Abstract: For obtaining stable servo-signals without receiving ill influences of stray lights from other layers, on both a focus error signal and a tracking error signal, when recording/reproducing a multi-layer optical disc having small gap between layers thereof, a light beam is divided with using a first and a second diffraction gratings. The first diffraction grating is a polarization diffraction grating, and is mounted on an actuator. The second diffraction grating is disposed on a fixed portion. The first diffraction grating has a first region having a center of a light beam and other(s), and among signal lights reflecting from the disc, the light beam entering into the first region is diffracted, and the light beam entering into the second region transmits therethrough. The second diffraction grating transmits the light beam diffracting on the first region of the polarization diffraction grating therethrough, while diffracting the light beam diffracting on the second region.

Abstract: An optical disc drive according to the present invention is designed to read data from a multilayer optical disc 100, from/on which data can be read or written using a light beam. The drive includes a light source 222 for emitting a light beam, an objective lens 230 for converging the light beam, a photodetector 236 for detecting the light beam that has been reflected from the disc, and a control section 246 for setting a read power for a particular one of the multiple storage layers of the disc by reference to a read power table 501b. The table 501b stores multiple read powers for the respective storage layers in order to make S-curves of a focus error signal obtained from the respective layers have predetermined amplitudes. In this manner, the optical disc drive of the present invention can be loaded with a multilayer optical disc more smoothly by setting the best read powers for the respective storage layers of the disc.

Abstract: An optical disc drive for reading or writing information on a multilayer optical disc having a plurality of recording layers by irradiating the disc with a light beam includes an optical pickup for irradiating the disc with the light beam, a focus error signal generator for generating a focus error signal that indicates a state of displacement of a focal point of the light beam from a recording layer based on reflection from the disc, a recording state detector for detecting a data recording state at a landing point of the focal point in a focus jump, a threshold setting unit for setting a threshold to be compared with the focus error signal based on the data recording state at the landing point, and a focus jump controller for controlling the focus jump based on a result of comparison of the focus error signal with the threshold.

Abstract: An optical drive device includes first and second light sources, an objective lens configured to receive a first light emitted from the first light source and a second light emitted from the second light source and to irradiate both the first light and the second light to an optical disc recording medium, a first focus mechanism configured to drive the objective lens in a focus direction, a second focus mechanism configured to change collimation of the second light incident to the objective lens and changing the focusing position of the second light independently of the first light, a first focus servo control unit configured to drive the first focus mechanism, an error signal subtraction unit configured to subtract the first focus error signal from a second focus error signal, and a second focus servo control unit configured to drive the second focus mechanism.

Abstract: An optical recording medium driving apparatus includes an optical pickup which irradiates first and second laser lights from one object lens with respect to an optical recording medium having a bulk layer and a tilt detection surface; a focus control portion that performs the focus control relative to each predetermined position of the optical recording medium in regard to each of the first and second laser lights; a tracking control portion that controls the position of the object lens to perform the tracking control of the first and second laser lights relative to the optical recording medium; and a tilt control portion.

Abstract: A layer-to-layer jumping method according to the present invention includes, after a layer-to-layer jump has been started in a multilayer optical disc, the step ST7 of detecting an S-curve signal from an information layer, which is located shallower than the target information layer of the layer-to-layer jump, with a spherical aberration correction made adaptively to that shallower information layer, and the step ST8 of generating a deceleration signal based on the S-curve signal detected to get the layer-to-layer jump done.