Abstract: To provide a light receiving device, a light detecting device, and an optical signal reproducing device each of which allows one to perform many different computations in detecting aberration amounts and focus error quantities without requiring exact position relations between laser light to be received and light receiving elements, and between the light receiving elements. First and second light receiving elements 43+ and 43? are used which receive condensed light at positions equidistantly spaced from an focal point X before and after the light images, respectively.

Abstract: It is an object of the present invention to provide an apparatus for discriminating an optical recording medium which can reliably discriminate the kind of an optical recording medium even in the case where the optical recording medium to be discriminated is warped and formed with periodical undulation in the circumferential direction thereof.

Abstract: A laser diode driving circuit includes two chip capacitors disposed in the vicinity of one side portion of an IC along which a high voltage power supply terminal, a low voltage power supply terminal and a driving signal output terminal are disposed. One end portion of each of the chip capacitors is connected to the high voltage power supply terminal and the other end portion of each of the chip capacitors is connected to the low voltage power supply terminal. The chip capacitors are adapted for serving to reduce a ripple component superposed on a power supply voltage when a switching element is operated. The chip capacitors are disposed so that the distance between itself and the high voltage power supply terminal, the low voltage power supply terminal and the driving signal output terminal is equal to or shorter than 10 mm.

Abstract: The invention relates to a diffraction grating, a light-receiving element, and an optical head and an optical recording/reproducing apparatus utilizing them and provides a diffraction grating and a light-receiving element capable of detecting a signal of high quality and an optical head and an optical recording/reproducing apparatus utilizing them. A diffraction grating includes a diffracting region which is formed only on a light exit surface and which diffracts and separates first laser light or second laser light emitted by a two-wavelength semiconductor laser to generate a main beam and positive and negative first order sub beams. The depth of concavity formed on the diffracting region is 220 nm. The irregularities are formed such that the pitch length thereof is 22 ?m and such that a convexity thereof has a width of 17.6 ?m. The ratio of the width of the convexity to the pitch length of the irregularities is 0.8.

Abstract: It is an object of the present invention to provide an apparatus for discriminating an optical recording medium and a method for discriminating an optical recording medium which can reliably discriminate the kind of an optical recording medium even in the case where the optical recording medium to be discriminated is warped.

Abstract: The invention relates to a method of detecting a focus error signal of an optical head to be used for adjusting the position of an objective lens for converging a light beam on an optical recording medium and to an optical head and an optical recording/reproducing apparatus employing the method. The invention provides a method of detecting a focus error signal of an optical headwhich allows a focus error signal to be detected with track cross signals therein attenuated from a plural types of optical recording media having different physical track pitches and an optical head and an optical recording/reproducing apparatus employing the method. A main beam reflected by an optical recording medium is received by a light-receiving element, and electrical signals output from four light receiving regions of the element are used to generate a focus error signal MFES based on the main beam according to astigmatic focus error detection and a push-pull signal MPS based on the main beam according to the push-pull method.

Abstract: The invention relates to a method of detecting a focus error signal of an optical head to be used for controlling the focus position of an objective lens for converging a light beam on an optical recording medium and an optical recording/reproducing apparatus. The invention provides a method of detecting a focus error signal of an optical head which allows a focus error signal to be detected a track cross signal therein attenuated at a plural types of optical recording medium having different physical track pitches and an optical recording/reproducing apparatus employing the method. A light beam emitted by a laser diode is diffracted by a diffraction grating to split it into a main beam and two sub beams of orders of ±1.

Abstract: A semiconductor laser driving circuit comprises a driving IC and a substrate on which the IC is mounted. The IC incorporates: a switching element for generating a driving signal; a high-potential power terminal and a low-potential power terminal for feeding supply voltage to the switching element; and a driving signal output terminal for outputting the driving signal generated at the switching element to an external device. These three terminals are disposed side by side at one of sides of a main body of the IC. The substrate incorporates three conductors to be connected to the three terminals. Two chip capacitors are disposed beside the one of the sides of the IC at which the three terminals are disposed. An end of each of the capacitors is connected to the high-potential power terminal while the other end is connected to the low-potential power terminal.

Abstract: It is an object of the present invention is to provide an apparatus for discriminating an optical recording medium and a method for discriminating an optical recording medium which can reliably discriminate the kind of an optical recording medium even in the case where the optical recording medium to be discriminated is formed with periodical undulation in the circumferential direction thereof. The apparatus for discriminating an optical recording medium according to the present invention includes a first electrode 11, a second electrode 12, an alternate current signal generation circuit 13 for applying an alternate current A to the first electrode 11, a detection circuit 14 for detecting a level of an alternate current B appearing at the second electrode 12, and a control circuit 15 for controlling the operations of the alternate current signal generation circuit 13 and the detection circuit 14.

