Device for suppressing magnetic noise of dual-layered disk in a disk drive

Abstract

There is disclosed a disk drive having a magnetic device for applying a direct current magnetic field to the disk 1 by using a disk with a double-layered structure in which a soft magnetic layer is provided on a lower layer of the recording magnetic layer. The magnetic device generates a direct current magnetic field to uniform a magnetic domain state of the soft magnetic layer of the disk. The intensity of the direct current is larger than the anisotropic magnetic field of the soft magnetic layer and is smaller than the coercive force of the recording magnetic layer. As a consequence, the stabilization of the magnetic domain state of the soft magnetic layer of the disk can be realized to make an attempt of decreasing the magnetic noise and establishing stabilization with respect to the disturbance magnetic field.

1 - 16 . (Cancelled)  
   
   
       17 . A disk drive comprising: a disk medium which is a three-layered structure data recording medium having a magnetic recording layer, a soft magnetic layer and a magnetic pinning layer; a head conducting a read/write operation of data with respect to said recording medium of said disk medium; an actuator mounting said head and having a voice coil motor for moving said head in a radial direction on said disk medium; and a device applying a direct current magnetic field approximately in the same direction as the magnetization direction of the magnetic pining layer in a longitudinal direction corresponding to a horizontal direction in the case where the axial direction of said disk medium is set to a perpendicular direction.  
   
   
       18 . The disk drive according to  claim 17 , wherein said device is provided at a position where the intensity of the magnetic field acting upon said head with the generated magnetic field becomes less than a predetermined value.  
   
   
       19 . The disk drive according to  claim 17 , wherein said device is a permanent magnet member.  
   
   
       20 . The disk drive according to  claim 17 , wherein said device is located at a position where the effective range of said direct current magnetic field becomes the range of said disk medium corresponding to the movement range of said head, the intensity of the magnetic field acting upon the head becomes less than a predetermined value.  
   
   
       21 . The disk drive according to  claim 17 , wherein said actuator mounts said head, and has a voice coil motor for moving said head in a radial direction of said disk medium; said magnetic device is a magnet member constituted integrally with the magnet member of said voice coil motor.  
   
   
       22 . The disk drive according to  claim 17 , wherein a drive main body accommodating said disk medium, said head, and said device is constituted of a casing made of a ferromagnetic substance.  
   
   
       23 . The disk drive according to  claim 17 , wherein said magnetic recording layer of said disk medium is a recording layer for recording data with a perpendicular magnetic recording method, and said head has a write head for writing data with the perpendicular magnetic recording method.