Abstract: An optical pickup device for focusing a light beam includes a focus error detecting optical element which splits and leads return light to a photodetector. The focus error detecting element has an area quadrisected by two division lines defining a plane substantially perpendicular to the optical path of the return light for applying astigmatism to the return light in directions rotated by 90° from each other and for separating the return light into at least four by the respective quadrants. The photodetector has a plurality of spaced light receiving elements for receiving the separated return light, each receiving element has contour lines corresponding to the division lines on an image plane on which a light beam is shaped into a circular beam. The light receiving elements are comprised of two light receiving areas divided by a bisect line extending substantially in parallel with one of the contour lines.

Abstract: An optical pickup device is adapted to read information signals from optical recording media of two different types such as a “DVD” and a “CD” for which two light beams with different wavelengths are used and comprises a photodetector having a single light receiving section that can be shared by optical recording media of two different types. Both the light beam reflected from the signal recording surface of the “DVD” 106a and the light beam reflected from the signal recording surface of the “CD” 106b are diffracted by the diffraction element 6 and focussed to a same spot on the light receiving surface of the photodiode of a photodetector 7.

Abstract: An optical recording medium and method of formatting the optical recording medium is disclosed. In the present invention, the location information of the supplementary spare area, if assigned, is reset when the optical recording medium is formatted. The resetting of the location information results in consistency between a file system and a driver of the optical recording medium with respect to the supplementary spare area.

Abstract: An apparatus generating a seek direction detecting signal includes a light dividing unit dividing an incident light beam into at least two beams having a main beam and a sub-beam so that at least two beam spots including a main beam spot and at least one sub-beam spot having an optical aberration, can be focused in the track direction of an optical disk, the light dividing unit providing that the direction of the optical aberration of the sub-beam spot can be the tangential direction of the optical disk, an optical detector unit, a first signal processing portion processing a track error signal from signals output from the optical detector, a second signal processing portion processing a track cross signal from the signals output from the optical detector, and a generator generating the seek direction detecting signal from the phase difference between the track cross signal and the track error signal.

Abstract: In an optical head device for recording/reproducing information on/from an optical recording medium, at least one laser light source emits a laser light beam provided with a first polarized light component and a second polarized light component which are perpendicular to each other. A plurality of optical elements transmit a return light beam reflected by the optical recording medium passes to the light receiving element. A transmission efficiency for the first polarized light component and a transmission efficiency for the second polarized light component in each optical element is made different. A total transmission efficiency for the first polarized light component and a total transmission efficiency for the second polarized light component, which are defined by the respective transmission efficiencies of all the optical elements, are made substantially identical.

Abstract: An information reproducing apparatus which reads compressed information recorded on a recording medium by one of a plurality of different compression methods, writes the compressed information read into a memory, supplies the compressed information in the memory, to an expander in the order of writing and outputs reproduced information. The type of compression method used in compressing the information read from the recording medium is determined and the timing of starting to read the compressed information from the memory is controlled in accordance with a determination.

Abstract: To resume data writing onto a disk, a recording start position detection means (19) detects a recording start position, and a synchronous setting means (20) synchronizes recording data with recorded data on a disk so that recording data successive to the recorded data on the disk can be additionally written onto the disk without a break. Data writing onto a disk is suspended until an amount of data equivalent to data writing capacity has been stored in the buffer memory (13). Data writing is resumed upon detection of the fact that an amount of data equivalent to data writing capacity has been stored in the buffer memory (13). With the above, power consumption can be reduced during a period when recording capability of a disk recording device exceeds the data transfer speed.

Abstract: When record information is recorded on a recording medium with recording control information pre-recorded thereon by forming pre-pits so that the recording control information will be used to control the recording of the record information to be recorded on the recording medium, a first light beam having first power and a second light beam having second power different from the first power are irradiated to the pre-pits on a time-shared basis according to the record information to generate read signals generated from electrical signals according to the amounts of reflected light of the respective beams so that the pre-pits will be detected from inputs of the read signals. In this configuration, the pre-pits are detected from only the read signals input during a period of irradiation of the second light beam.

Abstract: A laser waveform generation function is provided in a laser driving waveform generator 2 near a laser 3. A recording clock generator 9 is included in the laser driving waveform generator 2 to generate a clock with a frequency higher than that of a synchronizing clock 202. This allows a recording laser current (waveform) to be generated without transmission of a high frequency signal from the modulator 6. Further, because the synchronizing clock 202 is stopped upon a reproduction operation including reproduction operation in an ID unit, undesired effects on a reproduction operation such as ID reproduction can be reduced. Because the response speed of the recording clock generator 9 can be changed, a high precision clock can be generated. Thus, a high-precision recording laser current (waveform) can be generated.

Abstract: A plurality of light receiving detectors receive a plurality of segments of a beam returning from an optical disc when a reading beam of light is radiated to the optical disc. An optical pickup assembly produces a plurality of signals from the beam segments in accordance with, for instance, optical intensities of the beam segments. A level adjusting circuit adjusts signal levels of these signals such that each of the signal levels of the signals becomes equal to a reference level. The reference level is determined from at least one of the signal levels of the received beam segments.

