Abstract: A noise removal circuit of the present invention comprises a 180-degree odd multiple shifting section for outputting a 180-degree shifted signal that is phase-shifted from an input signal by an odd multiple of 180 degrees and difference output section for outputting a difference between the input signal and the 180-degree shifted signal. The noise removal circuit comprises a 360-degree shifting section for outputting a 360-degree shifted signal that is phase-shifted from an input signal by an integral multiple of 360 degrees and sum output section for outputting a sum of the input signal and the 360-degree shifted signal.

Abstract: The present invention provides a focus position adjustment method for adjusting a focus position by which an optical storage device reads an optical storage medium. The optical storage medium comprises a header and a recording area. The optical storage device generates a focus error signal as reading the medium and utilizes the focus error signal to control the focus of the optical pickup head. After the optical storage device finishes tracking closed loop, the method is performed according to the deviation value between the levels of focus error signals of the header and the recording area to adjust the focus position to make the deviation value fall in a predetermined range. The system comprises a deviation value detection module for determining the deviation value and a focus control module for adjusting the focus position.

Abstract: A method and an apparatus for performing high-quality read and write operations through a simple operation without being affected by an interruption even when the interruption has occurred in the course of a read/write operation between information storage media. When an interruption occurs in the course of reading program information stored on an optical disc to write the program information onto a hard disk, the write status of the program information which has encountered the interruption and the information for identifying the program information are stored on the hard disk. After the recovery from the interruption, read and write operations are restarted. Then, the program information capable of ensuring the continuity with the program information which has been properly written on the hard disk prior to the interruption is determined in accordance with the write status of the program information which has encountered the interruption and the information for identifying the program information.

Abstract: A two-stage amplifier of a first-stage amplifier 21 and second-stage amplifiers 22 and 23 is provided. A writing mode and reproducing modes are switched in the first-stage amplifier 21 by switching a parallel circuit of a feedback capacitor Cf1w and a feedback resistor Rf1w and a parallel circuit of a feedback capacitor Cf1r and a feedback resistor Rf1r. The second-stage amplifier 23 is provided with feedback resistors Rf22 and Rf23 that are connected to each other in parallel. The feedback resistor Rf23 is connected in the feedback loop by a switch transistor QSW only when reproducing a high-reflective disk. This enables an amplifier gain to be suitably set for each of writing, low-reflective disk reproducing, and high-reflective disk reproducing. As a result, desirable reproducing characteristics can be obtained for the low-reflective disk while accommodating high-speed writing with a large laser power.

Abstract: A digital signal recording disc has a first area storing an audio title set. The audio title set has data representing audio information and data representing a still picture. The audio title set is void of a pack of data for playback control. The first area also stores information for managing the audio title set. The digital signal recording disc is void of a second area storing a video title set and information for managing the video title set.

Abstract: An optical disk apparatus having a high reliability by evading collision between a condensing lens and an optical disk regardless whether the focus control is in the operative state or in the inoperative state, thereby preventing damage to the condensing lens and the optical disk. When the focus control is in the inoperative state, by using a reflection light amount from the optical disk (1), it is ascertained that the focus of the light beam is in the vicinity of the information surface and the condensing lens (15) is driven to be apart from the optical disk (1).

Abstract: The present invention relates to a method of searching for a recordable position of a writable disk, the method comprising the steps of (a) reading data recording information of the writable disk, the data recording information indicating a position of a last track recorded and a recordable position for data to be recorded; (b) examining whether or not an area after the recordable position indicated by the read data recording information has recorded data; and (c) determining whether to change the recordable position to another position for new input data based on the examination result.

Abstract: An optical disc drive includes a spindle motor and a computer program. The spindle motor is adapted for rotating an optical disc. The computer program configures the optical disc drive to perform consecutive steps of a method for detecting eccentricity of the optical disc, including: a) while the optical disc drive operates under focused and track-locked conditions, controlling the spindle motor to rotate the optical disc at a specified rotation speed; b) measuring an eccentricity value of the optical disc being rotated by the spindle motor; and c) comparing the eccentricity value measured in step b) with a reference value to determine extent of eccentricity of the optical disc.

Abstract: A digital signal recording disc has a first area storing an audio title set. The audio title set has data representing audio information and data representing a still picture. The audio title set is void of a pack of data for playback control. The first area also stores information for managing the audio title set. The digital signal recording disc is void of a second area storing a video title set and information for managing the video title set.

Abstract: An optical disk drive that can automatically adjust an erase power to an appropriate level to keep the error rate low and not to shorten the life of an erasable optical disk. The optical disk drive obtains a reference erasing modulation factor using a test area of the erasable optical disk when the disk is set. While overwriting data in the erasable optical disk, the optical disk drive obtains an erasing modulation factor based on the read signal detected in an erased region from time to time to adjust the erase power so that the erase power continually adjusted to the appropriate level.

Abstract: An unknown optical disc is identified as a CD when an all sum signal value AS-max by a photodetector on a signal surface of the unknown optical disc is larger than an all sum signal value AS-cdref for CD signal surface reference for identifying the CD and the hybrid SACD as a CD based on each CD signal surface thereof, and a focus search driving voltage Y corresponding to the signal surface of the unknown optical disc is lager than a voltage value acquired by a predetermined relational expression between a focus search driving voltage Q corresponding to a DVD signal surface of a reference DVD and a focus search driving voltage R corresponding to a CD signal surface of a reference CD.

