Writing method and optical disk device

A writing method of writing information in an optical disk medium having not less than two data recording layers, comprising the steps of:

• forming a write power calibration block by writing a data pattern for power calibration in a first recording layer of the optical disk medium while a plurality of write powers are changed in a stepwise manner;
• calculating a first signal modulation depth and a first asymmetry amount, which depend on the write power, from a readout signal obtained by reading the write power calibration block;
• estimating a first signal offset amount due to inter-layer interference from the recording layer other than the first recording layer by referring to previously stored standard data based on a relationship between the first signal modulation depth and the first asymmetry amount;
• calculating a second signal modulation depth, which depends on the write power, and in which the inter-layer interference is compensated, in consideration of the first signal offset amount;
• determining a first write power based on the second signal modulation depth;
• after erasing the write power calibration block, forming an inter-layer interference calibration block by writing the data pattern for power calibration with the write power set constantly at the first write power in a way that the write power calibration block is written over the erased write power calibration block;
• reading the inter-layer interference calibration block and calculating a third signal modulation depth and a third asymmetry amount at a spot corresponding to each of the write powers in the write power calibration block;
• estimating a second signal offset amount at the spot corresponding to each of the write powers in the write power calibration block due to the inter-layer interference from the recording layer other than the first recording layer, by referring to the standard data, based on a relationship between the third signal modulation depth and the third asymmetry amount;
• calculating a fourth signal modulation depth, which depends on the write power, and in which the inter-layer interference is compensated, in consideration of the second signal offset amount;
• and
• determining a write power for writing user data, based on the fourth signal modulation depth.

An optical disk device which writes information in an optical disk medium having not less than two data recording layers, comprising:

• means which holds a standard relationship between a signal modulation depth and an asymmetry amount as standard data;
• means which writes a data pattern for power calibration in a first recording layer of the optical disk medium while a write power is changed in a stepwise manner;
• means which calculates a signal modulation depth and an asymmetry amount from a readout signal of the data pattern recorded in the optical disk medium;
• means which estimates a signal offset amount due to inter-layer interference from the recording layer other than the first recording layer, by referring to the standard data, based on the calculated signal modulation depth and asymmetry amount, and which calculates a signal modulation depth in which the inter-layer interference is compensated in consideration of the signal offset amount;
• and
• means which determines a write power for writing user data based on the signal modulation depth, which depends on the write power, and in which the inter-layer interference is compensated.