Patent ID: 8406107

Claim:
A write-once information recording medium on which a read/write operation is performed on a block-by-block basis, wherein the information recording medium has 1 st through n th recording layers (where n is an integer that satisfies n≧1), and wherein the 1 st through n th recording layers have 1 st through n th user data areas to write user data on, and wherein at least one of the 1 st through n th recording layers has a disc management area to store disc management information about the information recording medium, and wherein the disc management information includes a disc definition structure for use to manage the data structure of the information recording medium, and 1 st through n th space bitmaps for use to manage the recording statuses of the 1 st through n th user data areas, and wherein each of the 1 st through n th space bitmaps includes bitmap information for use to manage the recording status of its associated one of the 1 st through n th user data areas on a block-by-block basis, and wherein if in a situation where the largest space is allocated to an i th user data area (where i is an integer that falls within the range 1≦i≦n) the number of blocks to use to store the i th space bitmap is N i (where N i is an integer that satisfies N i ≧2), and if the number of blocks to use to store the i th space bitmap for the i th user data area of an actual size is M i (where M i is an integer that satisfies 1≦M i ≦N i ) and if M i is equal to or greater than two, then the i th space bitmap is divided into the 1 st through M i th space bitmaps, each of which has a size that is still equal to or smaller than one block even when combined with the disc definition structure, and stored in an associated one of the M i blocks in the disc management area, and wherein the disc definition structure is recorded on the first sector of each of the M i blocks, and wherein the M i blocks are consecutive blocks, and wherein the disc definition structure is recorded on the first sector of (N i -M i ) blocks that follow the M i blocks, and wherein in the (N i -M i ) blocks, data of all zeros is written on every sector except for the sector on which the disc definition structure is recorded.