Optical pickup apparatus
US7020055B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 4, 2002 |
| Grant date | Mar 28, 2006 |
| Priority date | — |
| Expiry date | Nov 5, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1369
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical pickup apparatus includes a detection unit detecting a light beam reflected/diffracted by the recording medium and passing through the objective lens by dividing the light beam into a plurality of light areas, and a signal processor detecting a difference between widths T1 and T2 indicating that first and second focusing signals are greater than a predetermined threshold value and a thickness signal of the recording medium by using the detected difference when an S-curve of a focus error signal detected by using detection signals of the light areas output from the detection unit is obtained by subtracting a second detecting signal from a first detecting signal or by subtracting the first focusing signal from the second signal. Thus, a spherical aberration due to a change in thickness of the recording medium can be corrected by driving a spherical aberration correcting device according to a thickness signal corresponding to the change in thickness of the recording medium.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.