Laser beam power modulation pattern decision method, device for recording data onto optical recording medium, and optical recording medium

A method for determining a pulse train pattern including a pulse whose level is set to a level corresponding to a level of a recording power set to be higher than a reproducing power and a pulse whose level is set to a level corresponding to a level of a bottom power set to be higher than the reproducing power and adapted for modulating the power of a laser beam used for recording data in a write-once type optical recording medium, the method comprising:

• varying the level of the recording power while fixing the level of the bottom power at a level substantially equal to the level of the reproducing power;
• modulating the power of the laser beam in accordance with the pulse train patterns to record first test signals in the write-once type optical recording medium;
• reproducing the first test signals;
• tentatively determining optimum level of the recording power based on the thus reproduced first test signals;
• varying the level of the bottom power while fixing the recording power at the tentatively determined optimum level;
• modulating the power of the laser beam in accordance with the pulse train patterns to record second test signals in the write-once type optical recording medium;
• reproducing the second test signals;
• and
• determining an optimum level of the bottom power based on the thus reproduced second test signals.

An apparatus for recording data in a write-once type optical recording medium comprising laser beam power modulation pattern determining means for determining a pulse train pattern and for modulating the power of a laser beam used for recording data in the write-once type optical recording medium, the pulse train including a pulse whose level is set to a level corresponding to a level of a recording power set to be higher than a reproducing power and a pulse whose level is set to a level corresponding to a level of a bottom power set to be higher than the reproducing power, the laser beam power modulation pattern determining means being constituted so as to:

• vary the level of the bottom power while fixing the recording power at a predetermined level;
• modulate the power of the laser beam in accordance with the pulse train patterns to record first test signals in the write-once type optical recording medium;
• reproduce the first test signals;
• determine an optimum level of the bottom power based on amplitudes of the thus reproduced first test signals;
• vary the level of the recording power while fixing the bottom power at the optimum level;
• modulate the power of the laser beam in accordance with the pulse train patterns to record second test signals in the optical recording medium;
• reproduce the second test signals;
• and
• determine an optimum level of the recording power based on at least one of jitter and error rates of the thus reproduced second test signals.

An apparatus for recording data in a write-once type optical recording medium comprising laser beam power modulation pattern determining means for determining a pulse train pattern and for modulating the power of a laser beam used for recording data in the write-once type optical recording medium, the pulse train including a pulse whose level is set to a level corresponding to a level of a recording power set to be higher than a reproducing power and a pulse whose level is set to a level corresponding to a level of a bottom power set to be higher than the reproducing power, the laser beam power modulation pattern determining means being constituted so as to:

• varying the level of the recording power while fixing the level of the bottom power at a level substantially equal to the level of the reproducing power;
• modulating the power of the laser beam in accordance with the pulse train patterns to record first test signals in the write-once type optical recording medium;
• reproducing the first test signals;
• tentatively determining the optimum level of the recording power based on the thus reproduced first test signals;
• fixing the recording power at the tentatively determined optimum level and varying the level of the bottom power;
• modulating the power of the laser beam in accordance with the pulse train patterns to record second test signals in the write-once type optical recording medium;
• reproducing the second test signals;
• and
• determining the optimum level of the bottom power based on at least one of jitter, amplitude, and error rates of the thus reproduced second test signals.

A write-once type optical recording medium comprising a substrate and at least one recording layer disposed on the substrate and being constituted so that data are recorded by projecting a laser beam whose power is modulated in accordance with a pulse train pattern, the pulse train pattern including at least pulses whose levels are set to levels corresponding to a recording power and a bottom power, onto the at least one recording layer to form a recording mark in the at least one recording layer, the write-once type optical recording medium being recorded with modulation pattern setting data for setting a pulse train pattern used for modulating a power of the laser beam, which modulation pattern setting data are produced by:

• determining pulse train patterns by varying the level of the bottom power while fixing the recording power at a predetermined level;
• modulating the power of the laser beam in accordance with the pulse train patterns to record first test signals in the write-once type optical recording medium;
• reproducing the first test signals;
• determining an optimum level of the bottom power based on the thus reproduced first test signals;
• varying the level of the recording power while fixing the bottom power at the optimum level;
• modulating the power of the laser beam in accordance with the pulse train patterns to record second test signals in the optical recording medium;
• reproducing the second test signals;
• and
• determining an optimum level of the recording power based on the thus reproduced second test signals.

A write-once type optical recording medium comprising a substrate and at least one recording layer disposed on the substrate and being constituted so that data are recorded by projecting a laser beam whose power is modulated in accordance with a pulse train pattern, the pulse train pattern including at least pulses whose levels are set to levels corresponding to a recording power and a bottom power, onto the at least one recording layer to form a recording mark in the at least one recording layer, the write-once type optical recording medium being recorded with modulation pattern setting data for setting a pulse train pattern used for modulating a power of the laser beam, which modulation pattern setting data are produced by:

• determining pulse train patterns by varying the level of the recording power while fixing the level of the bottom power at a level substantially equal to the level of the reproducing power,
• modulating the power of the laser beam in accordance with the pulse train patterns to record first test signals in the write-once type optical recording medium,
• reproducing the first test signals,
• tentatively determining the optimum level of the recording power based on the thus reproduced first test signals,
• varying the level of the bottom power while fixing the recording power at the tentatively determined optimum level,
• modulating the power of the laser beam in accordance with the pulse train patterns to record second test signals in the write-once type optical recording medium,
• reproducing the second test signals, and
• determining the optimum level of the bottom power based on the thus reproduced second test signals.