| 摘要 |
PURPOSE:To attain a recording/erasing action having high electro-magnetic converting efficiency by allowing to coincide the form of an external magnetic field generating means with the locus of a beam in which the distribution of the maximum magnetic field strength swings. CONSTITUTION:The title device is composed so that the form of a cavity 6 of an external magnetic field generating means 3 can be made into an approximately sector shape, and the maximum strength distribution of a generated magnetic field can approximately coincide with a sector-shaped locus A of an optical head 2. Namely, the moving of the optical head 2 by a swinging system, the locus A, and the form of the cavity 6 of the external magnetic field generating means 3 are opposed in parallel in almost the same manner. Consequently, the maximum strength distribution of the generated magnetic field in the inner circumferential part of a recording medium 1 and that in the outer circumferential part of the recording medium 1 have no change, and desired magnetic field strength can be obtained. Thus, the recording/erasing action having the high electro-magnetic converting efficiency can be attained. |
