Abstract: An optical disk device includes: an objective lens for focusing an optical beam on a recording layer of an optical disk; a converging lens for converging the reflected optical beam reflected on the recording layer; first and second light receiving units disposed at positions spaced ahead and behind at equal distances from the focal point of the reflected optical beam converged by the converging lens; and a focused recording layer discriminating unit for deciding, on the basis of the output signal of the first light receiving unit and the output signal of the second light receiving unit, the positional relation in a two-layer optical disk between a focused recording layer, on which the optical beam is focused, and a defocused recording layer, on which the optical beam is not focused, thereby to discriminate the focused recording layer on the basis of the decision result.

Abstract: A tilt amount detector includes inputting means for inputting a reproduction signal supplied from an optical disc, a first filter portion and a second filter portion for correcting an optical transfer characteristic of the reproduction signal, a reference clock extracting means for extracting a reference clock signal from the input reproduction signal, a first jitter meter and a second jitter meter for measuring jitter amounts of output signals from the filter portions and the extracted reference clock signal and outputting the measured jitter amounts, and a difference calculating means for calculating a difference between the jitter amount measured by the first jitter measuring means and the jitter amount measured by the second jitter measuring means.

Abstract: An optical disk device includes: an objective lens for focusing an optical beam on a recording layer of an optical disk; a converging lens for converging the reflected optical beam reflected on the recording layer; first and second light receiving units disposed at positions spaced ahead and behind at equal distances from the focal point of the reflected optical beam converged by the converging lens; and a focused recording layer discriminating unit for deciding, on the basis of the output signal of the first light receiving unit and the output signal of the second light receiving unit, the positional relation in a two-layer optical disk between a focused recording layer, on which the optical beam is focused, and a defocused recording layer, on which the optical beam is not focused, thereby to discriminate the focused recording layer on the basis of the decision result.

Abstract: The present invention relates to a disc drive apparatus and method, a recording medium, and a program that can securely execute tracking control. The coefficient switching controller 152 inquires of the coefficient register 153 about coefficient values based on disc information supplied from a controller 161 and showing a type of an optical disc 111 mounted on an optical disc apparatus 101, mode information supplied from a gain mode switch unit 162 and showing that a mode is any one of “write” and “read”, and RF information supplied from an RF signal detection unit 151 and showing whether or not an RF signal is detected. The coefficient switching controller 152 supplies the obtained coefficient values to a servo matrix amplifier 118 to thereby create a tracking error signal so that the tracking control can be securely executed. The present invention can be applied to a disc drive apparatus.

Abstract: A tilt amount detector includes inputting means for inputting a reproduction signal supplied from an optical disc, a first filter portion and a second filter portion for correcting an optical transfer characteristic of the reproduction signal, a reference clock extracting means for extracting a reference clock signal from the input reproduction signal, a first jitter meter and a second jitter meter for measuring jitter amounts of output signals from the filter portions and the extracted reference clock signal and outputting the measured jitter amounts, and a difference calculating means for calculating a difference between the jitter amount measured by the first jitter measuring means and the jitter amount measured by the second jitter measuring means.

Abstract: A small size, high performance optical pickup device using a light reception/emission element (laser coupler) and more particularly, an optical pickup device which is capable of excellent recording and reproduction for a magnetic optical recording medium. A prism disposed over optical detectors is made of double refractive crystal material. An optical detector for receiving extraordinary ray is formed at a position laterally deviated corresponding to so-called walk-off of the extraordinary ray. Tracking error signal is detected depending on a distribution of intensities of spots formed by reflective beams on respective optical detectors.