Abstract: A semiconductor laser element has the following configuration: a dual-wavelength monolithic laser where semiconductor lasers with emission wavelengths of 650 nm and 780 nm are integrated on one chip is soldered on a heat sink which then is soldered on a can package. Two beam emission points of the semiconductor laser element are positioned so that beam spots, formed on an optical disk, of light beams emitted from the two semiconductor lasers are aligned substantially along a pit-row direction in the optical disk. Thus, an optical head device and an optical recording and reproducing apparatus can be obtained that can record information on or reproduce recorded information from optical information recording media with different optical characteristics and recording densities from one another and that do not cause instability in tracking servo operation.

Abstract: An optical disc playback method is provided which includes steps of reading identification data recorded in an optical disc loaded in an optical disc player and starting reading data from a second recording area of the optical disc loaded in the optical disc player when it is determined that the loaded optical disc is a one having at least a first recording area and second recording area, a first lead-in area provided along the inner circumference of the first recording area, a second lead-out area provided along the outer circumference of the first recording area, a second lead-in area provided between the outer circumference of the first lead-out area and second recording area, and a second lead-out area provided along the outer circumference of the second recording area.

Abstract: A link writing method for a recordable or rewritable compact disk includes recording a writing interruption address and enabling a succeeding writing process after the writing interruption. Enabling a succeeding writing process includes searching the linking area and enabling a start writing signal and activating a laser power. The method can link a succeeding writing area with a previously written interrupted area with sufficient accuracy to allow the data frame to be successfully processed by error correction within the host drive. The linking area may be positioned by counting the values of the interrupted block, the interrupted data frame, and the interrupted bit count or by detecting a blank area. Other techniques for positioning the linking area include detecting an unwritten area having a length greater than a maximum or writing a characteristic pattern after an interruption.

Abstract: The method of controlling data writing velocity of an optical disk player is capable of correctly writing data on a nonstandard optical disk as well as a standard optical disk. The method comprises the steps of: analyzing a track pitch of an optical disk on the basis of a moving distance of an optical pick-up in a prescribed time and the address thereof when a data writing test is executed in an innermost area of the optical disk; judging if the optical disk is a standard optical disk having a standard track pitch or not; calculating an address of changing data writing velocity on the basis of the analyzed track pitch if the optical disk is a nonstandard optical disk; and changing the data writing velocity when the address to which the optical pick-up irradiates the laser beam reaches the calculated address.

Abstract: An optical disc that has a recognition mark area behind a recorded area and in which the last data in the recorded area is stably accessed, the recognition mark area can be accessed without bringing about an abnormal state, and the first data in a succeeding recorded area, if it exists, is stably accessed. An unrecorded area (5) is provided outside the recorded area (4) of the optical disc (1). A mark area (6) is provided between the recorded area (4) and unrecorded area (5). A recognition mark area (6d) is provided in the mark area (6) in order to recognize the boundary between the recorded area (4) and the unrecorded area (5). In the mark area (6), first and second buffer areas (6b and 6c) are provided respectively in front of and behind the recognition mark area (6d).

Abstract: An optical pickup comprises a light source, a three-way split light diffracting section for dividing light emitted from a light source into one main beam and two subbeams, a hologram for dividing each of the main beam and the subbeams reflected from a recording medium into two predetermined directions, and a light receiving section for receiving the beams divided by the hologram. The hologram includes two regions having a small-pitch grating for diffracting each beam to a predetermined direction, the small-pitch gratings have substantially the same pitch and are symmetrical about a split line separating the two regions.

Abstract: An optical head (1) for scanning optical record carriers (2) is provided with a compensator (16) for compensating spherical aberration of the objective system (18) or defocus of the collimator lens (14) caused by operation of the optical head at a temperature different from the design temperature. A surface of the compensator (16) comprises a phase structure in the form of annular areas (52, 53, 54), the areas forming a non-periodic pattern of optical paths of different length. The optical paths change as a function of temperature and form a temperature-dependent wavefront deviation that compensates the spherical aberration and/or defocus.

Abstract: A track jump method for an optical recording/reproducing medium is provided. In the track jump method, once a track jump command is input, a track jump operation is held until a falling edge of a header mask signal is detected. The track jump starts at the falling edge of the header mask signal and ends before a rising edge of the header mask signal so that a TZC signal is not influenced by a header during the track jump. Therefore, the track jump can be exactly and stably performed. In particular, when the track jump command is input, a PLL of a wobble signal is inhibited, and a PLL-wobble signal is held to a previous value obtained before the track jump is performed, during the track jump, or a header mask signal is generated using a read channel signal which is not influenced by a wobble period, until a wobble signal becomes stable after a track jump. During a normal servo, a header mask signal is generated using a PLL-wobble signal to mask a header area.

Abstract: An information recording medium having at least a read only area and a recording and reproducing area is composed of at least: a substrate; a recording layer formed on the substrate so as to record and reproduce information; and a light transmission layer having transparency formed on the recording layer. The information recording medium is further characterized in that a wobbling groove corresponding to the read only area and another wobbling groove corresponding to the recording and reproducing area is formed on the substrate without overlapping with each other, the recording and light transmitting layers are continuously adhered over at least two areas of the read only area and the recording and reproducing area, reflectivity of the recording layer is more than 5%, and a push-pull signal output T3 reproduced from the read only area and another push-pull signal output T4 reproduced from the recording and reproducing area before recording satisfies relations of T3?0.1, T4?0.1 and 1.5?T3/T4?0.5.

