| US 7,613,082 B2 | ||
| Optical pickup device, optical recording and reproducing apparatus and gap detection method | ||
| Tsutomu Ishimoto, Saitama (Japan); and Kimihiro Saito, Saitama (Japan) | ||
| Assigned to Sony Corporation, Tokyo (Japan) | ||
| Filed on May 02, 2005, as Appl. No. 11/118,559. | ||
| Claims priority of application No. 2004-148012 (JP), filed on May 18, 2004. | ||
| Prior Publication US 2005/0259530 A1, Nov. 24, 2005 | ||
| Int. Cl. G11B 7/00 (2006.01) | ||
| U.S. Cl. 369—44.32 [369/13.33; 369/53.19; 369/112.24] | 19 Claims |
| 1. An optical pickup device comprising:
a light source configured to generate a plurality of light beams, said plurality of light beams including a first light beam
and a second light beam;
a head unit located in an opposing relation to an optical recording medium and configured to irradiate said plurality of light
beams emitted from said light source on said optical recording medium as near field lights so as to form a plurality of light
beam spots on said optical recording medium; and
a photo-detecting unit configured to detect a plurality of quantities of returned light respectively of said plurality of
light beams returned from said head unit so as to detect a gap between said head unit and a recording surface of said optical
recording medium based on at least one of said plurality of quantities of returned light, and so as to detect a tilt angle
of said head unit relative to said recording surface of said optical recording medium based on a difference between two quantities
of returned light from among said plurality of quantities of returned light, said two quantities of returned light being quantities
of returned light respectively of said first light beam and said second light beam that are returned from said head unit,
wherein said head unit includes a first lens and a second lens located between said first lens and said optical recording
medium, and wherein said second lens is configured to generate near field light.
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