Optical disk reading method for multi-layered optical disk system
US5909422A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 10, 1997 |
| Grant date | Jun 1, 1999 |
| Priority date | — |
| Expiry date | Dec 10, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0013
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A multi-layered optical disk reading method which makes possible to reproduce encoded data from each data layer by focusing laser beam precisely onto a data layer of the multi-layered optical disk. After a multi-layered optical disk is loaded, a central processing unit (CPU) receives an operator's signal to access certain data layer. Then the CPU refers to stored data in the CPU's memory for a diffraction angle to focus laser beam onto a certain data layer. The CPU retrieves an operational coded signal, and transmits the signal to a liquid crystal diffraction device to modulate the liquid crystal diffraction device to deflect and focus the laser beam onto the certain data layer. After the liquid crystal diffraction device is modulated by the operational signal from the CPU, the CPU also operates a routing circuit to transmit read-out signal from a detector which receives reflected laser beam from the certain data layer, to a selected decoding circuit in a data processor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.