| US 7,573,798 B2 | ||
| Multi-level information reproducing method | ||
| Masakuni Yamamoto, Yamato (Japan); and Yasuyuki Miyaoka, Yokohama (Japan) | ||
| Assigned to Canon Kabushiki Kaisha, Tokyo (Japan) | ||
| Filed on May 18, 2006, as Appl. No. 11/435,895. | ||
| Claims priority of application No. 2005-150985 (JP), filed on May 24, 2005. | ||
| Prior Publication US 2006/0280069 A1, Dec. 14, 2006 | ||
| Int. Cl. G11B 5/09 (2006.01) | ||
| U.S. Cl. 369—59.23 [369/275.4; 369/59.15; 369/53.33] | 2 Claims |
| 1. A method of reproducing a multi-level information recorded on a track of an optical information recording medium by virtually
providing cells at equal intervals and by varying a width of an information pit in a track direction or an area of an information
pit, the method comprising the steps of:
detecting a reproduced signal from the optical information recording medium by use of an optical head;
when a center of a light spot from the optical head is located at a center of one of the cells, sampling the reproduced signal
to obtain a cell center value;
when the center of the light spot is located at a boundary between preceding one of the cells and following one cell adjacent
thereto, sampling the reproduced signal to obtain a cell boundary value;
correcting the cell boundary value based on a difference between the cell center values of the adjacent, preceding and following
cells; and
reproducing the multi-level information based on the corrected cell boundary value.
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