| 摘要 |
PURPOSE:To contrive the miniaturization of a power unit by selecting the intensity of a magnetic field giving effect onto the recording/erasure of leaked magnetic field generated from an objective lens driving device to be a prescribed relation with respect to the intensity of the magnetic field required for recording/erasure at a spot position on a recording medium face. CONSTITUTION:A laser beam is radiated to a point O on a recording medium 100 through an objective lens 211 to cause a current to flow through a coil 301a of an electromagnet 301 and to apply the magnetic field Hw generated thereby to the point O to record information and read out the information through the radiation of a weak laser beam. Moreover, a current is given in the coil 301a to apply a magnetic field He to the point O, thereby erasing the information through the use of an intensive laser beam. in this case, the power consumption consumed in the coil 301a of a device 300 is reduced by selecting the arrangement between the magnetic circuit of an objective lens driving device 200 and a magnetic field application device 300 so as to obtain the relation of Hm=1/2(Hw+He), where Hm is the magnetic field intensity, thereby reducing the heat production. Thus, the small-sized device is realized. |
