Magnetic disc apparatus having protective shield for eliminating spurious magnetism at a magnetic head

Claim 1

A magnetic disc apparatus comprising: a magnetic disc positioned on a rotatable spindle and having a face on which magnetically encoded information is stored; a driving means for rotating the spindle on which the magnetic disc rests to drive the disc; a magnetic head positioned so that a reading portion of the magnetic head faces the face of said magnetic disc on which magnetically encoded information is stored, said magnetic head reading information from said magnetic disc; a shield member having a first side facing the peripheral edge of said magnetic disc to isolate the magnetic head from sources of magnetism other than magnetism of information magnetically encoded on said face of said disc and a second support side wherein distance across said shield member from the first side to the second side varies along a line orthogonal to the plane of the disc to provide a clearance distance between said shield member and the peripheral edge of the disc; and a supporting body member including means for slidably supporting said shield member at its support side, said means for slidably supporting said shield member facilitating sliding of the shield member along the line orthogonal to the plane of the disc, whereby the clearance distance between said shield member and the peripheral edge of said magnetic disc is changeable due to the sliding of said shield member along said line orthogonal to the plane of the disc.