Optical pickup used with both DVD and CD

Details Optical pickup used with both DVD and CD Optical pickup used with both DVD and CD

1997-12-18

1999-05-04

Huber, Paul W.

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

369118, 369 58, G11B 700

Patent

active

059011319

ABSTRACT:
An optical pickup of a compatible type which can be switched for a DVD and a CD by a completely electrical control without the need of a mechanical moving device or the like and is suitable for the reduction in size and also has an excellent efficiency in the use of light. A liquid crystal panel of a transmission type which gives a phase difference of a 1/4 wavelength or a wavelength that is an odd number multiple of 1/4 wavelength to a transmission light and has a transparent electrode having an aperture pattern of a predetermined shape is used and the liquid crystal panel is arranged so that its plane of polarization crosses a plane of polarization of a polarization beam splitter at a predetermined angle. An applied voltage to the transparent electrode is controlled so that the whole surface of the liquid crystal panel functions as a 1/4 wavelength plate during a reproduction operation or a recording operation of the DVD and only the aperture pattern portion functions as a 1/4 wavelength plate during the reproduction operation of the CD.

REFERENCES:
patent: 5281797 (1994-01-01), Tatsuno et al.
patent: 5416757 (1995-05-01), Luecke et al.
patent: 5526336 (1996-06-01), Park et al.
patent: 5734637 (1998-03-01), Ootaki et al.

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