Abstract: An RDS compatible receiver has a demodulator which demodulates RDS data, a register which converts the demodulated RDS data to block data and outputs the block data, an offset generating unit which predicts and outputs an offset word of the block data based on values of a pattern match flag signal and a synchronization flag signal, an error correction processing unit which performs error correction of the block data using the predicted offset word, compares the number of error corrections with a predetermined correction threshold, determines whether the predicted offset word is right or not based on the comparison result, and outputs the pattern match flag signal based on the determination result, and a synchronization determining unit which detects whether or not the predicted offset word determined to be right matches a predetermined offset sequence pattern, determines whether RDS block synchronization is established or not, and outputs the synchronization flag signal based on the determination result.

Abstract: An RDS compatible receiver has a demodulator which demodulates RDS data, a register which converts the demodulated RDS data to block data and outputs the block data, an offset generating unit which predicts and outputs an offset word of the block data based on values of a pattern match flag signal and a synchronization flag signal, an error correction processing unit which performs error correction of the block data using the predicted offset word, compares the number of error corrections with a predetermined correction threshold, determines whether the predicted offset word is right or not based on the comparison result, and outputs the pattern match flag signal based on the determination result, and a synchronization determining unit which detects whether or not the predicted offset word determined to be right matches a predetermined offset sequence pattern, determines whether RDS block synchronization is established or not, and outputs the synchronization flag signal based on the determination result.

Abstract: The depth of pits is determined by a trade-off between the level of a push-pull signal used for servo application by a push-pull method and the level of an RF signal as a reproduced signal of information. The depth d is set to be the optimum for a disk system, which has a refractive index n of a medium, an optical wavelength ?, and an optical system with a NA (Numerical Aperture) of 0.75. The most suitable depth d for both the push-pull signal level and the RF signal level falls within a range of ?/5.5n?d??/4.7n, the second most suitable depth d falls with a range of ?/5.5n?d??/4.5n, and the depth d as the widest standard falls within a range of ?/8n?d??/4.5n.

Abstract: An optical disc player executes a focus pull-in operation while avoiding an inconvenience that an objective lens comes into contact with an optical disc, or the like. The objective lens is forcedly moved gradually from a position that is away from the surface of the optical disc and outside a capture range of a focus servo toward the surface of the optical disc. When the objective lens reaches the capture range of the focusing servo loop by the moving operation and a distance between the objective lens and the disc surface is at the minimum distance or is changing in a widening direction, the moving operation of the objective lens is stopped.

Abstract: A light beam from a light source is introduced to a grating element of a pickup device to create zero order diffracted light, ±first order diffracted light, and ±second order diffracted light. An irradiation system focuses the zero order, ±first order and ±second order diffracted light onto tracks extending on a recording surface of an optical recording medium to form spots. A spot of the zero order diffracted light is formed on a target track, spots of the ±second order diffracted light are formed on tracks adjacent to the target track, and spots of the ±first order diffracted light are formed midway between the spots of the ±zero order and ±second order diffracted light. An optical system guides returning light reflected from the spots to an optical detector. The optical detector has independent light-receiving elements for receiving the returning light. A servo signal calculator creates an error signal based on the output signals from the optical detector.

Abstract: An information recording apparatus capable of detecting an accurate tracking error even if a reflectance or a transmittance of respective information recording layers varies when information is recorded onto a multilayer optical information recording medium having a plurality of information recording layers, wherein the apparatus comprises a detecting device for detecting a position of a boundary portion between a recorded area where the information has already been recorded and an unrecorded area in the information recording layer; an inhibiting device for inhibiting recording the information onto an area in one information recording layer in a case where the boundary portion in an information recording layer may affect a tracking servo for recording the information onto said one information recording layer.

Abstract: An optical pickup apparatus includes a photodetector for receiving a diffracted light reflected from the recording medium; and a tilt detector for detecting a tilt amount of the recording medium on the basis of a light intensity within an interference region of a 0th-order diffraction light and at least one diffraction light other than the 0th-order diffraction light of the reflected light received by the photodetector.

Abstract: A recording method of a multilayer recording medium includes a first initializing step of initializing a lower recording layer based on a first initializing condition and a second initializing step of initializing an upper recording layer on the basis of a second initializing condition different from the first initializing condition. The second initializing condition is determined so that a transmittance of the recording layer after execution of the second initializing step is approximately equal to a transmittance of the recording layer after a predetermined data signal is recorded on an upper recording layer.

Abstract: An information recording and reproducing apparatus for optically recording/reproducing information to/from a two-layer optical disk comprises a cylindrical lens, which gives astigmatism to a reflected light from a target information recording layer, two caustic curve positions are arranged in the front and in the rear of the optical detector, and an unnecessary reflected light from an another information recording layer has two caustic curve positions arranged in the rear of the optical detector. In this condition, assuming an astigmatism direction of the cylindrical lens is inclined at 45 degree angle to a track direction, a projected image of the target information recording layer is inclined at 90 degree angle to an another projected image of the another information recording layer in a light receiving surface of the optical detector.

