Optical disc apparatus having five light receiving areas for detecting focus error and tracking error
US5278401A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 12, 1992 |
| Grant date | Jan 11, 1994 |
| Priority date | — |
| Expiry date | Aug 12, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B11/10576
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A signal detecting apparatus in an optical disc apparatus having an objective lens which converges light emitted from a light source onto an optical disc and a condenser lens which converges light reflected by the optical disc and transmitted through the objective lens includes first and second light receiving elements, each having a light receiving surface located before or behind a convergence point on which the light reflected from the optical disc is converged when the objective lens is in a focal position. Each of the light receiving surfaces are split into at least four light receiving areas. The signal detecting apparatus also includes a means for calculating a sum of differences of outputs of the light receiving surfaces' inner light receiving areas, calculating a sum of differences of outputs of the light receiving surfaces' outer light receiving areas, and then calculating a difference of the sums of differences, so that a track error signal is output in accordance with the difference of sums of differences calculated by the calculating means.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.