Patent ID: 6898049

Claim:
A magnetic disk apparatus comprises a plurality of magnetic disks stacked on a rotating shaft, arms adapted to be inserted between said magnetic disks and supporting magnetic heads thereon, a motor for moving said arms, a housing forming at least a part of an arcuate-shaped shroud which substantially surrounds a portion of side surfaces of said magnetic disks which is concentric with said magnetic disks so as to define a gap between said shroud and said portion of the side surfaces of said magnetic disks and which permits movement of said arms, said arcuate-shaped shroud having portions delimiting an open space therebetween which is adjacent another portion of the side surfaces of said magnetic disks located on a downstream side of said arms relative to an air flow generated by revolution of said magnetic disks and which moves on surfaces of said magnetic disks, a bypass channel for providing communication and air flow between an upstream side of said arms and said open space so as to provide air flow to said disks in a region of said open space at a reduced pressure on the downstream side of said arms with respect to pressure at the upstream side of said arms, wherein said bypass channel is configured so that air flow there through bypasses the motor so as to reduce flutter and suppress wind turbulence and has a linear section extending from an entry of said bypass channel with a length and width in which said length is at least 5D, where D is said width of said linear section of said bypass channel.