Abstract: On an information record medium (1), information is optically recorded and reproduced while a servo control is performed with respect to the information record medium by a push-pull method. The information record medium is provided with: a record/reproduction area (DA) having a groove track (2), which is wobbled and continuously formed and on which the information is recorded and reproduced by a phase changing method by use of a light beam (B) having a wavelength of not less than 630 nm (nanometer) and not more than 680 nm; and a reproduction-dedicated area (RA) where a plurality of phase pits (PI) are wobbled and formed in advance, each having a depth of not less than 60 nm and not more than 90 nm and where only an information reproduction is possible by the light beam.

Abstract: The light intensity of a light beam emitted from a light source is appropriately controlled when the light beam is transmitted through a variable optical coupling efficiency device in an optical head. During a read mode, the light beam from the light source is incident on an optical disk at an intensity relatively weaker than that of the light source. By switching the optical coupling efficiency of the variable optical coupling efficiency device between a write mode and a read mode, the light intensity directed to an optical recording medium is substantially varied from the write mode to the read mode. This arrangement eliminates the need for substantially increasing the optical output power ratio of the light source of write power to read power.

Abstract: A rewritable data storage medium has a rewritable recording layer provided with a tracking structure. The recording layer has a data recording area. An erasable identification mark is present in an identification mark area other than the data recording area. The data recording area has a first tracking structure, whereas the identification mark area is substantially free from a tracking structure or has a second tracking structure substantially different from the first tracking structure, such as including concentric or interrupted spiral grooves. Thus erasure of the identification mark is practically impossible, because the location of the erasing spot of a recorder cannot be controlled precisely in radial direction in the identification mark area.

Abstract: A multi-layer record carrier and method of manufacturing thereof and recording thereon, includes data written in units of blocks on tracks of at least two information layers. A first guard field is written at the start of a data block and a second guard field is written at the end of the data block. The power in the focused spot in the deepest of the at least two information layers is maintained substantially at an optimal value, by setting the length of the first and second guard fields such that the end position of the second guard field of a preceding data block is located within the area of the first guard field of the succeeding data block. Thereby, gap portions between the first and second guard fields can be prevented.

Abstract: The present invention provides an information disc recording/playback apparatus which includes a track cross detection means, a track cross direction detection means, a rotation angle detection means, and a count means, detects the track pitch of a disc, evaluates the vibration amount, vibration speed, or vibration acceleration considering the track pitch of the disc, and determines a maximum rotation speed that is lower than the allowable vibration amplitude, vibration speed, or vibration acceleration of the information disc recording/playback apparatus. The present invention also provides a vibration detection method for the information disc recording/playback apparatus. This information disc recording/playback apparatus can perform vibration detection using a single threshold value that is independent of the type of the disc, without using an acceleration sensor, and further, the apparatus can accurately perform vibration detection even when direction detection is difficult.

Abstract: In an optical recording/reproducing apparatus of the present invention, a semiconductor laser driver supplies a selected one of a plurality of drive currents, including at least a first-level drive current and a second-level drive current, to a semiconductor laser to control the emission of a laser beam by the laser. A current driver selectively outputs one of a plurality of increment currents to the laser driver in response to control signals, the plurality of increment currents including a first increment current supplied to the laser driver during an automatic power control process and a second increment current supplied to the laser driver during a special power setting process.

Abstract: An optical information recording apparatus for recording information on an optical information recording medium with multiple recording layers is disclosed. The optical information recording apparatus, performing an OPC operation before performing the recording, includes a reading part reading information on the type of the medium recorded thereon, a storage unit storing information on a recording condition at the time of performing the OPC operation for each recording layer with respect to each medium type, a recording condition obtaining part reading out the recording condition corresponding to the read type when the recording condition is stored in the storage unit, and reading the recording condition recorded in a corresponding one of the recording layers recording their respective recording conditions when the recording condition is not stored in the storage unit, and an OPC performance part performing the OPC operation using the obtained recording condition.

Abstract: The present invention relates to a method for controlling recording optical power. When a recording operation is paused, a playback signal characteristic for recorded data is detected. The recording optical power is controlled based upon the detected playback signal characteristic and hence the recording operation is resumed at the controlled recording optical power. Therefore, even though a characteristic of an optical pickup or disc varies when the recording operation is paused and resumed, an optimum recording operation can be performed and a playback characteristic for recorded data can be improved.

Abstract: When a detection device detects any kind of change regarding track recording after the start of the track recording, a grouping instruction is given to information attaching and generating device. Then, the information attaching and generating device attaches the same group name information to a group, in which a track where the recording has been started in an information recording medium to a track recorded at the point when the grouping instruction has been received are made to be the same group, and group control information is generated. Therefore, since the grouping is automatically performed by any kind of change regarding the track recording, a user can omit the operation that he/she performs the grouping by himself/herself, and thus the operation load of the user can be reduced.