| US 7,486,606 B2 | ||
| Optical head and optical information apparatus for recording or reproducing information on an information recording medium | ||
| Kousei Sano, Osaka (Japan); Yoshiaki Komma, Hirakata (Japan); and Sadao Mizuno, Ibaraki (Japan) | ||
| Assigned to Panasonic Corporation, Osaka (Japan) | ||
| Filed on Jun. 14, 2005, as Appl. No. 11/151,272. | ||
| Claims priority of application No. 2004-175130 (JP), filed on Jun. 14, 2004. | ||
| Prior Publication US 2005/0276202 A1, Dec. 15, 2005 | ||
| Int. Cl. G11B 7/00 (2006.01) | ||
| U.S. Cl. 369—112.06 [369/112.1; 369/120] | 20 Claims |
| 1. An optical head, comprising:
a light source for emitting a beam of light;
a light-concentrating element arranged to concentrate the beam of light on an information recording medium that includes a
track in a recording area;
a transfer mechanism for transferring the light-concentrating element at least between an outermost circumference and an innermost
circumference of the recording area along the information recording medium;
a splitting element arranged to split a beam of light that returns from the information recording medium into a plurality
of beams of light; and
a detector arranged to detect the plurality of beams of light that is obtained by the splitting element, wherein,
the splitting element includes a plurality of areas which are divided by a division line,
the division line is set parallel to tangential directions of the track in a middle in radius directions of the recording
area on a transfer line of the light-concentrating element between the outermost circumference and the innermost circumference
of the recording area, and
the division line is set in directions which halve an angle at which the tangential directions of the track at the outermost
circumference of the recording area on the transfer line meet the tangential directions of the track at the innermost circumference
of the recording area on the transfer line.
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