| US 7,474,598 B2 | ||
| Optical reproducing device that controls the strength of the light beam during reproduction | ||
| Tetsuya Okumura, Neyagawa (Japan); and Shigemi Maeda, Yamatokoriyama (Japan) | ||
| Assigned to Sharp Kabushiki Kaisha, Osaka (Japan) | ||
| Filed on Feb. 25, 2002, as Appl. No. 10/82,466. | ||
| Claims priority of application No. 2001-055066 (JP), filed on Feb. 28, 2001. | ||
| Prior Publication US 2002/0145956 A1, Oct. 10, 2002 | ||
| Int. Cl. G11B 7/135 (2006.01) | ||
| U.S. Cl. 369—47.5 [369/116] | 20 Claims |
| 1. An optical reproducing device comprising:
predetermined length mark signal measurement means for measuring reproduction signal characteristics respectively of a short
reproducing power control mark and of a long reproducing power control mark from information data that are recorded in a data
recording area of a sector of an optical recording medium; and
power control means for controlling reproducing power of a light beam based on the measured reproduction signal characteristics
of the short and long reproducing power control marks,
wherein the predetermined length mark signal measurement means further includes a pattern detection means for detecting a
specific pattern including therein an arrangement of a plurality of short reproducing power control marks from amongst a bit
arrangement pattern of the information data in the data recording area, and when the specific pattern is detected, to measure
the reproduction signal characteristic of short reproducing power control marks, the measured reproduction signal characteristic
of short reproducing power control marks corresponding only to the plurality of short reproducing power control marks included
in the specific pattern.
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