Abstract: Based on a left tooth surface (28) having a maximum accumulated pitch error ALmax (when clockwise direction is a positive direction) and a right tooth surface (29) having a minimum accumulated pitch error ARmin (when clockwise direction is a positive direction), which are conceived to most likely have insufficiently ground portions, a correction value ?? which cancels these accumulated pitch errors for suppressing the accumulated pitch error after grinding is obtained. A reference tooth groove angle ?0 is corrected by the correction value ??, thereby obtaining the meshing angle ? of the work gear. All teeth detection and signal processing in a short period of time is realized by using a displacement sensor and a high-speed meshing-dedicated circuit board.

Abstract: A kind of an optical disc is discriminated by a disc discriminating section, an order of aberrations to be corrected is set by an order setting section by the kind of the optical disc, drive of a liquid crystal optical element is controlled by a drive control section through a liquid crystal driver, and an aberration of an optical beam is corrected based on the order of the aberration. The level of importance of the aberration correction differs by the kind of the optical disc, and the order of the aberration is set by the level of importance of the aberration correction.

Abstract: A disc device (100) implements information processing with respect to, for example, a zeroth recording layer of an optical disk by an information processing section (510), and outputs a double-layer main voltage value and a double-layer sub voltage value corresponding to the intensities of a zeroth-order light beam and ±first-order light beams which are received by a photodetecting element (350) to an offset calculating section (522) by a voltage value acquiring section (521). The voltage value acquiring section (521) stores voltage values corresponding to the intensities of the zeroth-order light beam and ±first-order light beams which are received by the photodetecting element (350) as a single-layer main voltage value and a single-layer sub voltage value in a memory (400) in a state where a single-layer disc is loaded.

Abstract: Based on a left tooth surface (28) having a maximum accumulated pitch error ALmax (when clockwise direction is a positive direction) and a right tooth surface (29) having a minimum accumulated pitch error ARmin (when clockwise direction is a positive direction), which are conceived to most likely have insufficiently ground portions, a correction value ?? which cancels these accumulated pitch errors for suppressing the accumulated pitch error after grinding is obtained. A reference tooth groove angle ?0 is corrected by the correction value ??, thereby obtaining the meshing angle ? of the work gear. All teeth detection and signal processing in a short period of time is realized by using a displacement sensor and a high-speed meshing-dedicated circuit board.

Abstract: A kind of an optical disc is discriminated by a disc discriminating section, an order of aberrations to be corrected is set by an order setting section by the kind of the optical disc, drive of a liquid crystal optical element is controlled by a drive control section through a liquid crystal driver, and an aberration of an optical beam is corrected based on the order of the aberration. The level of importance of the aberration correction differs by the kind of the optical disc, and the order of the aberration is set by the level of importance of the aberration correction.

Abstract: A disc device (100) implements information processing with respect to, for example, a zeroth recording layer of an optical disk by an information processing section (510), and outputs a double-layer main voltage value and a double-layer sub voltage value corresponding to the intensities of a zeroth-order light beam and ±first-order light beams which are received by a photodetecting element (350) to an offset calculating section (522) by a voltage value acquiring section (521). The voltage value acquiring section (521) stores voltage values corresponding to the intensities of the zeroth-order light beam and ±first-order light beams which are received by the photodetecting element (350) as a single-layer main voltage value and a single-layer sub voltage value in a memory (400) in a state where a single-layer disc is loaded.

Abstract: It is an object of the present invention to provide an optical pickup astigmatism adjusting method capable of easily correcting an astigmatism even if the spot shape of a light beam converged on an optical disc is not a true circle. An optical pickup astigmatism adjusting system of the present invention finds an inter-focal distance L0 between a focal position where a light beam is converged in RAD direction and another focal position where a light beam is converged in TAN direction, and a further inter-focal distance L45 between a focal position where a light beam is converged in a direction inclined 45 degrees from RAD direction and another focal position where a light beam is converged in a direction inclined 45 degrees from TAN direction, thereby measuring an astigmatism in accordance with the inter-focal distances L0 and L45. Then, an installation angle of a reflection mirror is adjusted in accordance with the inter-focal distances L0 and L45, thus correcting the astigmatism.

