| US RE40,371 E1 | ||
| Optical disc recording/reproduction apparatus and method | ||
| Isao Ichimura, Kanagawa (Japan); Fumisada Maeda, Tokyo (Japan); Kenji Yamamoto, Tokyo (Japan); Kiyoshi Ohsato, Chiba (Japan); Toshio Watanabe, Kanagawa (Japan); and Akira Suzuki, Kanagawa (Japan) | ||
| Assigned to Sony Corporation, (Japan) | ||
| Filed on Dec. 01, 2000, as Appl. No. 9/726,436. | ||
| Application 09/726436 is a reissue of application No. 08/994455, filed on Dec. 19, 1997, now 6,041,031, filed on Mar. 21, 2000. | ||
| Claims priority of application No. P08-340904 (JP), filed on Dec. 20, 1996. | ||
| Int. Cl. G11B 7/00 (2006.01) | ||
| U.S. Cl. 369—13.32 [369/112.24; 369/44.14; 369/44.23] | 11 Claims |
| 1. An optical disc recording/reproduction apparatus for recording and/or reproducing data by applying a beam from an optical
head unit through a substrate of an optical disc onto/from a recording layer of the optical disc, wherein said substrate of
said optical disc has a thickness of 0.3 mm or below, and said optical head unit comprises:
an objective lens for converging an incident beam and emitting the beam toward said optical disc;
a forward lens for converging the beam introduced through said objective lens and applying the beam to said optical disc;
a lens holder in which said objective lens and said forward lens are fixed; and
an actuator for driving said objective lens and said forward lens as a unitary block and controlling at least focusing,
said objective lens and said forward lens having (1) a total numerical aperture of 0.8 or above, (2) a center position shift
tolerance of ±80 μm, (3) [ an assembly accuracy of ] a distance between the objective lens and the forward lens of [ ±] 25 μm
|