Abstract: A multilayer optical disc which has three or more recording layers and enables easy positioning of a focused beam spot onto a particular recording layer in which a BCA is disposed. An inter-layer distance between a particular recording layer and a recording layer adjacent to the particular recording layer is larger than the other inter-layer distances in which, at the focused beam spot positioning, the focused beam spot traverses the said adjacent recording layer earlier than the other recording layer adjacent to the particular recording layer.

Abstract: At a comparatively early stage, members to be bonded are pressurized together by an applied pressure that is a comparatively low pressure. Under an applied pressure condition (a gas venting process) of the comparatively low pressure, an organic protective film is vaporized by heating a bonding material, and a void portion of a porous structure that is formed by metal nanoparticles and a binder in the bonding material is not collapsed any more than necessary due to the applied pressure. Thus, the void portion of the porous structure functions as a degassing path for the gasified organic protective film, and the gas is smoothly released from between the members to be bonded. At the time point when the temperature of the bonding material has reached a predetermined temperature, the applied pressure is increased from the comparatively low pressure to a comparatively high pressure (a pressure increase process).

Abstract: There are provided a multi-layered optical disk and an optical disk device capable of swiftly reproducing control information recorded into a predetermined recording layer in advance. The object can be accomplished by employing the following configuration: When the optical disk device performs a focus lead-in operation into the multi-layered optical disk, the device positions its optical pickup at a BCA radius position, and takes advantage of a signal which is generated such that an influence exerted on the signal by BCA is avoided. Also, the object can be accomplished by employing the following configuration: An angle index unit for indicating a rotation reference position is provided in the multi-layered optical disk, and a partial area of the BCA is selected as an unrecording area. The optical disk device starts the focus lead-in operation in synchronization with rotation angle information created from the rotation reference position.

Abstract: A large current flowing out from video signal line driver is prevented whenever the video signal line is being grounded. The system includes a video signal line driver circuit transmitting video signal at pre-determined DC level, a large current prevention circuit detecting video signal line being shorted to ground and cut-off excessive current source out from video signal line driver circuit into video signal line, a start-up time enhancement circuit improving start-up time of ground detection circuit so that system start-up time is not limited by large current prevention circuit, and a switching threshold control circuit setting the switching threshold of large current prevention circuit and start-up time enhancement circuit.

Abstract: A servo control signal generation device for discriminating a kind of an optical disk, changing over between top and bottom envelope signals of an RF signal, and generating a defect signal and a mirror signal includes an RF generator for generating the RF signal from reflected light of an optical disk, a disk discriminator for discriminating a kind of the optical disk from the RF signal, and a top envelope generator and a bottom envelope generator respectively for generating the top and bottom envelope signals of the RF signal. If the disk has reflectance after recording which is lower than that before recording, the defect and mirror signals are generated respectively from the top and bottom envelope signals. If the disk has reflectance after recording which is higher than that before recording, the defect and mirror signals are generated respectively from the bottom and top envelope signals.

Abstract: An object of the present invention is to provide a focus out detecting apparatus which detects focus out with accuracy during reproducing or recording of data from/on an optical disc having a plurality of recording layers. Further, another object of the present invention is to provide an optical disc apparatus in which a recording or reproducing performance of data is improved by use of the focus out detecting apparatus. A focus out detection signal is output when a level of a focus error signal exceeds a first predetermined level, then reflected light quantity from the optical disc becomes lower than a third predetermined level in a predetermined period, and then the level of the focus error signal exceeds a second predetermined level of an opposite polarity to the first predetermined level.

Abstract: A servo control signal generation device for discriminating a kind of an optical disk, changing over between top and bottom envelope signals of an RF signal, and generating a defect signal and a mirror signal includes an RF generator for generating the RF signal from reflected light of an optical disk, a disk discriminator for discriminating a kind of the optical disk from the RF signal, and a top envelope generator and a bottom envelope generator respectively for generating the top and bottom envelope signals of the RF signal. If the disk has reflectance after recording which is lower than that before recording, the defect and mirror signals are generated respectively from the top and bottom envelope signals. If the disk has reflectance after recording which is higher than that before recording, the defect and mirror signals are generated respectively from the bottom and top envelope signals.

