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US 7,065,013 B2Granted
Optical disk apparatus
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsKatsuhiko Yasuda, Kousei Sano, Daisuke Ogata, Yuuichi Kuze
Life of this patent
Estimating the term…
Abstract
The quantity of spherical aberration correction is predetermined for each recording plane of an optical disk on which focusing control is performed. Before operating the focusing control, the quantity of spherical aberration to be corrected by an aberration correcting system is set based on an output signal from an aberration correction quantity switching device that corresponds to the type of the optical disk and the recording plane to be subjected to the focusing control. This makes it possible to perform stable focusing control on each recording plane of a multi-layer optical disk with high density by using an objecting lens having a large NA after spherical aberration has been corrected properly.
Claims11
An optical disk apparatus comprising:
- an optical pickup comprising a laser source, a focusing optical system for receiving a light beam emitted from the laser source and focusing the light beam on an optical disk to form a tiny spot, a transfer system for transferring the focusing optical system in a direction substantially perpendicular to the optical disk, a photodetector for receiving a light beam reflected from the optical disk and outputting an electric signal in accordance with a quantity of light, and an aberration correcting system for correcting spherical aberration of the focusing optical system;
- a focusing error detection device for detecting a focused state of the tiny spot on the optical disk based on the output signal from the photodetector;
- a focusing control device for controlling the focused state of the tiny spot on the optical disk so as to be a predetermined state by driving the transfer system based on an output signal from the focusing error detection device;
- a disk discrimination device for discriminating a type of the optical disk;
- a reference value storage device for storing at least one quantity of spherical aberration correction of the aberration correcting system with respect to at least one optical disk having at least one reference thickness, and
- an aberration correction quantity switching device for switching a quantity of spherical aberration correction of the aberration correcting system selectively based on a signal from the disk discrimination device,
- wherein the aberration correction quantity switching device presets the quantity of spherical aberration correction of the aberration correcting system based on an output signal from the reference value storage device before operating the focusing control device.
4 more elements
An optical disk apparatus comprising:
- an optical pickup comprising a laser source, a focusing optical system for receiving a light beam emitted from the laser source and focusing the light beam on an optical disk to form a tiny spot, a transfer system for transferring the focusing optical system in a direction substantially perpendicular to the optical disk, a photodetector for receiving a light beam reflected from the optical disk and outputting an electric signal in accordance with a quantity of light, and an aberration correcting system for correcting spherical aberration of the focusing optical system;
- a focusing error detection device for detecting a focused state of the tiny spot on the optical disk based on the output signal from the photodetector;
- a focusing control device for controlling the focused state of the tiny spot on the optical disk so as to be a predetermined state by driving the transfer system based on an output signal from the focusing error detection device;
- a disk discrimination device for discriminating a type of the optical disk;
- an aberration correction quantity switching device for switching a first quantity of spherical aberration correction of the aberration correcting system selectively based on a signal from the disk discrimination device;
- a reference value storage device for storing a second quantity of spherical aberration correction of the aberration correcting system with respect to an optical disk having a reference thickness;
- and
- an adder for adding the first and second quantities of spherical aberration correction,
- wherein a quantity of spherical aberration correction of the aberration correcting system is preset based on an output signal from the adder before operating the focusing control device.
6 more elements
An optical disk apparatus comprising:
- an optical pickup comprising a laser source, a focusing optical system for receiving a light beam emitted from the laser source and focusing the light beam on an optical disk to form a tiny spot, a transfer system for transferring the focusing optical system in a direction substantially perpendicular to the optical disk, a photodetector for receiving a light beam reflected from the optical disk and outputting an electric signal in accordance with a quantity of light, and an aberration correcting system for correcting spherical aberration of the focusing optical system;
- a focusing error detection device for detecting a focused state of the tiny spot on the optical disk based on the output signal from the photodetector;
- and
- a focusing control device for controlling the focused state of the tiny spot on the optical disk so as to be a predetermined state by driving the transfer system based on an output signal from the focusing error detection device,
- wherein a learning operation for spherical aberration correction quantity is performed before operating the focusing control device, the learning operation comprising steps of obtaining a first amplitude of the output signal from the focusing error detection device, storing the first amplitude, obtaining a second amplitude of the output signal from the focusing error detection device after changing a quantity of spherical aberration correction of the aberration correcting system, and comparing the first amplitude with the second amplitude.
2 more elements
An optical disk apparatus comprising:
- an optical pickup comprising a laser source, a focusing optical system for receiving a light beam emitted from the laser source and focusing the light beam on an optical disk to form a tiny spot, a transfer system for transferring the focusing optical system in a direction substantially perpendicular to the optical disk, a photodetector for receiving a light beam reflected from the optical disk and outputting an electric signal in accordance with a quantity of light, and an aberration correcting system for correcting spherical aberration of the focusing optical system;
- a focusing error detection device for detecting a focused state of the tiny spot on the optical disk based on the output signal from the photodetector;
- and
- a focusing control device for controlling the focused state of the tiny spot on the optical disk so as to be a predetermined state by driving the transfer system based on an output signal from the focusing error detection device,
- wherein a learning operation for spherical aberration correction quantity is performed before operating the focusing control device, the learning operation comprising steps of obtaining a first amplitude of a reproduction signal, storing the first amplitude, obtaining a second amplitude of the reproduction signal after changing a quantity of spherical aberration correction of the aberration correcting system, and comparing the first amplitude with the second amplitude.
2 more elements
Dependencies are inferred from the claim text.