Abstract: An aberration correction device for correcting aberration produced in a light beam, which includes: a first electrode layer and a second electrode layer being opposed to each other; and a liquid crystal disposed between the first electrode layer and the second electrode layer for producing a change in phase in a light beam passing therethrough in accordance with voltages applied to the first electrode layer and the second electrode layer. The first electrode layer is divided into a plurality of phase adjustment portions which are electrically isolated each other. Each of the plurality of phase adjustment portions includes a pair of electrodes arranged in such a form that produces an electric field distribution for correcting the aberration by applying predetermined voltages thereto.

Abstract: The collision preventing device is used for an optical pickup device for recording or reproducing information to or from an optical information recording medium. The collision preventing device has a shock absorbing layer to prevent a contact of an objective lens and a surface of the recording medium. The shock absorbing layer is laminated on the portion extending from the circumferential edge of the effective-diameter area of the objective lens to the outside edge or to the outside of the objective lens and has a thickness in such a manner that the shock absorbing layer comes in contact with the surface of the recording medium prior to the effective-diameter area, when the objective lens comes close to the surface of the recording medium.

Abstract: An aberration correcting element includes a first electrode layer including a plurality of electrode portions; a second electrode layer opposed to the first electrode layer; and a liquid crystal sandwiched between the first and second electrode layers for producing a phase change corresponding to voltages applied to the first and second electrode layers in a light beam passing therethrough. The first electrode layer includes a plurality of position markers.

Abstract: The present invention relates to an optical multi-layer information recording medium for recording information therein and/or retrieving information therefrom upon radiation of a convergent beam of light. The recording medium includes at least two pairs of recording layer and light-transmissive layer stacked one after another. A first recording layer proximal to a beam radiation side and a second recording layer distal from the beam radiation side are made from a material that satisfies a function including the following parameters; transmissivity and absorptance of the first recording layer, absorptance of the second recording layer, a numerical aperture on the first recording layer, a numerical aperture of the second recording layer, and transmissivity of between the first and second recording layers. Even if the numerical apertures change with spherical aberration compensation made to respective recording layers, a power density of a light spot does not change.

Abstract: The depth of pits is determined by a trade-off between the level of a push-pull signal used for servo application by a push-pull method and the level of an RF signal as a reproduced signal of information. The depth d is set to be the optimum for a disk system, which has a refractive index n of a medium, an optical wavelength &lgr;, and an optical system with a NA (Numerical Aperture) of 0.75. The most suitable depth d for both the push-pull signal level and the RF signal level falls within a range of &lgr;/5.5 n≦d≦&lgr;/4.7 n, the second most suitable depth d falls with a range of &lgr;/5.5 n≦d≦&lgr;/4.5 n, and the depth d as the widest standard falls within a range of &lgr;/8 n≦d≦&lgr;/4.5 n.

Abstract: A substrate of an optical disc is formed by injection molding. One of the surfaces of the substrate has a plurality of pits corresponding to information signals. The other surface has a plurality of dummy pits.

Abstract: The present invention relates to a cartridge and a method that can sweep away dust or the like from a recordation medium housed in the cartridge in a simple way without adversely influencing recording and replaying of the recordation medium. The cartridge includes a shutter opposed to a surface of the recordation medium, a cleaner member, a support for supporting the cleaner member, and a sweeping mechanism actuated upon opening and closing movements of the shutter. The support pivots in a plane substantially in parallel to the surface of the recordation medium when the sweeping mechanism is actuated. When the sweeping mechanism moves forwards, the cleaner member moves without contacting the recordation medium surface. When the sweeping mechanism moves backwards, the cleaner member moves in contact with the recordation medium surface to clean the recordation medium surface.

Abstract: An optical pickup system includes a light source, an objective lens, a beam splitter for splitting light received from the light source and reflected light from an optical disc, a detector for receiving the reflected light, a liquid crystal panel for providing passing light with a phase difference in accordance with a control signal and a control means for providing the control signal to the liquid crystal panel to eliminate an influence of birefringence of the optical disc.

Abstract: So as to prevent from illegally copying and illegally reproducing data with reliability, a ROM disk comprises: a data area where data to be reproduced is recorded; and a PEP area where the information necessary to reproduce the data recorded in the data area is recorded in the form of the zonal pit rows, and a recordable optical disk records a signal which prevents from recording the zonal pit rows into the area which is equivalent to the PEP area of the ROM disk, of the recordable optical disk.

Abstract: An optical disc player executes a focus pull-in operation while avoiding an inconvenience that an objective lens comes into contact with an optical disc, or the like. The objective lens is forcedly moved gradually from a position that is away from the surface of the optical disc and outside a capture range of a focus servo toward the surface of the optical disc. When the objective lens reaches the capture range of the focusing servo loop by the moving operation and a distance between the objective lens and the disc surface is at the minimum distance or is changing in a widening direction, the moving operation of the objective lens is stopped.

Abstract: A driving apparatus (100, 200, 300, 400, 506) for driving an actuator (507) with electric current is provided with: a current monitor device for generating a voltage corresponding to an electric current that passes through the actuator and that includes the counter electromotive force component generated according to the movement of the actuator; and a feedback device for giving negative of the generated voltage. The feedback device makes it difficult for the actuator to move by giving the negative feedback with a large gain in presence of a defect, in accessing, in a stop condition, and the like.