Abstract: An optical scanning device for scanning an optical record carrier comprising an information layer. Crosstalk cancellation is provided using a phase modulating element (40, 140) for generating a non-rotationally-symmetric phase profile in a subsidiary radiation beam. The phase profile varies with an azimuthal angle measured about the optical axis of the beam portion, the phase profile varying such that successively different phases are introduced in at least five locations which are each at successive azimuthal angles (?1, ?2, ?N) and each at a given radial distance from the optical axis, wherein the phase profile is such that the phases introduced, when taken in modulo 2? form, successively cycle through 0 to 2? at least twice, whereby the subsidiary beam spot is provided with an intensity distribution on the information layer which overlaps that of the side-lobe of the main beam spot.

Abstract: A wobble demodulator for reproducing digital information from an optical recording medium in which a track is formed in accordance with a wobble signal that is MSK-modulated so as to contain the digital information by a carrier signal with a predetermined frequency and a sine wave signal with a frequency different from that of the carrier signal, includes: a wobble signal detector for detecting a wobble signal of the track from the optical recording medium; a wobble PLL for detecting the carrier signal based on the wobble signal detected by the wobble signal detector; a multiplier for multiplying the carrier signal detected by the wobble PLL by the wobble signal detected by the wobble signal detector and outputting a multiplied output; a MSK detector for detecting a MSK modulation mark having a phase or a frequency different from that of the carrier signal, based on an integrated value obtained by integrating the multiplied output from the multiplier on a predetermined section basis; and a MSK synchronization

Abstract: An apparatus which stabilizes an operation of a disc driver in a mode conversion setting section includes a pickup which reads information from a disc that is inserted into the disc driver, a filter which performs a low-pass filtering of a servo error signal that is generated during an operation of the pickup, a selector which selects one of the servo error signal and the low-pass filtered servo error signal from the filter and outputs the selected servo error signal to drive the pickup using the selected servo error signal, and a control signal generator which generates a signal to control the selector to select the low-pass filtered servo error signal in a mode conversion setting section of the disc driver. Accordingly, a defocus and a detrack can be prevented in the mode conversion setting section of the disc driver.

Abstract: There is provided a method and a device for recording optical data able to improve recording power setting during recording by means of PWM with a small number of pulses. During the test recording, using a period of a recording channel clock Tw as the minimum unit, marks having different mark lengths of n1·Tw and n2·Tw (n1<n2) are recorded with the same number of m (m<n) light emitting pulses, while successively changing the maximum power Pw of the recording signals. The recorded marks are reproduced and the mark lengths T1 and T2 are measured from the reproduced signals. The recording power can be set by evaluating the deviations D1=T1?n1·Tw and D2=T2?n2·Tw.

Abstract: An information recording apparatus and method can prevent an information recording medium having a plurality of recording layers from being incompatible with a reproduction-only information recording medium due to an unrecorded area, which is produced by completion of recording in a middle of a data area of the recording layer. The recording layers include at least a first recording layer and a second recording layer, the first recording layer providing a reference with respect to a position of said data area in each of the recording layers. The user data is recorded in response to a recording request. After recording the user data, predetermined data is recorded in a predetermined unrecorded area in the second recording layer.

Abstract: A pickup control circuit (5) for performing a control operation of an optical pickup (3) and an error detection circuit (14) for detecting an error signal from a servo signal obtained from the pickup control circuit (5) are provided. During an operation to change to a faster recording speed, a playback operation for an already recorded signal is performed at the recording speed after the change, and an error detection level is set on the basis of characteristics of the servo signal in the playback operation state.

Abstract: In an optical pickup projecting a laser beam from a laser diode onto a disk through a half mirror, a collimator lens and an objective lens and receiving the laser beam reflected by the disk in a photodiode through the half mirror thereby reading information recorded in the disk, a portion of a metal board body having a pattern of a printed board corresponding to a connector pin fed with a high-frequency signal is notched to cause no electrostatic capacitance between the metal board body and the printed board thereby preventing a read signal from the photodiode from a jitter. Thus obtained is a high-performance and low-priced optical pickup causing no reading error.