Patent ID: 7848200
Filing Date: 2010-12-07
Classification: G11B

Abstract:
1. A method of reproducing multilevel information using a light spot, the multilevel information being recorded by defining virtual cells at regular intervals on tracks of an optical information recording medium and varying sizes of information pits in the cells, the method comprising the steps of: obtaining cell boundary values, each of the cell boundary values being obtained by performing sampling when the center of the light spot reaches a boundary between adjacent cells; calculating cell boundary value metrics on the basis of the cell boundary values and prestored reference values for the cell boundary values; calculating path metrics on the basis of the cell boundary value metrics; selecting a path metric having a minimum value of the path metrics; and reproducing the multilevel information on the basis of the path metric having the minimum value of the path metrics, wherein the cell boundary value metrics are calculated as follows: (mb: cell boundary value metrics, B wherein the path metrics are sequentially calculated while selecting a path having a minimum of cell boundary value metrics.