Abstract: The disclosure provides a wire-wound coil that can prevent contact between an outer flange portion of the wire-wound coil and a mount board so as to prevent breakage of the outer flange portion and misalignment and unwinding of a wound conductive wire. A groove is provided in an outer side face of a flange at an end of a winding core, and an inner flange portion and an outer flange portion are provided on opposite sides of the groove. A distance from a bottom face of the groove to at least an outer side face of the outer flange portion that would be facing a mount board or is attached to a mount board is shorter than a distance from the bottom face of the groove to the inner flange portion.

Abstract: The disclosure provides a wire-wound coil that can prevent contact between an outer flange portion of the wire-wound coil and a mount board so as to prevent breakage of the outer flange portion and misalignment and unwinding of a wound conductive wire. A groove is provided in an outer side face of a flange at an end of a winding core, and an inner flange portion and an outer flange portion are provided on opposite sides of the groove. A distance from a bottom face of the groove to at least an outer side face of the outer flange portion that would be facing a mount board or is attached to a mount board is shorter than a distance from the bottom face of the groove to the inner flange portion.

Abstract: A defocus amount specifying circuit specifies, as a focus error minimum defocus amount FMDF, a defocus amount by which the amplitude of a focus error signal becomes minimum in a state in which tracking servo is off in a period after insertion of an optical disc and before a seek operation, and specifies, as a jitter minimum defocus amount JMDF, a defocus amount by which a jitter amount becomes minimum in a state in which tracking servo is on. A defocus amount supplying circuit transmits the focus error minimum defocus amount FMDF to a focus servo circuit to perform focus control during a seek operation, and transmits the jitter minimum defocus amount JMDF to the focus servo circuit to perform focus control after the seek operation.

Abstract: A circuit board has, jointed together with adhesive, a single-layer flexible PCB having a through hole formed therein in the thickness direction and a rigid member having copper foil formed on one side of an insulating base member. A conductive pattern on the single-layer flexible PCB and the copper foil are electrically connected together via solder filling the through hole. Thus, with a low-cost circuit board, unnecessary electromagnetic emissions can be effectively reduced.

Abstract: An optical pickup of an optical disc apparatus has a lens holder for holding an objective lens is pivoted with a guide shaft slidably in a direction in parallel with an optical axis of the objective lens and rotatably around the guide shaft in a direction perpendicular to the optical axis. For focusing a laser beam on a data recording face of an optical disc in a focusing on operation, a wobble signal of rectangular waveform having a predetermined voltage and a predetermined frequency is applied to a tracking coil for reciprocally displacing the lens holder in the direction perpendicular to the optical axis, while a focusing coil is driven for moving the lens holder in the direction in parallel with the optical axis. Thus, the lens holder can be moved smoothly along the guide shaft, so that the possibility of failure of the focusing the laser beam on the optical disc can be reduced drastically.

Abstract: A controller configures a balance position of a tracking error signal at a point at which an error rate indicates a minimum value while the balance position of the tracking error signal from an optical pickup is shifted from the center in reproducing the optical disk. Therefore, even when a pit on the track of the optical disk is asymmetrical with respect to the center, the error rate in reproducing the optical disk is reduced and the precision of the reproducing signal is enhanced.

Abstract: With conventional test discs, changing them takes much time when a pickup is subjected to signal evaluation with respect to DVD- family discs (DVD-R and DVD-RW) and DVD+ family discs (DVD+R and DVD+RW), leading to low testing efficiency. A test disc of the invention has, formed on a single glass substrate, areas where there are provided regions where pits or no pits are formed and areas where there are provided regions where wobbles and land prepits are formed with varying parameters.

Abstract: A defocus amount specifying circuit specifies, as a focus error minimum defocus amount FMDF, a defocus amount by which the amplitude of a focus error signal becomes minimum in a state in which tracking servo is off in a period after insertion of an optical disc and before a seek operation, and specifies, as a jitter minimum defocus amount JMDF, a defocus amount by which a jitter amount becomes minimum in a state in which tracking servo is on. A defocus amount supplying circuit transmits the focus error minimum defocus amount FMDF to a focus servo circuit to perform focus control during a seek operation, and transmits the jitter minimum defocus amount JMDF to the focus servo circuit to perform focus control after the seek operation.

Abstract: An optical pickup of an optical disc apparatus has a lens holder for holding an objective lens is pivoted with a guide shaft slidably in a direction in parallel with an optical axis of the objective lens and rotatably around the guide shaft in a direction perpendicular to the optical axis. For focusing a laser beam on a data recording face of an optical disc in a focusing on operation, a wobble signal of rectangular waveform having a predetermined voltage and a predetermined frequency is applied to a tracking coil for reciprocally displacing the lens holder in the direction perpendicular to the optical axis, while a focusing coil is driven for moving the lens holder in the direction in parallel with the optical axis. Thus, the lens holder can be moved smoothly along the guide shaft, so that the possibility of failure of the focusing the laser beam on the optical disc can be reduced drastically.

Abstract: A controller configures a balance position of a tracking error signal at a point at which an error rate indicates a minimum value while the balance position of the tracking error signal from an optical pickup is shifted from the center in reproducing the optical disk. Therefore, even when a pit on the track of the optical disk is asymmetrical with respect to the center, the error rate in reproducing the optical disk is reduced and the precision of the reproducing signal is enhanced.