Abstract: A drive current or a drive voltage is controlled corresponding to change of load by sampling the drive current or drive voltage of a motor to move an optical pickup and then detecting change of the sampling signal as change of the optical pickup when it is moved. Moreover, change of the sampling signal is obtained from a difference of the sampling signals by comparing these sampling signals at the first and second points. Comparison of these sampling signals is conducted in unit of drive pulse.

Abstract: A disk physical strain correction signal generator outputs a signal obtained by allowing a phase compensation signal to pass a LPF as a disk physical strain correction signal during a normal period. During a defect detection period, it outputs the output signal of the LPF sampled at the time of the defect detection start as the disk physical strain correction signal. A disturbance pulse correction signal is output based upon a disturbance pulse obtained by subtracting the disk physical strain correction signal from the phase compensation signal. The disk physical strain correction signal and the disturbance pulse correction signal are added to output a defect compensation signal. This defect compensation signal is applied as an actuator control signal during the defect detection period. Thus, it is possible to provide an optical disk device which can carry out a stable driving control for a reproducing operation, etc.

Abstract: An optical scanning device for scanning a dual-layer optical record carrier with dual orthogonally polarized radiation beams. The device having a spherical aberration compensation optical subsystem including a switchable liquid crystal cell of birefringent material for altering different optical paths lengths provided by a phase structure of stepped annular zones.

Abstract: A low-profile optical disk device which performs recording and reproducing using a plurality of laser light sources with different wavelengths, without thug need for additional components. It is used as a DVD-Ram, CD-R or the like. It comprises a plurality of neighboring laser light sources with different wavelengths: a beam-shaping prism for expanding the width of laser beams in a direction in which the plural laser light sources are arranged; and a focus lens which forms an optical spot on an optical disk, where laser light sources with longer wavelengths are positioned closer to an extension line of a refracted beam created by the beam-shaping prism. The above arrangement enables correction of optical spot coma aberrations caused by a laser light source positioned out of the optical axis of the focus lens, thereby realizing a low-profile optical disk device with high optical performance.

Abstract: A method of reproducing information by scanning information marks, disposed with a predetermined mark pitch therebetween and recorded on tracks inside a predetermined information recording region, by an optical spot. The method includes detecting the size of the optical change resulting from the information mark, calculating a plurality of equalization coefficients used for an equalization processing for the size of the optical change detected for each of the information marks, and reducing the inter-symbol interference on the basis of the equalization coefficients by the equalization processing. The equalization coefficient used for the equalization processing of the size of the optical change by a first information mark is greater than said equalization coefficient used for the equalization processing of the size of said optical change by a second information mark which is longer than the first information mark.

Abstract: A method of compensating for tilt and/or defocus and an apparatus therefor. The apparatus has a tilt and/or defocus detector detecting the tilt and/or defocus of an optical recording medium, and a recording compensator compensating a write pulse having a predetermined recording pattern using a predetermined system with respect to the detected tilt and/or defocus. The apparatus both adjusts write power with respect to the detected defocus, shifts the recording pattern with respect to the detected tilt, adjusts a power level and/or write time required for recording, and records a recording mark having a desired size (length and width). The apparatus is useful in compensating for tilt and/or defocus in a high-density optical system.

Abstract: An information recording medium includes a data recording area for recording data; a first drive information area for recording first drive information: and a second drive information area for recording second drive information. The first drive information and the second drive information each include a plurality of recording and reproduction conditions, and the plurality of recording and reproduction conditions each define an operation condition of an information recording and reproduction apparatus, which can have the information recording medium mounted thereon, for recording and reproducing the data. The plurality of recording and reproduction conditions are arranged in the order of time at which the plurality of recording and reproduction conditions are recorded.

Abstract: An optical disk device starts movement of a thread in a track-on state, and releases the track-on state when the thread moves by a certain amount, and gives a driving kick signal to an actuator. The movement of the thread and actuator can be placed in sufficiently good balance so that failure of track jump is prevented, thereby improving the reliability of the device body and suppressing the cost-up of the device body.

Abstract: A PRML detector includes a waveform equalizer for equalizing a waveform of a reproduction signal obtained by reproducing marks and non-marks recorded on a recording medium, and a decoder for generating binary-coded data of the reproduction signal based on the waveform equalized by the waveform equalizer. The decoder outputs a temporary data string which is obtained before the binary-coded data is obtained. The waveform equalizer includes an equalizer that includes a delay element that delays propagation of the reproduction signal, a plurality of multipliers that multiply predetermined coefficients by the reproduction signal and the delayed signal from the delay element, and an adder that adds outputs from the plurality of multipliers.

Abstract: In an optical disk recording device for projecting a recording light beam onto an optical disk to form 3T-11T pits in a land of the optical disk, timing to sample and hold a reflected light detection signal for tracking servo control is delayed behind timing to sample and hold the reflected light detection signal for wobble signal detection. Further, a sample-and-hold time period of the reflected light detection signal for tracking servo control is set to be shorter than a sample-and-hold time period of the reflected light detection signal for wobble signal detection. Such arrangements permit appropriate recording, even at high recording speeds, irrespective of residual optical axis deviations.