Data reading apparatus

An apparatus for reading data recorded on a disk having sectors with each sector including a header portion having an address sync mark and address information and a data portion where the data is recorded, the apparatus comprising:

• a read clock generating circuit for generating a read clock signal based on a rotational speed and recording density of the disk;
• a first ID reading apparatus which operates in accordance with the read clock signal, the first ID reading apparatuses including:
• a first address sync mark detection circuit for detecting the address sync mark from data read from the header portion in accordance with the read clock signal and generating an address sync mark detection signal;
• a first ID reading circuit for reading address information from the read data in accordance with the address sync mark detection signal and the read clock signal;
• and
• a first ID decision circuit for generating a read address read from the address information and a decision result indicating whether the read address is normal in accordance with the read clock signal;
• a plurality of delay circuits for generating a plurality of delay clock signals having different phases from one another from the read clock signal;
• a plurality of second ID reading apparatuses which operate in accordance with the plurality of delay clock signals, the second ID reading apparatuses including:
• a second address sync mark detection circuit for detecting the address sync mark from data read from the header portion in accordance with an associated one of the plurality of delay clock signals and generating an address sync mark detection signal;
• a second ID reading circuit for reading address information from the read data in accordance with the address sync mark detection signal and the associated one of the plurality of delay clock signals;
• and
• a second ID decision circuit for generating a read address read from the address information and a decision result indicating whether the read address is normal in accordance with the associated one of the plurality of delay clock signals;
• and
• a selector circuit which receives a plurality of read addresses and a plurality of decision results from the first reading apparatus and the plurality of second reading apparatuses and selects a best read address and decision result from thereamong.

A method of reading data from a disk, the method comprising:

• generating a read clock signal based on rotational speed and recording density of the disk;
• reading address information from a header portion recorded in each sector of the disk in accordance with the read clock signal;
• and
• reading data recorded in a data portion of each sector based on the address information.

A method of reading data from a disk, the method comprising:

• generating a read clock signal based on rotational speed and recording density of the disk;
• generating a plurality of delay clock signals having different phases from one another from the read clock signal;
• reading address information recorded in a header portion of each sector of the disk in accordance with the read clock signal;
• reading the address information in accordance with the plurality of delay clock signals;
• selecting the address information which has the greatest number of matches from the address information read at different timings;
• and
• reading the data based on the selected address information.