Discrimination method for optical disc types and optical disc apparatus
US7920450B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | May 23, 2008 |
| Grant date | Apr 5, 2011 |
| Priority date | — |
| Expiry date | Mar 27, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B19/12
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical disc apparatus, which discriminates types of optical discs having different thicknesses of transparent layers by using the same wavelength of laser light, includes an aberration correction unit for correcting spherical aberration, an objective lens for condensing the laser beam onto a recording surface of an optical disc, an actuator for moving the objective lens with respect to the optical disc, a signal detection unit for delivering a focus error signal or a sum light signal, a control unit for controlling the aberration correction unit, the actuator and the signal detection unit. The control unit drives and sets the aberration correction unit so that the laser beam has a predetermined spherical aberration, performs a focus search operation of moving the objective lens to approach the optical disc in a state where the laser beam is projected onto the optical disc, and uses at least one of the focus error signal and the sum light signal delivered from the signal detection unit at a just focus position as an optical disc type discrimination signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.