PURPOSE: To improve the erasing rate of a phase changing type optical disk and to shorten the erasing time by setting the disk to an erasing state by transiting the recording layer of the disk to a quasistable state and to a writing state by transiting the layer to a balanced state.
CONSTITUTION: When optical ON/OFF information is inputted to an erasing means 5 and writing means 6, an erasing area is decided in the means 5 by means of an erasing area deciding means 51 and the ON/OFF information is tentatively stored in a storing means 61 in the means 6. An indication indicating the recorded length of the ON/OFF information is added to the leading edge of the ON/OFF information and the area of a phase changing type optical disk corresponding to the indication is collectively erased by irradiating the area with high-power DC optical signals at high linear speed which is the optimum to set the area to an erasing state by transiting the recording layer of the area to be quasi stable state. Then writing is successively performed in the erased area by irradiating the area with low-power optical pulse signals at linear speed which is the optimum to set the area to a writing state by transiting the recording layer to a balance state. Therefore, the erasing rate is improved and, accordingly, the erasing time is shortened and the recording capacity is increased.
ETSUNO NAGAAKI
NAKADA MASAHIRO
GOTO YASUYUKI
TSUGAWA IWAO
