configured to process an electrical signal that is generated in response to reading data on a storage medium, and a feed-forward correction module. The feed-forward correction module is configured to detect a profile variation based the electrical signal in a time window, and correct the electrical signal in the time window based on the detected profile variation.

Abstract: A method and apparatus for recovering clock timing from a bi-phase modulated portion of a high frequency modulation (HFM) signal. The HFM signal includes signal transitions between a high level and a low level. A clock count is initiated upon detection of a first signal transition in the bi-phase modulated portion of the HFM signal. The clock count corresponds to an expected clock timing of the HFM signal. The clock count is stopped upon detection of a second signal transition in the bi-phase modulated portion of the HFM signal subsequent to the first signal transition. An actual clock count includes a number of clock cycles occurring between the first and second signal transitions based on the expected clock timing. An expected clock count between signal transitions of the bi-phase modulated portion of the HFM signal is identified if the actual clock count between the first and second signal transitions falls within a range of clock counts.

Abstract: In the multi-tone demodulation (MTD) technique, even if an input bandwidth is widened to obtain a larger SNR gain, an increase in the signal to noise ration (SNR) gain cannot always be obtained due to clock jitter that increases clock noise. Also, noise is sometimes superimposed on the clock supplied to an analog to digital converter circuit (ADS) and the noise lowers the performance. Accordingly, the optical disc apparatus loosely regulates the bandwidth of a pulsed read signal; boosts the high-frequency components of a waveform of a driving signal of a laser diode; and synchronizes autonomously a driving clock of the ADC and a digital to analog converter circuit (DAC) with a clock of the pulsed read signal.

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: A digital disk device is provided in which the quality of a digital signal is improved without causing the development cost for and power consumption by the digital disk device to increase. An ADC included in a signal conversion circuit samples an analog signal which represents the intensity of a laser beam reflected, after being emitted from a laser source driven by a current superimposed with a high-frequency signal, from an optical disk using a clock signal whose frequency is substantially the same as that of the high-frequency signal and converts the sampled analog signal into a digital signal. An LPF provided in a stage preceding the ADC passes a component, not exceeding a predetermined frequency, of the analog signal with the frequency of the clock signal set to be higher than the predetermined frequency.

Abstract: The invention relates to an optical drive (10) and a method for determining a reading and/or writing position of an optical drive (10). The optical drive (10) in accordance with the invention comprises control means (12) and at least three PLL units (20, 22, 24), wherein the control means (12) are adapted to control the three PLL units (20, 22, 24) to try to lock on to three different frequencies characteristic for an optical disc (26). The method in accordance with the invention comprises the step of controlling at least three PLL units (20, 22, 24) to try to lock on to three different frequencies characteristic for an optical disc (26). If the optical disc (26) is a Blue Ray Disc, the three different frequencies can be the HFM frequency, the wobble frequency, and the expected HF frequency.

Abstract: An address detection circuit includes a correction signal generator that generates a plurality of timing correction signals based on an ADIP (Address In Pre-groove) signal that is read out from a wobble of an optical disk, the timing correction signals having different cycles with each other, a correction signal selector that selects one of the timing correction signals generated by the correction signal generator and outputs the selected signal, and a timing corrector that outputs a data address detected based on a data signal that is read out from a data track of the optical disk at a timing in accordance with the timing correction signal transmitted from the correction signal selector.

Abstract: A recording control apparatus includes a waveform rectification section for receiving a digital signal generated from an analog signal representing information reproduced from an information recording medium, and rectifying a waveform of the digital signal; a maximum likelihood decoding section for performing maximum likelihood decoding of the digital signal having the waveform thereof rectified, and generating a binary signal representing a result of the maximum likelihood decoding; a reliability calculation section for calculating a reliability of the result of the maximum likelihood decoding based on the digital signal having the waveform thereof rectified and the binary signal; and an adjusting section for adjusting a shape of a recording signal for recording the information on the information recording medium based on the calculated reliability.

Abstract: A laser driving circuit employing a recording compensation circuit configured to generate a light emission timing of a laser on the basis of recorded data and a recording clock signal which are supplied to the recording compensation circuit includes: a phase synchronization circuit; a skew determination circuit; and a data latching circuit.

