ERASING METHOD FOR RECORDING DATA ON OPTICAL DISK

摘要

PURPOSE:To reduce the distortion quantity on the boundary between high and low temperature parts by setting intermittently the high power level of a laser beam which increases the temperature of a recorded data erasing area up to a level higher than a phase transfer temperature. CONSTITUTION:A 1st laser beam of a high power output level P1(H) is projected to an amorphous dot 4 for a period of pulse width Th. Thus the area of the dot 4 is heated up to a temperature higher than a phase transfer temperature. The area of the dot 4 is separated from the area irradiated by the 1st laser beam by the revolutions of an optical disk. Then the dot 4 is illuminated by a low power output level P2(L) and the area of this dot 4 is cooled slowly to be turned into a crystalline area. Thus data are erased. At the same time, a crystalline area 6 reaches the area irradiated by the 1st laser beam with revolutions of the optical disk. In such a case, the 1st laser beam is changed into the state of a low power output level PL(L) for a period T1 to prevent a case where the temperature of the area 6 is increased.