Patent ID: 7701820

Claim:
An optical disc apparatus for a rewritable optical disc having a power calibration area for optimum recording power calibration, the apparatus comprising: an optical pickup for recording or erasing information on or from the optical disc by use of an optimum recording power obtained using the power calibration area; a used area detection unit for detecting a second radially innermost end of a used area in the power calibration area based on a reproduction signal of a laser beam which the optical pickup receives during a seek movement, at the time of the optimum recording power calibration, by moving the optical pickup to seek from a first radially innermost end of the power calibration area to radially outward of the power calibration area; a remaining usable area determination unit for determining, based on the second radially innermost end of the used area detected by the used area detection unit, whether the power calibration area has a remaining usable area which is an unused area beginning from the first radially innermost end of the power calibration area, and which is of a size for carrying out the optimum recording power calibration at least one time; an optimum recording power obtaining unit for obtaining an optimum recording power (i) by performing the optimum recording power calibration in the power calibration area beginning from the first radially innermost end of the power calibration area by partial or entire overwriting if the remaining power calibration area is smaller than a size for carrying out one-time optimum recording power calibration, and (ii) by performing the optimum recording power calibration in a portion of the remaining usable area in the power calibration area, which portion is neighboring and inner from the second radially innermost end of the used area if the remaining usable area is equal to or larger than a size for carrying out one-time optimum recording power calibration; a DC erase unit for erasing the used area in the power calibration area by use of the optimum recording power obtained by the optimum recording power obtaining unit using the used area in the power calibration area by the partial or entire overwriting, if the remaining usable area detection unit determines that the remaining usable area in the power calibration area is smaller than a size for carrying out one-time optimum recording power calibration; and wherein the optimum recording power obtaining unit obtains the optimum recording power by overwriting to perform normal optimum recording power calibration that continuously records test data on the power calibration area while increasing the recording power during which the test data, when reproduced, shows an inflection point before which the reproduced test data shows an increase of amplitude with an increase of the recording power and after which the reproduced test data shows a decrease of amplitude with an increase of the recording power, the recording power giving the inflection point being determined as the optimum recording power.