Abstract: According to one embodiment, an optical recording medium is provided in which interlayer crosstalk is low and in which stable and high-quality recording characteristics can be obtained. To this end, an optical recording medium comprises a first recording part which includes a first recording layer and a first light reflecting layer and which is disposed on a side closer to a light receiving surface, and a second recording part which includes a second recording layer and a second light reflecting layer and which is disposed on a side farther from the light receiving surface, the first recording part and the second recording part being stacked, wherein the thickness of the second light reflecting layer is larger than the thickness of the first light reflecting layer.

Abstract: A method and apparatus for recovering clock timing from a hi-phase modulated portion of an HFM signal. The signal includes transitions between high and low levels. A clock count is initiated upon detection of a first transition, which corresponds to an expected clock timing of the signal. The count is stopped upon detection of a second transition. An actual clock count includes a number of clock cycles occurring between the transitions based on the expected timing. A first expected clock count between transitions is identified if the actual clock count between the transitions falls within a first range of clock counts. A first error between the actual and first expected clock counts is determined. A second expected clock count between transitions is identified if the actual clock count between transitions falls within a second range of clock counts. A second error between the actual expected clock counts is determined.

Abstract: There is provided an optical disc having preformed thereon a spiral wobbled track as a grove and/or land along with data is to be recorded. The track is wobbled for a series of predetermined signal units each composed of an FSK information bit part based on a waveform resulted from FSK modulation of information bit and a singe-frequency part based on a waveform of a single frequency. The FSK modulation uses two different frequencies of which the one is the same as the single frequency and the other is different from the single frequency. These different frequencies are in such a relation that each of them has an even number of wobbles and an odd number of wobbles alternately in a predetermined cycle.

Abstract: A technique capable of realizing a power saving in a device for reproducing/recording digital signals by properly controlling a frequency of a clock. The device for reproducing/recording digital signals (device for reproducing an optical disk) includes: a difference comparing circuit for comparing a first parameter (demodulating block counter) updated each time a process for one correcting block is done in a demodulating circuit with a second parameter (error correcting block counter) updated each time a process of one correcting block is done in an error correcting circuit; and a circuit (clock controlling circuit etc.) for switching a frequency of a master clock (MCLK) depending on a comparison result of the difference comparing circuit. Thereby, the frequency of the clock can be switched both of when the demodulation for one correcting block is ended and when the correcting process for one correcting block is ended by using the switched master clock.

Abstract: A digital data demodulator which can reduce a loss of decodable digital data, and increase capability of reproducing digital data inputted through a transmission line even when an error occurs in the transmission line. In the digital data demodulator, a specific pattern detector (113) detects a specific pattern to be included in a modulation code, from a bit string inputted through a transmission line (104). A modulation code identifying unit (117) generates a demodulation data strobe signal (119) according to a phase of the modulation code including the specific pattern. An error corrector (121) samples demodulation data (109) in response to the demodulation data strobe signal (119) and reproduces the data to the original digital data.

Abstract: An optical disk apparatus is provided which can: prevent an SNR deterioration attributable to an increase in read speed; overcome difficulty in separating a read signal and HF signal components; reduce laser noise; and maintain high reliability even during a high-speed read operation. An optical disk is irradiated with laser light pulsed by a high-frequency signal generated by a HF oscillator. The output of an optical detector which receives laser light reflected from the optical disk is converted into an electric pulse read signal using a current amplifier. The pulse read signal is converted into a temporally continuous read signal using a combination of an AD converter and a DA converter.

Abstract: Aspects of the disclosure provide a method for recording. The method includes receiving a tracking signal corresponding to a recording track on a storage medium, phase-locking an internal signal to the tracking signal by reducing a phase error generated based on the internal signal and the tracking signal, generating a phase bias, combining the phase bias into the phase error to phase-shift the internal signal from the tracking signal, and recording on the recording track based on the internal signal.