Abstract: It is an object of the present invention to adjust the focus position of an optical pickup. A brightness measuring apparatus having a half mirror and an objective lens focusing on the half mirror is disposed at a position facing an optical pickup PUi, in a manner such that the objective lens OB of the optical pickup PUi faces the half mirror. Then, the optical pickup PUi is operated to start a focus servo, while the position of multi-lens provided in the optical pickup PUi is changed continuously, thereby measuring a highest brightness of a spot light image incident on the half mirror through the objective lens, by virtue of the brightness measuring apparatus. Subsequently, a highest brightness change caused by changing the position of the multi-lens ML is inspected so as to fix the multi-lens ML at a position when the maximum highest brightness has been obtained, thereby effecting an optimum focus position adjustment for an optical pickup.

Abstract: An information recording/reproducing apparatus includes an optical device, a photo-detector and a calculation unit. The optical device irradiates light beams, including one main beam and at least two sub-beams with respect to an information recording medium. The photo-detector receives return lights of the main beam and sub-beams to output light detection signals. The calculation unit produces a tracking error signal and a position information signal based on the light detection signals. The optical device irradiates the at least two sub-beams onto positions shifted to opposite sides of a center of the guide track, respectively, when the main beam is being irradiated onto a center of the information recording track. Thus, the apparatus produces the tracking error signal and the position information signal by utilizing a common optical system and a common signal processing system and thereby executes tracking servo control and random access processing with high accuracy.

Abstract: An optical pickup apparatus and a laser diode chip which can simplify and miniaturize a construction of the apparatus is provided for using a plurality of laser beams of different wavelengths. The laser diode chip is a chip for the optical pickup apparatus in which a plurality of light emitting portions for emitting the laser beams of the different wavelengths in the same emitting direction are formed on a substrate. Light emitting points of the plurality of light emitting portions are located at positions which are different in the emitting direction.

Abstract: It is an object of the present invention to provide an optical pickup astigmatism adjusting method capable of easily correcting an astigmatism even if the spot shape of a light beam converged on an optical disc is not a true circle. An optical pickup astigmatism adjusting system of the present invention finds an inter-focal distance L0 between a focal position where a light beam is converged in RAD direction and another focal position where a light beam is converged in TAN direction, and a further inter-focal distance L45 between a focal position where a light beam is converged in a direction inclined 45 degrees from RAD direction and another focal position where a light beam is converged in a direction inclined 45 degrees from TAN direction, thereby measuring an astigmatism in accordance with the inter-focal distances L0 and L45. Then, an installation angle of a reflection mirror is adjusted in accordance with the inter-focal distances L0 and L45, thus correcting the astigmatism.

Abstract: A reflective mirror 14 is inclined and placed with respect to an objective lens 16 and a photoelectric conversion element 15 for monitor is placed in the back side of the reflective mirror 14. The reflective mirror 14 is formed into a structure in which a semi-transmission film HM having predetermined reflectance and transmittance is formed on one surface of a substrate of a transparent medium. When a laser beam for information record or information reproduction is launched from semiconductor lasers 2a, 3 to the reflective mirror 14, the semi-transmission film HM splits the laser beam into a reflected beam and a transmitted beam and the reflected beam is emitted to the side of the objective lens 16 and the transmitted beam is emitted to the side of the photoelectric conversion element 15.

Abstract: Laser beams h1, h2 with different wavelengths emitted from semiconductor lasers 2a, 3 are incident to an optical path joint prism 13 and each of optical intensities of the laser beams h1, h2 is detected by a photoelectric conversion element 15 provided in an optical path integrated by the optical path joint prism 13 on which a semi-transmission film HM is provided and APC control of each of light emission intensities of the semiconductor lasers 2a, 3 is performed on a basis of each of detection results. As a result of this, the beam intensity of the laser beam h1 passing through the optical path joint prism 13 to be applied to an information recording medium and the laser beam h2 reflecting the optical path joint prism 13 to be applied to the information recording medium are controlled properly.