Abstract: There is a need to accurately lock focus of a laser beam onto a target data layer of a multilayer optical disc. The above need can be addressed by, for example, performing a focus lock operation after a spherical aberration correction amount is set in such a way as to make smaller the ratio of the focus error signal waveform amplitude at the data layer adjacent to a target data layer through which a laser beam passes earlier than through the target data layer to the focus error signal waveform amplitude at the target data layer than that when the spherical aberration correction amount is set so as to be optimal for the target data layer.

Abstract: There is a need to prevent a possible erroneous detection of an off-track condition during recording to an optical disk. The above need can be addressed by, for example, determining an off-track condition has occurred when a light spot is located at least half-way from the track being recorded toward another track adjacent the track being recorded, and stopping a recording operation. In another example, the above need can be addressed by determining that off-track has occurred based on an output of a first off-track detector which detects that the light spot is off the track based on a wobble signal, an output of a second off-track detector which detects that the light spot is off the track based on a tracking error signal, and an output of a zero-cross detector which detects that the tracking error signal crosses zero based on an output of the tracking error signal.

Abstract: A powder metal cladding nozzle which is coaxially attached to a laser processing head that irradiates a process portion (W) with a laser beam (L) and that discharges powder metal (P) to a laser beam irradiation portion in the process portion (W). The powder metal cladding nozzle includes a body portion (2) that has a ring-shaped powder metal holding space (7) in which the powder metal (P) is held; and a nozzle portion (3) that is connected to the body portion (2) and that has plural discharge passages (18) which are communicated with the powder metal holding space (7) and which open at an outlet (19) for discharging the powder metal (P). The powder metal holding space (7) is formed in the body portion (2) and is divided into plural powder metal holding regions corresponding to plural supply passages (10) that open into the powder metal holding space (7) and that supply the powder metal (P) to the powder metal holding space (7).

Abstract: There is provided a method for manufacturing a cast iron member in which the production of gas defects such as blowholes or pinholes in a clad layer formed on the surface of a cast iron material can be reduced, and the generation of bead cracks in the clad layer can be restrained. In the method for manufacturing a cast iron member, including a step of forming the clad layer by melting a material for cladding by means of irradiation of a laser emitted from a laser irradiation device and by depositing the melted material on the surface of a part of the cast iron material, the step of forming the clad layer is performed by using a material the main ingredient of which is a copper element as the material for cladding so that when the clad layer is formed, a hardened layer having a thickness of 0.01 to 2.0 mm is formed on the surface of the cast iron material.

Abstract: Defocus detection device and method capable of detecting a defocus accurately during recording of information to an optical disk having a plurality of recording layers and an optical disk unit using the device and method are provided. A temporal restriction is imposed on defocus detection and besides, in comparison with a level for detection of a first change of a focus error signal developing during a defocus, a level for detection of a successively occurring second change of a polarity inverse to that of the first change is made to be smaller. When the first level is exceeded and thereafter the second level is exceeded within a restricted time, a defocus is detected.

Abstract: Defocus detection device and method capable of detecting a defocus accurately during recording of information to an optical disk having a plurality of recording layers and an optical disk unit using the device and method are provided. A temporal restriction is imposed on defocus detection and besides, in comparison with a level for detection of a first change of a focus error signal developing during a defocus, a level for detection of a successively occurring second change of a polarity inverse to that of the first change is made to be smaller. When the first level is exceeded and thereafter the second level is exceeded within a restricted time, a defocus is detected.

Abstract: A focus jump technique enables focus control on recording layers of a disc in such a manner that its effect is not absorbed by disturbance or a variation in the movement speed of an objective lens. The technique involves monitoring level of a focus error signal and rejecting noise from the error signal. A speed sensor detects movement speed of an objective lens; and a speed control circuit generates a voltage for controlling the objective lens, based on the detected movement speed. Movement speed of the objective lens is detected during focus jump, a corresponding lens drive signal is generated, and an end position is determined from behavior of the error signal immediately before the end of the jump. A focus control is pulled, from a focus point corresponding to one recording layer, into a focus point corresponding to another recording layer forcibly in a stable manner.

