Patent ID: 7072250

Claim:
An optical disk drive comprising: a light emission assembly to irradiate a light beam upon an optical disk; a magnetic field emission assembly to apply a magnetic field to an optical disk; and a power control system to control the power of said light beam and a magnetic field control system to control the magnitude and direction of the magnetic field, wherein said power control system and said magnetic field control system are configured such that: during a data recording process, the light beam is controlled to a recording power to raise the temperature of a portion of an optical disk being recorded to a first temperature and the magnitude of the magnetic field is controlled to apply a recording magnetic field, such that magnetic domains in a recording layer of an optical disk are reoriented, without reorienting associated magnetic domains in a playback layer of an optical layer; and during a data reproducing process, the light beam is controlled to a reproducing power to raise the temperature of a portion of an optical disk being recorded to a second temperature, which is lower than said first temperature, and the magnitude of the magnetic field is controlled to apply a reproducing magnetic field, which is lower than said recording magnetic field, such that magnetic domains of a playback layer of an optical disk are reoriented to coincide with associated magnetic domains in a recording layer of a magnetic disk.