Abstract: It is an object of the present invention to adjust the focus position of an optical pickup. A brightness measuring apparatus having a half mirror and an objective lens focusing on the half mirror is disposed at a position facing an optical pickup PUi, in a manner such that the objective lens OB of the optical pickup PUi faces the half mirror. Then, the optical pickup PUi is operated to start a focus servo, while the position of multi-lens provided in the optical pickup PUi is changed continuously, thereby measuring a highest brightness of a spot light image incident on the half mirror through the objective lens, by virtue of the brightness measuring apparatus. Subsequently, a highest brightness change caused by changing the position of the multi-lens ML is inspected so as to fix the multi-lens ML at a position when the maximum highest brightness has been obtained, thereby effecting an optimum focus position adjustment for an optical pickup.

Abstract: An information recording/reproducing apparatus includes an optical device, a photo-detector and a calculation unit. The optical device irradiates light beams, including one main beam and at least two sub-beams with respect to an information recording medium. The photo-detector receives return lights of the main beam and sub-beams to output light detection signals. The calculation unit produces a tracking error signal and a position information signal based on the light detection signals. The optical device irradiates the at least two sub-beams onto positions shifted to opposite sides of a center of the guide track, respectively, when the main beam is being irradiated onto a center of the information recording track. Thus, the apparatus produces the tracking error signal and the position information signal by utilizing a common optical system and a common signal processing system and thereby executes tracking servo control and random access processing with high accuracy.

Abstract: An optical pickup apparatus which supports two wavelengths and is amenable to a reduction in size without employing a combining prism. The optical pickup apparatus employs a semiconductor laser device implemented in the form of a one-chip laser diode having two light sources for emitting a first laser beam and a second laser beam at a wavelength different from that of the first laser beam. A photodetector unit has a first detector section for receiving the first laser beam and a second detector section for receiving the second laser beam, and is set at positions at which the first and second laser beams follow return light paths of different lengths from an optical disc to the first and second detector sections.

Abstract: An optical pickup apparatus capable of reading information from recording media of different read wavelengths, includes a light-emitter having a first light source for emitting a first laser beam integrated with a second light source for emitting a second laser beam of a different wavelength from that of the first laser beam. The optical pickup apparatus includes a photodetector for receiving a beam reflected by each of the recording media and an optical system having a plurality of optical elements which form an optical path to guide the first and second laser beams to the recording media and which form an optical path for guiding the reflected beam to the photodetector and through which the first and second laser beams pass.

Abstract: An optical pickup apparatus includes a semiconductor laser device having a plurality of light emitting portions for emitting laser beams having different wavelengths on a substrate for emitting a laser beam from one of the plurality of light emitting portions in response to a light emitter selecting instruction in the same emitting direction. The laser beam emitted from the semiconductor laser device is converged by an objective lens and led to a recording surface of an optical disk, and the objective lens is moved to one of a plurality of different positions in a radial direction of the optical disk, corresponding to the selected light emitting portion.

Abstract: Laser beams h1, h2 with different wavelengths emitted from semiconductor lasers 2a, 3 are incident to an optical path joint prism 13 and each of optical intensities of the laser beams h1, h2 is detected by a photoelectric conversion element 15 provided in an optical path integrated by the optical path joint prism 13 on which a semi-transmission film HM is provided and APC control of each of light emission intensities of the semiconductor lasers 2a, 3 is performed on a basis of each of detection results. As a result of this, the beam intensity of the laser beam h1 passing through the optical path joint prism 13 to be applied to an information recording medium and the laser beam h2 reflecting the optical path joint prism 13 to be applied to the information recording medium are controlled properly.

Abstract: A reflective mirror 14 is inclined and placed with respect to an objective lens 16 and a photoelectric conversion element 15 for monitor is placed in the back side of the reflective mirror 14. The reflective mirror 14 is formed into a structure in which a semi-transmission film HM having predetermined reflectance and transmittance is formed on one surface of a substrate of a transparent medium. When a laser beam for information record or information reproduction is launched from semiconductor lasers 2a, 3 to the reflective mirror 14, the semi-transmission film HM splits the laser beam into a reflected beam and a transmitted beam and the reflected beam is emitted to the side of the objective lens 16 and the transmitted beam is emitted to the side of the photoelectric conversion element 15.