Abstract: At a comparatively early stage, members to be bonded are pressurized together by an applied pressure that is a comparatively low pressure. Under an applied pressure condition (a gas venting process) of the comparatively low pressure, an organic protective film is vaporized by heating a bonding material, and a void portion of a porous structure that is formed by metal nanoparticles and a binder in the bonding material is not collapsed any more than necessary due to the applied pressure. Thus, the void portion of the porous structure functions as a degassing path for the gasified organic protective film, and the gas is smoothly released from between the members to be bonded. At the time point when the temperature of the bonding material has reached a predetermined temperature, the applied pressure is increased from the comparatively low pressure to a comparatively high pressure (a pressure increase process).

Abstract: A focus jump technique enables focus control on recording layers of a disc in such a manner that its effect is not absorbed by disturbance or a variation in the movement speed of an objective lens. The technique involves monitoring level of a focus error signal and rejecting noise from the error signal. A speed sensor detects movement speed of an objective lens; and a speed control circuit generates a voltage for controlling the objective lens, based on the detected movement speed. Movement speed of the objective lens is detected during focus jump, a corresponding lens drive signal is generated, and an end position is determined from behavior of the error signal immediately before the end of the jump. A focus control is pulled, from a focus point corresponding to one recording layer, into a focus point corresponding to another recording layer forcibly in a stable manner.

Abstract: There is provided an optical disc recording/reproduction device capable of accurately performing the focus offset and spherical aberration correction even for an optical disc having no data recorded. The optical disc recording/reproduction device includes: an optical pickup having a spherical aberration corrector for correcting the spherical aberration of an objective lens; and various control units; and can generate a tracking error signal (TE) at least by a push-pull signal by the push-pull method. When an optical disc mounted is in an unrecorded state, the spherical aberration correction amount and the objective lens focus offset amount are adjusted according to the push-pull signal, predetermined data is recorded on the optical disc, and the reproduction signal obtained by the data is used to adjust the spherical aberration correction amount in the spherical aberration corrector of the optical pickup and the focus offset amount of the objective lens.

Abstract: Even in an optical disk which includes, within a single disk, plural record areas whose track-pitches differ from each other, a tracking parameter is adjusted in a short time and with a high accuracy. At first, an optical pickup for reading information recorded in the optical disk is displaced into a reference track-pitch area which is one of the plural record areas of the optical disk. Moreover, the tracking gain is adjusted so that the tracking servo gain in this area may exhibit a predetermined characteristic. Also, the value thus acquired is recorded into, e.g., a non-volatile memory. After that, based on the tracking parameter learned/adjusted in the reference track-pitch area, the tracking parameter in another track-pitch area is calculated using the track-pitch ratio therebetween. Thereby it becomes possible to adjust the tracking parameter in a short time and with a high accuracy.

Abstract: An object of the present invention is to provide a focus out detecting apparatus which detects focus out with accuracy during reproducing or recording of data from/on an optical disc having a plurality of recording layers. Further, another object of the present invention is to provide an optical disc apparatus in which a recording or reproducing performance of data is improved by use of the focus out detecting apparatus. A focus out detection signal is output when a level of a focus error signal exceeds a first predetermined level, then reflected light quantity from the optical disc becomes lower than a third predetermined level in a predetermined period, and then the level of the focus error signal exceeds a second predetermined level of an opposite polarity to the first predetermined level.

Abstract: A focus jump technique enables focus control on recording layers of a disc in such a manner that its effect is not absorbed by disturbance or a variation in the movement speed of an objective lens. The technique involves monitoring level of a focus error signal and rejecting noise from the error signal. A speed sensor detects movement speed of an objective lens; and a speed control circuit generates a voltage for controlling the objective lens, based on the detected movement speed. Movement speed of the objective lens is detected during focus jump, a corresponding lens drive signal is generated, and an end position is determined from behavior of the error signal immediately before the end of the jump. A focus control is pulled, from a focus point corresponding to one recording layer, into a focus point corresponding to another recording layer forcibly in a stable manner.