Patent ID: 7095696

Claim:
A device for writing data expressed by sets of marks and spaces formed on a recording medium in said recording medium, and/or reading said data from said recording medium, comprising: a writing unit for writing on said recording medium predetermined data matching a recording pattern so specified as to include a plurality of contiguous, mutually different sets of mark lengths and space lengths; a reading unit for reading said predetermined data from said recording medium to generate a data signal matching said predetermined data; an edge shift detector for measuring an edge shift amount of each of said marks formed on said recording medium for each one of said sets of mark lengths and space lengths using said data signal; and a record controller for setting a recording parameter for each one of said sets of mark lengths and space lengths based on said measured edge shift amount, wherein said recording pattern includes all of the sets of mark lengths and space lengths, the mark lengths ranging from mT to (m+a)T and the space lengths ranging from mT to (m+b)T, a and b each being an integer of 0 or greater, and the shortest mark space and the shortest space length each being represented by mT, m being a predetermined integer of 1 or greater and T being a period of a clock signal, and wherein said edge shift detector measures separately an edge shift amount of a leading edge of each said mark and an edge shift amount of a trailing edge of each said mark for each of said sets of mark lengths and space lengths.