Detection apparatus for detecting sector marks of optical disk and optical disk access apparatus

A sector mark detection apparatus which detects a sector mark added to an arbitrary sector of an optical disk when seeking the arbitrary sector, said optical disk having a predetermined recording format in which a predetermined number of sectors are arranged on the optical disk, said sector mark detection apparatus comprising:

• gate signal generating means for generating a predetermined number of gate signals at predetermined intervals based on timings between pulse signals which are read from the optical disk;
• mark length generating means, coupled to said gate signal generating means, for generating mark length data related to lengths of the sector marks from the read pulse signals based on said timings;
• counter means, coupled to said gate signal generating means, for measuring widths of the gate signals by counting at a predetermined frequency and for outputting counted values;
• matching means, coupled to said counter means, for comparing the counted values and match data and for outputting a matched result;
• and
• judging means, coupled to said matching means, for judging the sector mark of the arbitrary sector based on the mark length data and the matching result.