Abstract: The invention relates to a light-receiving element for receiving a reflection of laser light irradiated to a rotating multi-layer recording medium having a plurality of information recording layers stacked one over another and for converting the light into an electrical signal, an optical head having the element for recording information in the multi-layer recording medium or reproducing information recorded therein, and an optical recording/reproducing apparatus and a method of optical recording and reproduction. The invention provides a light-receiving element, an optical head, an optical recording/reproducing apparatus, and a method of optical recording and reproduction which make it possible to eliminate a noise component superimposed on reflected light from a multi-layer recording medium to reproduce an RF signal of high quality.

Abstract: The invention relates to an optical head and an optical recording/reproducing apparatus for recording information in an optical recording medium or reproducing information recorded therein and a method of optical recording/reproduction utilizing the same. The invention provides an optical head and an optical recording/reproducing apparatus capable of reproducing an RF signal of high quality by eliminating a noise component superimposed on reflected light from a recording medium and a method of optical recording/reproduction utilizing the same. The optical head has an RF signal extraction circuit for extracting an RF signal including information recorded in a rotating recording medium.

Abstract: It is an object of the present invention is to provide an apparatus for discriminating an optical recording medium and a method for discriminating an optical recording medium which can quickly discriminate the kind of an optical recording medium. The apparatus for discriminating an optical recording medium according to the present invention includes a first electrode and a second electrode, an alternating current signal generation circuit for applying an alternating current A to the first electrode, a detection circuit for detecting the level of an alternating current B appearing at the second electrode, and a control circuit for controlling the operations of the alternating current signal generation circuit and the detection circuit, and a table provided in the control circuit.

Abstract: It is an object of the present invention to provide an apparatus for discriminating an optical recording medium which can reliably discriminate the kind of an optical recording medium even in the case where the optical recording medium to be discriminated is warped and formed with periodical undulation in the circumferential direction thereof.

Abstract: It is an object of the present invention to provide an apparatus for discriminating an optical recording medium and a method for discriminating an optical recording medium which can reliably discriminate the kind of an optical recording medium even in the case where the optical recording medium to be discriminated is warped.

Abstract: A beam emitted from a light source 1 is separated into a main beam and a sub beam by a diffraction element 2. Because the diffraction element 2 has a diffraction pattern shaped like sinusoidal wave, the spot of the sub beam becomes larger than that of the main beam. As a result, the sub beam little contains any tracking cross component which is generated when the spot crosses any one of tracks of an optical disk 5. Accordingly, when a signal output from a detector provided for detecting the sub beam is subtracted from a push pull signal of the main beam, it is possible to obtain a tracking error signal or a focusing error signal substantially containing no DC offset component.

Abstract: A laser diode driving circuit includes two chip capacitors disposed in the vicinity of one side portion of an IC along which a high voltage power supply terminal, a low voltage power supply terminal and a driving signal output terminal are disposed. One end portion of each of the chip capacitors is connected to the high voltage power supply terminal and the other end portion of each of the chip capacitors is connected to the low voltage power supply terminal. The chip capacitors are adapted for serving to reduce a ripple component superposed on a power supply voltage when a switching element is operated. The chip capacitors are disposed so that the distance between itself and the high voltage power supply terminal, the low voltage power supply terminal and the driving signal output terminal is equal to or shorter than 10 mm.

Abstract: Two light sources radiating two light beams having different wavelengths are simultaneously operated. Reflected beams of these two types of laser beams from an optical recording medium are simultaneously detected by two detectors. When one of the two types of light beams having different wavelengths is used while being focused on an optical recording medium, the spot diameter of the other non-focused metering beam on the optical recording medium is set larger than that of the one of the two light beams. A reflected light having a larger spot diameter is used to reduce DC offset in a tracking error signal.

Abstract: To provide a light receiving device, a light detecting device, and an optical signal reproducing device each of which allows one to perform many different computations in detecting aberration amounts and focus error quantities without requiring exact position relations between laser light to be received and light receiving elements, and between the light receiving elements.

Abstract: A semiconductor laser driving circuit comprises a driving IC and a substrate on which the IC is mounted. The IC incorporates: a switching element for generating a driving signal; a high-potential power terminal and a low-potential power terminal for feeding supply voltage to the switching element; and a driving signal output terminal for outputting the driving signal generated at the switching element to an external device. These three terminals are disposed side by side at one of sides of a main body of the IC. The substrate incorporates three conductors to be connected to the three terminals. Two chip capacitors are disposed beside the one of the sides of the IC at which the three terminals are disposed. An end of each of the capacitors is connected to the high-potential power terminal while the other end is connected to the low-potential power terminal.

Abstract: The spot diameter D3 of a side beam 21 imaged on a disc 5 is set to at least 2.5 times as large as that of a main beam. Via this configuration, an output signal from a detector detecting a reflected light via a side beam, that is, a signal representing a different in the output from photo-detection devices split by split lines in the radial contains a negligible track cross component caused by a beam spot crossing a track. The signal substantially contains a DC offset component alone caused by the shift of an objective lens in the radial direction under tracking control. Thus, by subtracting the output signal of the detector from the push-pull signal of the main beam, a tracking signal substantially containing no DC offset.