Abstract: An optical disc device performs tracking control using a light amount difference at two overlapping areas. The optical disc device includes a splitter, objective lens, detection-signal generator, tracking-signal generator, and driver. The splitter splits the light beam from a light source into a main beam and sub-beams. The objective lens converges the split beams and illuminates a signal-recording-layer track. The detection-signal generator receives reflected light beams and generates a detection signal according to the reflected-light-beam light amounts. The tracking-signal generator generates a tracking error signal on the basis of the detection signal. The driver drives the objective lens in a tracking direction on the basis of the tracking error signal. The splitter causes the light amounts of the overlapping areas at sub-reflected-light beams to be less than a light amount of an area other than the overlapping areas.

Abstract: An optical pickup for recording or reproducing an information signal in an optical disc includes a light source for emitting a light beam toward the optical disc, an objective lens for focusing the light beam emitted from the light source onto a recording surface of the optical disc, and a photodetector for receiving the light beam reflected by the recording surface of the optical disc and outputting a signal corresponding to an intensity of the received light beam. A spot of the light beam received by the photodetector is asymmetric in both a radial direction and a tangential direction of the optical disc. A lens shift signal for the objective lens is detected by a controller on the basis of the signal output from the photodetector, the controller controlling the objective lens to follow the optical disc.

Abstract: A polycarbonate copolymer which comprises 30 to 70 mol % of a structural unit comprising a bisphenyl fluorene structure and 70 to 30 mol % of a structural unit comprising tricyclo [5.2.1.02,6] decanedimethanol and causes little occurrence of birefringence even when extrusion, injection molding or stretch processing is conducted and a process for producing the same.

Abstract: A polycarbonate resin composition obtained by blending a polycarbonate resin (A) obtained by forming a carbonate bond from 95 to 5 mol % of a dihydroxy compound having a fluorene structure represented by the general formula (1) and 5 to 95 mol % of a dihydroxy compound having a dimethanol structure represented by the general formula (2) and a carbonic diester and a polycarbonate resin (B) obtained by forming a carbonate bond from bisphenol A and a carbonic acid diester or phosgene in a ratio of (100×(A)/((A)+(B))=1 to 99% by weight and a polarizing sheet used the same.

Abstract: An optical disk device performing data reproducing and/or data recording of a disk with the disk being clamped and rotated. The disk device has a simple structure in which light emitted from an optical pickup can be securely made incident on the disk at right angles. The disk device includes the optical pickup for reproducing or recording on the disk clamped by a clamping mechanism, and an optical pickup driving mechanism. The optical pickup includes a guided part. The optical pickup driving mechanism includes a guide shaft for guiding the movement of the optical pickup via the guided part of the optical pickup. The center axis of the guided part is shifted from the direction perpendicular to the direction of light emitted from the optical pickup so that the direction of light emitted from the optical disk can make an approximately right angle with the disk surface.

Abstract: A disk device for improving a S/N ratio is provided with a spindle motor control substrate 10 arranged below a tray 3 via a buffer material and a medium substrate 12 arranged at a position different from the spindle motor control substrate 10 below the tray 3. The spindle motor control substrate 10, the medium substrate 12 and the main control substrate 7 of the device body are connected each other with a flexible print circuit (FPC) 9. The medium substrate 12 and a pickup head 1c are connected with other FPC. The head detection signal is provided to the main control substrate 7 through the medium substrate 12. A driver IC for motor drive system is carried on the spindle motor control substrate 10. The motor drive signal is apart from the head detection signal and is provided to a spindle motor 1a or a head transferring motor.

Abstract: A polycarbonate resin composition obtained by blending a polycarbonate resin (A) obtained by forming a carbonate bond from 95 to 5 mol % of a dihydroxy compound having a fluorene structure represented by the general formula (1) and 5 to 95 mol % of a dihydroxy compound having a dimethanol structure represented by the general formula (2) and a carbonic diester and a polycarbonate resin (B) obtained by forming a carbonate bond from bisphenol A and a carbonic acid diester or phosgene in a ratio of (100×(A)/((A)+(B))=1 to 99% by weight and a polarizing sheet used the same.

Abstract: A disk device for improving a SIN ratio is provided with a spindle motor control substrate 10 arranged below a tray 3 via a buffer material and a medium substrate 12 arranged at a position different from the spindle motor control substrate 10 below the tray 3. The spindle motor control substrate 10, the medium substrate 12 and the main control substrate 7 of the device body are connected each other with a flexible print circuit (FPC) 9. The medium substrate 12 and a pickup head 1c are connected with other FPC. The head detection signal is provided to the main control substrate 7 through the medium substrate 12. A driver IC for motor drive system is carried on the spindle motor control substrate 10. The motor drive signal is apart from the head detection signal and is provided to a spindle motor 1a or a head transferring motor.

Abstract: An optical disk device performing data reproducing and/or data recording of a disk with the disk being clamped and rotated. The disk device has a simple structure in which light emitted from an optical pickup can be securely made incident on the disk at right angles. The disk device includes the optical pickup for reproducing or recording on the disk clamped by a clamping mechanism, and an optical pickup driving mechanism. The optical pickup includes a guided part. The optical pickup driving mechanism includes a guide shaft for guiding the movement of the optical pickup via the guided part of the optical pickup. The center axis of the guided part is shifted from the direction perpendicular to the direction of light emitted from the optical pickup so that the direction of light emitted from the optical disk can make an approximately right angle with the disk surface.

Abstract: A method of making a tool path, wherein a shape to which an object surface is to be processed and processing conditions are inputted, and a processing region is designated on the processing region, and a tool path on the processing region is calculated on the basis of the reference lines. When the number of the processing region is one, a tool escaping expansion region is added to a terminal end in the picking direction of the processing region, or a tool approaching expansion region is added to a starting end in the picking direction of the processing region. When the number of the processing regions is not smaller than two, a tool escaping expansion region is added to a final end in the picking direction of the processing region precedingly, and a tool approaching expansion region to a starting end in the picking direction of the processing region posteriorly.

Abstract: A method and apparatus is provided for allowing the innermost radial position of the optical pickup on an optical disk mounted on an optical disk drive to be detected, without having to use the inner switch.

Abstract: A method of making a tool path, capable of making a difference in level of a part of a surface being processed inconspicuous, and obtaining a smooth processed surface. According to this method, a shape to which an object surface is to be processed and processing conditions are inputted, and a processing region is designated on the surface to be processed. Reference lines are designated on the processing region, and a tool path on the processing region is calculated on the basis of the reference lines. When the number of the processing region is one, a tool escaping expansion region is added to a terminal end in the picking direction of the processing region, or a tool approaching expansion region is added to a starting end in the picking direction of the processing region.