Abstract: According to one embodiment, a disk drive configured to write data to a disk being rotated by a spindle motor has a synchronous clock generator that generates a synchronous clock to use during the write operation. The synchronous clock generator inputs the rotational acceleration of the spindle motor, as feed-forward control value, to the feedback control system provided in the drive disk, thereby generating a clock that is synchronous with the rotational speed of the disk.

Abstract: Various embodiments of the present invention provide systems and methods for reduced latency feedback in a data processing system. For example, some embodiments provide a data processing system that includes a variable gain amplifier, a processing circuit, a data detector, and an error signal calculation circuit. The variable gain amplifier amplifies a data input signal and provides an amplified signal. The processing circuit generates a signal output corresponding to the amplified signal, and includes a conditional multiplication circuit. The conditional multiplication circuit conditionally multiplies the signal output by a gain correction signal and provides the result as an interim output. The data detector applies a data detection algorithm to the signal output and provides an ideal output. The error signal calculation circuit generates a gain correction signal based at least in part on the interim output and a derivative of the ideal output.

Abstract: A method and apparatus demodulate pre-formatted information embedded in an optical recording medium. The demodulation includes (a) receiving a wobble signal representing data symbols frequency-modulated on a carrier frequency, (b) generating a phase delta signal representing a phase difference between the wobble signal and a corresponding locked signal having the carrier frequency, (c) first sampling the phase delta signal at a data sampling interval to produce first values, (d) second sampling the phase delta signal at each halfway of the data sampling interval to generate second values, (e) determining, based on a difference between two successive second values, if the first sampling is performed at timing corresponding to an end of each data symbol, and (e) adjusting sampling timing of the first sampling towards the timing corresponding to each end of the data symbols, if the sampling timing does not corresponds to the end of each data symbol.

Abstract: A recording unit records data read from a buffer for storing therein data reproduced by a CD drive apparatus capable of adjusting a data reproduction volume which is a volume of data to be reproduced per unit time. A decision unit generates a signal which adjusts the data reproduction volume based on a buffering quantity in the buffer or a volume of dataflow in the recording unit, and outputs the generated signal to the CD drive apparatus.

Abstract: A jitter counter according to the present invention is connected to a PLL circuit for generating a clock signal, which is necessary for signal processing, from a binary signal, and counts jitters of the binary signal.

Abstract: A method and system for allowing a media player to transfer digital audio to an accessory is disclosed. The method and system comprises sending a play command to the media player; returning information about the media player; and providing digital audio to the accessory based upon the information about the media player. In a system and method in accordance with the present invention a plurality of commands allow a media player to transfer digital audio to an accessory. These commands are used by the media player to gather a list of supported sample rates from the accessory and to inform the accessory of the media player's information.

Abstract: A recording system records data by retrieving it from a portable medium such as CD-ROM or the like. The recording system determines a data retrieval speed for a specific data track on the portable medium by calculating a retrieval time of the specific data track at an increased retrieval speed and a playback time of a preceding data track on the portable medium. When the retrieval time of the specific data track at the increased retrieval speed is smaller than the playback time of the preceding data track, the recording system reduces the retrieval speed for the specific data track.

Abstract: This invention involves irradiating an optical disk with laser light, pulse-driven by a high-frequency signal from an HF oscillator, and converting the output of a photo-detector that receives laser light reflected from the optical disk into an electronic pulse readout signal using a current amplifier. The pulse readout signal is converted into a temporally continuous readout signal by a peak hold circuit. The invention solves the problems of SNR deterioration of the readout signal and the difficulty of removing the impact of high-frequency modulation accompanying the increase in the readout speed factor in optical disk devices.

Abstract: An optical disk structure and optical disk recorder which enables data to be re-written onto the recording layer of the optical disk. A clock reference structure is permanently formed along servo tracks of the optical disk. An optical transducer is coupled to the clock reference structure and generates a clock reference signal simultaneously with writing new data onto the recording layer of the optical disk. The data is written as data marks along the servo tracks. Each of the data marks includes edges. The edges of the data marks are recorded in synchronization with a write clock. The write clock is phase-locked with the clock reference signal. Therefore, the edges of the data marks are aligned with the clock reference structure with sub-bit accuracy. Standard DVD-ROM disk readers are not able to detect the high spatial frequency of the clock reference structure.