| US 7,580,327 B2 | ||
| Optical element, optical head, optical recording reproducing apparatus and optical recording/reproducing method | ||
| Hidenori Wada, Uji (Japan); Tetsuo Saimi, Hirakata (Japan); Daisuke Ogata, Amagasaki (Japan); Seiji Nishino, Osaka (Japan); Hiroaki Yamamoto, Kawabe-gun (Japan); Shin-ichi Kadowaki, Sanda (Japan); and Yoshiaki Komma, Hirakata (Japan) | ||
| Assigned to Panasonic Corporation, Osaka (Japan) | ||
| Filed on Dec. 17, 2007, as Appl. No. 12/2,380. | ||
| Application 11/031634 is a division of application No. 09/911143, filed on Jul. 23, 2001, abandoned. | ||
| Application 12/002380 is a continuation of application No. 11/031634, filed on Jan. 07, 2005, granted, now 7,352,664. | ||
| Claims priority of application No. 2000-222265 (JP), filed on Jul. 24, 2000. | ||
| Prior Publication US 2008/0112303 A1, May 15, 2008 | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. G11B 7/00 (2006.01) | ||
| U.S. Cl. 369—44.23 [369/44.32; 369/94; 369/112.02] | 2 Claims |
| 1. An optical head operable to record or reproduce signals on a first optical recording medium including only one recording
layer and on a second optical recording medium including a plurality of recording layers, the optical head comprising:
a light source; and
a spherical aberration correction device arranged between the optical recording medium and the light source;
wherein the spherical aberration correction device corrects spherical aberration of a recording layer disposed at a first
predetermined distance on the first optical recording medium and a second predetermined distance on the second optical recording
medium, before recording or reproducing signals, the first predetermined distance being a distance from a light-incident surface
of the first optical recording medium to the one recording layer included therein and the second predetermined distance being
a distance from a light-incident surface of the second optical recording medium to one of the plurality of recording layers
included therein, and the first predetermined distance and the second predetermined distance are the same distance, and
wherein, after driving the spherical aberration correction device so as to correct spherical aberration of the recording layer
included in the first optical recording medium or the second optical recording medium, focus control is performed.
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