The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 07, 2012
Filed:
Oct. 29, 2004
Akira Kurozuka, Fujiidera, JP;
Yoshihiro Mushika, Neyagawa, JP;
Akira Kurozuka, Fujiidera, JP;
Yoshihiro Mushika, Neyagawa, JP;
Panasonic Corporation, Osaka, JP;
Abstract
For a recording and playback optical head used for a dual layer disc, it is difficult to reduce the size and the cost due to the need to correct spherical aberration caused by a difference in thickness of a light-transmitting layer. A reflection mirror having a reflection surface on which light is reflected and provided with a member having ferromagnetism at the center, and a switching device that switches between a deformed state and a non-deformed state of the reflection mirror using a magnetic force are provided. The switching device includes a hard magnetic member, and a magnetizing member that magnetizes and demagnetizes the hard magnetic member. When light is concentrated on a first recording layer farther from the light-incident surface, the reflection mirror is used as a plane mirror, and when light is concentrated on a second recording layer closer to the light-incident surface, the reflection mirror is deformed in the shape of a concave surface by means of the switching device.