Optical pickup apparatus and method for controlling phases...

Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system

Reexamination Certificate

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C369S044410

Reexamination Certificate

active

07369466

ABSTRACT:
An optical pickup apparatus and method are provided. The apparatus and method include a light source unit having a holder in which an optical module having first and second light sources for emitting light having different wavelengths and a grating are installed, an optical path changer for changing a path of the light emitted from the first or second light sources, an object lens for focusing light passing through the optical path changer on a relatively thin disc or a relatively thick disc, and a photodetector unit. The photodetector unit includes a first photodetector having a first main photodetector, a first sub-photodetector, and a second sub-photodetector for receiving light diffracted into three beams by the grating and reflected by the relatively thin disc and converting the received light into an electrical signal, and a second photodetector having a second main photodetector, a third sub-photodetector, and a fourth sub-photodetector for receiving light diffracted into three beams by the grating and reflected by the relatively thick disc and converting the received light into an electrical signal.

REFERENCES:
patent: 5610879 (1997-03-01), Moriya et al.
patent: 5715218 (1998-02-01), Ikeda
patent: 6587481 (2003-07-01), Seong et al.
patent: 6597642 (2003-07-01), Ijima et al.
patent: 2002/0003766 (2002-01-01), Kadowaki et al.
patent: 2001-0047945 (2001-06-01), None
patent: 2001-0111641 (2001-12-01), None

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