| 摘要 |
PURPOSE:To surely erase old information in spite of the change of ambient temperature by changing the dust factor of a high frequency optical pulse for erasure to be inserted to a write optical pulse corresponding to the temperature of a disk. CONSTITUTION:A table representing the relation of the temperature measured in advance with respect to an optical disk 4 with a pulse duty factor is stored in a computer 5, and the computer 5 finds a corresponding pulse duty factor based on the temperature monitored by a monitor 3, and supplies it to a pulse generator 6 as a duty factor command. The pulse generator 6 outputs a write pulse and the high frequency pulse for erasure to the laser diode of a head 7 corresponding to the input of write data. The high frequency pulse for erasure is outputted from the diode to the optical pulse 1, and the disk 4 is irradiated with the pulse. In such a way, it is possible to surely erase the old information in spite of the change of the environmental temperature. |