Abstract: An optical disk recording apparatus operates on an optical disk having circular tracks which are provisionally written with an index signal used for securing a constant linear velocity of the optical disk from an innermost circular track to an outermost circular track, and records data along the circular tracks at different linear densities on different annular zones of the optical disk. In the apparatus, a disk drive section rotates the optical disk while synchronizing the index signal successively read from the rotated optical disk with a predetermined reference clock signal to thereby maintain the constant linear velocity of the circular tracks. A clock generating section multiples or divides the reference clock signal by different rates to generate different writing clock signals in correspondence to the different annular zones of the optical disk.

Abstract: An information recording device comprising at least a recording pulse generating means and a recording pulse selecting means capable of generating various multi-pulses each of which is a combination of a leading heating pulse and a succeeding heating pulse, and rectangular pulses each of which is a single pulse, as a recording pulse, is disclosed. The recording pulse selecting means switches and selects among the multi-pulses and the rectangular pulses according to a recording condition, and then causes a light emission of a laser light source through a light source driving means. Even though in a high recording linear velocity recording condition that is insufficient in power for the recommended multi-pulse recording, a very low recording power can still be used by switching to the rectangular pulse recording, so as to achieve a recording with a much higher recording speed. In addition, good recording marks can be formed without exceeding a maximum allowable recording power.

Abstract: An information recording medium according to an aspect of this invention includes a data area (A2) for recording user data and an address area (DMA address area) for recording address data that indicates the position of a defect management area that manages a defect present in the data area.

Abstract: Holographic recording and reproducing using a compact configuration provides no reduction in the recording/reproducing capability. Information light and recording-specific reference light having a spatially modulated phase are generated and projected onto an optical recording medium coaxially that converge on a reflecting surface of a recording medium. P-polarized recording-specific reference light and S-polarized information light are each optically rotated by a two-way split optical rotation plate in directions different between respective half areas of the cross section of the beam thereof.

Abstract: A method for determining an optical write power and an optical disc access system using the same. In addition to a typical Inner Power Calibration Area, the method includes an Outer (second) Power Calibration Area implementation on the outer area of a Readable/Writable Optical disc with a constant linear velocity (CLV) format; when a data writing speed selected by a user causes a rotation speed required by an optical power calibration on an Inner (first) Power Calibration Area of the disc greater than an Optical Power Calibration (OPC) limit, the optical disc access system uses a lower rotation speed for the optical power calibration on the Outer Power Calibration Area to ensure the accuracy of the power calibration.

Abstract: A lens includes a plane surface whose normal direction virtually conforms to an optical axis direction, and a reflecting part is provided on the plane surface to reflect only light within a predetermined waveband. Consequently, inclination of the lens can be detected with high accuracy.

Abstract: A disc apparatus is designed for recording a signal on an optical disc by irradiating an optical beam according to a strategy which is stepwise updated by a given step amount. In the disc apparatus, a detector successively detects a linear velocity of the optical disc relative to the optical beam in realtime basis. A strategy generator operates every time the detector detects the linear velocity of the optical disc for successively generating the strategy according to the detected linear velocity. A storage has a plurality of storage areas, each being capable of memorizing the strategy successively generated by the strategy generator. A write controller rewrites one of the storage areas every time the strategy is generated until the strategy is updated by a given step amount and then rewrites another of the storage areas every time the strategy is generated while leaving said one storage area to hold the updated strategy, thereby updating the strategy through the plurality of the storage areas.

Abstract: There is provided an information reproducing device which outputs an equalization signal P by applying equalization processing to a signal detected from a storage medium based on equalization coefficients C0 to CN, outputs a decoding signal d by applying maximum likelihood decoding processing based on reference levels R0 to R6, generates an ideal waveform signal I based on the equalization signal, and has a target waveform generator which generates a target waveform signal T by changing at least one level of the ideal waveform signal I, wherein erroneous decoding is reduced by optimizing reproduction processing parameters such as the equalization coefficients C0 to CN or the reference levels R0 to R6 based on the target waveform signal T and the information on the storage medium is stably reproduced.

Abstract: An optical disk recording and reproducing apparatus operates in a read mode for controlling a laser driver to maintain a laser power at a target read level so as to read a signal from an optical disk, and operates in a write mode for controlling the laser driver to alternate the laser power between a target write level and a target bottom level comparative with the target read level so as to write a signal into the optical disk. In the write mode, a value obtained by sampling and holding the bottom level is set as the target value of a bottom level, and a bottom level control signal is outputted according to a difference between this target value and the detected value of the bottom level. Thus, the laser power control can be performed without any errors being generated even if an offset has occurred in the detected bottom power. Thus, the bottom laser power can be maintained constant.

Abstract: A method of recording data optically to an optical disk having a plurality of sectors, in which each sector has a region to be recorded with data, the data is recorded in units of blocks, and the block includes a predetermined number of sectors and is a data unit including error correction codes. In recording data related to a content by dividing and recording the data in a plurality of sectors continuously, dummy data to be used for extracting a clock in PLL for data reproduction is recorded on a region adjacent before a sector from which data recording is started. The data related to the contents is recorded on sectors following the region recorded with the dummy data.

Abstract: In a data recording apparatus, values of parity bits to be additionally provided every one predetermined length block in data obtained by demodulating the original data are determined so as to satisfy a part of or an entire the predetermined run length limitation rule in ranges of a current predetermined length block, the plurality of parity bits, and a next predetermined length block that is positioned next to the current block. The parity bits having the values are additionally provided to the current block.