Disk drive employing a voice coil motor comprising a yoke for generating a undirectional magnetic flux and a voice coil partially interacting with the undirectional magnetic flux

A disk drive comprising:

• (a) a disk;
• (b) an actuator arm comprising a head;
• and
• (c) a voice coil motor for actuating the actuator arm to position the head radially over the disk, the voice coil motor comprising:
• i. a voice coil portion connected to a base end of the actuator arm, the voice coil portion comprising a first side and a second side opposite the first side for conducting a current, wherein
• the current conducted by the first side generates a first side magnetic flux in a first direction;
• and
• the current conducted by the second side generates a second side magnetic flux in a second direction different from the first direction,
• ii. a rotary voice coil yoke comprising:
• a first magnet for generating a unidirectional magnetic flux, the first magnet being magnetized perpendicular to the plane of motion of the actuator arm;
• and
• a magnetic flux conductor shaped to form an air gap with respect to the first magnet, the magnetic flux conductor for guiding the unidirectional magnetic flux through the air gap, wherein:
• the first side of the voice coil portion is located substantially within the air gap such that the first side magnetic flux substantially interacts with the unidirectional magnetic flux;
• and
• the second side of the voice coil portion is located substantially outside the air gap such that the second side magnetic flux does not substantially interact with any magnetic flux.