Patent ID: 7817528
Filing Date: 2010-10-19
Classification: G11B

Abstract:
1. An optical disk medium having a spiral recording track, the recording track being divided into a plurality of address segments with a predetermined address-segment length, a format modulation area being formed at a predetermined position in each of a part of the address segments, so as to overlap the recording track, wherein a length of the format modulation area is approximately 25% of the address-segment length or less, wherein the position of the format modulation area in the address segment is selectable of one of two positions of a first modulation area and a second modulation area, the second modulation area being apart from the first modulation area by a distance that is twice as long as a length of the modulation area or more and that is shorter than a distance obtained by subtracting a length twice as long as the length of the modulation area from the address-segment length, wherein format modulation areas in adjacent recording tracks are selected in position so as not to overlap each other in the radius direction of the optical disk medium, and wherein, when an amount of displacement between address segments of adjacent recording tracks is approximately zero, the address segments are provided so that the first modulation area and the second modulation area exist in an alternating manner.