| 摘要 |
PURPOSE:To improve the accuracy of recording and erasure by providing a high-magnetic-permeability plate which constitutes a recording and playback magnetic field generating means between an information recording medium and a lens driving magnetic circuit and eliminating the influence of a leak magnetic field upon the information recording medium. CONSTITUTION:When the magnetic circuit 29 for driving an objective is put in operation, both center and objective driving magnetic pole plates 13 and 14 shields a recording layer 22 from a magnetic field leaking from the objective lens magnetic circuit 29 to the air by arranging the flat plate type magnetic pole plate 13 and external magnetic pole plate 14 between the information recording medium 35 and objective driving magnetic circuit 29. The high- magnetic-permeability material is employed for the center magnetic pole plate 13, etc., so the discharged magnetic flux extend at right angles to its surface. Further, the center magnetic pole plate 13 is arranged in parallel to the recording layer and the magnetic field crosses the recording layer 22 at right angles. Therefore, a stable intense magnetic field is obtained and recording and erasure are carried out accurately. |
