Optical pick-up device
US6160783A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 27, 1998 |
| Grant date | Dec 12, 2000 |
| Priority date | — |
| Expiry date | Aug 27, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0006
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical pick-up device includes an optical active element (11) which transmits an introduced laser beam (18) with its polarization direction (17) rotated by 90.degree. in playback of a DVD and also transmits an introduced laser beam (18) without rotating its polarization direction (17) in playback of a CD, and a polarizer (14) which transmits the entirety of a laser beam with its polarization direction rotated in playback of a DVD and also blocks the perimeter of a laser beam with its polarization direction not rotated in playback of a CD to reduce the effective numerical aperture of an objective lens (15). A rubbing direction (28) of an rubbing film (24) of the optical active element (11) that is positioned at the incident side of the laser beam, is adapted to be parallel to the polarization direction (17) of the introduced laser beam (18). Thus, the optical pick-up device can play back DVD as well as CD while reducing laser beam loss.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.