| US 7,542,396 B2 | ||
| Information recording apparatus, information recording medium and information recording medium | ||
| Motoyasu Terao, Hinode (Japan); Toshimasa Kamisada, Hiratsuka (Japan); Shinichi Nakatsuka, Hino (Japan); Takeshi Shimano, Yokohama (Japan); Hitoshi Ishii, Kaisei (Japan); Kazuhiro Soga, Odawara (Japan); and Yoshiaki Ogino, Ninomiya (Japan) | ||
| Assigned to Hitachi, Ltd., Tokyo (Japan); and Hitachi Computer Peripherals Co., Ltd, Kanagawa (Japan) | ||
| Filed on Aug. 24, 2005, as Appl. No. 11/209,648. | ||
| Claims priority of application No. 2005-080847 (JP), filed on Mar. 22, 2005. | ||
| Prior Publication US 2006/0227670 A1, Oct. 12, 2006 | ||
| Int. Cl. G11B 7/00 (2006.01) | ||
| U.S. Cl. 369—112.01 [369/94; 369/44.23] | 14 Claims |
| 1. An information recording and/or playback device which irradiates an information recording medium having plural recording
layers with light to perform recording and/or playback, said device comprising:
first light irradiation means;
second light irradiation means;
an optical path changeable member installed midway in divergent optics irradiated by said first light irradiation means, which
varies the optical path between said first light irradiation means and said information recording medium; and
an actuator which drives said optical path changeable member so that the optical thickness of said optical path changeable
member through which light irradiated from said first light irradiation means passes, changes according to the position of
said recording layer where recording or reading is performed.
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