Optical disc and optical disc device

A recording method for recording an optical disc, containing a first recording layer, having a track upon which a first laser beam having a first wavelength is focused to write data on the first recording layer, and a management area on said first recording layer, said recording method comprising:

• recording first information representing if a second recording layer is present in said optical disc on a first position of said management area by using the first laser beam,
• recording second information representing if a third recording layer is present in said optical disc on a second position of said management area by using the first laser beam;
• wherein data on the second recording layer is written by using a second laser beam,
• wherein a second wavelength of the second laser beam which is focused to write data on the second recording layer, is longer than the first wavelength,
• wherein data on the third recording layer is written by using a third laser beam,
• wherein a third wavelength of the third laser beam which is focused to write data on the third recording layer is longer than the second wavelength,
• wherein said first information and said second information comprise two bits respectively, wherein said first information indicating said second recording layer represents absence of said second recording layer by bit values of 00 in the first position,
• wherein said second information indicating said third recording layer represents absence of said third recording layer by bit values of 00 in the second position.

A reproducing method for reproducing an optical disc, containing a first recording layer, having a track upon which a first laser beam having a first wavelength is focused to read data recorded on the first recording layer, and a management area on said first recording layer, said management area having first recorded information representing if a second recording layer is present in said optical disc and second recorded information representing if a third recording layer is present in said optical disc, said reproducing method comprising:

• reading said first recorded information from a first position of said management area by using the first laser beam and reading said second recorded information from a second position of said management area by using the first laser beam;
• and
• reproducing data recorded on said first recording layer,
• wherein data recorded on the second recording layer is read by using a second laser beam,
• wherein a second wavelength of the second laser beam which is focused to read data recorded on the second recording layer is longer than the first wavelength,
• wherein data recorded on the third recording layer is read by using a third laser beam,
• wherein a third wavelength of the third laser beam which is focused to read data recorded on the third recording layer is longer than the second wavelength,
• wherein said first recorded information and said second recorded information comprise two bits respectively,
• wherein said first recorded information indicating said second recording layer represents absence of said second recording layer by bit values of 00 in the first position,
• wherein said second recorded information indicating said third recording layer represents absence of said third recording layer by bit values of 00 in the second position.

An identifying method for identifying the type of an optical disc, containing a first recording layer, having a track upon which a first laser beam having a first wavelength is focused to read data recorded on the first recording layer, and a management area on said first recording layer, said management area having first recorded information representing if a second recording layer is present in said optical disc and second recorded information representing if a third recording layer is present in said optical disc, said identifying method comprising:

• reading said first recorded information from a first position of said management area bar using the first laser beam and reading said second recorded information from a second position of said management area by using the first laser beam;
• and
• identifying the type of said optical disc based on said first recorded information and said second recorded information,
• wherein data recorded on the second recording layer is read by using a second laser beam,
• wherein a second wavelength of the second laser beam which is focused to read data recorded on the second recording layer is longer than the first wavelength,
• wherein data on the third recording layer is read by using a third laser beam,
• wherein a third wavelength of the third laser beam which is focused to read data recorded on the third recording layer is longer than the second wavelength,
• wherein said first recorded information and said second recorded information comprise two bits respectively,
• wherein said first recorded information indicating said second recording layer represents absence of said second recording layer by bit values of 00 in the first position,
• wherein said second recorded information indicating said third recording layer represents absence of said third recording layer by bit values of 00 in the second position.