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...http://www.google.fr/patents/US5734637?utm_source=gb-gplus-shareBrevet US5734637 - Optical pickup used with both DVD and CD
